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  1. Fensin receives Young Leaders Award

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fensin receives Young Leaders Award March 3, 2016 Saryu Fensin of LANL's Materials Science in Radiation and Dynamics Extremes group has been selected to receive the 2015 TMS Young Leaders International Scholar- Japanese Institute of Metals (JIM) Award. She will represent the Minerals, Metals & Materials Society (TMS) at the JIM Spring Annual Meeting at the Tokyo University of Science in Japan and present her research. The award is part of the TMS Young Leaders International Scholar Program,

  2. YoungHo Shin | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Photo of YoungHo Shin YoungHo Shin Principal Process Development Engineer Telephone (630) 252-4861 E-mail yshin@anl.gov

  3. Young Women's Conference in Science, Technology, Engineering...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Young Women's Conference in Science, Technology, Engineering & Mathematics The 16th annual ... The Young Women's Conference in Science, Technology, Engineering, and Mathematics ...

  4. QER- Comment of Allen Young

    Broader source: Energy.gov [DOE]

    There is much that I can say about energy policy, but most important to me is the have no new infrastructure for fossil fuels, especially a proposed Kinder Morgan "northeast extension" pipeline through beautiful countryside in Massachusetts. There needs to be focus on renewables, plus conservation and efficiency. Allen Young

  5. Young, Jupiter-like planet discovered

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Young, Jupiter-like planet discovered Young, Jupiter-like planet discovered A team of researchers has discovered a Jupiter-like planet within a young system that could provide a new understanding of how planets formed around our sun. August 13, 2015 A team of researchers has discovered a Jupiter-like planet within a young system that could provide a new understanding of how planets formed around our sun. Jupiter-like planet Contact Los Alamos National Laboratory Nancy Ambrosiano Communications

  6. Youngs modulus of [111] germanium nanowires

    SciTech Connect (OSTI)

    Maksud, M.; Yoo, J.; Harris, C. T.; Palapati, N. K. R.; Subramanian, A.

    2015-11-02

    Our paper reports a diameter-independent Youngs modulus of 91.9 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ~75%. Furthermore, with increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.

  7. Microsoft Word - young_abstract

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    May 13th, at 1:30 pm "Measurements of Beta-Decay in the Neutron and 19Ne: Some Recent Progress" Professor A. R. Young Dept. of Physics, North Carlina State Univ., Raleigh, NC We present recent measurements of the beta-decay of the neutron and 19Ne. Both systems have spin 1/2, and are characterized by isobaric analog decays involving, in leading order, two form factors. Precise characterization of these decays requires two independent measurements, one of which is typically the lifetime

  8. Give Young Scientists a Break

    SciTech Connect (OSTI)

    Wiley, H. S.

    2009-11-01

    There has been much concern about the impact of tight funding on the careers of young scientists. When only a small percentage of grants are approved, even the smallest problem or error with an application can push it out of the funding range. Unfortunately, the relative lack of grant writing skills by new investigators often has this effect. To avoid a situation where only experienced investigators with polished writing skills are funded, the National Institutes of Health has instituted a more generous ranking scale for new investigators. Not surprisingly, some senior investigators have protested, calling it reverse discrimination. I say that their anger is misplaced. New investigators do deserve a break.

  9. CHRISTIE PABARUE MORTENSEN AND YOUNG

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CHRISTIE PABARUE MORTENSEN AND YOUNG **......---------- A PROFESSIONAL CORPORATION Susan B. Thaucr 215-587-1633 sbthauer@cpmy.com 1880 JOHN F. KENNEDY BOULEVARD 10TH FLOOR PHILADELPHIA, PA 19103 TE.l: 215.587,1600. FAX: 215.587,1699. WWW.CPMY.COM January \5.2010 FOIA OFFICER U.S. Department of Energy 1000 Independence Avenue, SW Washington, DC 20585 iY'):'W,'F"~-', ",: " . -* . '-" . ;.. Re: Freedom of Information Act (FOIA) Request Our File Number: 100-2127 Dear Sir or

  10. CHRISTIE PABARUE MORTENSEN AND YOUNG

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    - -, CHRISTIE PABARUE MORTENSEN AND YOUNG _.-------- ,.. PROf'ESSIONAl. CORPORATION 1880 JOHN F. KENNEDY BOULEVARD 10TH FLOOR PHIlADeLPHIA, PA 19103 Tel: 215.587.1600 * FAX: 215.587,1699 * WWW.CPMY,COM LINDA M. LAMMENDOLA Paralegal 215-587-1660 lmlammendola@cpmy.com April 21, 2010 FOIA OFFICER U.S. Department of Energy 1000 Independence Avenue, SW Washington, DC 20585 Re: Freedom of Information Act (FOIA) Request Our File Number: 100-2127 Dear Sir or Madame: Pursuant to the Freedom of

  11. Adam Young | Argonne Leadership Computing Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Young Guest Researcher Argonne National Laboratory 9700 S. Cass Avenue Building 240 Wkstn. 4D15 Argonne, IL 60439 younga@anl...

  12. EA-1974: Wallooskee-Youngs Confluence Restoration Project; Clatsop...

    Energy Savers [EERE]

    4: Wallooskee-Youngs Confluence Restoration Project; Clatsop County, Oregon EA-1974: Wallooskee-Youngs Confluence Restoration Project; Clatsop County, Oregon Summary Bonneville ...

  13. The effect of frequency on Young`s modulus and seismic wave attenuation

    SciTech Connect (OSTI)

    Price, R.H.; Martin, R.J. III; Haupt, R.W.

    1994-07-01

    Laboratory experiments were performed to measure the effect of frequency, water-saturation, and strain amplitude on Young`s modulus and seismic wave attenuation on rock cores recovered on or near the site of a potential nuclear waste repository at Yucca Mountain, Nevada. The purpose of this investigation is to perform the measurements using four techniques: cyclic loading, waveform inversion, resonant bar, and ultrasonic velocity. The measurements ranged in frequency between 10{sup {minus}2} and 10{sup 6} Hz. For the dry specimens Young`s modulus and attenuation were independent of frequency; that is, all four techniques yielded nearly the same values for modulus and attenuation. For saturated specimens, a frequency dependence for both Young`s modulus and attenuation was observed. In general, saturation reduced Young`s modulus and increased seismic wave attenuation. The effect of strain amplitude on Young`s modulus and attenuation was measured using the cyclic loading technique at a frequency of 10{sup {minus}1} Hz. The effect of strain amplitude in all cases was small. For some rocks, such as the potential repository horizon of the Topopah Spring Member tuff (TSw2), the effect of strain amplitude on both attenuation and modulus was minimal.

  14. Young, Jupiter-like planet discovered

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Young, Jupiter-like planet discovered Alumni Link: Opportunities, News and Resources for Former Employees Latest Issue:September 2015 all issues All Issues » submit Young, Jupiter-like planet discovered A team of researchers has discovered a Jupiter-like planet within a young system that could provide a new understanding of how planets formed around our sun. September 1, 2015 Jupiter-like planet Jupiter-like planet Contact Linda Anderman Email A team of researchers has discovered a Jupiter-like

  15. Young Energy, LLC | Open Energy Information

    Open Energy Info (EERE)

    Energy, LLC Jump to: navigation, search Name: Young Energy, LLC Place: Texas Phone Number: 888-963-9363 Website: www.puc.texas.govindustryele Outage Hotline: 888-963-9363...

  16. Fun and inspiration for 575 young women at PPPL's Young Women's

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Conference | Princeton Plasma Physics Lab Fun and inspiration for 575 young women at PPPL's Young Women's Conference May 17, 2016 By: Jeanne Jackson DeVoe March 22, 2016 Some 575 seventh- to tenth-grade girls from throughout New Jersey, as well as Pennsylvania and Maryland, found fun and inspiration doing myriad hands-on activities and meeting female scientists at The Princeton Plasma Physics Laboratory's 15thannual Young Women's Conference in Science, Technology, Engineering, and

  17. Raquel C Young | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Raquel C Young Administrative Assistant Raquel Young received her B.A. in Organizational Leadership from Lewis University in 2013. In 2009, Raquel received her Associates Degree in Business Management from Triton College. Currently Raquel provides administrative support for the following groups within the HEP Division: Detector R&D; Intensity Frontier; Mechanical Support; Mu2e Telephone (630) 252-6290 E-mail rcyoung@anl.gov

  18. THE GALEX NEARBY YOUNG-STAR SURVEY

    SciTech Connect (OSTI)

    Rodriguez, David R.; Faherty, Jacqueline K.; Zuckerman, B.; Kastner, Joel H.; Bessell, M. S.; Murphy, Simon J.

    2013-09-10

    We describe a method that exploits data from the Galaxy Evolution Explorer (GALEX) ultraviolet and Wide-field Infrared Survey Explorer and Two Micron All Sky Survey infrared source catalogs, combined with proper motions and empirical pre-main sequence isochrones, to identify candidate nearby, young, low-mass stars. Applying our method across the full GALEX-covered sky, we identify 2031 mostly M-type stars that, for an assumed age of 10 (100) Myr, all lie within {approx}150 ({approx}90) pc of Earth. The distribution of M spectral subclasses among these {approx}2000 candidate young stars peaks sharply in the range M3-M4; these subtypes constitute 50% of the sample, consistent with studies of the M star population in the immediate solar neighborhood. We focus on a subset of 58 of these candidate young M stars in the vicinity of the Tucana-Horologium association. Only 20 of these 58 candidates were detected in the ROSAT All-Sky X-ray Survey-reflecting the greater sensitivity of GALEX for the purposes of identifying active nearby, young stars, particularly for stars of type M4 and later. Based on statistical analysis of the kinematics and/or spectroscopic followup of these 58 M stars, we find that 50% (29 stars) indeed have properties consistent with Tuc-Hor membership, while 12 are potential new members of the Columba association, and 2 may be AB Dor moving group members. Hence, {approx}75% of our initial subsample of 58 candidates are likely members of young (age {approx} 10-40 Myr) stellar moving groups within 100 pc, verifying that the stellar color- and kinematics-based selection algorithms described here can be used to efficiently isolate nearby, young, low-mass objects from among the field star population. Future studies will focus on characterizing additional subsamples selected from among this list of candidate nearby, young M stars.

  19. Low Voltage, Low Power Organic Light Emitting Transistors for AMOLED Displays

    SciTech Connect (OSTI)

    McCarthy, M. A. [University of Florida, Gainesville; Liu, B. [University of Florida, Gainesville; Donoghue, E. P. [University of Florida, Gainesville; Kravchenko, Ivan I [ORNL; Kim, D. Y. [University of Florida, Gainesville; Reynolds, J. R. [University of Florida, Gainesville; So, Franky [University of Florida, Gainesville; Rinzler, A. G. [University of Florida, Gainesville

    2011-01-01

    Low voltage, low power dissipation, high aperture ratio organic light emitting transistors are demonstrated. The high level of performance is enabled by a carbon nanotube source electrode that permits integration of the drive transistor and the organic light emitting diode into an efficient single stacked device. Given the demonstrated performance, this technology could break the technical logjam holding back widespread deployment of active matrix organic light emitting displays at flat panel screen sizes.

  20. NREL: Photovoltaics Research - David L. Young, Ph.D.

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    p. 073502. Young, D.L., B. Egaas, S. Pinegar, and P. Stradins. A new real-time quantum efficiency measurement system. in 33rd IEEE PVSC 2008. San Diego, CA: IEEE. Young, D.L.,...

  1. William E. and Diane M. Spicer Young Investigator Award | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    William E. and Diane M. Spicer Young Investigator Award William E. and Diane M. Spicer Young Investigator Award William E. Spicer (1929-2004) was an esteemed member of the...

  2. Registration for the 2015 Conference for Young Women in STEM...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Registration for the 2015 Conference for Young Women in STEM is OPEN October 15, 2014 The 2015 Young Women's Conference in STEM will be held on Thursday, March 19, 2015 at...

  3. W. C. Young and D. J. Den Hartog

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    pulse-burst laser for Thomson scatteringa) W. C. Young and D. J. Den Hartog Citation: ... pulse-burst laser for Thomson scattering a) W. C. Young 1,2,b) and D. J. Den Hartog 1,2 1 ...

  4. Over 150 Young Women to Learn About Careers, Research Opportunities...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Over 150 Young Women to Learn About Careers, Research Opportunities in Physics at Jefferson Lab on Jan. 16 Over 150 Young Women to Learn About Careers, Research Opportunities in ...

  5. Jefferson Lab Activities Group Invites Young and Not-So-Young...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Holiday Events Holiday Party on Dec. 12 for Jefferson Lab Children and the Young at Heart The JAG Holiday Party is scheduled for Saturday, Dec. 12, 10 a.m.-1 p.m. in the CEBAF...

  6. Fun and inspiration for 575 young women at PPPL's Young Women's

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Conference | Princeton Plasma Physics Lab Fun and inspiration for 575 young women at PPPL's Young Women's Conference By Jeanne Jackson DeVoe March 22, 2016 Tweet Widget Google Plus One Share on Facebook Kathryn Wagner, a lecturer demonstrator in the Princeton University Chemistry Department, center, along with Princeton undergraduate Monica Wei, create a green-colored flame using copper during a chemistry demonstration. (Photo by Elle Starkman/PPPL Office of Communications) Kathryn Wagner, a

  7. Fun and inspiration for 575 young women at PPPL's Young Women's

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Conference | Princeton Plasma Physics Lab Fun and inspiration for 575 young women at PPPL's Young Women's Conference By Jeanne Jackson DeVoe March 22, 2016 Tweet Widget Google Plus One Share on Facebook Kathryn Wagner, a lecturer demonstrator in the Princeton University Chemistry Department, center, along with Princeton undergraduate Monica Wei, create a green-colored flame using copper during a chemistry demonstration. (Photo by Elle Starkman/PPPL Office of Communications) Kathryn Wagner, a

  8. Sponsoring, Mentoring and Guiding Cultural Diverse Young Scientists...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sponsoring, Mentoring and Guiding Cultural Diverse Young Scientists and Engineers Presentation on successful mentoring. PDF icon Partnership meeting presentation 020711...

  9. Young Women's Conference cheers on girls interested in STEM | Princeton

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Plasma Physics Lab Young Women's Conference cheers on girls interested in STEM By Jeanne Jackson DeVoe March 27, 2014 Tweet Widget Google Plus One Share on Facebook PPPL engineer Han Zhang shows off a plasma ball to a few of the 400 young women who attended PPPL's Young Women's Conference on March 21 at Princeton University. (Photo by Elle Starkman/ PPPL Office of Communications) PPPL engineer Han Zhang shows off a plasma ball to a few of the 400 young women who attended PPPL's Young Women's

  10. Young Women's Conference cheers on girls interested in STEM | Princeton

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Plasma Physics Lab Young Women's Conference cheers on girls interested in STEM By Jeanne Jackson DeVoe March 28, 2014 Tweet Widget Google Plus One Share on Facebook PPPL engineer Han Zhang shows off a plasma ball to a few of the 400 young women who attended PPPL's Young Women's Conference on March 21. (Photo by Elle Starkman/ PPPL Office of Communications) PPPL engineer Han Zhang shows off a plasma ball to a few of the 400 young women who attended PPPL's Young Women's Conference on March 21.

  11. NEW YOUNG STAR CANDIDATES IN CG4 AND Sa101

    SciTech Connect (OSTI)

    Rebull, L. M.; Laine, S.; Laher, R.; Legassie, M.; Hoette, V.; Kim, J. S.; Foster, M.; Mallory, C. R.; McCarron, K.; Sherry, W. H.

    2011-07-15

    The CG4 and Sa101 regions together cover a region of {approx}0.5 deg{sup 2} in the vicinity of a 'cometary globule' that is part of the Gum Nebula. There are seven previously identified young stars in this region; we have searched for new young stars using mid- and far-infrared data (3.6-70 {mu}m) from the Spitzer Space Telescope, combined with ground-based optical data and near-infrared data from the Two Micron All Sky Survey. We find infrared excesses in all six of the previously identified young stars in our maps and identify 16 more candidate young stars based on apparent infrared excesses. Most (73%) of the new young stars are Class II objects. There is a tighter grouping of young stars and young star candidates in the Sa101 region, in contrast to the CG4 region, where there are fewer young stars and young star candidates, and they are more dispersed. Few likely young objects are found in the 'fingers' of the dust being disturbed by the ionization front from the heart of the Gum Nebula.

  12. SEARCHING FOR YOUNG M DWARFS WITH GALEX

    SciTech Connect (OSTI)

    Shkolnik, Evgenya L.; Weinberger, Alycia J.; Liu, Michael C.; Dupuy, Trent; Reid, I. Neill E-mail: alycia@dtm.ciw.edu E-mail: tdupuy@ifa.hawaii.edu

    2011-01-20

    The census of young moving groups in the solar neighborhood is significantly incomplete in the low-mass regime. We have developed a new selection process to find these missing members based on the Galaxy Evolution Explorer (GALEX) All-Sky Imaging Survey (AIS). For stars with spectral types {approx}>K5 (R - J {approx}> 1.5) and younger than {approx}300 Myr, we show that near-UV (NUV) and far-UV (FUV) emission is greatly enhanced above the quiescent photosphere, analogous to the enhanced X-ray emission of young low-mass stars seen by ROSAT but detectable to much larger distances with GALEX. By combining GALEX data with optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified an initial sample of 34 young M dwarf candidates in a 1000 deg{sup 2} region around the {approx}10 Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30 of these found 16 which had H{alpha} in emission, which were then followed up at high resolution to search for spectroscopic evidence of youth and to measure their radial velocities. Four objects have low surface gravities, photometric distances and space motions consistent with TWA, but the non-detection of Li indicates that they may be too old to belong to this moving group. One object (M3.5, 93 {+-} 19 pc) appears to be the first known accreting low-mass member of the {approx}15 Myr Lower Centaurus Crux OB association. Two objects exhibit all the characteristics of the known TWA members, and thus we designate them as TWA 31 (M4.2, 110 {+-} 11 pc) and TWA 32 (M6.3, 53 {+-} 5 pc). TWA 31 shows extremely broad (447 km s{sup -1}) H{alpha} emission, making it the sixth member of TWA found to have ongoing accretion. TWA 32 is resolved into a 0.''6 binary in Keck laser guide star adaptive optics imaging. Our search should be sensitive down to spectral types of at least M4-M5 in TWA and thus the small numbers of new member is puzzling. This might indicate TWA has an atypical mass function or that the presence of

  13. Los Alamos computational scientist wins 2016 Carcinogenesis Young

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Investigator Award 2016 Carcinogenesis Young Investigator Award Los Alamos computational scientist wins 2016 Carcinogenesis Young Investigator Award Ludmil Alexandrov is the winner of the 2016 Carcinogenesis Young Investigator Award. July 11, 2016 Ludmil Alexandrov Ludmil Alexandrov Contact Los Alamos National Laboratory Nick Njegomir Communications Office (505) 665-9394 Email "Ludmil's research uses large-scale computational screening and analysis to understand the mutational processes

  14. The Science Training Program for Young Italian Physicists and...

    Office of Scientific and Technical Information (OSTI)

    Title: The Science Training Program for Young Italian Physicists and Engineers at Fermilab Since 1984 Fermilab has been hosting a two-month summer training program for selected ...

  15. Young County, Texas: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    Young County, Texas: Energy Resources Jump to: navigation, search Equivalent URI DBpedia Coordinates 33.2200087, -98.7481167 Show Map Loading map... "minzoom":false,"mappingse...

  16. 2013 Young Women's Conference | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    400 students and chaperones attended the 2013 Young Women's Conference in Science, Mathematics, Technology, and Engineering - the largest YWC ever View larger image View larger...

  17. Young Physicist from Syracuse University Receives Jefferson Lab...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Physicist from Syracuse University Receives Jefferson Lab's 2014 Thesis Prize Beminiwattha Rakitha Beminiwattha NEWPORT NEWS, VA, June 6, 2014 - A young researcher, who worked on...

  18. Catching the entrepreneurial spirit at a young age

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mockingbird Books. "Our mission is to create a comfortable, welcoming and inclusive environment for people who want and love to read," the young team wrote. "We will have...

  19. Sponsoring, Mentoring and Guiding Cultural Diverse Young Scientists and

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Engineers | Argonne National Laboratory Sponsoring, Mentoring and Guiding Cultural Diverse Young Scientists and Engineers Presentation on successful mentoring. PDF icon Partnership meeting presentation 020711

  20. Young Womens Conference attracts more attendees in 2014! | Princeton...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    June 9, 2014 Gallery: The 2014 Young Women's Conference is Science, Engineering, Technology, and Mathematics attracted students from all over New Jersey With almost 400 students, ...

  1. Tunable Young's Modulus in Carbon MEMS using Graphene-based Stiffeners...

    Office of Scientific and Technical Information (OSTI)

    Tunable Young's Modulus in Carbon MEMS using Graphene-based Stiffeners. Citation Details In-Document Search Title: Tunable Young's Modulus in Carbon MEMS using Graphene-based ...

  2. David Young Named NNSA Security Professional of the Year | National Nuclear

    National Nuclear Security Administration (NNSA)

    Security Administration | (NNSA) David Young Named NNSA Security Professional of the Year November 20, 2008 Microsoft Office document icon NR-09-08 Young

  3. Anglers needed - Save young salmon and reel in cash

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    young salmon need your help. Today marks the start of a new Northern Pikeminnow Sport Reward Fishery Program that pays anglers for catching one of the biggest predators of...

  4. Women @ Energy: Young-Kee Kim | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Professor of Physics at the University of Chicago Young-Kee Kim is the Deputy Director of Fermi National Accelerator Laboratory and a Louis Block Professor of Physics at the ...

  5. Sandia Energy - Sandian Selected for Outstanding Young Engineer...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Award The Albuquerque Section of the Institute of Electrical and Electronics Engineers (IEEE) has selected Dr. Jose Luis Cruz-Campa as the recipient of the 2014 Outstanding Young...

  6. William E. and Diane M. Spicer Young Investigator Award | Stanford

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Synchrotron Radiation Lightsource William E. and Diane M. Spicer Young Investigator Award William E. and Diane M. Spicer Young Investigator Award William E. Spicer (1929-2004) was an esteemed member of the international scientific community as a teacher and researcher in electrical engineering, applied physics and materials science. Bill spent the past 40 years as a professor at Stanford where he pioneered the technique ofultraviolet photoemission spectroscopy and its subsequent expansion

  7. Environmental Contractor Mentors Young Students | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Environmental Contractor Mentors Young Students Environmental Contractor Mentors Young Students November 26, 2014 - 12:00pm Addthis Jeff Boulton of LATA Kentucky works with middle school students to demonstrate and test the acidity and basicity levels of groundwater. Jeff Boulton of LATA Kentucky works with middle school students to demonstrate and test the acidity and basicity levels of groundwater. Middle school students use water bottles and powdered drink mix to learn how contamination

  8. Young Physicist from Syracuse University Receives Jefferson Lab's 2014

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Thesis Prize | Jefferson Lab Physicist from Syracuse University Receives Jefferson Lab's 2014 Thesis Prize Young Physicist from Syracuse University Receives Jefferson Lab's 2014 Thesis Prize Beminiwattha Rakitha Beminiwattha NEWPORT NEWS, VA, June 6, 2014 - A young researcher, who worked on software development and data analysis for a major physics experiment conducted at the Thomas Jefferson National Accelerator Facility, has received an award for the thesis he wrote about his efforts.

  9. CANDIDATES FOR THE YOUNG STELLAR OUTFLOWS: WATER AND METHANOL MASERS FROM YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Lim, Wanggi; Lyo, A-Ran; Kim, Kee-Tae; Byun, Do-Young

    2012-11-01

    We conducted simultaneous 22 GHz water maser and 44 GHz class I methanol maser surveys of newly identified 282 H{sub 2} emission features from the 2.122 {mu}m H{sub 2} narrowband image survey in the Galactic plane (UWISH2 project) using Korean VLBI Network 21 m radio telescopes. We detected 16 and 13 new water and methanol maser sources, respectively. This result indicates that at least {approx}5% of the H{sub 2} emission features originate from young stellar objects (YSOs) that are in the right physical condition to produce the water and methanol masers. The masers are closely related to the current outflow activities in the Galactic plane. The power sources of these 23 diffused/collimated H{sub 2} emission features (six sources are detected for both masers) are likely to be intermediate- to high-mass YSOs, based on a comparison with the maser luminosities of other well-studied YSOs. Both maser velocities are mostly close to their own systemic velocities within {approx}<5 km s{sup -1}, even though water masers generally show larger variabilities in the intensity, velocity, and shape than methanol masers. We also discovered three new water maser sources with high-velocity components: {approx}25 km s{sup -1} redshifted CMHO 019, {approx}50 km s{sup -1} blueshifted CMHO 132, and {approx}120 km s{sup -1} blueshifted CMHO 182. In particular, we propose that the dominant blueshifted water maser of CHMO 182 can be a unique laboratory for the study of the high-mass young stellar jet and its acceleration.

  10. Young scientist discovers magnetic material unnecessary to create spin

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    current | Argonne National Laboratory Young scientist discovers magnetic material unnecessary to create spin current By Carla Reiter * July 23, 2015 Tweet EmailPrint It doesn't happen often that a young scientist makes a significant and unexpected discovery, but postdoctoral researcher Stephen Wu of the U.S. Department of Energy's Argonne National Laboratory just did exactly that. What he found-that you don't need a magnetic material to create spin current from insulators-has important

  11. The Young Planet-mass Ob ject 2M1207b: A cool, cloudy, and methane...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The Young Planet-mass Ob ject 2M1207b: A cool, cloudy, and methane-poor atmosphere Citation Details In-Document Search Title: The Young Planet-mass Ob ject ...

  12. EVIDENCE FOR A WEAK WIND FROM THE YOUNG SUN

    SciTech Connect (OSTI)

    Wood, Brian E.; Mller, Hans-Reinhard; Redfield, Seth; Edelman, Eric

    2014-02-01

    The early history of the solar wind has remained largely a mystery due to the difficulty of detecting winds around young stars that can serve as analogs for the young Sun. Here we report on the detection of a wind from the 500Myr old solar analog ?{sup 1} UMa (G1.5V), using spectroscopic observations from the Hubble Space Telescope. We detect H I Ly? absorption from the interaction region between the stellar wind and interstellar medium, i.e., the stellar astrosphere. With the assistance of hydrodynamic models of the ?{sup 1} UMa astrosphere, we infer a wind only half as strong as the solar wind for this star. This suggests that the Sun and solar-like stars do not have particularly strong coronal winds in their youth.

  13. NETL Researcher Selected to Receive Nation's Highest Award for Young

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Researcher Selected to Receive Nation's Highest Award for Young Scientists Pittsburgh, Pa.-Dr. Paul R. Ohodnicki, a materials scientist at the National Energy Technology Laboratory (NETL), has been named by President Obama as a recipient of the Presidential Early Career Award for Scientists and Engineers (PECASE). The PECASE award is the highest honor the U.S. government can bestow on scientists or engineers in the early stages of their research careers. Dr. Ohodnicki was selected for his

  14. Young awarded Helmholtz International Fellow leading up to start of

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    powerful new X-ray laser | Argonne National Laboratory You may also like Diamonds help generate new record for static pressures for study July 28, 2016 High schoolers study ancient pottery at Advanced Photon Source June 16, 2016 New X-ray method allows scientists to probe molecular explosions June 15, 2016 X-rays reveal the photonic crystals in butterfly wings that create color June 10, 2016 Tasty fat: X-rays finding the blueprint of why fat is yummy May 27, 2016 Young awarded Helmholtz

  15. Charles D. Young Project Engineer Government Support Directorate

    Office of Legacy Management (LM)

    Please call if you have questions regarding the attached recommendation. i?&,o-o; ~~~pApv $l$I Charles D. Young Project Engineer Government Support Directorate Architecture Planning and Technology Division CDY/smb Attachment cc: J. Fiore ;;,ewis (w/o) TH' E AEROSPACE CORPORATION i ' 0 A Suite 7900, 955 L' Enfam Plaza. S. W., Woshingron. D.C. 20024-2174. Tekphonc (202) 488-6000 7117-03.87.cdy.43 23 September 1987 CA Mr. Andrew Wallo, III, NE-23 Division of Facility & Site Decosunissioning

  16. STEM Mentoring Café- Engaging Young Women in an Authentic Mentoring...

    Office of Environmental Management (EM)

    STEM Mentoring Caf- Engaging Young Women in an Authentic Mentoring Experience Melinda Higgins Albert Einstein Distinguished Educator Fellow, NASA Office of Education, ...

  17. Registration for the 2015 Conference for Young Women in STEM is OPEN! |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Princeton Plasma Physics Lab Registration for the 2015 Conference for Young Women in STEM is OPEN! October 15, 2014 The 2015 Young Women's Conference in STEM will be held on Thursday, March 19, 2015 at Princeton University's Frick Chemistry building and registration is now OPEN! Please visit our Young Women's Conference program page to find out more about this great event and to register your group here! Remember, young women must be in grades 7-10 there is a 10 student and 1 chaperone limit

  18. NEW YOUNG STAR CANDIDATES IN BRC 27 AND BRC 34

    SciTech Connect (OSTI)

    Rebull, L. M.; Laher, R.; Legassie, M.; Gibbs, J. C.; Aryal, S.; Canakapalli, T. S.; Linahan, M.; Ezyk, N.; Fagan, J.; Sartore, D.; Badura, K. S.; Armstrong, J. D.; Allen, L. E.; McGehee, P.; and others

    2013-01-01

    We used archival Spitzer Space Telescope mid-infrared data to search for young stellar objects (YSOs) in the immediate vicinity of two bright-rimmed clouds, BRC 27 (part of CMa R1) and BRC 34 (part of the IC 1396 complex). These regions both appear to be actively forming young stars, perhaps triggered by the proximate OB stars. In BRC 27, we find clear infrared excesses around 22 of the 26 YSOs or YSO candidates identified in the literature, and identify 16 new YSO candidates that appear to have IR excesses. In BRC 34, the one literature-identified YSO has an IR excess, and we suggest 13 new YSO candidates in this region, including a new Class I object. Considering the entire ensemble, both BRCs are likely of comparable ages, within the uncertainties of small number statistics and without spectroscopy to confirm or refute the YSO candidates. Similarly, no clear conclusions can yet be drawn about any possible age gradients that may be present across the BRCs.

  19. DIRECT DETECTIONS OF YOUNG STARS IN NEARBY ELLIPTICAL GALAXIES

    SciTech Connect (OSTI)

    Ford, H. Alyson; Bregman, Joel N.

    2013-06-20

    Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-infrared dust emission. Such star formation has previously been difficult to directly detect, but using ultraviolet Hubble Space Telescope Wide Field Camera 3 imaging, we have identified individual young stars and star clusters in four nearby ellipticals. Ongoing star formation is detected in all galaxies, including three ellipticals that have previously exhibited potential signposts of star-forming conditions (NGC 4636, NGC 4697, and NGC 4374), as well as the typical ''red and dead'' NGC 3379. The current star formation in our closest targets, where we are most complete, is between 2.0 and 9.8 Multiplication-Sign 10{sup -5} M{sub Sun} yr{sup -1}. The star formation history was roughly constant from 0.5 to 1.5 Gyr (at (3-5) Multiplication-Sign 10{sup -4} M{sub Sun} yr{sup -1}), but decreased by a factor of several in the past 0.3 Gyr. Most star clusters have a mass between 10{sup 2} and 10{sup 4} M{sub Sun }. The specific star formation rates of {approx}10{sup -16} yr{sup -1} (at the present day) or {approx}10{sup -14} yr{sup -1} (when averaging over the past Gyr) imply that a fraction 10{sup -8} of the stellar mass is younger than 100 Myr and 10{sup -5} is younger than 1 Gyr, quantifying the level of frosting of recent star formation over the otherwise passive stellar population. There is no obvious correlation between either the presence or spatial distribution of postulated star formation indicators and the star formation we detect.

  20. THE ANATOMY OF THE YOUNG PROTOSTELLAR OUTFLOW HH 211

    SciTech Connect (OSTI)

    Tappe, A.; Forbrich, J.; Lada, C. J.; Martin, S.; Yuan, Y.

    2012-05-20

    We present Spitzer Space Telescope 5-36 {mu}m mapping observations toward the southeastern lobe of the young protostellar outflow HH 211. The southeastern terminal shock of the outflow shows a rich mid-infrared spectrum including molecular emission lines from OH, H{sub 2}O, HCO{sup +}, CO{sub 2}, H{sub 2}, and HD. The spectrum also shows a rising infrared continuum toward 5 {mu}m, which we interpret as unresolved emission lines from highly excited rotational levels of the CO v = 1-0 fundamental band. This interpretation is supported by a strong excess flux observed in the Spitzer/IRAC 4-5 {mu}m channel 2 image compared to the other IRAC channels. The extremely high critical densities of the CO v = 1-0 ro-vibrational lines and a comparison to H{sub 2} and CO excitation models suggest jet densities larger than 10{sup 6} cm{sup -3} in the terminal shock. We also observed the southeastern terminal outflow shock with the Submillimeter Array and detected pure rotational emission from CO 2-1, HCO{sup +} 3-2, and HCN 3-2. The rotationally excited CO traces the collimated outflow backbone as well as the terminal shock. HCN traces individual dense knots along the outflow and in the terminal shock, whereas HCO{sup +} solely appears in the terminal shock. The unique combination of our mid-infrared and submillimeter observations with previously published near-infrared observations allow us to study the interaction of one of the youngest known protostellar outflows with its surrounding molecular cloud. Our results help us to understand the nature of some of the so-called green fuzzies (Extended Green Objects), and elucidate the physical conditions that cause high OH excitation and affect the chemical OH/H{sub 2}O balance in protostellar outflows and young stellar objects. In an appendix to this paper, we summarize our Spitzer follow-up survey of protostellar outflow shocks to find further examples of highly excited OH occurring together with H{sub 2}O and H{sub 2}.

  1. The 2015 Conference for Young Women in STEM is a smashing success! |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Princeton Plasma Physics Lab The 2015 Conference for Young Women in STEM is a smashing success! April 2, 2015 A beautiful Thursday morning at the usually quiet and peaceful Frick Chemistry building at Princeton University, turned into a bustling hub of science and technology for a day on March 19, 2015. Over 450 young women, in grades 7-10, and their chaperones came from all over NJ, PA and even MD, to attend PPPL's 14th Annual young Women's Conference in STEM. With over 25 exhibits, the

  2. Over 150 Young Women to Learn About Careers, Research Opportunities in

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Physics at Jefferson Lab on Jan. 16 | Jefferson Lab Over 150 Young Women to Learn About Careers, Research Opportunities in Physics at Jefferson Lab on Jan. 16 Over 150 Young Women to Learn About Careers, Research Opportunities in Physics at Jefferson Lab on Jan. 16 NEWPORT NEWS, VA, Jan. 11, 2016 -- Several hundred young women - from across the country - will gather Jan. 15-17 to learn about many career and research opportunities available in fields associated with physics. They will be

  3. The evolutionary tracks of young massive star clusters

    SciTech Connect (OSTI)

    Pfalzner, S.; Steinhausen, M.; Vincke, K.; Menten, K.; Parmentier, G.

    2014-10-20

    Stars mostly form in groups consisting of a few dozen to several ten thousand members. For 30 years, theoretical models have provided a basic concept of how such star clusters form and develop: they originate from the gas and dust of collapsing molecular clouds. The conversion from gas to stars being incomplete, the leftover gas is expelled, leading to cluster expansion and stars becoming unbound. Observationally, a direct confirmation of this process has proved elusive, which is attributed to the diversity of the properties of forming clusters. Here we take into account that the true cluster masses and sizes are masked, initially by the surface density of the background and later by the still present unbound stars. Based on the recent observational finding that in a given star-forming region the star formation efficiency depends on the local density of the gas, we use an analytical approach combined with N-body simulations to reveal evolutionary tracks for young massive clusters covering the first 10 Myr. Just like the Hertzsprung-Russell diagram is a measure for the evolution of stars, these tracks provide equivalent information for clusters. Like stars, massive clusters form and develop faster than their lower-mass counterparts, explaining why so few massive cluster progenitors are found.

  4. Evaluation of 1991-1992 Brood Overwinter-Reared Coho Released from Net Pens in Youngs Bay, Oregon : Final Completion Report Youngs Bay Terminal Fishery Project.

    SciTech Connect (OSTI)

    Hirose, Paul S.

    1997-01-01

    Funding from Bonneville Power Administration was provided to the Oregon Department of Fish and Wildlife and the Clatsop County Economic Development Council`s Fisheries Project to identify and develop terminal fishing opportunities. The 1991 and 1992 brood fingerling coho from Oregon Department of Fish and Wildlife hatcheries were successfully reared during the winter period to smolt stage in Youngs Bay utilizing floating net pens. Based on coded-wire-tag recoveries during 1991--93 from 2-week net-pen acclimation releases, total accountability of coho adults averaged 40,540 fish, with the Youngs Bay commercial harvest accounting for 39%. With reduced ocean harvest impacts during 1994 and 1995, 92% of 51,640 coho in 1994 and 68% of 23,599 coho in 1995 (based on coded-wire-tag recoveries) were accounted for in the Youngs Bay commercial fishery for combined 2-week and overwinter acclimation net-pen releases. Overwinter net-pen acclimation coho accounted for 35,063 and 15,775 coho adults in 1994 and 1995 with 93% and 68% accountable in the Youngs Bay commercial harvest. Based on coded-wire-tag recoveries, less than 1% of the adults resulting from releases at Youngs Bay net pens strayed to hatcheries, while none were recovered on spawning ground surveys during 1991--95. The highest survival rates were observed for 1991 and 1992 brood overwinter coho released in early May. Time of release, not rearing strategy, appears to be the determining factor affecting survival in Youngs Bay.

  5. The Young Planet-mass Ob ject 2M1207b: A cool, cloudy, and methane...

    Office of Scientific and Technical Information (OSTI)

    A cool, cloudy, and methane-poor atmosphere Citation Details In-Document Search Title: The Young Planet-mass Ob ject 2M1207b: A cool, cloudy, and methane-poor atmosphere You ...

  6. Young Professionals in Nuclear Industry Group Forms at Savannah River Site

    Broader source: Energy.gov [DOE]

    AIKEN, S.C. – Supporting the development of young nuclear professionals in the Central Savannah River Area (CSRA) is the purpose behind a new group forming at the Savannah River Site (SRS).

  7. Optical Third-Harmonic Generation in Graphene Hong, Sung-Young...

    Office of Scientific and Technical Information (OSTI)

    Third-Harmonic Generation in Graphene Hong, Sung-Young; Dadap, Jerry I.; Petrone, Nicholas; Yeh, Po-Chun; Hone, James; Osgood, Richard M. American Physical Society None USDOE...

  8. Successful Field-Scale In Situ Thermal NAPL Remediation at the Young -

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Rainey STAR Center | Department of Energy Successful Field-Scale In Situ Thermal NAPL Remediation at the Young - Rainey STAR Center Successful Field-Scale In Situ Thermal NAPL Remediation at the Young - Rainey STAR Center Proceedings of the Fourth International Conference on Remediation of Chlorinated and Recalcitrant Compounds. May 2004, Monterey, California. Randall Juhlin, Michael Butherus, Joseph Daniel, David S. Ingle, Dr. Gorm Heron, Dr. Bruce McGee Successful Field-Scale In Situ

  9. Los Alamos County is among 100 Best Communities for Young People

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    100 Best Communities for Young People Community Connections: Your link to news and opportunities from Los Alamos National Laboratory Latest Issue: September 1, 2016 all issues All Issues » submit Los Alamos County is among 100 Best Communities for Young People The recognition is given to locations that make youth a priority through caring adults, safe places, a healthy start, effective education, and opportunities to help others. October 1, 2012 dummy image Read our archives Contacts Editor

  10. LANL gets young women involved in math and science at 31st Expanding Your

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Horizons Conference April 6 31st Expanding Your Horizons Conference LANL gets young women involved in math and science at 31st Expanding Your Horizons Conference April 6 The young women will participate in hands-on activities in such fields as astronomy, robotics, forensics, chemistry, and earth science. March 4, 2010 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering

  11. Young Investigator Program > Research > The Energy Materials Center at

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cornell Young Investigator Program In This Section YIA1 - Chen YIA2 - Rodríguez-Calero YIA3 - Rodriguez-López YIA4 - Hernández-Burgos YIA5 - Khurana YIA6 - Potash Young Investigator Program This program is designed to encourage Center postdocs and students to submit collaborative proposals for new research projects that advance the Center's overall programmatic goal of advancing the science of energy conversion and storage by understanding and exploiting fundamental properties of active

  12. THE ENIGMATIC YOUNG, LOW-MASS VARIABLE TWA 30

    SciTech Connect (OSTI)

    Looper, Dagny L.; Rayner, John; Pitts, Mark A.; Mohanty, Subhanjoy; Bochanski, John J.; Burgasser, Adam J.; Mamajek, Eric E.; Herczeg, Gregory J.; West, Andrew A.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy

    2010-05-01

    TWA 30 is a remarkable young (7 {+-} 3 Myr), low-mass (0.12 {+-} 0.04 M{sub sun}), late-type star (M5 {+-} 1) residing 42 {+-} 2 pc away from the Sun in the TW Hydrae Association (TWA). It shows strong outflow spectral signatures such as [S II], [O I], [O II], [O III], and Mg I], while exhibiting weak H{alpha} emission (-6.8 {+-} 1.2 A). Emission lines of [S II] and [O I] are common to T Tauri stars still residing in their natal molecular clouds, while [O III] and Mg I] emission lines are incredibly rare in this same population; in the case of TWA 30, these latter lines may arise from new outflow material colliding into older outflow fronts. The weak H{alpha} emission and small radial velocity shifts of line emission relative to the stellar frame of rest (generally {approx_lt}10 km s{sup -1}) suggest that the disk is viewed close to edge-on and that the stellar axis may be inclined to the disk, similar to the AA Tau system, based on its temporal changes in emission/absorption line strengths/profiles and variable reddening (A{sub V} = 1.5-9.0). The strong Li absorption (0.61 {+-} 0.13 A) and common kinematics with members of the TWA confirm its age and membership to the association. Given the properties of this system such as its proximity, low mass, remarkable outflow signatures, variability, and edge-on configuration, this system is a unique case study at a critical time in disk evolution and planet-building processes.

  13. Uranium and thorium decay series disequilibria in young volcanic rocks

    SciTech Connect (OSTI)

    Williams, R.W.

    1988-01-01

    Two of the central questions in igneous geochemistry that study of radioactive disequilibria can help to answer are: what are the rates of magma genesis; and what are the timescales of magma separation and transport. In addition to the temporal information that may be extracted from disequilibria data, the {sup 230}Th/{sup 232}Th of a young rock may be used as a tracer of the Th/U ratio of its source region. Measurements were made by isotope dilution alpha-spectrometry of {sup 238}U, {sup 234}U, {sup 230}Th, and {sup 232}Th in 20 subduction related, 3 oceanic intraplate, and 10 continental intraplate volcanics. {sup 210}Pb was measured in all, {sup 226}Ra was measured in about half, and {sup 228}Th was measured in 10 of the most recent samples. Disequilibrium between {sup 228}Th and {sup 232}Th was found only in the Nacarbonatite samples from Oldoinyo Lengai volcano in Tanzania, which is attributable to {sup 228}Ra/{sup 232}Th {approximately} 27 at the time of eruption. These rocks also have {sup 226}Ra/{sup 230}Th > 60. Three Ra-enrichment models are developed which constrain carbonatite magma formation at less than 20 years before eruption. The effects of different partial melting processes on the {sup 238}U decay series are investigated. If mid-ocean ridge basalts are formed by a dynamic melting process, the {sup 230}Th/{sup 232}Th of the basalts provides a minimum estimate of the Th/U ratio of the source region. The {sup 238}U enrichment in arc volcanics is probably the results of metasomatism of the source by fluids derived from the subducting slab, and the {sup 230}Th enrichment observed for other volcanics is probably due to the partial melting process in the absence of U-bearing fluids.

  14. THREE-DIMENSIONAL RADIATION TRANSFER IN YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Whitney, B. A.; Honor, J.; Robitaille, T. P.; Bjorkman, J. E.; Dong, R.; Wolff, M. J.; Wood, K.

    2013-08-15

    We have updated our publicly available dust radiative transfer code (HOCHUNK3D) to include new emission processes and various three-dimensional (3D) geometries appropriate for forming stars. The 3D geometries include warps and spirals in disks, accretion hotspots on the central star, fractal clumping density enhancements, and misaligned inner disks. Additional axisymmetric (2D) features include gaps in disks and envelopes, ''puffed-up inner rims'' in disks, multiple bipolar cavity walls, and iteration of disk vertical structure assuming hydrostatic equilibrium (HSEQ). We include the option for simple power-law envelope geometry, which, combined with fractal clumping and bipolar cavities, can be used to model evolved stars as well as protostars. We include non-thermal emission from polycyclic aromatic hydrocarbons (PAHs) and very small grains, and external illumination from the interstellar radiation field. The grid structure was modified to allow multiple dust species in each cell; based on this, a simple prescription is implemented to model dust stratification. We describe these features in detail, and show example calculations of each. Some of the more interesting results include the following: (1) outflow cavities may be more clumpy than infalling envelopes. (2) PAH emission in high-mass stars may be a better indicator of evolutionary stage than the broadband spectral energy distribution slope; and related to this, (3) externally illuminated clumps and high-mass stars in optically thin clouds can masquerade as young stellar objects. (4) Our HSEQ models suggest that dust settling is likely ubiquitous in T Tauri disks, in agreement with previous observations.

  15. AmeriFlux US-Wi8 Young hardwood clearcut (YHW)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Chen, Jiquan [Michigan State University

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Wi8 Young hardwood clearcut (YHW). Site Description - The Wisconsin Clearcut Young Hardwood site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. The young hardwood clearcut site is one of ten sites that collectively represent the successional stages of development in the predominant stand types of a physically homogeneous landscape. In 2001, northern hardwood stands of all ages occupied 45% of the region.

  16. Peter (Jun Young) Ko > Project Scientist - CHESS > Researchers, Postdocs &

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Graduates > The Energy Materials Center at Cornell (Jun Young) Ko Project Scientist - CHESS jpk96@cornell.edu While he has never taken any formal courses in "synchrotron beamline science", Jun Young Peter Ko has worked on projects over the past 10 years that were clearly moving him towards expertise in the field. His current position at CHESS is "project scientist." Peter has played a key role in designing a new type of x-ray monochromator that provides uniquely

  17. AmeriFlux US-Me3 Metolius-second young aged pine

    SciTech Connect (OSTI)

    Law, Bev

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Me3 Metolius-second young aged pine. Site Description - This site is located on a Forest Service mensuration plot (various seed sources) that was planted in 1987. Deer browsing is prevented by a fence.

  18. EA-1974: Wallooskee-Youngs Confluence Restoration Project; Clatsop County, Oregon

    Broader source: Energy.gov [DOE]

    Bonneville Power Administration is preparing an EA to assess the potential environmental impacts of the proposed restoration of a tidal marsh in the Columbia River Estuary, near Astoria in Clatsop County, Oregon. The project website is https://www.bpa.gov/goto/WallooskeeYoungs.

  19. AmeriFlux US-Wi0 Young red pine (YRP)

    SciTech Connect (OSTI)

    Chen, Jiquan

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Wi0 Young red pine (YRP). Site Description - The Wisconsin Young Red Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Thinned every 7 years until they reach 100 to 150 years of age, the red pine plantations of all ages occupy approximately 25% of the region.

  20. AmeriFlux US-Wi5 Mixed young jack pine (MYJP)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Chen, Jiquan [Michigan State University

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Wi5 Mixed young jack pine (MYJP). Site Description - The Wisconsin Mixed Young Jack Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Clearcut on 40 to 70 year intervals, jack pine stands occupy approximately 13% of the region.

  1. AmeriFlux US-Wi9 Young Jack pine (YJP)

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Chen, Jiquan [Michigan State University

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Wi9 Young Jack pine (YJP). Site Description - The Wisconsin Young Jack Pine site is located in the Washburn Ranger District of the northeastern section of Chequamegon National Forest. A member of the northern coniferous-deciduous biome, surveys from the mid-19th century indicate the region consisted of a mixed stand of red, white, and jack pines. After extensive timber harvesting, wildfires, and farming activity, the region turned into a fragmented mosaic of stands of various ages and composition. As an assemblage, the ten Wisconsin sites are indicative of the successional stages of development in the predominant stand types of a physically homogeneous landscape. Clearcut on 40 to 70 year intervals, jack pine stands occupy approximately 13% of the region.

  2. AmeriFlux US-SO3 Sky Oaks- Young Stand

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Oechel, Walt [San Diego State University

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-SO3 Sky Oaks- Young Stand. Site Description - The Sky Oaks Young site is located near the Sky Oaks Field station, owned and operated by San Diego State University. Chaparral vegetation, associated with a Mediterranean climate, covers nearly half of the rough and rocky terrain. Precipitation is almost exclusively confined to the winter months. During the summer and early fall, hot and dry Santa Ana winds from the northeast bring desert heat to the site. A high intensity natural wildfire occurred in July of 2003. The stand age at the time of the wildfire was 10 years old, following a controlled burn in 1993.

  3. S M Stoller Pinellas Environmental Restoration Project - Young- Rainey Star Center

    Office of Legacy Management (LM)

    Pinellas Environmental Restoration Project - Young- Rainey Star Center 110406202 Accutest Job Number: F33039 Sampling Date: 07/06/05 Report to: S M Stoller Cathy.Kelleher@gjo.doe.gov ATTN: Cathy Kelleher Total number of pages in report: Certifications: FL (DOH E83510), NC (573), NJ (FL002), MA (FL946), IA (366), LA (03051), KS (E-10327), SC, AK This report shall not be reproduced, except in its entirety, without the written approval of Accutest Laboratories. Southeast * 4405 Vineland Road *

  4. BAYESIAN ANALYSIS TO IDENTIFY NEW STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS

    SciTech Connect (OSTI)

    Malo, Lison; Doyon, Rene; Lafreniere, David; Artigau, Etienne; Gagne, Jonathan; Baron, Frederique; Riedel, Adric E-mail: doyon@astro.umontreal.ca E-mail: artigau@astro.umontreal.ca E-mail: baron@astro.umontreal.ca

    2013-01-10

    We present a new method based on a Bayesian analysis to identify new members of nearby young kinematic groups. The analysis minimally takes into account the position, proper motion, magnitude, and color of a star, but other observables can be readily added (e.g., radial velocity, distance). We use this method to find new young low-mass stars in the {beta} Pictoris and AB Doradus moving groups and in the TW Hydrae, Tucana-Horologium, Columba, Carina, and Argus associations. Starting from a sample of 758 mid-K to mid-M (K5V-M5V) stars showing youth indicators such as H{alpha} and X-ray emission, our analysis yields 214 new highly probable low-mass members of the kinematic groups analyzed. One is in TW Hydrae, 37 in {beta} Pictoris, 17 in Tucana-Horologium, 20 in Columba, 6 in Carina, 50 in Argus, 32 in AB Doradus, and the remaining 51 candidates are likely young but have an ambiguous membership to more than one association. The false alarm rate for new candidates is estimated to be 5% for {beta} Pictoris and TW Hydrae, 10% for Tucana-Horologium, Columba, Carina, and Argus, and 14% for AB Doradus. Our analysis confirms the membership of 58 stars proposed in the literature. Firm membership confirmation of our new candidates will require measurement of their radial velocity (predicted by our analysis), parallax, and lithium 6708 A equivalent width. We have initiated these follow-up observations for a number of candidates, and we have identified two stars (2MASSJ01112542+1526214, 2MASSJ05241914-1601153) as very strong candidate members of the {beta} Pictoris moving group and one strong candidate member (2MASSJ05332558-5117131) of the Tucana-Horologium association; these three stars have radial velocity measurements confirming their membership and lithium detections consistent with young age.

  5. IDENTIFYING THE YOUNG LOW-MASS STARS WITHIN 25 pc. II. DISTANCES, KINEMATICS, AND GROUP MEMBERSHIP

    SciTech Connect (OSTI)

    Shkolnik, Evgenya L.; Anglada-Escude, Guillem; Liu, Michael C.; Bowler, Brendan P.; Weinberger, Alycia J.; Boss, Alan P.; Reid, I. Neill; Tamura, Motohide

    2012-10-10

    We have conducted a kinematic study of 165 young M dwarfs with ages of {approx}<300 Myr. Our sample is composed of stars and brown dwarfs with spectral types ranging from K7 to L0, detected by ROSAT and with photometric distances of {approx}<25 pc assuming that the stars are single and on the main sequence. In order to find stars kinematically linked to known young moving groups (YMGs), we measured radial velocities for the complete sample with Keck and CFHT optical spectroscopy and trigonometric parallaxes for 75 of the M dwarfs with the CAPSCam instrument on the du Pont 2.5 m Telescope. Due to their youthful overluminosity and unresolved binarity, the original photometric distances for our sample underestimated the distances by 70% on average, excluding two extremely young ({approx}<3 Myr) objects found to have distances beyond a few hundred parsecs. We searched for kinematic matches to 14 reported YMGs and identified 10 new members of the AB Dor YMG and 2 of the Ursa Majoris group. Additional possible candidates include six Castor, four Ursa Majoris, two AB Dor members, and one member each of the Her-Lyr and {beta} Pic groups. Our sample also contains 27 young low-mass stars and 4 brown dwarfs with ages {approx}<150 Myr that are not associated with any known YMG. We identified an additional 15 stars that are kinematic matches to one of the YMGs, but the ages from spectroscopic diagnostics and/or the positions on the sky do not match. These warn against grouping stars together based only on kinematics and that a confluence of evidence is required to claim that a group of stars originated from the same star-forming event.

  6. IDENTIFYING NEARBY, YOUNG, LATE-TYPE STARS BY MEANS OF THEIR CIRCUMSTELLAR DISKS

    SciTech Connect (OSTI)

    Schneider, Adam; Song, Inseok; Melis, Carl; Zuckerman, B.; Bessell, Mike E-mail: song@physast.uga.edu E-mail: ben@astro.ucla.edu

    2012-10-01

    It has recently been shown that a significant fraction of late-type members of nearby, very young associations (age {approx}<10 Myr) display excess emission at mid-IR wavelengths indicative of dusty circumstellar disks. We demonstrate that the detection of mid-IR excess emission can be utilized to identify new nearby, young, late-type stars including two definite new members ('TWA 33' and 'TWA 34') of the TW Hydrae Association (TWA). Both new TWA members display mid-IR excess emission in the Wide-field Infrared Survey Explorer catalog and they show proper motion and youthful spectroscopic characteristics-namely, H{alpha} emission, strong lithium absorption, and low surface gravity features consistent with known TWA members. We also detect mid-IR excess-the first unambiguous evidence of a dusty circumstellar disk-around a previously identified UV-bright, young, accreting star (2M1337) that is a likely member of the Lower-Centaurus Crux region of the Scorpius-Centaurus Complex.

  7. Radiation-driven warping of circumbinary disks around eccentric young star binaries

    SciTech Connect (OSTI)

    Hayasaki, Kimitake; Sohn, Bong Won; Jung, Taehyun; Zhao, Guangyao; Okazaki, Atsuo T.; Naito, Tsuguya

    2014-12-10

    We study a warping instability of a geometrically thin, non-self-gravitating, circumbinary disk around young binary stars on an eccentric orbit. Such a disk is subject to both the tidal torques due to a time-dependent binary potential and the radiative torques due to radiation emitted from each star. The tilt angle between the circumbinary disk plane and the binary orbital plane is assumed to be very small. We find that there is a radius within/beyond which the circumbinary disk is unstable to radiation-driven warping, depending on the disk density and temperature gradient indices. This marginally stable warping radius is very sensitive to viscosity parameters, a fiducial disk radius and the temperature measured there, the stellar luminosity, and the disk surface density at a radius where the disk changes from optically thick to thin for the irradiation from the central stars. On the other hand, it is insensitive to the orbital eccentricity and binary irradiation parameter, which is a function of the binary mass ratio and luminosity of each star. Since the tidal torques can suppress the warping in the inner part of the circumbinary disk, the disk starts to be warped in the outer part. While the circumbinary disks are most likely to be subject to the radiation-driven warping on an AU to kilo-AU scale for binaries with young massive stars more luminous than 10{sup 4} L {sub ?}, the radiation-driven warping does not work for those around young binaries with the luminosity comparable to the solar luminosity.

  8. S M Stoller Pinellas Environmental Restoration Project - Young - Rainey Star Center

    Office of Legacy Management (LM)

    Young - Rainey Star Center 110406202 Accutest Job Number: F35489 Sampling Date: 10/05/05 Report to: S M Stoller Cathy.Kelleher@gjo.doe.gov ATTN: Cathy Kelleher Total number of pages in report: Certifications: FL (DOH E83510), NC (573), NJ (FL002), MA (FL946), IA (366), LA (03051), KS (E-10327), SC, AK This report shall not be reproduced, except in its entirety, without the written approval of Accutest Laboratories. Southeast * 4405 Vineland Road * Suite C-15 * Orlando, FL 32811 * tel:

  9. S M Stoller Pinellas Environmental Restoration Project - Young - Rainey Star Center

    Office of Legacy Management (LM)

    Young - Rainey Star Center 110406202 Accutest Job Number: F30886 Sampling Date: 04/06/05 Report to: S M Stoller Cathy.Kelleher@gjo.doe.gov ATTN: Cathy Kelleher Total number of pages in report: Certifications: FL (DOH E83510), NC (573), NJ (FL002), MA (FL946), IA (366), LA (03051), KS (E-10327), SC, AK This report shall not be reproduced, except in its entirety, without the written approval of Accutest Laboratories. Southeast * 4405 Vineland Road * Suite C-15 * Orlando, FL 32811 * tel:

  10. S M Stoller Pinellas Environmental Restoration Project - Young - Rainey Star Center

    Office of Legacy Management (LM)

    6/06 Technical Report for S M Stoller Pinellas Environmental Restoration Project - Young - Rainey Star Center 110406202 Accutest Job Number: F43553 Sampling Date: 09/07/06 Report to: U.S. Dept of Energy, Grand Jct Office 2597 B 3/4 Road Grand Juction, CO 81503 ATTN: Contracts Department, PO# 24231 x Total number of pages in report: Certifications: FL (DOH E83510), NC (573), NJ (FL002), MA (FL946), IA (366), LA (03051), KS (E-10327), SC, AK This report shall not be reproduced, except in its

  11. S M Stoller Pinellas Environmental Restoration Project - Young- Rainey Star Center

    Office of Legacy Management (LM)

    Pinellas Environmental Restoration Project - Young- Rainey Star Center 7030-226 Accutest Job Number: F29125 Sampling Date: 01/06/05 Report to: S M Stoller Cathy.Kelleher@gjo.doe.gov ATTN: Cathy Kelleher Total number of pages in report: Certifications: FL (DOH E83510), NC (573), NJ (FL002), MA (FL946), IA (366), LA (03051), KS (E-10327), SC, AK This report shall not be reproduced, except in its entirety, without the written approval of Accutest Laboratories. Southeast * 4405 Vineland Road * Suite

  12. Sitewide Environmental Monitoring Quarterly Progress Report for the Young-Rainy STAR Center

    Office of Legacy Management (LM)

    2-TAC GJO-PIN 11.6.2 Pinellas Environmental Restoration Project January through March 2003 Sitewide Environmental Monitoring Quarterly Progress Report for the Young-Rainey STAR Center April 2003 Grand Junction Office Grand Junction Office Grand Junction Office U.S. Department of Energy Work Performed Under DOE Contract No. for the U.S. Department of Energy DE-AC13-02GJ79491 Approved for public release; distribution is unlimited. N0060700 GJO-2003-432-TAC GJO-PIN 11.6.2 Pinellas Environmental

  13. AmeriFlux US-Me5 Metolius-first young aged pine

    SciTech Connect (OSTI)

    Law, Bev

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Me5 Metolius-first young aged pine. Site Description - Previously old-growth ponderosa pine, clearcut in 1978 and allowed to regenerate naturally. Law et al (2001) Global Change Biology 7, 755-777; Law et al (2001) Agricultural and Forest Meteorology 110, 27-43; Anthoni et al (2002) Agricultural and Forest Meteorology 111, 203-222; Irvine & Law (2002) Global Change biology 8,1183-1194, Irivne et al (2004) Tree Physiology 24,753-763.

  14. YOUNG STARS IN AN OLD BULGE: A NATURAL OUTCOME OF INTERNAL EVOLUTION IN THE MILKY WAY

    SciTech Connect (OSTI)

    Ness, M.; Debattista, Victor P.; Cole, D. R.; Bensby, T.; Feltzing, S.; Roškar, R.; Johnson, J. A.; Freeman, K.

    2014-06-01

    The center of our disk galaxy, the Milky Way, is dominated by a boxy/peanut-shaped bulge. Numerous studies of the bulge based on stellar photometry have concluded that the bulge stars are exclusively old. The perceived lack of young stars in the bulge strongly constrains its likely formation scenarios, providing evidence that the bulge is a unique population that formed early and separately from the disk. However, recent studies of individual bulge stars using the microlensing technique have reported that they span a range of ages, emphasizing that the bulge may not be a monolithic structure. In this Letter we demonstrate that the presence of young stars that are located predominantly nearer to the plane is expected for a bulge that has formed from the disk via dynamical instabilities. Using an N-body+ smoothed particle hydrodynamics simulation of a disk galaxy forming out of gas cooling inside a dark matter halo and forming stars, we find a qualitative agreement between our model and the observations of younger metal-rich stars in the bulge. We are also able to partially resolve the apparent contradiction in the literature between results that argue for a purely old bulge population and those that show a population comprised of a range in ages; the key is where to look.

  15. Modeling tracers of young stellar population age in star-forming galaxies

    SciTech Connect (OSTI)

    Levesque, Emily M.; Leitherer, Claus

    2013-12-20

    The young stellar population of a star-forming galaxy is the primary engine driving its radiative properties. As a result, the age of a galaxy's youngest generation of stars is critical for a detailed understanding of its star formation history, stellar content, and evolutionary state. Here we present predicted equivalent widths for the H?, H?, and Br? recombination lines as a function of stellar population age. The equivalent widths are produced by the latest generations of stellar evolutionary tracks and the Starburst99 stellar population synthesis code, and are the first to fully account for the combined effects of both nebular emission and continuum absorption produced by the synthetic stellar population. Our grid of model stellar populations spans six metallicities (0.001 < Z < 0.04), two treatments of star formation history (a 10{sup 6} M {sub ?} instantaneous burst and a continuous star formation rate of 1 M {sub ?} yr{sup 1}), and two different treatments of initial rotation rate (v {sub rot} = 0.0v {sub crit} and 0.4v {sub crit}). We also investigate the effects of varying the initial mass function. Given constraints on galaxy metallicity, our predicted equivalent widths can be applied to observations of star-forming galaxies to approximate the age of their young stellar populations.

  16. Recollimation boundary layers as X-ray sources in young stellar jets

    SciTech Connect (OSTI)

    Gnther, Hans Moritz; Li, Zhi-Yun; Schneider, P. C.

    2014-11-01

    Young stars accrete mass from circumstellar disks and, in many cases, the accretion coincides with a phase of massive outflows, which can be highly collimated. Those jets emit predominantly in the optical and IR wavelength range. However, in several cases, X-ray and UV observations reveal a weak but highly energetic component in those jets. X-rays are observed both from stationary regions close to the star and from knots in the jet several hundred AU from the star. In this article, we show semianalytically that a fast stellar wind that is recollimated by the pressure from a slower, more massive disk wind can have the right properties to power stationary X-ray emission. The size of the shocked regions is compatible with observational constraints. Our calculations support a wind-wind interaction scenario for the high-energy emission near the base of young stellar object jets. For the specific case of DG Tau, a stellar wind with a mass-loss rate of 5 10{sup 10} M {sub ?} yr{sup 1} and a wind speed of 800 km s{sup 1} reproduces the observed X-ray spectrum. We conclude that a stellar wind recollimation shock is a viable scenario to power stationary X-ray emission close to the jet launching point.

  17. Discovery of the young L dwarf wise J174102.78-464225.5

    SciTech Connect (OSTI)

    Schneider, Adam C.; Cushing, Michael C.; Kirkpatrick, J. Davy; Mace, Gregory N.; Gelino, Christopher R.; Fajardo-Acosta, Sergio; Faherty, Jacqueline K.; Sheppard, Scott S.

    2014-02-01

    We report the discovery of the L dwarf WISE J174102.78464225.5, which was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its near-infrared spectrum and its red near-infrared colors (J K{sub S} = 2.35 0.08 mag) are indicative of a young age. Via comparison to spectral standards and other red L dwarfs, we estimate a near-infrared spectral type of L7 2 (pec). From a comparison to spectral and low-mass evolutionary models, we determine self-consistent effective temperature, log g, age, and mass values of 1450 100 K, 4.0 0.25 (cm s{sup 2}), 10-100 Myr, and 4-21 M {sub Jup}, respectively. With an estimated distance of 10-30 pc, we explore the possibility that WISE J174102.78464225.5 belongs to one of the young nearby moving groups via a kinematic analysis and we find potential membership in the ? Pictoris or AB Doradus associations. A trigonometric parallax measurement and a precise radial velocity can help to secure its membership in either of these groups.

  18. YOUNG PLANETARY NEBULAE: HUBBLE SPACE TELESCOPE IMAGING AND A NEW MORPHOLOGICAL CLASSIFICATION SYSTEM

    SciTech Connect (OSTI)

    Sahai, Raghvendra; Villar, Gregory G.; Morris, Mark R.

    2011-04-15

    Using Hubble Space Telescope images of 119 young planetary nebulae (PNs), most of which have not previously been published, we have devised a comprehensive morphological classification system for these objects. This system generalizes a recently devised system for pre-planetary nebulae, which are the immediate progenitors of PNs. Unlike previous classification studies, we have focused primarily on young PNs rather than all PNs, because the former best show the influences or symmetries imposed on them by the dominant physical processes operating at the first and primary stage of the shaping process. Older PNs develop instabilities, interact with the ambient interstellar medium, and are subject to the passage of photoionization fronts, all of which obscure the underlying symmetries and geometries imposed early on. Our classification system is designed to suffer minimal prejudice regarding the underlying physical causes of the different shapes and structures seen in our PN sample, however, in many cases, physical causes are readily suggested by the geometry, along with the kinematics that have been measured in some systems. Secondary characteristics in our system, such as ansae, indicate the impact of a jet upon a slower-moving, prior wind; a waist is the signature of a strong equatorial concentration of matter, whether it be outflowing or in a bound Keplerian disk, and point symmetry indicates a secular trend, presumably precession, in the orientation of the central driver of a rapid, collimated outflow.

  19. SPIN EVOLUTION OF ACCRETING YOUNG STARS. II. EFFECT OF ACCRETION-POWERED STELLAR WINDS

    SciTech Connect (OSTI)

    Matt, Sean P.; Greene, Thomas P.; Pudritz, Ralph E. E-mail: thomas.p.greene@nasa.gov E-mail: pudritz@physics.mcmaster.ca

    2012-01-20

    We present a model for the rotational evolution of a young, solar-mass star interacting magnetically with an accretion disk. As in a previous paper (Paper I), the model includes changes in the star's mass and radius as it descends the Hayashi track, a decreasing accretion rate, and a prescription for the angular momentum transfer between the star and disk. Paper I concluded that, for the relatively strong magnetic coupling expected in real systems, additional processes are necessary to explain the existence of slowly rotating pre-main-sequence stars. In the present paper, we extend the stellar spin model to include the effect of a spin-down torque that arises from an accretion-powered stellar wind (APSW). For a range of magnetic field strengths, accretion rates, initial spin rates, and mass outflow rates, the modeled stars exhibit rotation periods within the range of 1-10 days in the age range of 1-3 Myr. This range coincides with the bulk of the observed rotation periods, with the slow rotators corresponding to stars with the lowest accretion rates, strongest magnetic fields, and/or highest stellar wind mass outflow rates. We also make a direct, quantitative comparison between the APSW scenario and the two types of disk-locking models (namely, the X-wind and Ghosh and Lamb type models) and identify some remaining theoretical issues for understanding young star spins.

  20. Detection of water masers toward young stellar objects in the Large Magellanic Cloud

    SciTech Connect (OSTI)

    Johanson, A. K.; Migenes, V.; Breen, S. L.

    2014-02-01

    We present results from a search for water maser emission toward N4A, N190, and N206, three regions of massive star formation in the Large Magellanic Cloud (LMC). Four water masers were detected; two toward N4A, and two toward N190. In the latter region, no previously known maser emission has been reported. Future studies of maser proper motion to determine the galactic dynamics of the LMC will benefit from the independent data points the new masers in N190 provide. Two of these masers are associated with previously identified massive young stellar objects (YSOs), which strongly supports the authenticity of the classification. We argue that the other two masers identify previously unknown YSOs. No masers were detected toward N206, but it does host a newly discovered 22 GHz continuum source, also associated with a massive YSO. We suggest that future surveys for water maser emission in the LMC be targeted toward the more luminous, massive YSOs.

  1. Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager

    SciTech Connect (OSTI)

    Macintosh, B.; Graham, J. R.; Barman, T.; De Rosa, R. J.; Konopacky, Q.; Marley, M. S.; Marois, C.; Nielsen, E. L.; Pueyo, L.; Rajan, A.; Rameau, J.; Saumon, D.; Wang, J. J.; Patience, J.; Ammons, M.; Arriaga, P.; Artigau, E.; Beckwith, S.; Brewster, J.; Bruzzone, S.; Bulger, J.; Burningham, B.; Burrows, A. S.; Chen, C.; Chiang, E.; Chilcote, J. K.; Dawson, R. I.; Dong, R.; Doyon, R.; Draper, Z. H.; Duchene, G.; Esposito, T. M.; Fabrycky, D.; Fitzgerald, M. P.; Follette, K. B.; Fortney, J. J.; Gerard, B.; Goodsell, S.; Greenbaum, A. Z.; Hibon, P.; Hinkley, S.; Cotten, T. H.; Hung, L. -W.; Ingraham, P.; Johnson-Groh, M.; Kalas, P.; Lafreniere, D.; Larkin, J. E.; Lee, J.; Line, M.; Long, D.; Maire, J.; Marchis, F.; Matthews, B. C.; Max, C. E.; Metchev, S.; Millar-Blanchaer, M. A.; Mittal, T.; Morley, C. V.; Morzinski, K. M.; Murray-Clay, R.; Oppenheimer, R.; Palmer, D. W.; Patel, R.; Perrin, M. D.; Poyneer, L. A.; Rafikov, R. R.; Rantakyro, F. T.; Rice, E. L.; Rojo, P.; Rudy, A. R.; Ruffio, J. -B.; Ruiz, M. T.; Sadakuni, N.; Saddlemyer, L.; Salama, M.; Savransky, D.; Schneider, A. C.; Sivaramakrishnan, A.; Song, I.; Soummer, R.; Thomas, S.; Vasisht, G.; Wallace, J. K.; Ward-Duong, K.; Wiktorowicz, S. J.; Wolff, S. G.; Zuckerman, B.

    2015-10-02

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10–6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twice that of Jupiter. As a result, this planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.

  2. MAGNETIC FIELD STRUCTURE IN THE FLATTENED ENVELOPE AND JET IN THE YOUNG PROTOSTELLAR SYSTEM HH 211

    SciTech Connect (OSTI)

    Lee, Chin-Fei; Rao, Ramprasad; Hirano, Naomi; Ho, Paul T. P.; Hwang, Hsiang-Chih; Ching, Tao-Chung; Lai, Shih-Ping

    2014-12-10

    HH 211 is a young Class 0 protostellar system with a flattened envelope, a possible rotating disk, and a collimated jet. We have mapped it with the Submillimeter Array in the 341.6 GHz continuum and SiO J = 8-7 at ∼0.''6 resolution. The continuum traces the thermal dust emission in the flattened envelope and the possible disk. Linear polarization is detected in the continuum in the flattened envelope. The field lines implied from the polarization have different orientations, but they are not incompatible with current gravitational collapse models, which predict a different orientation depending on the region/distance. Also, we might have detected for the first time polarized SiO line emission in the jet due to the Goldreich-Kylafis effect. Observations at higher sensitivity are needed to determine the field morphology in the jet.

  3. AmeriFlux US-Me6 Metolius Young Pine Burn

    SciTech Connect (OSTI)

    Law, Bev

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Me6 Metolius Young Pine Burn. Site Description - The study site is located east of the Cascade mountains, near Sisters, Central Oregon and is part of the Metolius cluster sites with different age and disturbance classes within the AmeriFlux network. After a severe fire in 1979, the site was salvage logged, was acquired by the US Forest Service land and re-forested in 1990. The dominant overstory vegetation are 20-year old ponderosa pine trees with an average height of 5.2 +/- 1.1 m. The season maximum overstory half-sided LAI was 0.6 m2 m-2 in 2010. Tree density is low, with ca. 162 trees ha-1.

  4. Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Macintosh, B.; Graham, J. R.; Barman, T.; De Rosa, R. J.; Konopacky, Q.; Marley, M. S.; Marois, C.; Nielsen, E. L.; Pueyo, L.; Rajan, A.; et al

    2015-10-02

    Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10–6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twicemore » that of Jupiter. As a result, this planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.« less

  5. Radon Laboratory: A Proposal for Scientific Culture Dissemination Among Young Students in Italy

    SciTech Connect (OSTI)

    Groppi, Flavia; Manenti, Simone; Gini, Luigi; Bonardi, Mauro L.; Bazzocchi, Anna

    2009-08-19

    In Italy the 'nuclear issue' was for a long time a taboo. A way to approach this theme to make the public more trusting of nuclear issues is to discuss radioactivity and ionizing radiation starting from young students. An experimental activity that involves secondary school students has been developed. The approach is to have students engaged in activities that will allow them to understand how natural radioactivity is a part of our everyday environment. This would include how radiation enters our lives in different ways, to demonstrate that natural radioactive sources found in soil, water, and air contribute to our exposure to natural ionizing radiation and how this exposure effects human health. Another objective is to develop a new technique for teaching physics which will enhance scientific interest of students in applications of nuclear physics in both environmental and physical sciences.

  6. Economic Development Activities at the Young - Rainey Science, Technology, & Research (STAR) Center

    SciTech Connect (OSTI)

    Paul S. Sacco; Carl Smeigh; John Caponiti, Jr.

    2008-06-30

    Project mission was to mitigate the adverse economic effects of closing the U.S. Department of Energy's Pinellas Plant in Largo, Florida. This project was to facilitate the physical renovation of the plant and to help maintain and create jobs for the employees that worked at the plant when DOE terminated its operations. It also included finding and attracting high technology, industrial manufacturing and related firms to utilize the space and high tech equipment to remain at the plant. Stakeholders included the affected plant employees, local government and related public organizations, and businesses and universities in the Tampa Bay Florida area. The $17.6 million funded for this project helped produce 2,780 jobs at the Young - Rainey STAR Center at an average cost of $6,328. Rental income from STAR Center tenants and third party cash input amounted to approximately $66 million over the project period of 13.3 years.

  7. Effects of turbulence on cosmic ray propagation in protostars and young star/disk systems

    SciTech Connect (OSTI)

    Fatuzzo, Marco; Adams, Fred C. E-mail: fca@umich.edu

    2014-05-20

    The magnetic fields associated with young stellar objects are expected to have an hour-glass geometry, i.e., the magnetic field lines are pinched as they thread the equatorial plane surrounding the forming star but merge smoothly onto a background field at large distances. With this field configuration, incoming cosmic rays experience both a funneling effect that acts to enhance the flux impinging on the circumstellar disk and a magnetic mirroring effect that acts to reduce that flux. To leading order, these effects nearly cancel out for simple underlying magnetic field structures. However, the environments surrounding young stellar objects are expected to be highly turbulent. This paper shows how the presence of magnetic field fluctuations affects the process of magnetic mirroring, and thereby changes the flux of cosmic rays striking circumstellar disks. Turbulence has two principle effects: (1) the (single) location of the magnetic mirror point found in the absence of turbulence is replaced with a wide distribution of values. (2) The median of the mirror point distribution moves outward for sufficiently large fluctuation amplitudes (roughly when ?B/B {sub 0} > 0.2 at the location of the turbulence-free mirror point); the distribution becomes significantly non-Gaussian in this regime as well. These results may have significant consequences for the ionization fraction of the disk, which in turn dictates the efficiency with which disk material can accrete onto the central object. A similar reduction in cosmic ray flux can occur during the earlier protostellar stages; the decrease in ionization can help alleviate the magnetic braking problem that inhibits disk formation.

  8. THE YOUNG STELLAR OBJECT POPULATION IN THE VELA-D MOLECULAR CLOUD

    SciTech Connect (OSTI)

    Strafella, F.; Maruccia, Y.; Maiolo, B.; Lorenzetti, D.; Giannini, T.; Elia, D.; Molinari, S.; Pezzuto, S.; Massi, F.; Olmi, L.

    2015-01-10

    We investigate the young stellar population in the Vela Molecular Ridge, Cloud-D, a star-forming region observed by both the Spitzer/NASA and Herschel/ESA space telescopes. The point-source, band-merged, Spitzer-IRAC catalog complemented with MIPS photometry previously obtained is used to search for candidate young stellar objects (YSOs), also including sources detected in less than four IRAC bands. Bona fide YSOs are selected by using appropriate color-color and color-magnitude criteria aimed at excluding both Galactic and extragalactic contaminants. The derived star formation rate and efficiency are compared with the same quantities characterizing other star-forming clouds. Additional photometric data, spanning from the near-IR to the submillimeter, are used to evaluate both bolometric luminosity and temperature for 33 YSOs located in a region of the cloud observed by both Spitzer and Herschel. The luminosity-temperature diagram suggests that some of these sources are representative of Class 0 objects with bolometric temperatures below 70 K and luminosities of the order of the solar luminosity. Far-IR observations from the Herschel/Hi-GAL key project for a survey of the Galactic plane are also used to obtain a band-merged photometric catalog of Herschel sources intended to independently search for protostars. We find 122 Herschel cores located on the molecular cloud, 30 of which are protostellar and 92 of which are starless. The global protostellar luminosity function is obtained by merging the Spitzer and Herschel protostars. Considering that 10 protostars are found in both the Spitzer and Herschel lists, it follows that in the investigated region we find 53 protostars and that the Spitzer-selected protostars account for approximately two-thirds of the total.

  9. A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS

    SciTech Connect (OSTI)

    Gutermuth, R. A.; Pipher, J. L.; Megeath, S. T.; Allen, T. S.; Myers, P. C.; Allen, L. E.

    2011-10-01

    We report the discovery and characterization of a power-law correlation between the local surface densities of Spitzer-identified, dusty young stellar objects (YSOs) and the column density of gas (as traced by near-IR extinction) in eight molecular clouds within 1 kpc and with 100 or more known YSOs. This correlation, which appears in data smoothed over size scales of {approx}1 pc, varies in quality from cloud to cloud; those clouds with tight correlations, MonR2 and Ophiuchus, are fit with power laws of slope 2.67 and 1.87, respectively. The spread in the correlation is attributed primarily to local gas disruption by stars that formed there or to the presence of very young subregions at the onset of star formation. We explore the ratio of the number of Class II to Class I sources, a proxy for the star formation age of a region, as a function of gas column density; this analysis reveals a declining Class II to Class I ratio with increasing column density. We show that the observed star-gas correlation is consistent with a star formation law where the star formation rate per area varies with the gas column density squared. We also propose a simple picture of thermal fragmentation of dense gas in an isothermal, self-gravitating layer as an explanation for the power law. Finally, we briefly compare the star-gas correlation and its implied star formation law with other recent proposed of star formation laws at similar and larger size scales from nearby star-forming regions.

  10. CSI 2264: characterizing accretion-burst dominated light curves for young stars in NGC 2264

    SciTech Connect (OSTI)

    Stauffer, John; Cody, Ann Marie; Rebull, Luisa; Carey, Sean; Baglin, Annie; Alencar, Silvia; Hillenbrand, Lynne A.; Carpenter, John; Findeisen, Krzysztof; Venuti, Laura; Bouvier, Jerome; Plavchan, Peter; Terebey, Susan; Morales-Caldern, Mara; Micela, Giusi; Flaccomio, Ettore; Song, Inseok; Gutermuth, Rob; Hartmann, Lee; and others

    2014-04-01

    Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many briefseveral hours to one daybrightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u g versus g r color-color diagram with the largest UV excesses. These stars also have large H? equivalent widths, and either centrally peaked, lumpy H? emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest H? equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.

  11. Jet emission in young radio sources: A Fermi large area telescope gamma-ray view

    SciTech Connect (OSTI)

    Migliori, G.; Siemiginowska, A.; Kelly, B. C.; Stawarz, ?.; Celotti, A.; Begelman, M. C.

    2014-01-10

    We investigate the contribution of the beamed jet component to the high-energy emission in young and compact extragalactic radio sources, focusing for the first time on the ?-ray band. We derive predictions on the ?-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high-energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales (?10 kpc). Simulations show a wide range of ?-ray luminosities, with intensities up to ?10{sup 46}-10{sup 48} erg s{sup 1} depending on the assumed jet parameters. We find a highly linear relation between the simulated X-ray and ?-ray luminosities that can be used to select candidates for ?-ray detection. We compare the simulated luminosity distributions in the radio, X-ray, and ?-ray regimes with observations for the largest sample of X-ray-detected young radio quasars. Our analysis of ?4-yr Fermi Large Area Telescope (LAT) data does not yield any statistically significant detections. However, the majority of the model-predicted ?-ray fluxes for the sample are near or below the current Fermi-LAT flux threshold and compatible with the derived upper limits. Our study gives constraints on the minimum jet power (L {sub jet,} {sub kin}/L {sub disk} > 0.01) of a potential jet contribution to the X-ray emission in the most compact sources (? 1 kpc) and on the particle-to-magnetic field energy density ratio that are in broad agreement with equipartition assumptions.

  12. ORIGIN OF THE UNUSUALLY LOW NITROGEN ABUNDANCES IN YOUNG POPULATIONS OF THE LARGE MAGELLANIC CLOUD

    SciTech Connect (OSTI)

    Bekki, Kenji [ICRAR, M468, University of Western Australia, 35 Stirling Highway, Crawley Western Australia 6009 (Australia); Tsujimoto, Takuji [National Astronomical Observatory, Mitaka-shi, Tokyo 181-8588 (Japan)

    2010-10-01

    It is a longstanding problem that H II regions and very young stellar populations in the Large Magellanic Cloud (LMC) have nitrogen abundances ([N/H]) that are a factor of {approx}7 lower than the solar value. We here discuss a new scenario in which the observed unusually low nitrogen abundances can be closely associated with recent collisions and subsequent accretion of H I high velocity clouds (HVCs) that surround the Galaxy and have low nitrogen abundances. We show that if the observed low [N/H] is limited to very young stars with ages less than {approx}10{sup 7} yr, then the collision/accretion rate of the HVCs onto the LMC needs to be {approx}0.2 M{sub sun} yr{sup -1} (corresponding to the total HVC mass of 10{sup 6}-10{sup 7} M{sub sun}) to dilute the original interstellar medium (ISM) before star formation. The required accretion rate means that even if the typical mass of HVCs accreted onto the LMC is {approx}10{sup 7} M{sub sun}, the Galaxy needs to have {approx}2500 massive HVCs within the LMC's orbital radius with respect to the Galactic center. The rather large number of required massive HVCs drives us to suggest that the HVCs are not likely to efficiently dilute the ISM of the LMC and consequently lower the [N/H]. We thus suggest the transfer of gas with low [N/H] from the Small Magellanic Cloud to the LMC as a promising scenario that can explain the observed low [N/H].

  13. M-dwarf rapid rotators and the detection of relatively young multiple M-star systems

    SciTech Connect (OSTI)

    Rappaport, S.; Joss, M.; Sanchis-Ojeda, R. E-mail: mattjoss@mit.edu; and others

    2014-06-20

    We have searched the Kepler light curves of ?3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, 'sonograms', and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, P {sub rot}, of <2 days, and 110 with P {sub rot} < 1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have 3 or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M stars, this could prove a valuable way discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ?5% occurrence rate of rapid rotation among the ?3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days.

  14. TENTATIVE EVIDENCE FOR RELATIVISTIC ELECTRONS GENERATED BY THE JET OF THE YOUNG SUN-LIKE STAR DG Tau

    SciTech Connect (OSTI)

    Ainsworth, Rachael E.; Ray, Tom P.; Taylor, Andrew M.; Scaife, Anna M. M.; Green, David A.; Buckle, Jane V.

    2014-09-01

    Synchrotron emission has recently been detected in the jet of a massive protostar, providing further evidence that certain jet formation characteristics for young stars are similar to those found for highly relativistic jets from active galactic nuclei. We present data at 325 and 610MHz taken with the Giant Metrewave Radio Telescope of the young, low-mass star DG Tau, an analog of the Sun soon after its birth. This is the first investigation of a low-mass young stellar object at such low frequencies. We detect emission with a synchrotron spectral index in the proximity of the DG Tau jet and interpret this emission as a prominent bow shock associated with this outflow. This result provides tentative evidence for the acceleration of particles to relativistic energies due to the shock impact of this otherwise very low-power jet against the ambient medium. We calculate the equipartition magnetic field strength B {sub min} ? 0.11mG and particle energy E {sub min} ? 4 10{sup 40}erg, which are the minimum requirements to account for the synchrotron emission of the DG Tau bow shock. These results suggest the possibility of low energy cosmic rays being generated by young Sun-like stars.

  15. OBSERVED LUMINOSITY SPREAD IN YOUNG CLUSTERS AND FU Ori STARS: A UNIFIED PICTURE

    SciTech Connect (OSTI)

    Baraffe, I.; Chabrier, G.; Vorobyov, E. E-mail: eduard.vorobiev@univie.ac.at

    2012-09-10

    The idea that non-steady accretion during the embedded phase of protostar evolution can produce the observed luminosity spread in the Herzsprung-Russell diagram (HRD) of young clusters has recently been called into question. Observations of FU Ori, for instance, suggest an expansion of the star during strong accretion events, whereas the luminosity spread implies a contraction of the accreting objects, decreasing their radiating surface. In this paper, we present a global scenario based on calculations coupling episodic accretion histories derived from numerical simulations of collapsing cloud prestellar cores of various masses and subsequent protostar evolution. Our calculations show that, assuming an initial protostar mass M{sub i} {approx} 1 M{sub Jup}, typical of the second Larson's core, both the luminosity spread in the HRD and the inferred properties of FU Ori events (mass, radius, accretion rate) can be explained by this scenario, providing two conditions. First, there must be some variation within the fraction of accretion energy absorbed by the protostar during the accretion process. Second, the range of this variation should increase with increasing accretion burst intensity and thus with the initial core mass and final star mass. The numerical hydrodynamics simulations of collapsing cloud prestellar cores indeed show that the intensity of the accretion bursts correlates with the mass and initial angular momentum of the prestellar core. Massive prestellar cores with high initial angular momentum are found to produce intense bursts characteristic of FU Ori-like events. Our results thus suggest a link between the burst intensities and the fraction of accretion energy absorbed by the protostar, with some threshold in the accretion rate, of the order of 10{sup -5} M{sub Sun} yr{sup -1}, delimitating the transition from 'cold' to 'hot' accretion. Such a transition might reflect a change in the accretion geometry with increasing accretion rate, i.e., a

  16. STAR FORMATION AND YOUNG POPULATION OF THE H II COMPLEX Sh2-294

    SciTech Connect (OSTI)

    Samal, M. R.; Pandey, A. K.; Chauhan, N.; Jose, J.; Ojha, D. K.; Pandey, B.

    2012-08-10

    The Sh2-294 H II region ionized by a single B0V star features several infrared excess sources, a photodissociation region, and also a group of reddened stars at its border. The star formation scenario in this region seems to be quite complex. In this paper, we present follow-up results of Sh2-294 H II region at 3.6, 4.5, 5.8, and 8.0 {mu}m observed with the Spitzer Space Telescope Infrared Array Camera (IRAC), coupled with H{sub 2} (2.12 {mu}m) observation, to characterize the young population of the region and to understand its star formation history. We identified 36 young stellar object (YSO, Class I, Class II, and Class I/II) candidates using IRAC color-color diagrams. It is found that Class I sources are preferentially located at the outskirts of the H II region and associated with enhanced H{sub 2} emission; none of them are located near the central cluster. Combining the optical to mid-infrared (MIR) photometry of the YSO candidates and using the spectral energy distribution fitting models, we constrained stellar parameters and the evolutionary status of 33 YSO candidates. Most of them are interpreted by the model as low-mass (<4 M{sub Sun }) YSOs; however, we also detected a massive YSO ({approx}9 M{sub Sun }) of Class I nature, embedded in a cloud of visual extinction of {approx}24 mag. Present analysis suggests that the Class I sources are indeed a younger population of the region relative to Class II sources (age {approx} 4.5 Multiplication-Sign 10{sup 6} yr). We suggest that the majority of the Class I sources, including the massive YSOs, are second-generation stars of the region whose formation is possibly induced by the expansion of the H II region powered by a {approx}4 Multiplication-Sign 10{sup 6} yr B0 main-sequence star.

  17. OUTFLOWS AND YOUNG STARS IN ORION'S LARGE COMETARY CLOUDS L1622 AND L1634

    SciTech Connect (OSTI)

    Bally, John; Walawender, Josh; Reipurth, Bo; Megeath, S. Thomas E-mail: joshw@ifa.hawaii.edu E-mail: megeath@physics.utoledo.edu

    2009-04-15

    New observations of protostellar outflows associated with young stars in two of Orion's outlying cometary clouds, L1622 and L1634, are presented. The H{alpha} surface brightness of the bright rims are used to argue that both clouds are located at a distance of about 400 pc in the interior of the Orion superbubble where they are illuminated by Orion's massive stars. Spitzer IRAC and MIPS images reveal 28 candidate young stellar objects (YSOs). Combined with the 14 spectroscopically confirmed T Tauri stars, there are at least 34 YSOs in L1622. Narrow-band images have led to the identification of about a dozen shock complexes in L1622. At least six belong to a highly collimated externally irradiated, bipolar jet, HH 963, that is powered by a low-luminosity Class II YSO located outside the projected edge of the L1622 dark cloud. However, the sources of most shocks remain unclear. The Spitzer/IRAC images reveal a compact, highly obscured, S-symmetric outflow brightest in the 4.5 {mu}m images. A faint [S II] counter part, HH 962, is associated with the western end of this flow which appears to be powered by an obscured source in the L1622 cloud interior. The currently identified sample of YSOs implies a star formation efficiency of about 4% for L1622. The L1634 cloud contains nine YSOs and three outflows, including the well known HH 240/241 system. A new flow, HH 979, is powered by the embedded YSO IRS7 in L1634 and crosses the eastern lobe of the HH 240 outflow. Spitzer/IRAC images show 4.5 {mu}m emission indicating molecular shocks from the Herbig-Haro objects closest to IRS 7. A YSO embedded in a condensation located 5' north of HH 240/241 is identified in the Spitzer images. This source drives an irradiated outflow, HH 980, whose lobes emerge into the ionized environment of the Orion-Eridanus superbubble interior. The star formation efficiency of L1634 is estimated to be about 3%.

  18. TRIGGERED STAR FORMATION AND YOUNG STELLAR POPULATION IN BRIGHT-RIMMED CLOUD SFO 38

    SciTech Connect (OSTI)

    Choudhury, Rumpa; Bhatt, H. C.; Mookerjea, Bhaswati E-mail: hcbhatt@iiap.res.i

    2010-07-10

    We have investigated the young stellar population in and around SFO 38, one of the massive globules located in the northern part of the Galactic H II region IC 1396, using the Spitzer IRAC and MIPS observations (3.6-24 {mu}m), and followed up with ground-based optical photometric and spectroscopic observations. Based on the IRAC and MIPS colors and H{alpha} emission, we identify {approx}45 young stellar objects (Classes 0/I/II) and 13 probable pre-main-sequence candidates. We derive the spectral types (mostly K- and M-type stars), effective temperatures, and individual extinction of the relatively bright and optically visible Class II objects. Most of the Class II objects show variable H{alpha} emission as well as optical and near-infrared photometric variability, which confirm their 'youth'. Based on optical photometry and theoretical isochrones, we estimate the spread in stellar ages to be between 1 and 8 Myr with a median age of 3 Myr and a mass distribution of 0.3-2.2 M{sub sun} with a median value around 0.5 M{sub sun}. Using the width of the H{alpha} emission line measured at 10% peak intensity, we derive the mass accretion rates of individual objects to be between 10{sup -10} and 10{sup -8} M{sub sun} yr{sup -1}. From the continuum-subtracted H{alpha} line image, we find that the H{alpha} emission of the globule is not spatially symmetric with respect to the O-type ionizing star HD 206267, and the interstellar extinction toward the globule is also anomalous. We clearly detect an enhanced concentration of YSOs closer to the southern rim of SFO 38 and identify an evolutionary sequence of YSOs from the rim to the dense core of the cloud, with most of the Class II objects located at the bright rim. The YSOs appear to be aligned along two different directions toward the O6.5V type star HD 206267 and the B0V type star HD 206773. This is consistent with the Radiation Driven Implosion (RDI) model for triggered star formation. Further, the apparent speed of

  19. NEW BROWN DWARF COMPANIONS TO YOUNG STARS IN SCORPIUS-CENTAURUS

    SciTech Connect (OSTI)

    Janson, Markus; Jayawardhana, Ray; Bonavita, Mariangela; Girard, Julien H.; Lafreniere, David; Gizis, John; Brandeker, Alexis

    2012-10-10

    We present the discoveries of three faint companions to young stars in the Scorpius-Centaurus region, imaged with the NICI instrument on Gemini South. We have confirmed all three companions through common proper motion tests. Follow-up spectroscopy has confirmed two of them, HIP 65423 B and HIP 65517 B, to be brown dwarfs, while the third, HIP 72099 B, is more likely a very low mass star just above the hydrogen burning limit. The detection of wide companions in the mass range of {approx}40-100 M{sub jup} complements previous work in the same region, reporting detections of similarly wide companions with lower masses, in the range of {approx}10-30 M{sub jup}. Such low masses near the deuterium burning limit have raised the question of whether those objects formed like planets or stars. The existence of intermediate objects as reported here could represent a bridge between lower-mass companions and stellar companions, but in any case demonstrate that mass alone may not provide a clear-cut distinction for the formation of low-mass companions to stars.

  20. A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS

    SciTech Connect (OSTI)

    Allers, K. N.; Liu, Michael C.

    2013-08-01

    We present a near-infrared (0.9-2.4 {mu}m) spectroscopic study of 73 field ultracool dwarfs having spectroscopic and/or kinematic evidence of youth ( Almost-Equal-To 10-300 Myr). Our sample is composed of 48 low-resolution (R Almost-Equal-To 100) spectra and 41 moderate-resolution spectra (R {approx}> 750-2000). First, we establish a method for spectral typing M5-L7 dwarfs at near-IR wavelengths that is independent of gravity. We find that both visual and index-based classification in the near-IR provides consistent spectral types with optical spectral types, though with a small systematic offset in the case of visual classification at J and K band. Second, we examine features in the spectra of {approx}10 Myr ultracool dwarfs to define a set of gravity-sensitive indices based on FeH, VO, K I, Na I, and H-band continuum shape. We then create an index-based method for classifying the gravities of M6-L5 dwarfs that provides consistent results with gravity classifications from optical spectroscopy. Our index-based classification can distinguish between young and dusty objects. Guided by the resulting classifications, we propose a set of low-gravity spectral standards for the near-IR. Finally, we estimate the ages corresponding to our gravity classifications.

  1. MAIN-SEQUENCE STARS MASQUERADING AS YOUNG STELLAR OBJECTS IN THE CENTRAL MOLECULAR ZONE

    SciTech Connect (OSTI)

    Koepferl, Christine M.; Robitaille, Thomas P.; Morales, Esteban F. E.; Johnston, Katharine G.

    2015-01-20

    In contrast to most other galaxies, star formation rates in the Milky Way can be estimated directly from young stellar objects (YSOs). In the central molecular zone the star formation rate calculated from the number of YSOs with 24 μm emission is up to an order of magnitude higher than the value estimated from methods based on diffuse emission (such as free-free emission). Whether this effect is real or whether it indicates problems with either or both star formation rate measures is not currently known. In this paper, we investigate whether estimates based on YSOs could be heavily contaminated by more evolved objects such as main-sequence stars. We present radiative transfer models of YSOs and of main-sequence stars in a constant ambient medium which show that the main-sequence objects can indeed mimic YSOs at 24 μm. However, we show that in some cases the main-sequence models can be marginally resolved at 24 μm, whereas the YSO models are always unresolved. Based on the fraction of resolved MIPS 24 μm sources in the sample of YSOs previously used to compute the star formation rate, we estimate the fraction of misclassified ''YSOs'' to be at least 63%, which suggests that the star formation rate previously determined from YSOs is likely to be at least a factor of three too high.

  2. CLOSE STELLAR ENCOUNTERS IN YOUNG, SUBSTRUCTURED, DISSOLVING STAR CLUSTERS: STATISTICS AND EFFECTS ON PLANETARY SYSTEMS

    SciTech Connect (OSTI)

    Craig, Jonathan; Krumholz, Mark R.

    2013-06-01

    Both simulations and observations indicate that stars form in filamentary, hierarchically clustered associations, most of which disperse into their galactic field once feedback destroys their parent clouds. However, during their early evolution in these substructured environments, stars can undergo close encounters with one another that might have significant impacts on their protoplanetary disks or young planetary systems. We perform N-body simulations of the early evolution of dissolving, substructured clusters with a wide range of properties, with the aim of quantifying the expected number and orbital element distributions of encounters as a function of cluster properties. We show that the presence of substructure both boosts the encounter rate and modifies the distribution of encounter velocities compared to what would be expected for a dynamically relaxed cluster. However, the boost only lasts for a dynamical time, and as a result the overall number of encounters expected remains low enough that gravitational stripping is unlikely to be a significant effect for the vast majority of star-forming environments in the Galaxy. We briefly discuss the implications of this result for models of the origin of the solar system, and of free-floating planets. We also provide tabulated encounter rates and orbital element distributions suitable for inclusion in population synthesis models of planet formation in a clustered environment.

  3. Measurement of the temperature dependence of Young's modulus of cartilage by phase-sensitive optical coherence elastography

    SciTech Connect (OSTI)

    Liu, C H; Li, J; Singh, M; Larin, K V; Skryabina, M N; Sobol, E N

    2014-08-31

    The development of an effective system to monitor the changes in the elastic properties of cartilage tissue with increasing temperature in laser reconstruction is an urgent practical task. In this paper, the use of phase-sensitive optical coherence elastography for detection of elastic waves in the sample has allowed Young's modulus of cartilage tissue to be measured directly during heating. Young's modulus was calculated from the group velocity of propagation of elastic waves excited by means of a system supplying focused air pulses. The measurement results are in agreement with the results of measurements of the modulus of elasticity under mechanical compression. The technique developed allows for noninvasive measurements; its development is promising for the use in vivo. (laser biophotonics)

  4. Anomalous temperature-dependent Young's modulus of a cast LAST (Pb-Sb-Ag-Te) thermoelectric material

    SciTech Connect (OSTI)

    Ren, Fei; Case, Eldon D; Timm, Edward J; Lara-Curzio, Edgar; Trejo, Rosa M

    2010-01-01

    Thermomechanical characterization is important to material evaluation and device design in the development of thermoelectric technology. In this study, we utilize the resonant ultrasound spectroscopy (RUS) technique to examine the elastic behavior of a cast LAST (Pb Sb Ag Te) material with a composition of Ag0.86Pb19Sb1.0Te20 between room temperature and 823 K. The temperature-dependent Young s modulus exhibits a monotonically decreasing trend with increasing temperature. However, an abnormal slope change in the Young s modulus temperature curve around 500 K is observed. In addition, hysteresis between heating and cooling data in the temperature range of 450 550 K is observed, which appears to be dependent on the heating/cooling rate during the RUS experiments such that the hysteresis disappears when the heating/cooling rate was decreased from 5 to 2 K min 1. In this study we propose an order disorder transition model for the anomalous temperature-dependent Young s modulus behavior observed in this study.

  5. Near-infrared (JHK) spectroscopy of young stellar and substellar objects in orion

    SciTech Connect (OSTI)

    Ingraham, P.; Albert, L.; Doyon, R.; Artigau, E.

    2014-02-10

    We performed low-resolution (R ∼ 40) near-infrared (0.9-2.4 μm) multi-object spectroscopy of 240 isolated point sources having apparent H-band magnitudes between 9 and 18 in the central 5' × 6' of the Orion Trapezium cluster. The observations were performed over four nights at the Canada-France-Hawaii Telescope using the visiting instrument SIMON, an infrared imager and multi-object spectrograph. We present the spectra of 104 objects with accurately derived spectral types including 7 new objects having masses below the hydrogen-burning limit, and 6 objects with masses below the deuterium-burning limit. The spectral classification is performed by fitting previously classified spectral templates of dwarf stars (K4-M3) and optically classified young stellar and substellar objects (M4-L0), to the entire 0.9-2.4 μm spectral energy distribution in order to assign a spectral type and visual extinction for each object. Of the 104 objects studied, 44 have been previously classified spectroscopically using various techniques. We perform a rigorous comparison between the previous classifications and our own and find them to be in good agreement. Using the dereddened H-band magnitudes, the classified objects are used to create an Hertzsprung-Russell diagram for the cluster. We find that the previous age estimates of ∼1 Myr to be consistent with our results. Consistent with previous studies, numerous objects are observed to have luminosities several magnitudes above the 1 Myr isochrone. Numerous objects exhibiting emission features in the J band are also reported.

  6. A wide-field near- and mid-infrared Census of young stars in NGC 6334

    SciTech Connect (OSTI)

    Willis, S.; Marengo, M.; Allen, L.; Fazio, G. G.; Smith, H. A.; Carey, S.

    2013-12-01

    This paper presents a study of the rate and efficiency of star formation in the NGC 6334 star-forming region. We obtained observations at J, H, and K{sub s} taken with the NOAO Extremely Wide-Field Infrared Imager and combined them with observations taken with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope at wavelengths = 3.6, 4.5, 5.8, and 8.0 μm. We also analyzed previous observations taken at 24 μm using the Spitzer MIPS camera as part of the MIPSGAL survey. We have produced a point source catalog with >700, 000 entries. We have identified 2283 young stellar object (YSO) candidates, 375 Class I YSOs, and 1908 Class II YSOs using a combination of existing IRAC-based color classification schemes that we have extended and validated to the near-IR for use with warm Spitzer data. We have identified multiple new sites of ongoing star formation activity along filamentary structures extending tens of parsecs beyond the central molecular ridge of NGC 6334. By mapping the extinction, we derived an estimate for the gas mass, 2.2 × 10{sup 5} M {sub ☉}. The heavy concentration of protostars along the dense filamentary structures indicates that NGC 6334 may be undergoing a 'mini-starburst' event with Σ{sub SFR} > 8.2 M {sub ☉} Myr{sup –1} pc{sup –2} and SFE > 0.10. We have used these estimates to place NGC 6334 in the Kennicutt-Schmidt diagram to help bridge the gap between observations of local low-mass star-forming regions and star formation in other galaxies.

  7. SEARCH FOR IONIZED JETS TOWARD HIGH-MASS YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Guzman, Andres E.; Garay, Guido; Brooks, Kate J.; Voronkov, Maxim A.

    2012-07-01

    We are carrying out multi-frequency radio continuum observations, using the Australia Telescope Compact Array, to systematically search for collimated ionized jets toward high-mass young stellar objects (HMYSOs). Here we report observations at 1.4, 2.4, 4.8, and 8.6 GHz, made with angular resolutions of about 7'', 4'', 2'', and 1'', respectively, toward six objects of a sample of 33 southern HMYSOs thought to be in very early stages of evolution. The objects in the sample were selected from radio and infrared catalogs by having positive radio spectral indices and being luminous (L{sub bol} > 2 Multiplication-Sign 10{sup 4} L{sub Sun }), but underluminous in radio emission compared with that expected from its bolometric luminosity. This criterion makes the radio sources good candidates for being ionized jets. As part of this systematic search, two ionized jets have been discovered: one previously published and the other reported here. The rest of the observed candidates correspond to three hypercompact H II regions and two ultracompact H II regions. The two jets discovered are associated with two of the most luminous (7 Multiplication-Sign 10{sup 4} and 1.0 Multiplication-Sign 10{sup 5} L{sub Sun }) HMYSOs known to harbor this type of object, showing that the phenomena of collimated ionized winds appear in the formation process of stars at least up to masses of {approx}20 M{sub Sun} and provide strong evidence for a disk-mediated accretion scenario for the formation of high-mass stars. From the incidence of jets in our sample, we estimate that the jet phase in high-mass protostars lasts for {approx}4 Multiplication-Sign 10{sup 4} yr.

  8. High fat diet promotes achievement of peak bone mass in young rats

    SciTech Connect (OSTI)

    Malvi, Parmanand; Piprode, Vikrant; Chaube, Balkrishna; Pote, Satish T.; Mittal, Monika; Chattopadhyay, Naibedya; Wani, Mohan R.; Bhat, Manoj Kumar

    2014-12-05

    Highlights: • High fat diet helps in achieving peak bone mass at younger age. • Shifting from high fat to normal diet normalizes obese parameters. • Bone parameters are sustained even after withdrawal of high fat diet. - Abstract: The relationship between obesity and bone is complex. Epidemiological studies demonstrate positive as well as negative correlation between obesity and bone health. In the present study, we investigated the impact of high fat diet-induced obesity on peak bone mass. After 9 months of feeding young rats with high fat diet, we observed obesity phenotype in rats with increased body weight, fat mass, serum triglycerides and cholesterol. There were significant increases in serum total alkaline phosphatase, bone mineral density and bone mineral content. By micro-computed tomography (μ-CT), we observed a trend of better trabecular bones with respect to their microarchitecture and geometry. This indicated that high fat diet helps in achieving peak bone mass and microstructure at younger age. We subsequently shifted rats from high fat diet to normal diet for 6 months and evaluated bone/obesity parameters. It was observed that after shifting rats from high fat diet to normal diet, fat mass, serum triglycerides and cholesterol were significantly decreased. Interestingly, the gain in bone mineral density, bone mineral content and trabecular bone parameters by HFD was retained even after body weight and obesity were normalized. These results suggest that fat rich diet during growth could accelerate achievement of peak bone mass that is sustainable even after withdrawal of high fat diet.

  9. The Gemini NICI planet-finding campaign: the orbit of the young exoplanet ? Pictoris b

    SciTech Connect (OSTI)

    Nielsen, Eric L.; Liu, Michael C.; Chun, Mark; Ftaclas, Christ; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.; Kuchner, Marc J.; Rodigas, Timothy J.; Toomey, Douglas W.

    2014-10-20

    We present new astrometry for the young (12-21 Myr) exoplanet ? Pictoris b taken with the Gemini/NICI and Magellan/MagAO instruments between 2009 and 2012. The high dynamic range of our observations allows us to measure the relative position of ? Pic b with respect to its primary star with greater accuracy than previous observations. Based on a Markov Chain Monte Carlo analysis, we find the planet has an orbital semi-major axis of 9.1{sub ?0.5}{sup +5.3} AU and orbital eccentricity <0.15 at 68% confidence (with 95% confidence intervals of 8.2-48 AU and 0.00-0.82 for semi-major axis and eccentricity, respectively, due to a long narrow degenerate tail between the two). We find that the planet has reached its maximum projected elongation, enabling higher precision determination of the orbital parameters than previously possible, and that the planet's projected separation is currently decreasing. With unsaturated data of the entire ? Pic system (primary star, planet, and disk) obtained thanks to NICI's semi-transparent focal plane mask, we are able to tightly constrain the relative orientation of the circumstellar components. We find the orbital plane of the planet lies between the inner and outer disks: the position angle (P.A.) of nodes for the planet's orbit (211.8 0.3) is 7.4? greater than the P.A. of the spine of the outer disk and 3.2? less than the warped inner disk P.A., indicating the disk is not collisionally relaxed. Finally, for the first time we are able to dynamically constrain the mass of the primary star ? Pic to 1.76{sub ?0.17}{sup +0.18} M {sub ?}.

  10. Nonthermal radiation of young supernova remnants: The case of Cas A

    SciTech Connect (OSTI)

    Zirakashvili, V. N.; Aharonian, F. A.; Yang, R.; Oa-Wilhelmi, E.; Tuffs, R. J.

    2014-04-20

    The processes responsible for the broadband radiation of the young supernova remnant Cas A are explored by using a new code that is designed for a detailed treatment of the diffusive shock acceleration of particles in the nonlinear regime. The model is based on spherically symmetric hydrodynamic equations complemented with transport equations for relativistic particles. Electrons, protons, and the oxygen ions accelerated by forward and reverse shocks are included in the numerical calculations. We show that the available multi-wavelength observations in the radio, X-ray, and gamma-ray bands can be best explained by invoking particle acceleration by both forward and reversed shocks. Although the TeV gamma-ray observations can be interpreted by interactions of both accelerated electrons and protons/ions, the measurements by Fermi Large Area Telescope at energies below 1 GeV give a tentative preference to the hadronic origin of gamma-rays. Then, the acceleration efficiency in this source, despite the previous claims, should be very high; 25% of the explosion energy (or approximately 3 10{sup 50} erg) should already be converted to cosmic rays, mainly by the forward shock. At the same time, the model calculations do not provide extension of the maximum energy of accelerated protons beyond 100 TeV. In this model, the acceleration of electrons is dominated by the reverse shock; the required 10{sup 48} erg can be achieved under the assumption that the injection of electrons (positrons) is supported by the radioactive decay of {sup 44}Ti.

  11. SPIN EVOLUTION OF ACCRETING YOUNG STARS. I. EFFECT OF MAGNETIC STAR-DISK COUPLING

    SciTech Connect (OSTI)

    Matt, Sean P.; Greene, Thomas P.; Pinzon, Giovanni; De la Reza, Ramiro E-mail: thomas.p.greene@nasa.go E-mail: delareza@on.b

    2010-05-10

    We present a model for the rotational evolution of a young, solar mass star interacting with an accretion disk. The model incorporates a description of the angular momentum transfer between the star and the disk due to a magnetic connection, and includes changes in the star's mass and radius and a decreasing accretion rate. The model also includes, for the first time in a spin evolution model, the opening of the stellar magnetic field lines, as expected to arise from twisting via star-disk differential rotation. In order to isolate the effect that this has on the star-disk interaction torques, we neglect the influence of torques that may arise from open field regions connected to the star or disk. For a range of magnetic field strengths, accretion rates, and initial spin rates, we compute the stellar spin rates of pre-main-sequence stars as they evolve on the Hayashi track to an age of 3 Myr. How much the field opening affects the spin depends on the strength of the coupling of the magnetic field to the disk. For the relatively strong coupling (i.e., high magnetic Reynolds number) expected in real systems, all models predict spin periods of less than {approx}3 days, in the age range of 1-3 Myr. Furthermore, these systems typically do not reach an equilibrium spin rate within 3 Myr, so that the spin at any given time depends upon the choice of initial spin rate. This corroborates earlier suggestions that, in order to explain the full range of observed rotation periods of approximately 1-10 days, additional processes, such as the angular momentum loss from powerful stellar winds, are necessary.

  12. A PAN-STARRS + UKIDSS SEARCH FOR YOUNG, WIDE PLANETARY-MASS COMPANIONS IN UPPER SCORPIUS

    SciTech Connect (OSTI)

    Aller, Kimberly M.; Kraus, Adam L.; Liu, Michael C.; Burgett, William S.; Chambers, Kenneth C.; Hodapp, Klaus W.; Kaiser, Nick; Magnier, Eugene A.; Price, Paul A.

    2013-08-10

    We have combined optical and NIR photometry from Pan-STARRS 1 and UKIDSS to search the young (5-10 Myr) star-forming region of Upper Scorpius for wide ( Almost-Equal-To 400-4000 AU) substellar companions down to {approx}5 M{sub Jup}. Our search is Almost-Equal-To 4 mag deeper than previous work based on the Two Micron All Sky Survey. We identified several candidates around known stellar members using a combination of color selection and spectral energy distribution fitting. Our follow-up spectroscopy has identified two new companions as well as confirmed two companions previously identified from photometry, with spectral types of M7.5-M9 and masses of {approx}15-60 M{sub Jup}, indicating a frequency for such wide substellar companions of {approx}0.6% {+-} 0.3%. Both USco 1610-1913B and USco 1612-1800B are more luminous than expected for their spectral type compared with known members of Upper Sco. HIP 77900B has an extreme mass ratio (M{sub 2}/M{sub 1} Almost-Equal-To 0.005) and an extreme separation of 3200 AU. USco 1602-2401B also has a very large separation of 1000 AU. We have also confirmed a low-mass stellar companion, USco 1610-2502B (730 AU, M5.5). Our substellar companions appear both non-coeval with their primary stars according to evolutionary models and, as a group, are systematically more luminous than the Upper Sco cluster sequence. One possible reason for these luminosity discrepancies could be different formation processes or accretion histories for these objects.

  13. Report on enhancing young scholars in science and technology the Center for Excellence in Education

    SciTech Connect (OSTI)

    1996-09-30

    The present stock and flow of highly talented young persons engaged in the global discovery and application of science and technology are critical to the future pace of innovation. Historically, the world`s largest reservoirs of scientists and engineers have been in the Western economies. Overtime, however, Asia has begun to build equivalent pools of scientists and engineers among their university graduates. According to 1993 data from the National Science Foundation and the UNESCO World Science Report, Germany leads all economies with a 67% ratio of science and engineering degrees to total first university degrees compared to the United States with a distant fifth place at 32% behind Italy, Mexico and Poland. If the nation is to keep its scientific and technological prowess, it must capture its very best talent in the science and technology fields. The question is then raised as to the source within the United States of the science and technology talent pool. While between 1978 and 1991 there was an overall decline in male participation in undergraduate (-9%) and graduate degrees (-12%), the number of women receiving undergraduate (+8%) and graduate degrees (+34%) rose dramatically. These numbers are encouraging for women`s participation overall, however, women earn only a small percentage of physical science and engineering degrees. Why are there so few women in mathematics, engineering, and the physical sciences? The answers are complex and begin early in a woman`s exposure to science and mathematics. This report presents results on a study of careers of alumni from the Research Science Institute. Investigations were concerned with the timing of decision processes concerned with the sciences and math and factors that influenced people to turn away from or proceed with careers in science and math.

  14. Ozone induces glucose intolerance and systemic metabolic effects in young and aged brown Norway rats

    SciTech Connect (OSTI)

    Bass, V.; Gordon, C.J.; Jarema, K.A.; MacPhail, R.C.; Cascio, W.E.; Phillips, P.M.; Ledbetter, A.D.; Schladweiler, M.C.; Andrews, D.; Miller, D.; Doerfler, D.L.; Kodavanti, U.P.

    2013-12-15

    Air pollutants have been associated with increased diabetes in humans. We hypothesized that ozone would impair glucose homeostasis by altering insulin signaling and/or endoplasmic reticular (ER) stress in young and aged rats. One, 4, 12, and 24 month old Brown Norway (BN) rats were exposed to air or ozone, 0.25 or 1.0 ppm, 6 h/day for 2 days (acute) or 2 d/week for 13 weeks (subchronic). Additionally, 4 month old rats were exposed to air or 1.0 ppm ozone, 6 h/day for 1 or 2 days (time-course). Glucose tolerance tests (GTT) were performed immediately after exposure. Serum and tissue biomarkers were analyzed 18 h after final ozone for acute and subchronic studies, and immediately after each day of exposure in the time-course study. Age-related glucose intolerance and increases in metabolic biomarkers were apparent at baseline. Acute ozone caused hyperglycemia and glucose intolerance in rats of all ages. Ozone-induced glucose intolerance was reduced in rats exposed for 13 weeks. Acute, but not subchronic ozone increased ?{sub 2}-macroglobulin, adiponectin and osteopontin. Time-course analysis indicated glucose intolerance at days 1 and 2 (2 > 1), and a recovery 18 h post ozone. Leptin increased day 1 and epinephrine at all times after ozone. Ozone tended to decrease phosphorylated insulin receptor substrate-1 in liver and adipose tissues. ER stress appeared to be the consequence of ozone induced acute metabolic impairment since transcriptional markers of ER stress increased only after 2 days of ozone. In conclusion, acute ozone exposure induces marked systemic metabolic impairments in BN rats of all ages, likely through sympathetic stimulation. - Highlights: Air pollutants have been associated with increased diabetes in humans. Acute ozone exposure produces profound metabolic alterations in rats. Age influences metabolic risk factors in aging BN rats. Acute metabolic effects are reversible and repeated exposure reduces these effects. Ozone metabolic effects

  15. Young stellar object variability (YSOVAR): Long timescale variations in the mid-infrared

    SciTech Connect (OSTI)

    Rebull, L. M.; Cody, A. M.; Stauffer, J. R.; Morales-Calderón, M.; Carey, S. J.; Covey, K. R.; Günther, H. M.; Poppenhaeger, K.; Wolk, S. J.; Hora, J. L.; Hillenbrand, L. A.; Plavchan, P.; Gutermuth, R.; Song, I.; Barrado, D.; Bayo, A.; James, D.; Vrba, F. J.; Alves de Oliveira, C.; Bouvier, J.; and others

    2014-11-01

    The YSOVAR (Young Stellar Object VARiability) Spitzer Space Telescope observing program obtained the first extensive mid-infrared (3.6 and 4.5 μm) time series photometry of the Orion Nebula Cluster plus smaller footprints in 11 other star-forming cores (AFGL 490, NGC 1333, Mon R2, GGD 12-15, NGC 2264, L1688, Serpens Main, Serpens South, IRAS 20050+2720, IC 1396A, and Ceph C). There are ∼29,000 unique objects with light curves in either or both IRAC channels in the YSOVAR data set. We present the data collection and reduction for the Spitzer and ancillary data, and define the 'standard sample' on which we calculate statistics, consisting of fast cadence data, with epochs roughly twice per day for ∼40 days. We also define a 'standard sample of members' consisting of all the IR-selected members and X-ray-selected members. We characterize the standard sample in terms of other properties, such as spectral energy distribution shape. We use three mechanisms to identify variables in the fast cadence data—the Stetson index, a χ{sup 2} fit to a flat light curve, and significant periodicity. We also identified variables on the longest timescales possible of six to seven years by comparing measurements taken early in the Spitzer mission with the mean from our YSOVAR campaign. The fraction of members in each cluster that are variable on these longest timescales is a function of the ratio of Class I/total members in each cluster, such that clusters with a higher fraction of Class I objects also have a higher fraction of long-term variables. For objects with a YSOVAR-determined period and a [3.6]-[8] color, we find that a star with a longer period is more likely than those with shorter periods to have an IR excess. We do not find any evidence for variability that causes [3.6]-[4.5] excesses to appear or vanish within our data set; out of members and field objects combined, at most 0.02% may have transient IR excesses.

  16. PHOTOELECTRIC CHARGING OF DUST GRAINS IN THE ENVIRONMENT OF YOUNG STELLAR OBJECTS

    SciTech Connect (OSTI)

    Pedersen, Andreas; Gomez de Castro, Ana I.

    2011-10-20

    The evolution of disks around young stellar objects (YSOs) is deeply affected by the YSOs' ultraviolet (UV) radiation field especially in the 500-1100 A spectral range. The two dominant processes are: the photodissociation of H{sub 2} molecules in the Werner and Lyman bands, and the emission of photoelectrons from dust grains when high energy photons are absorbed. Photoelectrons are an important source of gas heating. In this paper, dust grain charging when exposed to various possible UV fields in the YSOs' environment is investigated. Numerical simulations of the evolution of photoelectrons in the electric field created by the charged dust grains are carried out to obtain the charging profile of dust grains. From the simulations it appears that the different spectra produce significant quantitative and qualitative differences in the charging processes. Both the UV background and the Ae-Herbig star radiation field produce a relatively slow charging of dust grains due to the low fraction of sufficiently energetic photons. The radiation field of T Tauri stars (TTSs) is harder due to the release of magnetic energy in the dense magnetospheric environment. These numerical results have been used to propose a new simple analytical model for grain charging in the atmosphere of protostellar disks around TTSs susceptible to be used in any disk modeling. It has been found that the yield decreases exponentially with the dust charge and that two populations of photoelectrons are produced: a low energy population with mean kinetic energy E = 2.5 eV and a high energy population with E = 5.5-6 eV; the energy dispersion within the populations is {approx}1.3 eV (T {approx} 1.5 x 10{sup 4} K). The high energy population is susceptible of dissociating the H{sub 2} and ionizing some low ionization potential species, such as the Mg. These results add an additional role to dust on the chemistry of the layers just below the H{sub 2} photoionization front. This photoelectic yield has been

  17. Greenhouse gas emissions from landfill leachate treatment plants: A comparison of young and aged landfill

    SciTech Connect (OSTI)

    Wang, Xiaojun; Jia, Mingsheng; Chen, Xiaohai; Xu, Ying; Lin, Xiangyu; Kao, Chih Ming; Chen, Shaohua

    2014-07-15

    Highlights: • Young and aged leachate works accounted for 89.1% and 10.9% of 33.35 Gg CO{sub 2} yr{sup −1}. • Fresh leachate owned extremely low ORP and high organic matter content. • Strong CH{sub 4} emissions occurred in the fresh leachate ponds, but small in the aged. • N{sub 2}O emissions became dominant in the treatment units of both systems. • 8.45–11.9% of nitrogen was removed as the form of N{sub 2}O under steady-state. - Abstract: With limited assessment, leachate treatment of a specified landfill is considered to be a significant source of greenhouse gas (GHG) emissions. In our study, the cumulative GHG emitted from the storage ponds and process configurations that manage fresh or aged landfill leachate were investigated. Our results showed that strong CH{sub 4} emissions were observed from the fresh leachate storage pond, with the fluxes values (2219–26,489 mg C m{sup −2} h{sup −1}) extremely higher than those of N{sub 2}O (0.028–0.41 mg N m{sup −2} h{sup −1}). In contrast, the emission values for both CH{sub 4} and N{sub 2}O were low for the aged leachate tank. N{sub 2}O emissions became dominant once the leachate entered the treatment plants of both systems, accounting for 8–12% of the removal of N-species gases. Per capita, the N{sub 2}O emission based on both leachate treatment systems was estimated to be 7.99 g N{sub 2}O–N capita{sup −1} yr{sup −1}. An increase of 80% in N{sub 2}O emissions was observed when the bioreactor pH decreased by approximately 1 pH unit. The vast majority of carbon was removed in the form of CO{sub 2}, with a small portion as CH{sub 4} (<0.3%) during both treatment processes. The cumulative GHG emissions for fresh leachate storage ponds, fresh leachate treatment system and aged leachate treatment system were 19.10, 10.62 and 3.63 Gg CO{sub 2} eq yr{sup −1}, respectively, for a total that could be transformed to 9.09 kg CO{sub 2} eq capita{sup −1} yr{sup −1}.

  18. PLANETS AROUND LOW-MASS STARS. III. A YOUNG DUSTY L DWARF COMPANION AT THE DEUTERIUM-BURNING LIMIT ,

    SciTech Connect (OSTI)

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Dupuy, Trent J.

    2013-09-01

    We report the discovery of an L-type companion to the young M3.5V star 2MASS J01225093-2439505 at a projected separation of 1.''45 ( Almost-Equal-To 52 AU) as part of our adaptive optics imaging search for extrasolar giant planets around young low-mass stars. 2MASS 0122-2439 B has very red near-infrared colors similar to the HR 8799 planets and the reddest known young/dusty L dwarfs in the field. Moderate-resolution (R Almost-Equal-To 3800) 1.5-2.4 {mu}m spectroscopy reveals a near-infrared spectral type of L4-L6 and an angular H-band shape, confirming its cool temperature and young age. The kinematics of 2MASS 0122-2439 AB are marginally consistent with members of the {approx}120 Myr AB Dor young moving group based on the photometric distance to the primary (36 {+-} 4 pc) and our radial velocity measurement of 2MASS 0122-2439 A from Keck/HIRES. We adopt the AB Dor group age for the system, but the high energy emission, lack of Li I {lambda}6707 absorption, and spectral shape of 2MASS 0122-2439 B suggest a range of {approx}10-120 Myr is possible. The age and luminosity of 2MASS 0122-2439 B fall in a strip where ''hot-start'' evolutionary model mass tracks overlap as a result of deuterium burning. Several known substellar companions also fall in this region (2MASS J0103-5515 ABb, AB Pic b, {kappa} And b, G196-3 B, SDSS 2249+0044 B, LP 261-75 B, HD 203030 B, and HN Peg B), but their dual-valued mass predictions have largely been unrecognized. The implied mass of 2MASS 0122-2439 B is Almost-Equal-To 12-13 M{sub Jup} or Almost-Equal-To 22-27 M{sub Jup} if it is an AB Dor member, or possibly as low as 11 M{sub Jup} if the wider age range is adopted. Evolutionary models predict an effective temperature for 2MASS 0122-2439 B that corresponds to spectral types near the L/T transition ( Almost-Equal-To 1300-1500 K) for field objects. However, we find a mid-L near-infrared spectral type, indicating that 2MASS 0122-2439 B represents another case of photospheric dust being

  19. BANYAN. II. Very low mass and substellar candidate members to nearby, young kinematic groups with previously known signs of youth

    SciTech Connect (OSTI)

    Gagn, Jonathan; Lafrenire, David; Doyon, Ren; Malo, Lison; Artigau, tienne

    2014-03-10

    We present Bayesian Analysis for Nearby Young AssociatioNs II (BANYAN II), a modified Bayesian analysis for assessing the membership of later-than-M5 objects to any of several Nearby Young Associations (NYAs). In addition to using kinematic information (from sky position and proper motion), this analysis exploits 2MASS-WISE color-magnitude diagrams in which old and young objects follow distinct sequences. As an improvement over our earlier work, the spatial and kinematic distributions for each association are now modeled as ellipsoids whose axes need not be aligned with the Galactic coordinate axes, and we use prior probabilities matching the expected populations of the NYAs considered versus field stars. We present an extensive contamination analysis to characterize the performance of our new method. We find that Bayesian probabilities are generally representative of contamination rates, except when a parallax measurement is considered. In this case contamination rates become significantly smaller and hence Bayesian probabilities for NYA memberships are pessimistic. We apply this new algorithm to a sample of 158 objects from the literature that are either known to display spectroscopic signs of youth or have unusually red near-infrared colors for their spectral type. Based on our analysis, we identify 25 objects as new highly probable candidates to NYAs, including a new M7.5 bona fide member to Tucana-Horologium, making it the latest-type member. In addition, we reveal that a known L2? dwarf is co-moving with a bright M5 dwarf, and we show for the first time that two of the currently known ultra red L dwarfs are strong candidates to the AB Doradus moving group. Several objects identified here as highly probable members to NYAs could be free-floating planetary-mass objects if their membership is confirmed.

  20. HERSCHEL FINDS EVIDENCE FOR STELLAR WIND PARTICLES IN A PROTOSTELLAR ENVELOPE: IS THIS WHAT HAPPENED TO THE YOUNG SUN?

    SciTech Connect (OSTI)

    Ceccarelli, C.; Lpez-Sepulcre, A.; Dominik, C.; Kama, M.; Padovani, M.; Caux, E.; Caselli, P.

    2014-07-20

    There is evidence that the young Sun emitted a high flux of energetic (?10MeV) particles. The collisions of these particles with the material at the inner edge of the Protosolar Nebula disk induced spallation reactions that formed short-lived radionuclei, like {sup 10}Be, whose trace is now visible in some meteorites. However, it is poorly known exactly when this happened, and whether and how it affected the solar system. Here, we present indirect evidence for an ejection of energetic particles in the young protostar, OMC-2 FIR 4, similar to that experienced by the young solar system. In this case, the energetic particles collide with the material in the protostellar envelope, enhancing the abundance of two molecular ions, HCO{sup +} and N{sub 2}H{sup +}, whose presence is detected via Herschel observations. The flux of energetic particles at a distance of 1AU from the emitting source, estimated from the measured abundance ratio of HCO{sup +} and N{sub 2}H{sup +}, can easily account for the irradiation required by meteoritic observations. These new observations demonstrate that the ejection of ?10MeV particles is a phenomenon occurring very early in the life of a protostar, before the disappearance of the envelope from which the future star accretes. The whole envelope is affected by the event, which sets constraints on the magnetic field geometry in the source and opens up the possibility that the spallation reactions are not limited to the inner edge of the Protosolar Nebula disk.

  1. Possible contribution of low shear modulus C{sub 44} to the low Young's modulus of Ti-36Nb-5Zr alloy

    SciTech Connect (OSTI)

    Meng, Qingkun; Xu, Huibin; Zhao, Xinqing; Guo, Shun; Ren, Xiaobing

    2014-09-29

    Despite the importance of single-crystal elastic constants of β-phase titanium alloys in understanding their low Young's modulus—a property crucial for many applications, such data are often difficult to obtain when the alloy composition is close to the instability limit of the β phase, where the presence of α' martensite precludes the fabrication of β-phase single crystal. In the present study, we extracted the single-crystal elastic constants of such a β-phase titanium alloy with low Young's modulus, Ti-36Nb-5Zr (wt. %), from polycrystalline specimens by using an in-situ synchrotron X-ray diffraction technique. It is indicated that the low Young's modulus of the alloy originates from the anomalously low shear modulus C{sub 44} as well as the low shear modulus C′, which is different from a common viewpoint that the Young's modulus of β-phase titanium alloys is dominantly controlled by the C′. This suggests that low C{sub 44} is an important contributor to low Young's modulus for instable β-phase titanium alloys.

  2. Geologic Characterization of Young Alluvial Basin-Fill Deposits from Drill Hole Data in Yucca Flat, Nye County, Nevada.

    SciTech Connect (OSTI)

    Donald S. Sweetkind; Ronald M. Drake II

    2007-01-22

    Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada, that has been the site of numerous underground nuclear tests; many of these tests occurred within the young alluvial basin-fill deposits. The migration of radionuclides to the Paleozoic carbonate aquifer involves passage through this thick, heterogeneous section of Tertiary and Quaternary rock. An understanding of the lateral and vertical changes in the material properties of young alluvial basin-fill deposits will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating ground-water flow in the Yucca Flat area. This report by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, presents data and interpretation regarding the three-dimensional variability of the shallow alluvial aquifers in areas of testing at Yucca Flat, data that are potentially useful in the understanding of the subsurface flow system. This report includes a summary and interpretation of alluvial basin-fill stratigraphy in the Yucca Flat area based on drill hole data from 285 selected drill holes. Spatial variations in lithology and grain size of the Neogene basin-fill sediments can be established when data from numerous drill holes are considered together. Lithologic variations are related to different depositional environments within the basin including alluvial fan, channel, basin axis, and playa deposits.

  3. KEPLER-63b: A GIANT PLANET IN A POLAR ORBIT AROUND A YOUNG SUN-LIKE STAR

    SciTech Connect (OSTI)

    Sanchis-Ojeda, Roberto; Winn, Joshua N.; Albrecht, Simon; Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W.; Johnson, John Asher; Torres, Guillermo; Carter, Joshua A.; Dawson, Rebekah I.; Geary, John C.; Campante, Tiago L.; Chaplin, William J.; Davies, Guy R.; Lund, Mikkel N.; Buchhave, Lars A.; Everett, Mark E.; Fischer, Debra A.; Gilliland, Ronald L.; Horch, Elliott P.; and others

    2013-09-20

    We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m{sub Kp} = 11.6, T{sub eff} = 5576 K, M{sub *} = 0.98 M{sub ☉}). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 ± 0.2 R{sub ⊕}, based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the existing radial-velocity data, due to the high level of stellar activity, but if we assume a circular orbit, then we can place a rough upper bound of 120 M{sub ⊕} (3σ). The host star has a high obliquity (ψ = 104°), based on the Rossiter-McLaughlin effect and an analysis of starspot-crossing events. This result is valuable because almost all previous obliquity measurements are for stars with more massive planets and shorter-period orbits. In addition, the polar orbit of the planet combined with an analysis of spot-crossing events reveals a large and persistent polar starspot. Such spots have previously been inferred using Doppler tomography, and predicted in simulations of magnetic activity of young Sun-like stars.

  4. THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A MULTIPLE SYSTEM ORBITING THE YOUNG A STAR HD 1160

    SciTech Connect (OSTI)

    Nielsen, Eric L.; Liu, Michael C.; Wahhaj, Zahed; Bowler, Brendan; Kraus, Adam; Chun, Mark; Ftaclas, Christ; Biller, Beth A.; Hayward, Thomas L.; Shkolnik, Evgenya L.; Tecza, Matthias; Clarke, Fraser; Close, Laird M.; Hartung, Markus; Males, Jared R.; Skemer, Andrew J.; Reid, I. Neill; Alencar, Silvia H. P.; Burrows, Adam; and others

    2012-05-01

    We report the discovery of two low-mass companions to the young A0V star HD 1160 at projected separations of 81 {+-} 5 AU (HD 1160 B) and 533 {+-} 25 AU (HD 1160 C) by the Gemini NICI Planet-Finding Campaign. Very Large Telescope images of the system taken over a decade for the purpose of using HD 1160 A as a photometric calibrator confirm that both companions are physically associated. By comparing the system to members of young moving groups and open clusters with well-established ages, we estimate an age of 50{sup +50}{sub -40} Myr for HD 1160 ABC. While the UVW motion of the system does not match any known moving group, the small magnitude of the space velocity is consistent with youth. Near-IR spectroscopy shows HD 1160 C to be an M3.5 {+-} 0.5 star with an estimated mass of 0.22{sup +0.03}{sub -0.04} M{sub Sun }, while NIR photometry of HD 1160 B suggests a brown dwarf with a mass of 33{sup +12}{sub -9} M{sub Jup}. The very small mass ratio (0.014) between the A and B components of the system is rare for A star binaries, and would represent a planetary-mass companion were HD 1160 A to be slightly less massive than the Sun.

  5. A LARGE, MASSIVE, ROTATING DISK AROUND AN ISOLATED YOUNG STELLAR OBJECT

    SciTech Connect (OSTI)

    Quanz, Sascha P.; Beuther, Henrik; Steinacker, Juergen; Linz, Hendrik; Krause, Oliver; Henning, Thomas; Birkmann, Stephan M.

    2010-07-10

    dense gas in the disk and the molecules' abundances are similar to those found in other circumstellar disks. We furthermore detected C{sub 2}H toward the objects and discuss this finding in the context of star formation. Finally, we have performed radiative transfer modeling of the K-band scattered light image varying a disk plus outflow two-dimensional density profile and the stellar properties. The model approximately reproduces extent and location of the dark lane, and the basic appearance of the outflow. We discuss our findings in the context of circumstellar disks across all mass regimes and conclude that our discovery is an ideal laboratory to study the early phases in the evolution of massive circumstellar disks surrounding young stellar objects.

  6. THE EXTREMELY RED, YOUNG L DWARF PSO J318.533822.8603: A FREE-FLOATING PLANETARY-MASS ANALOG TO DIRECTLY IMAGED YOUNG GAS-GIANT PLANETS

    SciTech Connect (OSTI)

    Liu, Michael C.; Magnier, Eugene A.; Kotson, Michael C.; Aller, Kimberly M.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Jedicke, R.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Deacon, Niall R.; Allers, Katelyn N.; Dupuy, Trent J.; Draper, P. W.; Price, P. A.; Metcalfe, N.

    2013-11-10

    We have discovered using Pan-STARRS1 an extremely red late-L dwarf, which has (J K){sub MKO} = 2.78 and (J K){sub 2MASS} = 2.84, making it the reddest known field dwarf and second only to 2MASS J120739b among substellar companions. Near-IR spectroscopy shows a spectral type of L7 1 and reveals a triangular H-band continuum and weak alkali (K I and Na I) lines, hallmarks of low surface gravity. Near-IR astrometry from the Hawaii Infrared Parallax Program gives a distance of 24.6 1.4 pc and indicates a much fainter J-band absolute magnitude than field L dwarfs. The position and kinematics of PSO J318.522 point to membership in the ? Pic moving group. Evolutionary models give a temperature of 1160{sup +30}{sub -40} K and a mass of 6.5{sup +1.3}{sub -1.0} M {sub Jup}, making PSO J318.522 one of the lowest mass free-floating objects in the solar neighborhood. This object adds to the growing list of low-gravity field L dwarfs and is the first to be strongly deficient in methane relative to its estimated temperature. Comparing their spectra suggests that young L dwarfs with similar ages and temperatures can have different spectral signatures of youth. For the two objects with well constrained ages (PSO J318.522 and 2MASS J0355+11), we find their temperatures are ?400 K cooler than field objects of similar spectral type but their luminosities are similar, i.e., these young L dwarfs are very red and unusually cool but not 'underluminous'. Altogether, PSO J318.522 is the first free-floating object with the colors, magnitudes, spectrum, luminosity, and mass that overlap the young dusty planets around HR 8799 and 2MASS J120739.

  7. Search for Pulsed TeV Gamma-Ray Emission from Young Pulsars with H.E.S.S

    SciTech Connect (OSTI)

    Schmidt, P.; Breitling, F.; Lohse, T.; Schlenker, S.; Schwanke, U.; Stegmann, C.; Gillessen, S.; Konopelko, A.

    2005-02-21

    The H.E.S.S. experiment is a next-generation imaging atmospheric Cherenkov detector with a {approx}1% Crab flux sensitivity for gamma-rays above 100 GeV. The full 4-telescope array has been operational since December 2003. The three young pulsars, Crab, Vela, and PSR B1706-44, are among the six pulsars whose pulsed emission has been detected up to energies of several GeV by EGRET. These pulsars have been selected for H.E.S.S. observations on grounds of their high rank in apparent spin-down luminosity Esd/d2 and observability for the H.E.S.S. array. No pulsed emission was found and flux upper limits are given.

  8. CHARACTERIZATION OF THE YOUNG OPEN CLUSTER G144.9+0.4 IN THE CAMELOPARDALIS OB1 ASSOCIATION

    SciTech Connect (OSTI)

    Lin, Chien-Cheng; Chen, W. P.; Panwar, Neelam

    2013-10-01

    Our star-count analysis of the Two Micron All Sky Survey point sources resulted in an identification of the star cluster G144.9+0.4. The cluster was found, but not characterized, by Glushkova et al. We show that the cluster is physically associated with the Cam OB1 association at a distance of about 1 kpc and with an age of 1-2 Myr. Pre-main sequence stars are identified on the basis of photometric and proper motion data. A total of 91 additional OB star candidates was found in subgroups 1A and 1B, a significant increase from the currently known 43 OB stars. The OB members show an age spread that indicates a sustained star formation for at least the last 10-15 Myr. The young cluster G144.9+0.4 represents the latest episode of sequential star formation in this cloud complex.

  9. Inventors Behind General Electric | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Amol Kolwalkar Amol Kolwalkar Senior Engineer Control & Optimization Systems Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new window) Click to share on LinkedIn (Opens in new window) Click to share on Tumblr (Opens in new window) "What motivates me is the thrill and anticipation of finding something that was not previously identified." -Amol Kolwalkar Amol Kolwalkar epitomizes the GE Belief "deliver

  10. CLOSE COMPANIONS TO YOUNG STARS. I. A LARGE SPECTROSCOPIC SURVEY IN CHAMAELEON I AND TAURUS-AURIGA

    SciTech Connect (OSTI)

    Nguyen, Duy Cuong; Brandeker, Alexis; Van Kerkwijk, Marten H.; Jayawardhana, Ray E-mail: mhvk@astro.utoronto.ca E-mail: dcnguyen@pas.rochester.edu E-mail: alexis@astro.su.se

    2012-02-01

    We present the results of a multiplicity survey of 212 T Tauri stars in the Chamaeleon I and Taurus-Auriga star-forming regions, based on high-resolution spectra from the Magellan Clay 6.5 m telescope. From these data, we achieved a typical radial velocity (RV) precision of {approx}80 m s{sup -1} with slower rotators yielding better precision, in general. For 174 of these stars, we obtained multi-epoch data with sufficient time baselines to identify binaries based on RV variations. We identified eight close binaries and four close triples, of which three and two, respectively, are new discoveries. The spectroscopic multiplicity fractions we find for Chamaeleon I (7%) and Taurus-Auriga (6%) are similar to each other, and to the results of field star surveys in the same mass and period regime. However, unlike the results from imaging surveys, the frequency of systems with close companions in our sample is not seen to depend on primary mass. Additionally, we do not find a strong correlation between accretion and close multiplicity. This implies that close companions are not likely the main source of the accretion shut down observed in weak-lined T Tauri stars. Our results also suggest that sufficient RV precision can be achieved for at least a subset of slowly rotating young stars to search for hot Jupiter planets.

  11. DYNAMICAL EVIDENCE FOR A MAGNETOCENTRIFUGAL WIND FROM A 20 M{sub Sun} BINARY YOUNG STELLAR OBJECT

    SciTech Connect (OSTI)

    Greenhill, L. J.; Goddi, C.; Humphreys, E. M. L.; Chandler, C. J.; Matthews, L. D.

    2013-06-20

    In Orion BN/KL, proper motions of {lambda}7 mm vibrationally excited SiO masers trace the rotation of a nearly edge-on disk and a bipolar wide-angle outflow 10-100 AU from radio source I, a binary young stellar object of {approx}20 M{sub Sun }. Here we map ground-state {lambda}7 mm SiO emission with the Very Large Array and track proper motions over 9 yr. The innermost and strongest emission lies in two extended arcs bracketing Source I. The proper motions trace a northeast-southwest bipolar outflow 100-1000 AU from Source I with a median three-dimensional motion of {approx}18 km s{sup -1}. An overlying distribution of {lambda}1.3 cm H{sub 2}O masers betrays similar flow characteristics. Gas dynamics and emission morphology traced by the masers suggest the presence of a magnetocentrifugal disk wind. Reinforcing evidence lies in the colinearity of the flow, apparent rotation across the flow parallel to the disk rotation, and recollimation that narrows the flow opening angle {approx}120 AU downstream. The arcs of ground-state SiO emission may mark the transition point to a shocked super-Alfvenic outflow.

  12. Prevalence of persistent cough and phlegm in young adults in relation to long-term ambient sulfur oxide exposure

    SciTech Connect (OSTI)

    Chapman, R.S.; Calafiore, D.C.; Hasselblad, V.

    1985-01-01

    In early 1976, a survey of persistent co gh and plegma (PCP) prevalence was conducted in 5623 young adults in four Utah communities. Over the previous five years, community specific mean sulfur dioxide levels had been 11, 18, 36, and 115 ug/mT. Corresponding mean suspended sulfate levels had been 5, 7, 8, and 14 g/mT No intercommunity exposure gradient of total suspended particulates or suspended nitrates was observed. In mothers, PCP prevalence among non-smokers was 4.2% in the high-exposure community and about 2.0% in all other communities. In smoking mothers, PCP prevalence was 21.8% in the high-exposure community and about 15.0% elsewhere. In fathers, PCP prevalence among non-smokers was about 8.0% in the high-exposure community and averaged about 3.0% elsewhere. In smoking fathers, PCP prevalence was less strongly associated with sulfur oxide exposure. PCP prevalence rates estimated in a categorical logistic regression model were qualitatively consistent with the prevalences presented above.

  13. Sowing the seeds of massive black holes in small galaxies: Young clusters as the building blocks of ultracompact dwarf galaxies

    SciTech Connect (OSTI)

    Amaro-Seoane, Pau; Konstantinidis, Symeon; Freitag, Marc Dewi; Coleman Miller, M.; Rasio, Frederic A. E-mail: simos@ari.uni-heidelberg.de E-mail: miller@astro.umd.edu

    2014-02-20

    Interacting galaxies often have complexes of hundreds of young stellar clusters of individual masses ∼10{sup 4}-10{sup 6} M {sub ☉} in regions that are a few hundred parsecs across. These cluster complexes interact dynamically, and their coalescence is a candidate for the origin of some ultracompact dwarf galaxies. Individual clusters with short relaxation times are candidates for the production of intermediate-mass black holes of a few hundred solar masses, via runaway stellar collisions prior to the first supernovae in a cluster. It is therefore possible that a cluster complex hosts multiple intermediate-mass black holes that may be ejected from their individual clusters due to mergers or binary processes, but bound to the complex as a whole. Here we explore the dynamical interaction between initially free-flying massive black holes and clusters in an evolving cluster complex. We find that, after hitting some clusters, it is plausible that the massive black hole will be captured in an ultracompact dwarf forming near the center of the complex. In the process, the hole typically triggers electromagnetic flares via stellar disruptions, and is also likely to be a prominent source of gravitational radiation for the advanced ground-based detectors LIGO and VIRGO. We also discuss other implications of this scenario, notably that the central black hole could be considerably larger than expected in other formation scenarios for ultracompact dwarfs.

  14. An anomalous extinction law in the Cep OB3b young cluster: Evidence for dust processing during gas dispersal

    SciTech Connect (OSTI)

    Allen, Thomas S.; Prchlik, Jakub J.; Megeath, S. Thomas; Gutermuth, Robert A.; Pipher, Judith L.; Naylor, Tim; Jeffries, R. D.

    2014-05-10

    We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with MMT/Hectospec spectra. Color excess ratios were determined toward each of the giants using V and R photometry from the literature, g, r, i, and z photometry from the Sloan Digital Sky Survey and J, H, and K{sub s} photometry from the Two Micron All Sky Survey. These color excess ratios were then used to construct the extinction law through the dusty material associated with Cep OB3b. The extinction law through Cep OB3b is intermediate between the R{sub V} = 3.1 and R{sub V} = 5 laws commonly used for the diffuse atomic interstellar medium and dense molecular clouds, respectively. The dependence of the extinction law on line-of-sight A{sub V} is investigated and we find the extinction law becomes shallower for regions with A{sub V} > 2.5 mag. We speculate that the intermediate dust law results from dust processing during the dispersal of the molecular cloud by the cluster.

  15. Fermi-LAT Discovery of GeV Gamma-ray Emission from the Young Supernova Remnant Cassiopeia A

    SciTech Connect (OSTI)

    Abdo, A.A.

    2011-08-19

    We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2{sigma} above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W{sub CR} {approx_equal} (1-4) x 10{sup 49} erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B {ge} 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

  16. Detached dust shell around Wolf-Rayet star WR60-6 in the young stellar cluster VVV CL036

    SciTech Connect (OSTI)

    Borissova, J.; Amigo, P.; Kurtev, R.; Kumar, M. S. N.; Chené, A.-N.; Minniti, D.

    2014-01-01

    The discovery of a detached dust shell around the Wolf-Rayet (WR) star WR60-6 in the young stellar cluster VVV CL036 is reported. This shell is uncovered through the Spitzer-MIPS 24 μm image, where it appears brightest, and it is invisible at shorter wavelengths. Using new APEX observations and other data available from the literature, we have estimated some of the shell parameters: the inner and outer radii of 0.15 and 0.90 pc, respectively; the overall systemic velocity of the molecular {sup 12}CO(3 → 2) emission of –45.7 ± 2.3 km s{sup –1}; an expansion velocity of the gas of 16.3 ± 1 km s{sup –1}; the dust temperature and opacity of 122 ± 12 K and 1.04, respectively; and an age of 2.8 × 10{sup 4} yr. The WR star displays some cyclic variability. The mass computed for the WR60-6 nebula indicates that the material was probably ejected during its previous stages of evolution. In addition, we have identified a bright spot very close to the shell, which can be associated with the Midcourse Space Experiment source G312.13+00.20.

  17. The young's modulus of 1018 steel and 67061-T6 aluminum measured from quasi-static to elastic precursor strain-rates

    SciTech Connect (OSTI)

    Rae, Philip J; Trujillo, Carl; Lovato, Manuel

    2009-01-01

    The assumption that Young's modulus is strain-rate invariant is tested for 6061-T6 aluminium alloy and 1018 steel over 10 decades of strain-rate. For the same billets of material, 3 quasi-static strain-rates are investigated with foil strain gauges at room temperature. The ultrasonic sound speeds are measured and used to calculate the moduli at approximately 10{sup 4} s{sup -1}. Finally, ID plate impact is used to generate an elastic pre-cursor in the alloys at a strain-rate of approximately 10{sup 6} s{sup -1} from which the longitudinal sound speed may be obtained. It is found that indeed the Young's modulus is strain-rate independent within the experimental accuracy.

  18. BANYAN. V. A SYSTEMATIC ALL-SKY SURVEY FOR NEW VERY LATE-TYPE LOW-MASS STARS AND BROWN DWARFS IN NEARBY YOUNG MOVING GROUPS

    SciTech Connect (OSTI)

    Gagn, Jonathan; Lafrenire, David; Doyon, Ren; Malo, Lison; Artigau, tienne

    2015-01-10

    We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ?13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the Two Micron All Sky Survey and AllWISE catalogs outside of the galactic plane to build a sample of 98,970 potential ?M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr{sup 1}. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNsII tool (BANYANII). We used the most probable statistical distances inferred from BANYANII to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segregation in the AB Doradus moving group and the Tucana-Horologium and Columba associations. The BASS sample has already been successful in identifying several new young brown dwarfs in earlier publications, and will be of great interest in studying the initial mass function of YMGs and for the search of exoplanets by direct imaging; the input sample of potential close-by ?M5 dwarfs will be useful to study the kinematics of low-mass stars and brown dwarfs and search for new proper motion pairs.

  19. PLANETS AROUND LOW-MASS STARS (PALMS). I. A SUBSTELLAR COMPANION TO THE YOUNG M DWARF 1RXS J235133.3+312720

    SciTech Connect (OSTI)

    Bowler, Brendan P.; Liu, Michael C.; Cieza, Lucas A.; Kraus, Adam L.; Shkolnik, Evgenya L.; Dupuy, Trent J.; Tamura, Motohide

    2012-07-10

    We report the discovery of a brown dwarf companion to the young M dwarf 1RXS J235133.3+312720 as part of a high contrast imaging search for planets around nearby young low-mass stars with Keck-II/NIRC2 and Subaru/HiCIAO. The 2.''4 ({approx}120 AU) pair is confirmed to be comoving from two epochs of high-resolution imaging. Follow-up low- and moderate-resolution near-infrared spectroscopy of 1RXS J2351+3127 B with IRTF/SpeX and Keck-II/OSIRIS reveals a spectral type of L0{sup +2}{sub -1}. The M2 primary star 1RXS J2351+3127 A exhibits X-ray and UV activity levels comparable to young moving group members with ages of {approx}10-100 Myr. UVW kinematics based the measured radial velocity of the primary and the system's photometric distance (50 {+-} 10 pc) indicate it is likely a member of the {approx}50-150 Myr AB Dor moving group. The near-infrared spectrum of 1RXS J2351+3127 B does not exhibit obvious signs of youth, but its H-band morphology shows subtle hints of intermediate surface gravity. The spectrum is also an excellent match to the {approx}200 Myr M9 brown dwarf LP 944-20. Assuming an age of 50-150 Myr, evolutionary models imply a mass of 32 {+-} 6 M{sub Jup} for the companion, making 1RXS J2351+3127 B the second lowest-mass member of the AB Dor moving group after the L4 companion CD-35 2722 B and one of the few benchmark brown dwarfs known at young ages.

  20. The slow ionized wind and rotating disklike system that are associated with the high-mass young stellar object G345.4938+01.4677

    SciTech Connect (OSTI)

    Guzmn, Andrs E.; Garay, Guido; Bronfman, Leonardo; Mardones, Diego; Rodrguez, Luis F.; Moran, James; Brooks, Kate J.; Nyman, Lars-ke; Sanhueza, Patricio

    2014-12-01

    We report the detection, made using ALMA, of the 92 GHz continuum and hydrogen recombination lines (HRLs) H40?, H42?, and H50? emission toward the ionized wind associated with the high-mass young stellar object G345.4938+01.4677. This is the luminous central dominating source located in the massive and dense molecular clump associated with IRAS 165623959. The HRLs exhibit Voigt profiles, which is a strong signature of Stark broadening. We successfully reproduce the observed continuum and HRLs simultaneously using a simple model of a slow ionized wind in local thermodynamic equilibrium, with no need for a high-velocity component. The Lorentzian line wings imply electron densities of 5 10{sup 7} cm{sup 3} on average. In addition, we detect SO and SO{sub 2} emission arising from a compact (?3000 AU) molecular core associated with the central young star. The molecular core exhibits a velocity gradient that is perpendicular to the jet-axis, which we interpret as evidence of rotation. The set of observations toward G345.4938+01.4677 are consistent with it being a young high-mass star associated with a slow photo-ionized wind.

  1. 2MASS 22344161+4041387AB: A WIDE, YOUNG, ACCRETING, LOW-MASS BINARY IN THE LkH{alpha}233 GROUP

    SciTech Connect (OSTI)

    Allers, K. N.; Liu, Michael C.; Cushing, Michael C.; Dupuy, Trent J.; Mathews, Geoffrey S.; Shkolnik, Evgenya; Reid, I. Neill; Cruz, Kelle L.; Vacca, W. D.

    2009-05-20

    We report the discovery of a young, 0.''16 binary, 2M2234+4041AB, found as the result of a Keck laser guide star adaptive optics imaging survey of young field ultracool dwarfs. Spatially resolved near-infrared photometry and spectroscopy indicate that the luminosity and temperature ratios of the system are near unity. From optical and near-infrared spectroscopy, we determine a composite spectral type of M6 for the system. Gravity-sensitive spectral features in the spectra of 2M2234+4041AB are best matched to those of young objects ({approx}1 Myr old). A comparison of the T {sub eff} and age of 2M2234+4041AB to evolutionary models indicates that the mass of each component is 0.10{sup +0.075} {sub -0.04} M {sub sun}. Emission lines of H{alpha} in the composite optical spectrum of the system and Br{gamma} in spatially resolved near-IR spectra of the two components indicate that the system is actively accreting. Both components of the system have IR excesses, indicating that they both harbor circumstellar disks. Though 2M2234+4041AB was originally identified as a young field dwarf, it lies 1.'5 from the well-studied Herbig Ae/Be star, LkH{alpha}233. The distance to LkH{alpha}233 is typically assumed to be 880 pc. It is unlikely that 2M2234+4041AB could be this distant, as it would then be more luminous than any known Taurus objects of similar spectral type. We re-evaluate the distance to the LkH{alpha}233 group and find a value of 325{sup +72} {sub -50} pc, based on the Hipparcos distance to a nearby B3-type group member (HD 213976). 2M2234+4041AB is the first low-mass star to be potentially associated with the LkH{alpha}233 group. At a distance of 325 pc, its projected physical separation is 51 AU, making it one of the growing number of wide, low-mass binaries found in young star-forming regions.

  2. THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS

    SciTech Connect (OSTI)

    Biller, Beth A.; Ftaclas, Christ; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Hayward, Thomas L.; Hartung, Markus; Chun, Mark; Clarke, Fraser; Thatte, Niranjan; Shkolnik, Evgenya L.; Reid, I. Neill; Boss, Alan; Lin, Douglas; Alencar, Silvia H. P.; De Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane [Universidade de Sao Paulo, IAG and others

    2013-11-10

    We report results of a direct imaging survey for giant planets around 80 members of the β Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ΔH = 13.9 mag at 1'' in combined CH{sub 4} narrowband ADI+SDI mode and median contrasts of ΔH = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 M{sub Jup}, 16.4 ± 1.0 AU), CD–35 2722B (31 ± 8 M{sub Jup}, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M{sub ☉}, 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M{sub ☉}, 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M{sub Jup} companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

  3. MULTIDIMENSIONAL CHEMICAL MODELING OF YOUNG STELLAR OBJECTS. III. THE INFLUENCE OF GEOMETRY ON THE ABUNDANCE AND EXCITATION OF DIATOMIC HYDRIDES

    SciTech Connect (OSTI)

    Bruderer, S.; Benz, A. O.; Staeuber, P.; Doty, S. D.

    2010-09-10

    The Herschel Space Observatory enables observations in the far-infrared at high spectral and spatial resolution. A particular class of molecules will be directly observable: light diatomic hydrides and their ions (CH, OH, SH, NH, CH{sup +}, OH{sup +}, SH{sup +}, NH{sup +}). These simple constituents are important both for the chemical evolution of the region and as tracers of high-energy radiation. If outflows of a forming star erode cavities in the envelope, protostellar far-UV (FUV; 6 < E{sub {gamma}} < 13.6 eV) radiation may escape through such low-density regions. Depending on the shape of the cavity, the FUV radiation then irradiates the quiescent envelope in the walls along the outflow. The chemical composition in these outflow walls is altered by photoreactions and heating via FUV photons in a manner similar to photo-dominated regions. In this work, we study the effect of cavity shapes, outflow density, and of a disk with the two-dimensional chemical model of a high-mass young stellar object introduced in the second paper in this series. The model has been extended with a self-consistent calculation of the dust temperature and a multi-zone escape probability method for the calculation of the molecular excitation and the prediction of line fluxes. We find that the shape of the cavity is particularly important in the innermost part of the envelope, where the dust temperatures are high enough ({approx}>100 K) for water ice to evaporate. If the cavity shape allows FUV radiation to penetrate this hot-core region, the abundance of FUV-destroyed species (e.g., water) is decreased. On larger scales, the shape of the cavity is less important for the chemistry in the outflow wall. In particular, diatomic hydrides and their ions CH{sup +}, OH{sup +}, and NH{sup +} are enhanced by many orders of magnitude in the outflow walls due to the combination of high gas temperatures and rapid photodissociation of more saturated species. The enhancement of these diatomic hydrides

  4. Mobile Technology and Social Media in the Clinical Practice of Young Radiation Oncologists: Results of a Comprehensive Nationwide Cross-sectional Study

    SciTech Connect (OSTI)

    Bibault, Jean-Emmanuel; Leroy, Thomas; Blanchard, Pierre; Biau, Julian; Cervellera, Mathilde; Diaz, Olivia; Faivre, Jean Christophe; and others

    2014-09-01

    Purpose: Social media and mobile technology are transforming the way in which young physicians are learning and practicing medicine. The true impact of such technologies has yet to be evaluated. Methods and Materials: We performed a nationwide cross-sectional survey to better assess how young radiation oncologists used these technologies. An online survey was sent out between April 24, 2013, and June 1, 2013. All residents attending the 2013 radiation oncology French summer course were invited to complete the survey. Logistic regressions were performed to assess predictors of use of these tools in the hospital on various clinical endpoints. Results: In all, 131 of 140 (93.6%) French young radiation oncologists answered the survey. Of these individuals, 93% owned a smartphone and 32.8% owned a tablet. The majority (78.6%) of the residents owning a smartphone used it to work in their department. A total of 33.5% had more than 5 medical applications installed. Only 60.3% of the residents verified the validity of the apps that they used. In all, 82.9% of the residents had a social network account. Conclusions: Most of the residents in radiation oncology use their smartphone to work in their department for a wide variety of tasks. However, the residents do not consistently check the validity of the apps that they use. Residents also use social networks, with only a limited impact on their relationship with their patients. Overall, this study highlights the irruption and the risks of new technologies in the clinical practice and raises the question of a possible regulation of their use in the hospital.

  5. Rsdometty C.M.R. Platt, J. W. Bennett, S. A. Young, M. D. Fenwick, P. J. Manson, G. R. Patterson, and B. Petraitis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Rsdometty C.M.R. Platt, J. W. Bennett, S. A. Young, M. D. Fenwick, P. J. Manson, G. R. Patterson, and B. Petraitis CSIRO Division of Atmospheric Research Station Street Aspendale, Victoria, Australia Introduction a suitable detector, such a radiometer can yield a response time of about one second, which will follow most cl6ud fluctuations with minimum lag. The LIRAD Method The use of narrow beam filter radiometers with lidars goes back some considerable time. The CSIRO Marl< I radiometer was

  6. Measurement of Young's modulus variation with layer pair and interplanar spacing in gold–nickel nanolaminates using nanoindentation and the tapping mode

    SciTech Connect (OSTI)

    Ahmed, H. S. Tanvir; Jankowski, Alan F.

    2015-03-28

    The features of grain size and interface separation strengthen the mechanical behavior of metallic nanolaminates. In addition, the presence of interlayer lattice strains can lead to a superlattice structure within the nanolaminate. The superlattice affects intrinsic properties of technological interest including electronic, magnetic, and elastic. The complex elastic and plastic behaviors of gold–nickel nanolaminate superlattice coatings as studied using nanoindentation are revisited with the tapping mode of a force microscope. Young's modulus is determined with nanoindentation during the initial elastic unloading after plastic deformation at depths up to one-fifth the coating thickness. The tapping mode provides a measurement during the initial elastic deformation at depths of only a few nanometers. The tapping mode utilizes the shift in the resonant frequency of the probe-cantilever system as contact is made with the sample surface. Both of these nanoprobe test methods produce results for measurements conducted with loading normal to the surface plane. A softening in the Young's modulus of gold–nickel nanolaminate coatings occurs for samples with layer pair spacing between 1 and 9 nm. The magnitude of softening corresponds with a progressive increase in the tensile state as measured with the change of interplanar spacing along the growth direction.

  7. THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A CLOSE SUBSTELLAR COMPANION TO THE YOUNG DEBRIS DISK STAR PZ Tel

    SciTech Connect (OSTI)

    Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Dupuy, Trent J.; Ftaclas, Christ; Nielsen, Eric L.; Close, Laird M.; Males, Jared; Skemer, Andrew; Hayward, Thomas L.; Hartung, Markus; Chun, Mark; Clarke, Fraser; Tecza, Matthias; Thatte, Niranjan; Reid, I. Neill; Shkolnik, Evgenya L.; Alencar, Silvia H. P.; Artymowicz, Pawel

    2010-09-01

    We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the {beta} Pic moving group observed with high-contrast adaptive optics imaging as part of the Gemini Near-Infrared Coronagraphic Imager Planet-Finding Campaign. The companion was detected at a projected separation of 16.4 {+-} 1.0 AU (0.''33 {+-} 0.''01) in 2009 April. Second-epoch observations in 2010 May demonstrate that the companion is physically associated and shows significant orbital motion. Monte Carlo modeling constrains the orbit of PZ Tel B to eccentricities >0.6. The near-IR colors of PZ Tel B indicate a spectral type of M7 {+-} 2 and thus this object will be a new benchmark companion for studies of ultracool, low-gravity photospheres. Adopting an age of 12{sup +8} {sub -4} Myr for the system, we estimate a mass of 36 {+-} 6 M {sub Jup} based on the Lyon/DUSTY evolutionary models. PZ Tel B is one of the few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system. Additionally, the primary star PZ Tel A shows a 70 {mu}m emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion.

  8. INDEPENDENT TECHNICAL REVIEW OF THE BUILDING 100 PLUME, FORMER DOE PINELLAS SITE (YOUNG - RAINEY STAR CENTER), LARGO, FLORIDA

    SciTech Connect (OSTI)

    Eddy-Dilek, C.; Rossabi, J.; Amidon, M.; Riha, B.; Kaback, D.

    2010-07-30

    Contaminated groundwater associated with Building 100 at the Young-Rainey Science, Technology, and Research Center, formerly the DOE Pinellas plant, is the primary remedial challenge that remains to be addressed at the site. Currently, Building 100 is an active industrial facility that is now owned and operated by the Pinellas county government. Groundwater samples collected from monitoring wells recently installed near the southern boundary of the site suggest that contaminated groundwater has migrated off the plant site. In response to the challenges presented by the Building 100 plume, the Office of Legacy Management (LM) requested assistance from the DOE Office of Groundwater and Soil Remediation (EM-32) to provide a review team to make technical recommendations so that they can efficiently and effectively address characterization and remediation of the plume. The review team was unanimous in the conclusion that a dynamic strategy that combines a phased implementation of direct push samplers, sensors, and tools can be used to better delineate the extent of contamination, control plume migration, and rapidly remediate the contaminated groundwater at the site. The initial efforts of the team focused on reviewing the site history and data, organizing the information into a conceptual model, identifying appropriate technologies, and recommending an integrated strategy. The current groundwater data from the site indicate a two-lobed plume extending to the east and south. To the east vinyl chloride is the primary contaminant of concern, to the south, vinyl chloride and cis1, 2-DCE are the primary contaminants. The limited data that are available suggest that reductive dechlorination of the TCE is already occurring but is not sufficient to prevent offsite migration of low concentrations of TCE daughter products. The team recommends that DOE pursue a strategy that builds on the natural cleansing capacity of the subsurface with reductive methods including biostimulation

  9. A SURVEY OF H{sub 2}O, CO{sub 2}, AND CO ICE FEATURES TOWARD BACKGROUND STARS AND LOW-MASS YOUNG STELLAR OBJECTS USING AKARI

    SciTech Connect (OSTI)

    Noble, J. A.; Fraser, H. J.; Aikawa, Y.; Pontoppidan, K. M.; Sakon, I.

    2013-10-01

    We present near-infrared spectroscopic observations of 19 molecular clouds made using the AKARI satellite, and the data reduction pipeline written to analyze those observations. The 2.5-5 ?m spectra of 30 objects22 field stars behind quiescent molecular clouds and 8 low-mass young stellar objects in coreswere successfully extracted using the pipeline. Those spectra are further analyzed to calculate the column densities of key solid phase molecular species, including H{sub 2}O, CO{sub 2}, CO, and OCN{sup }. The profile of the H{sub 2}O ice band is seen to vary across the objects observed and we suggest that the extended red wing may be an evolutionary indicator of both dust and ice mantle properties. The observation of 22 spectra with fluxes as low as < 5 mJy toward background stars, including 15 where the column densities of H{sub 2}O, CO, and CO{sub 2} were calculated, provides valuable data that could help to benchmark the initial conditions in star-forming regions prior to the onset of star formation.

  10. Intrinsic mechanical behavior of femoral cortical bone in young, osteoporotic and bisphosphonate-treated individuals in low- and high energy fracture conditions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zimmermann, Elizabeth A.; Schaible, Eric; Gludovatz, Bernd; Schmidt, Felix N.; Riedel, Christoph; Krause, Matthias; Vettorazzi, Eik; Acevedo, Claire; Hahn, Michael; Püschel, Klaus; et al

    2016-02-16

    Bisphosphonates are a common treatment to reduce osteoporotic fractures. This treatment induces osseous structural and compositional changes accompanied by positive effects on osteoblasts and osteocytes. Here, we test the hypothesis that restored osseous cell behavior, which resembles characteristics of younger, healthy cortical bone, leads to improved bone quality. Microarchitecture and mechanical properties of young, treatment-naïve osteoporosis, and bisphosphonate-treated cases were investigated in femoral cortices. Tissue strength was measured using three-point bending. Collagen fibril-level deformation was assessed in non-traumatic and traumatic fracture states using synchrotron small-angle x-ray scattering (SAXS) at low and high strain rates. The lower modulus, strength and fibrilmore » deformation measured at low strain rates reflects susceptibility for osteoporotic low-energy fragility fractures. Independent of age, disease and treatment status, SAXS revealed reduced fibril plasticity at high strain rates, characteristic of traumatic fracture. We find the significantly reduced mechanical integrity in osteoporosis may originate from porosity and alterations to the intra/extrafibrillar structure, while the fibril deformation under treatment indicates improved nano-scale characteristics. In conclusion, losses in strength and fibril deformation at low strain rates correlate with the occurrence of fragility fractures in osteoporosis, while improvements in structural and mechanical properties following bisphosphonate treatment may foster resistance to fracture during physiological strain rates.« less

  11. PLANETS AROUND LOW-MASS STARS (PALMS). II. A LOW-MASS COMPANION TO THE YOUNG M DWARF GJ 3629 SEPARATED BY 0.''2

    SciTech Connect (OSTI)

    Bowler, Brendan P.; Liu, Michael C.; Shkolnik, Evgenya L.; Tamura, Motohide

    2012-09-01

    We present the discovery of a 0.''2 companion to the young M dwarf GJ 3629 as part of our high-contrast adaptive optics imaging search for giant planets around low-mass stars with the Keck-II and Subaru telescopes. Two epochs of imaging confirm that the pair is comoving and reveal signs of orbital motion. The primary exhibits saturated X-ray emission which, together with its UV photometry from GALEX, points to an age younger than {approx}300 Myr. At these ages the companion lies below the hydrogen burning limit with a model-dependent mass of 46 {+-} 16 M{sub Jup} based on the system's photometric distance of 22 {+-} 3 pc. Resolved YJHK photometry of the pair indicates a spectral type of M7 {+-} 2 for GJ 3629 B. With a projected separation of 4.4 {+-} 0.6 AU and an estimated orbital period of 21 {+-} 5 yr, GJ 3629 AB is likely to yield a dynamical mass in the next several years, making it one of only a handful of brown dwarfs to have a measured mass and an age constrained from the stellar primary.

  12. LOW-VELOCITY SHOCKS TRACED BY EXTENDED SiO EMISSION ALONG THE W43 RIDGES: WITNESSING THE FORMATION OF YOUNG MASSIVE CLUSTERS

    SciTech Connect (OSTI)

    Nguyen-Luong, Q.; Martin, P. G.; Motte, F.; Louvet, F.; Hill, T.; Hennemann, M.; Didelon, P.; Lesaffre, P.; Gusdorf, A.; Menten, K. M.; Wyrowski, F.; Bendo, G.; Roussel, H.; Bernard, J.-P.; Bronfman, L.; and others

    2013-10-01

    The formation of high-mass stars is tightly linked to that of their parental clouds. Here, we focus on the high-density parts of W43, a molecular cloud undergoing an efficient event of star formation. Using a column density image derived from Herschel continuum maps, we identify two high-density filamentary clouds, called the W43-MM1 and W43-MM2 ridges. Both have gas masses of 2.1 10{sup 4} M{sub ?} and 3.5 10{sup 4} M{sub ?} above >10{sup 23} cm{sup -2} and within areas of ?6 and ?14 pc{sup 2}, respectively. The W43-MM1 and W43-MM2 ridges are structures that are coherent in velocity and gravitationally bound, despite their large velocity dispersion measured by the N{sub 2}H{sup +} (1-0) lines of the W43-HERO IRAM large program. Another intriguing result is that these ridges harbor widespread (?10 pc{sup 2}) bright SiO (2-1) emission, which we interpret to be the result of low-velocity shocks (?10 km s{sup 1}). We measure a significant relationship between the SiO (2-1) luminosity and velocity extent and show that it distinguishes our observations from the high-velocity shocks associated with outflows. We use state-of-the-art shock models to demonstrate that a small percentage (10%) of Si atoms in low-velocity shocks, observed initially in gas phase or in grain mantles, can explain the observed SiO column density in the W43 ridges. The spatial and velocity overlaps between the ridges of high-density gas and the shocked SiO gas suggest that ridges could be forming via colliding flows driven by gravity and accompanied by low-velocity shocks. This mechanism may be the initial conditions for the formation of young massive clusters.

  13. Surveying the agents of galaxy evolution in the tidally stripped, low metallicity small Magellanic Cloud (SAGE-SMC). III. Young stellar objects

    SciTech Connect (OSTI)

    Sewiło, M.; Carlson, L. R.; Seale, J. P.; Meixner, M.; Gordon, K.; Shiao, B. E-mail: carlson@strw.leidenuniv.nl E-mail: meixner@stsci.edu E-mail: shiao@stsci.edu; and others

    2013-11-20

    The Spitzer Space Telescope Legacy Program SAGE-SMC allows global studies of resolved stellar populations in the SMC in a different environment than our Galaxy. Using the SAGE-SMC IRAC (3.6-8.0 μm) and MIPS (24 and 70 μm) catalogs and images combined with near-infrared (JHK {sub s}) and optical (UBVI) data, we identified a population of ∼1000 intermediate- to high-mass young stellar objects (YSOs) in the SMC (three times more than previously known). Our method of identifying YSO candidates builds on the method developed for the Large Magellanic Cloud by Whitney et al. with improvements based on what we learned from our subsequent studies and techniques described in the literature. We perform (1) color-magnitude cuts based on five color-magnitude diagrams (CMDs), (2) visual inspection of multi-wavelength images, and (3) spectral energy distribution (SED) fitting with YSO models. For each YSO candidate, we use its photometry to calculate a measure of our confidence that the source is not a non-YSO contaminant, but rather a true YSO, based on the source's location in the color-magnitude space with respect to non-YSOs. We use this CMD score and the SED fitting results to define two classes of sources: high-reliability YSO candidates and possible YSO candidates. We found that, due to polycyclic aromatic hydrocarbon emission, about half of our sources have [3.6]-[4.5] and [4.5]-[5.8] colors not predicted by previous YSO models. The YSO candidates are spatially correlated with gas tracers.

  14. [Fe II] 1.64 μm FEATURES OF JETS AND OUTFLOWS FROM YOUNG STELLAR OBJECTS IN THE CARINA NEBULA

    SciTech Connect (OSTI)

    Shinn, Jong-Ho; Lee, Jae-Joon; Chun, Moo-Young; Lyo, A.-Ran; Moon, Dae-Sik; Kyeong, Jaemann; Park, Byeong-Gon; Pyo, Tae-Soo; Lee, Ho-Gyu; Kim, Hyun-Jeong; Koo, Bon-Chul; Lee, Yong-Hyun; Sung, Hwankyung; Hur, Hyeonoh

    2013-11-01

    We present [Fe II] 1.64 μm imaging observations for jets and outflows from young stellar objects (YSOs) over the northern part (∼24' × 45') of the Carina Nebula, a massive star-forming region. The observations were performed with IRIS2 of the Anglo-Australian Telescope and the seeing was ∼1.''5 ± 0.''5. Eleven jet and outflow features are detected at eight different regions and are termed ionized Fe objects (IFOs). One Herbig-Haro candidate that was missed in Hubble Space Telescope Hα observations is newly identified as HHc-16, referring to our [Fe II] images. IFOs have knotty or longish shapes, and the detection rate of IFOs against previously identified YSOs is 1.4%, which should be treated as a lower limit. Four IFOs show anti-correlated peak intensities in [Fe II] and Hα, where the ratio I([Fe II])/I(Hα) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux using two different methods. The jet-driving objects are identified for three IFOs (IFO-2, -4, and -7) for which we study the relations between the outflow mass loss rate and the YSO physical parameters from the radiative transfer model fitting. The ratios of the outflow mass loss rate over the disk accretion rate for IFO-4 and -7 are consistent with the previously reported values (10{sup –2}-10{sup +1}), while the ratio is higher for IFO-2. This excess may result from underestimating the disk accretion rate. The jet-driving objects are likely to be low- or intermediate-mass stars. Other YSO physical parameters, such as luminosity and age, show reasonable relations or trends.

  15. NREL: Energy Analysis - Katherine Young

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Rock Fracture Group, University of Wisconsin, Madison, WI (1998) Research Assistant, Stormwater Management Group, University of Wisconsin, Madison, WI (1997-1998) Field Engineer, ...

  16. Fensin receives Young Leaders Award

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fensin earned a doctorate in materials science and engineering from the University of ... cancer therapies based on how ribosomes differentiate in healthy versus cancerous tissue. ...

  17. CSI 2264: simultaneous optical and infrared light curves of young disk-bearing stars in NGC 2264 with CoRoT and Spitzerevidence for multiple origins of variability

    SciTech Connect (OSTI)

    Cody, Ann Marie; Stauffer, John; Rebull, Luisa M.; Carey, Sean; Baglin, Annie; Micela, Giuseppina; Flaccomio, Ettore; Morales-Caldern, Mara; Aigrain, Suzanne; Bouvier, Jrme; Gutermuth, Robert; Song, Inseok; Turner, Neal; Alencar, Silvia H. P.; Zwintz, Konstanze; Plavchan, Peter; Terebey, Susan; and others

    2014-04-01

    We present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30 day multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes and assess the fractional representation within each class. The largest category (>20%) are optical 'dippers' with discrete fading events lasting ?1-5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with H? emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk.

  18. Insecticide Transfer Efficiency and Lethal Load in Argentine Ants

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hooper-Bui, L. M.; Kwok, E S.C.; Buchholz, B. A.; Rust, M. K.; Eastmond, D. A.; Vogel, J. S.

    2015-07-03

    Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of 14C-sucrose, 14C-hydramethylnon, and 14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), butmore » dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). Moreover, the distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. The bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.« less

  19. Insecticide Transfer Efficiency and Lethal Load in Argentine Ants

    SciTech Connect (OSTI)

    Hooper-Bui, L. M.; Kwok, E S.C.; Buchholz, B. A.; Rust, M. K.; Eastmond, D. A.; Vogel, J. S.

    2015-07-03

    Trophallaxis between individual worker ants and the toxicant load in dead and live Argentine ants (Linepithema humile) in colonies exposed to fipronil and hydramethylnon experimental baits were examined using accelerator mass spectrometry (AMS). About 50% of the content of the crop containing trace levels of 14C-sucrose, 14C-hydramethylnon, and 14C-fipronil was shared between single donor and recipient ants. Dead workers and queens contained significantly more hydramethylnon (122.7 and 22.4 amol/μg ant, respectively) than did live workers and queens (96.3 and 10.4 amol/μg ant, respectively). Dead workers had significantly more fipronil (420.3 amol/μg ant) than did live workers (208.5 amol/μg ant), but dead and live queens had equal fipronil levels (59.5 and 54.3 amol/μg ant, respectively). Moreover, the distribution of fipronil differed within the bodies of dead and live queens; the highest amounts of fipronil were recovered in the thorax of dead queens whereas live queens had the highest levels in the head. Resurgence of polygynous ant colonies treated with hydramethylnon baits may be explained by queen survival resulting from sublethal doses due to a slowing of trophallaxis throughout the colony. The bait strategies and dose levels for controlling insect pests need to be based on the specific toxicant properties and trophic strategies for targeting the entire colony.

  20. A classification scheme for young stellar objects using the wide-field infrared survey explorer AllWISE catalog: revealing low-density star formation in the outer galaxy

    SciTech Connect (OSTI)

    Koenig, X. P.; Leisawitz, D. T.

    2014-08-20

    We present an assessment of the performance of WISE and the AllWISE data release for a section of the Galactic Plane. We lay out an approach to increasing the reliability of point-source photometry extracted from the AllWISE catalog in Galactic Plane regions using parameters provided in the catalog. We use the resulting catalog to construct a new, revised young star detection and classification scheme combining WISE and 2MASS near- and mid-infrared colors and magnitudes and test it in a section of the outer Milky Way. The clustering properties of the candidate Class I and II stars using a nearest neighbor density calculation and the two-point correlation function suggest that the majority of stars do form in massive star-forming regions, and any isolated mode of star formation is at most a small fraction of the total star forming output of the Galaxy. We also show that the isolated component may be very small and could represent the tail end of a single mechanism of star formation in line with models of molecular cloud collapse with supersonic turbulence and not a separate mode all to itself.

  1. THE SPITZER SPACE TELESCOPE SURVEY OF THE ORION A AND B MOLECULAR CLOUDS. I. A CENSUS OF DUSTY YOUNG STELLAR OBJECTS AND A STUDY OF THEIR MID-INFRARED VARIABILITY

    SciTech Connect (OSTI)

    Megeath, S. T.; Kryukova, E.; Gutermuth, R.; Muzerolle, J.; Flaherty, K.; Hora, J. L.; Myers, P. C.; Fazio, G. G.; Allen, L. E.; Hartmann, L.; Pipher, J. L.; Stauffer, J.; Young, E. T.

    2012-12-01

    We present a survey of the Orion A and B molecular clouds undertaken with the IRAC and MIPS instruments on board Spitzer. In total, five distinct fields were mapped, covering 9 deg{sup 2} in five mid-IR bands spanning 3-24 {mu}m. The survey includes the Orion Nebula Cluster, the Lynds 1641, 1630, and 1622 dark clouds, and the NGC 2023, 2024, 2068, and 2071 nebulae. These data are merged with the Two Micron All Sky Survey point source catalog to generate a catalog of eight-band photometry. We identify 3479 dusty young stellar objects (YSOs) in the Orion molecular clouds by searching for point sources with mid-IR colors indicative of reprocessed light from dusty disks or infalling envelopes. The YSOs are subsequently classified on the basis of their mid-IR colors and their spatial distributions are presented. We classify 2991 of the YSOs as pre-main-sequence stars with disks and 488 as likely protostars. Most of the sources were observed with IRAC in two to three epochs over six months; we search for variability between the epochs by looking for correlated variability in the 3.6 and 4.5 {mu}m bands. We find that 50% of the dusty YSOs show variability. The variations are typically small ({approx}0.2 mag) with the protostars showing a higher incidence of variability and larger variations. The observed correlations between the 3.6, 4.5, 5.8, and 8 {mu}m variability suggests that we are observing variations in the heating of the inner disk due to changes in the accretion luminosity or rotating accretion hot spots.

  2. Peter Fischer3,', Mi-Young lma, ...

    Office of Scientific and Technical Information (OSTI)

    ... Matter Phys., 1 (2010), pp. 7 1 - 88 2 J. Stoehr, H.C. Siegmann, Magnetism, Springer, ... The analysis of Magnetic Microstructure, Springer-Verlag, Berlin (1998) 19 H.J. Williams, ...

  3. Young, Jupiter-like planet discovered

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    orbiting bright stars. The GPI is located on the 8-meter Gemini South Telescope in Chile, although the coordinating science teams are spread globally. After GPI was installed...

  4. One Young World Summit |GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    One Year Anniversary, Office of the Ombudsman One Year Anniversary, Office of the Ombudsman March 7, 2013 - A Letter from Secretary Steven Chu Dear Colleagues, One year ago March 6, the Department of Energy established the Office of the Ombudsman. Earlier in my career, I watched a similar office at Stanford University provide a safe, independent, and confidential environment for university employees to resolve workplace matters. After spending time at the Department of Energy, I suggested the

  5. Nurturing young children's curiosity about the universe

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... For Ortega, early literacy, including early STEM literacy, is a logical place to start in attempting to reverse New Mexico's poverty statistics and educational challenges. Citing ...

  6. QER- Comment of Allen Young 2

    Broader source: Energy.gov [DOE]

    Here is a comment from me on the issue of energy infrastructure in Massachusetts. I will address only one issue: the proposed Kinder Morgan pipelines from Albany to Dracut. I am absolutely opposed to the construction of this pipeline and here are my reasons

  7. Young Inventor Award | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy You Asked, We're Answering Your Fuel Cell Questions You Asked, We're Answering Your Fuel Cell Questions January 24, 2014 - 2:20pm Addthis Watch a recording of our live discussion on Energy 101: Fuel Cells. | Video by the Energy Department. Sunita Satyapal Director, Fuel Cell Technologies Office Fuel Cell Resources: For fuel cell basics, watch a recording of our Google+ Hangout on Energy 101: Fuel Cells and check out our Fuel Cell topic page. Visit the Energy Department's Fuel Cell

  8. PLANETARY CONSTRUCTION ZONES IN OCCULTATION: DISCOVERY OF AN EXTRASOLAR RING SYSTEM TRANSITING A YOUNG SUN-LIKE STAR AND FUTURE PROSPECTS FOR DETECTING ECLIPSES BY CIRCUMSECONDARY AND CIRCUMPLANETARY DISKS

    SciTech Connect (OSTI)

    Mamajek, Eric E.; Quillen, Alice C.; Pecaut, Mark J.; Moolekamp, Fred; Scott, Erin L.; Kenworthy, Matthew A.; Cameron, Andrew Collier; Parley, Neil R.

    2012-03-15

    The large relative sizes of circumstellar and circumplanetary disks imply that they might be seen in eclipse in stellar light curves. We estimate that a survey of {approx}10{sup 4} young ({approx}10 million year old) post-accretion pre-main-sequence stars monitored for {approx}10 years should yield at least a few deep eclipses from circumplanetary disks and disks surrounding low-mass companion stars. We present photometric and spectroscopic data for a pre-main-sequence K5 star (1SWASP J140747.93-394542.6 = ASAS J140748-3945.7), a newly discovered {approx}0.9 M{sub Sun} member of the {approx}16 Myr old Upper Centaurus-Lupus subgroup of Sco-Cen at a kinematic distance of 128 {+-} 13 pc. This star exhibited a remarkably long, deep, and complex eclipse event centered on 2007 April 29 (as discovered in Super Wide Angle Search for Planets (SuperWASP) photometry, and with portions of the dimming confirmed by All Sky Automated Survey (ASAS) data). At least five multi-day dimming events of >0.5 mag are identified, with a >3.3 mag deep eclipse bracketed by two pairs of {approx}1 mag eclipses symmetrically occurring {+-}12 days and {+-}26 days before and after. Hence, significant dimming of the star was taking place on and off over at least a {approx}54 day period in 2007, and a strong >1 mag dimming event occurring over a {approx}12 day span. We place a firm lower limit on the period of 850 days (i.e., the orbital radius of the eclipser must be >1.7 AU and orbital velocity must be <22 km s{sup -1}). The shape of the light curve is similar to the lopsided eclipses of the Be star EE Cep. We suspect that this new star is being eclipsed by a low-mass object orbited by a dense inner disk, further girded by at least three dusty rings of optical depths near unity. Between these rings are at least two annuli of near-zero optical depth (i.e., gaps), possibly cleared out by planets or moons, depending on the nature of the secondary. For possible periods in the range 2.33-200 yr, the

  9. Fun and inspiration for 575 young women at PPPL's Young Women...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Engineering, and Mathematics (STEM) on March 18. They talked to investigators from the FBI, watched colorful infrared images of themselves, played with robots, learned about ...

  10. Young scientist discovers magnetic material unnecessary to create...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    implications for the field of spintronics and the development of high-speed, ... spin based computing (spintronics), and is also an area of great fundamental interest. ...

  11. Young-Sang Yu1, Dong-Soo Han1, ...

    Office of Scientific and Technical Information (OSTI)

    Engineering, Seoul National University, Seoul 151 -744, South Korea, 2Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA. Vortex structures in ...

  12. Three Young Scientists Earn DOE Graduate Research Grants at Jefferson...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... on applying for 2015 awards are available online: http:science.energy.govwdtsscgsr. ... For more information on DOE's Office of Science, visit: www.science.energy.gov. The ...

  13. THE NEARBY, YOUNG, ISOLATED, DUSTY STAR HD 166191

    SciTech Connect (OSTI)

    Schneider, Adam; Song, Inseok; Hufford, Tara; Melis, Carl; Zuckerman, B.; Bessell, Mike; Hinkley, Sasha E-mail: song@physast.uga.edu E-mail: cmelis@ucsd.edu E-mail: bessell@mso.anu.edu.au

    2013-11-01

    We report an in-depth study of the F8-type star HD 166191, identified in an ongoing survey for stars exhibiting infrared emission above their expected photospheres in the Wide-field Infrared Survey Explorer all-sky catalog. The fractional IR luminosity measured from 3.5 to 70 μm is exceptionally high (L{sub IR}/L{sub bol} ∼ 10%). Near-diffraction-limited imaging observations with the T-ReCS Si filter set on the Gemini South telescope and adaptive optics imaging with the NIRC2 Lp filter on the Keck II telescope confirmed that the excess emission coincides with the star. Si-band images show a strong solid-state emission feature at ∼10 μm. Theoretical evolutionary isochrones and optical spectroscopic observations indicate a stellar age in the range 10-100 Myr. The large dust mass seen in HD 166191's terrestrial planet zone is indicative of a recent collision between planetary embryos or massive ongoing collisional grinding associated with planet building.

  14. Thomas Edison's Legacy for Young Engineers | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Thomas Edison's Legacy: In the Eyes of an Edison Engineer Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new ...

  15. Penetration equations Young, C.W. [Applied Research Associates...

    Office of Scientific and Technical Information (OSTI)

    45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; EARTH PENETRATORS; EQUATIONS; NUCLEAR WEAPONS; SOILS; ICE; ROCKS; CONCRETES; PERMAFROST; SCALING LAWS In 1967, Sandia...

  16. STEM Mentoring Caf- Engaging Young Women in an Authentic Mentoring...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    role in choosing a career path. In addition, the more students identify with same-sex experts the more likely they will be to pursue a STEM career. So not only did the STEM...

  17. Young Women's Conference cheers on girls interested in STEM ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... characters, including a soldier in Iraq and a pregnant woman with a small business ... Another chose the military clothing and the invisibility cloak for the soldier in Iraq. ...

  18. Progress in Understanding Iron Peak Elements in Young Supernova...

    Office of Scientific and Technical Information (OSTI)

    Los Alamos National Laboratory Rutgers Univeristy University of Pittspurgh Harvard-Smithsonian Center for Astrophysics Publication Date: 2013-09-13 OSTI Identifier: 1093345 Report ...

  19. National Laboratory]; Kim, Young Jin [Los Alamos National Laboratory...

    Office of Scientific and Technical Information (OSTI)

    EDM Abstract Not Provided Los Alamos National Laboratory (LANL) DOELANL United States 2014-11-05 English Conference Conference: Challenges of the worldwide experimental search...

  20. Conference for young women aims to encourage pursuit of science...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Angela Hardin at (630) 252-5501 or media@anl.gov. Connect Find an Argonne expert by subject. Follow Argonne on Twitter, Facebook, Google+ and LinkedIn. For inquiries on...

  1. Progress in Understanding Iron Peak Elements in Young Supernova...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Conference: AtomDB Work Week and Workshop 2013 ; 2013-08-19 - 2013-08-23 ; Cambridge, Massachusetts, United States Research Org: Los Alamos National Laboratory ...

  2. ARM - Field Campaign - MPL Measurements, Norwegian Young sea...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The RV Lance was frozen into the winter sea ice north of Svalbard at approximately 83 N, ... Institute (AWI), Hokkaido University, Korea Polar Research Institute, University of ...

  3. Young PhDs in Physics | Jefferson Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Results Prepared for South Coast Air Quality Management District by the National Renewable Energy Laboratory CRD-01-098 Fischer-Tropsch Synthetic Fuel Demonstration in a Southern California Vehicle Fleet Yosemite Waters Vehicle Evaluation Report Yosemite Waters Vehicle Evaluation Report i Alternative Fuel Trucks YOSEMITE WATERS VEHICLE EVALUATION REPORT Authors Leslie Eudy, National Renewable Energy Laboratory (NREL) Robb Barnitt, NREL Teresa L. Alleman, NREL August 2005 Acknowledgements This

  4. Structure and Stratigraphy Beneath a Young Phreatic Vent: South...

    Open Energy Info (EERE)

    deformation. Authors John C. Eichelberger, Thomas A. Vogel, Leland W. Younker, C. Dan Miller, Grant H. Heiken and Kenneth H. Wohletz Published Journal Journal of Geophysical...

  5. A young person's view of the Superconducting Super Collider

    SciTech Connect (OSTI)

    Moya, A.

    1990-08-01

    This report gives a simple description of the Superconducting Super Collider, how it works, and what it is used for. (LSP)

  6. Hanford Grows Young Minds Through Site Tours | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    students have been working this quarter modeling and documenting contaminated site ... can see an ongoing cleanup process steeped in a complex social and technical context?" ...

  7. Quarterly Progress Report for the Young-Rainey STAR Center's...

    Office of Legacy Management (LM)

    ... changes during biosparge operations; * Determining biodegradation rates and oxygen consumption rates utilizing microcosm experiments with site soils and ground water; * Performing ...

  8. Quarterly Progress Report for the Young-Rainey STAR Center's...

    Office of Legacy Management (LM)

    ... Progress Report January 2003 Page 3 * Determining biodegradation rates and oxygen consumption rates utilizing microcosm experiments with site soils and ground water; * Performing ...

  9. Women @ Energy: Young-Kee Kim | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    in science, and in particular, my interest in physics, came only when I was in middle school. I had a fantastic science teacher who handpicked me to participate in a science...

  10. Calling all Young Entrepreneurs: Deadline for Energy Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... The national and regional Clean Energy Business Plan Competitions are designed to unleash student creativity and address the country's energy challenges by developing a new ...

  11. Bright Young Minds for a Clean Energy Future

    Broader source: Energy.gov [DOE]

    It’s that time again: Back to school season is officially here! Time for students to prepare for the new experiences and challenges that they will encounter throughout the upcoming school year.

  12. Catching the entrepreneurial spirit at a young age

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Administration | (NNSA) Catch up on the latest Sandia California news Tuesday, August 25, 2015 - 10:37am Each summer, Sandia National Laboratories focuses on news and events occurring at its California site in a special edition of its Lab News. This year's special edition issue focuses on stories about Sandia's telemetry work, recycling algae nutrients and looking how computer users handle phish. A story about the Sandia LED Pulser offers a glimpse of how the device is aiding other research

  13. Near-infrared (JHK) spectroscopy of young stellar and substellar...

    Office of Scientific and Technical Information (OSTI)

    7 new objects having masses below the hydrogen-burning limit, and 6 objects with masses ... SPECTRA; HERTZSPRUNG-RUSSELL DIAGRAM; HYDROGEN BURNING; LUMINOSITY; MASS; NEAR INFRARED ...

  14. Young galaxy candidates in the Hubble Frontier Fields. I. A2744

    SciTech Connect (OSTI)

    Zheng, Wei; Ford, Holland C.; Huang, Xingxing; Shu, Xinwen; Zitrin, Adi; Broadhurst, Tom; Kelson, Daniel D.; Smit, Renske

    2014-11-01

    We report the discovery of 24 Lyman-break candidates at 7 ≲ z ≲ 10.5, in the Hubble Frontier Fields (HFF) imaging data of A2744 (z = 0.308), plus Spitzer/IRAC data and archival ACS data. The sample includes a triple image system with a photometric redshift of z ≅ 7.4. This high redshift is geometrically confirmed by our lens model corresponding to deflection angles that are 12% larger than the lower-redshift systems used to calibrate the lens model at z = 2.019. The majority of our high-redshift candidates are not expected to be multiply lensed given their locations in the image plane and the brightness of foreground galaxies, but are magnified by factors of ∼1.3-15, so that we are seeing further down the luminosity function than comparable deep-field imaging. It is apparent that the redshift distribution of these sources does not smoothly extend over the full redshift range accessible at z < 12, but appears to break above z = 9. Nine candidates are clustered within a small region of 20'' across, representing a potentially unprecedented concentration. Given the poor statistics, however, we must await similar constraints from the additional HFF clusters to properly examine this trend. The physical properties of our candidates are examined using the range of lens models developed for the HFF program by various groups including our own, for a better estimate of underlying systematics. Our spectral-energy-distribution fits for the brightest objects suggest stellar masses of ≅ 10{sup 9} M {sub ☉}, star formation rates of ≅ 4 M {sub ☉} yr{sup –1}, and a typical formation redshift of z ≲ 19.

  15. Three Young Scientists Earn DOE Graduate Research Grants at Jefferson Lab |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    | Department of Energy Three Sustainability Tools are Enhancing Environmental Benefits of Biofuels Three Sustainability Tools are Enhancing Environmental Benefits of Biofuels October 28, 2015 - 11:20am Addthis The Landscape Environmental Assessment Framework (LEAF), the Water Assessment for Transportation Energy Resources (WATER), and the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model are three tools that are enabling an environmentally beneficial

  16. An adaptive optics multiplicity census of young stars in Upper Scorpius

    SciTech Connect (OSTI)

    Lafrenière, David; Jayawardhana, Ray; Van Kerkwijk, Marten H.; Brandeker, Alexis; Janson, Markus

    2014-04-10

    We present the results of a multiplicity survey of 91 stars spanning masses of ∼0.2-10 M {sub ☉} in the Upper Scorpius star-forming region, based on adaptive optics imaging with the Gemini North telescope. Our observations identified 29 binaries, 5 triples, and no higher order multiples. The corresponding raw multiplicity frequency is 0.37 ± 0.05. In the regime where our observations are complete—companion separations of 0.''1-5'' (∼15-800 AU) with magnitude limits ranging from K < 9.3 at 0.''1 to K < 15.8 at 5''—the multiplicity frequency is 0.27{sub −0.04}{sup +0.05}. For similar separations, the multiplicity frequency in Upper Scorpius is comparable to that in other dispersed star-forming regions, but is a factor of two to three higher than in denser star-forming regions or in the field. Our sample displays a constant multiplicity frequency as a function of stellar mass. Among our sample of binaries, we find that both wider (>100 AU) and higher-mass systems tend to have companions with lower companion-to-primary mass ratios. Three of the companions identified in our survey are unambiguously substellar and have estimated masses below 0.04 M {sub ☉} (two of them are new discoveries from this survey—1RXS J160929.1–210524b and HIP 78530B—although we have reported them separately in earlier papers). These three companions have projected orbital separations of 300-900 AU. Based on a statistical analysis factoring in sensitivity limits, we calculate an occurrence rate of 5-40 M {sub Jup} companions of ∼4.0% for orbital separations of 250-1000 AU, compared to <1.8% at smaller separations, suggesting that such companions are more frequent on wider orbits.

  17. BUOYANT MAGNETIC LOOPS IN A GLOBAL DYNAMO SIMULATION OF A YOUNG SUN

    SciTech Connect (OSTI)

    Nelson, Nicholas J.; Toomre, Juri; Brown, Benjamin P.; Brun, Allan Sacha

    2011-10-01

    The current dynamo paradigm for the Sun and Sun-like stars places the generation site for strong toroidal magnetic structures deep in the solar interior. Sunspots and starspots on Sun-like stars are believed to arise when sections of these magnetic structures become buoyantly unstable and rise from the deep interior to the photosphere. Here, we present the first three-dimensional global magnetohydrodynamic (MHD) simulation in which turbulent convection, stratification, and rotation combine to yield a dynamo that self-consistently generates buoyant magnetic loops. We simulate stellar convection and dynamo action in a spherical shell with solar stratification, but rotating three times faster than the current solar rate. Strong wreaths of toroidal magnetic field are realized by dynamo action in the convection zone. By turning to a dynamic Smagorinsky model for subgrid-scale turbulence, we here attain considerably reduced diffusion in our simulation. This permits the regions of strongest magnetic field in these wreaths to rise toward the top of the convection zone via a combination of magnetic buoyancy instabilities and advection by convective giant cells. Such a global simulation yielding buoyant loops represents a significant step forward in combining numerical models of dynamo action and flux emergence.

  18. 238U Decay Series Systematics Of Young Lavas From Batur Volcano...

    Open Energy Info (EERE)

    or post-eruptive condensation of volatile Pb salts in vesicles. Authors K. H. Rubin, G. E. Wheller, M. O. Tanzer, J. D. MacDougall, R. Varne and R. Finkel Published...

  19. Indoor risk factors for cough and their relation to wheeze and sensitization in Chilean young adults

    SciTech Connect (OSTI)

    Potts, J.F.; Rona, R.J.; Oyarzun, M.J.; Amigo, H.; Bustos, P.

    2008-04-15

    We assessed the effects of indoor risk factors, including smoking, on different types of cough and on cough and wheeze in combination. Our sample was composed of 1232 men and women residing in a semi-rural area of Chile. We used a standardized questionnaire, sensitization to 8 allergens, and bronchial hyperresponsiveness to methacholine to assess cough and wheeze characteristics. Information was gathered on dampness, mold, ventilation, heating, housing quality, smoking, and environmental tobacco smoke exposure. Most exposures were associated with cough alone or cough in combination with wheeze. Smoking, past smoking, and environmental tobacco smoke exposure were strongly associated with dry cough and wheeze. The use of coal for heating was associated with dry cough. Leaks, mold, and lack of kitchen ventilation were associated with cough and wheeze. Nocturnal cough and productive cough were associated with specific types of sensitization, but dry cough was not. Productive cough was associated with hyperresponsiveness to methacholine. Several different types of indoor exposures, including environmental tobacco smoke exposure, are important contributors to morbidity associated with cough and wheeze. A vigorous preventive strategy designed to lower exposures to indoor risk factors would lower rates of respiratory morbidity.

  20. A first-look atmospheric modeling study of the young directly...

    Office of Scientific and Technical Information (OSTI)

    Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON (Canada) Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, ...

  1. Variable accretion processes in the young binary-star system UY Aur

    SciTech Connect (OSTI)

    Stone, Jordan M.; Eisner, J. A.; Kulesa, Craig; McCarthy, Don; Salyk, Colette E-mail: jeisner@as.arizona.edu E-mail: dmccarthy@as.arizona.edu

    2014-09-01

    We present new K-band spectroscopy of the UY Aur binary star system. Our data are the first to show H{sub 2} emission in the spectrum of UY Aur A and the first to spectrally resolve the Br? line in the spectrum of UY Aur B. We see an increase in the strength of the Br? line in UY Aur A and a decrease in Br? and H{sub 2} line luminosity for UY Aur B compared to previous studies. Converting Br? line luminosity to accretion rate, we infer that the accretion rate onto UY Aur A has increased by 2 10{sup 9} M {sub ?} yr{sup 1} per year since a rate of zero was observed in 1994. The Br? line strength for UY Aur B has decreased by a factor of 0.54 since 1994, but the K-band flux has increased by 0.9 mag since 1998. The veiling of UY Aur B has also increased significantly. These data evince a much more luminous disk around UY Aur B. If the lower Br? luminosity observed in the spectrum of UY Aur B indicates an intrinsically smaller accretion rate onto the star, then UY Aur A now accretes at a higher rate than UY Aur B. However, extinction at small radii or mass pile-up in the circumstellar disk could explain decreased Br? emission around UY Aur B even when the disk luminosity implies an increased accretion rate. In addition to our scientific results for the UY Aur system, we discuss a dedicated pipeline we have developed for the reduction of echelle-mode data from the ARIES spectrograph.

  2. Distributions of short-lived radioactive nuclei produced by young embedded star clusters

    SciTech Connect (OSTI)

    Adams, Fred C.; Fatuzzo, Marco; Holden, Lisa

    2014-07-01

    Most star formation in the Galaxy takes place in clusters, where the most massive members can affect the properties of other constituent solar systems. This paper considers how clusters influence star formation and forming planetary systems through nuclear enrichment from supernova explosions, where massive stars deliver short-lived radioactive nuclei (SLRs) to their local environment. The decay of these nuclei leads to both heating and ionization, and thereby affects disk evolution, disk chemistry, and the accompanying process of planet formation. Nuclear enrichment can take place on two spatial scales: (1) within the cluster itself (ℓ ∼ 1 pc), the SLRs are delivered to the circumstellar disks associated with other cluster members. (2) On the next larger scale (ℓ ∼ 2-10 pc), SLRs are injected into the background molecular cloud; these nuclei provide heating and ionization to nearby star-forming regions and to the next generation of disks. For the first scenario, we construct the expected distributions of radioactive enrichment levels provided by embedded clusters. Clusters can account for the SLR mass fractions inferred for the early Solar Nebula, but typical SLR abundances are lower by a factor of ∼10. For the second scenario, we find that distributed enrichment of SLRs in molecular clouds leads to comparable abundances. For both the direct and distributed enrichment processes, the masses of {sup 26}Al and {sup 60}Fe delivered to individual circumstellar disks typically fall in the range 10-100 pM {sub ☉} (where 1 pM {sub ☉} = 10{sup –12} M {sub ☉}). The corresponding ionization rate due to SLRs typically falls in the range ζ{sub SLR} ∼ 1-5 × 10{sup –19} s{sup –1}. This ionization rate is smaller than that due to cosmic rays, ζ{sub CR} ∼ 10{sup –17} s{sup –1}, but will be important in regions where cosmic rays are attenuated (e.g., disk mid-planes).

  3. ALMA OBSERVATIONS OF THE DEBRIS DISK AROUND THE YOUNG SOLAR ANALOG HD 107146

    SciTech Connect (OSTI)

    Ricci, L.; Carpenter, J. M.; Fu, B.; Hughes, A. M.; Corder, S.; Isella, A.

    2015-01-10

    We present the Atacama Large Millimeter/submillimeter Array (ALMA) continuum observations at a wavelength of 1.25 mm of the debris disk surrounding the ∼100 Myr old solar analog HD 107146. The continuum emission extends from about 30 to 150 AU from the central star with a decrease in the surface brightness at intermediate radii. We analyze the ALMA interferometric visibilities using debris disk models with radial profiles for the dust surface density parameterized as (1) a single power law, (2) a single power law with a gap, and (3) a double power law. We find that models with a gap of radial width ∼8 AU at a distance of ∼80 AU from the central star, as well as double power-law models with a dip in the dust surface density at ∼70 AU provide significantly better fits to the ALMA data than single power-law models. We discuss possible scenarios for the origin of the HD 107146 debris disk using models of planetesimal belts in which the formation of Pluto-sized objects trigger disruptive collisions of large bodies, as well as models that consider the interaction of a planetary system with a planetesimal belt and spatial variation of the dust opacity across the disk. If future observations with higher angular resolution and sensitivity confirm the fully depleted gap structure discussed here, a planet with a mass of approximately a few Earth masses in a nearly circular orbit at ∼80 AU from the central star would be a possible explanation for the presence of the gap.

  4. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    SciTech Connect (OSTI)

    Ansdell, Megan; Baranec, Christoph; Gaidos, Eric; Mann, Andrew W.; Lpine, Sebastien; James, David; Buccino, Andrea; Mauas, Pablo; Petrucci, Romina; Law, Nicholas M.; Riddle, Reed

    2015-01-01

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lpine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 ) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5?) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ?16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.

  5. Health status of young children with cancer following discontinuation of therapy

    SciTech Connect (OSTI)

    Pastore, G.; Zurlo, M.G.; Acquaviva, A.; Calculli, G.; Castello, M.; Ceci, A.; Di Tullio, M.L.; Gandus, S.; Macchia, P.; Di Montezemolo, L.C.

    1987-01-01

    This paper reports late effects and health status of 198 children who had cancer or leukemia diagnosed under 2 years of age and their therapies electively withdrawn. This series (92 neuroblastoma (NBL), 57 Wilms' tumor (WT), 46 acute lymphoblastic leukemia (ALL), and 3 non-Hodgkin's lymphoma) was followed for 1-12 years after discontinuation of therapy. Thirty-three children were diagnosed before 1973, 92 between 1973 and 1977, and 73 after 1977 in 16 Italian Pediatric Oncology Centers. As of December 1983, 176 children were reported to be alive and without evidence of primary cancer by physicians responsible for their care. One child died from a second primary tumor, two from late recurrences of the primary cancer, and three from other causes; eight were alive with evidence of primary cancer; and eight were lost to follow-up. Kyphoscoliosis was found in 22 children and other musculoskeletal anomalies in 8. Neurological sequelae were observed in 8 of 35 children with ALL treated with radiotherapy (RT) and intrathecal methotrexate. All but one were in continuous complete remission when they developed seizures (three cases), leukoencephalopathy (three cases), or intracerebral calcifications (two cases). One child had cardiomyopathy and subsequently died from cardiac failure: he had received doxorubicin (400 mg/m2) and mediastinal RT (13 Gy) for NBL. Growth impairments were observed in children with NBL and WT.

  6. Norwegian Young Sea Ice Experiment (N-ICE) Field Campaign Report...

    Office of Scientific and Technical Information (OSTI)

    Spring and summer clouds were characterized by low, thick, uniform clouds. less Authors: Walden, V. P. 1 ; Hudson, S. R. 2 ; Cohen, L. 2 + Show Author Affiliations ...

  7. The 2015 Conference for Young Women in STEM is a smashing succes...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    toured cutting edge labs around campus, while others sat-in on an awe-inspiring neurology lecture and chatted with a panel of female scientists discussing their career paths....

  8. The Science Training Program for Young Italian Physicists and Engineers at Fermilab

    SciTech Connect (OSTI)

    Barzi, Emanuela; Bellettini, Giorgio; Donati, Simone

    2015-03-12

    Since 1984 Fermilab has been hosting a two-month summer training program for selected undergraduate and graduate Italian students in physics and engineering. Building on the traditional close collaboration between the Italian National Institute of Nuclear Physics (INFN) and Fermilab, the program is supported by INFN, by the DOE and by the Scuola Superiore di Sant`Anna of Pisa (SSSA), and is run by the Cultural Association of Italians at Fermilab (CAIF). This year the University of Pisa has qualified it as a “University of Pisa Summer School”, and will grant successful students with European Supplementary Credits. Physics students join the Fermilab HEP research groups, while engineers join the Particle Physics, Accelerator, Technical, and Computing Divisions. Some students have also been sent to other U.S. laboratories and universities for special trainings. The programs cover topics of great interest for science and for social applications in general, like advanced computing, distributed data analysis, nanoelectronics, particle detectors for earth and space experiments, high precision mechanics, applied superconductivity. In the years, over 350 students have been trained and are now employed in the most diverse fields in Italy, Europe, and the U.S. In addition, the existing Laurea Program in Fermilab Technical Division was extended to the whole laboratory, with presently two students in Master’s thesis programs on neutrino physics and detectors in the Neutrino Division. And finally, a joint venture with the Italian Scientists and Scholars North-America Foundation (ISSNAF) provided this year 4 professional engineers free of charge for Fermilab. More details on all of the above can be found below.

  9. NETL Researcher Selected to Receive Nation’s Highest Award for Young Scientists

    Broader source: Energy.gov [DOE]

    Dr. Paul R. Ohodnicki, a materials scientist at the National Energy Technology Laboratory (NETL), has been named by President Obama as a recipient of the Presidential Early Career Award for Scientist and Engineers (PECASE). The PECASE award is the highest honor the U.S. government can bestow on scientists or engineers in the early stages of their research careers.

  10. NETL-Regional University Alliance Researcher to Receive Nation’s Highest Award for Young Scientists

    Broader source: Energy.gov [DOE]

    Dr. Brian Anderson, a research fellow of the NETL-Regional University Alliance and associate professor of chemical engineering at West Virginia University, was recognized during a special event at U.S. Department of Energy Headquarters April 14 for receiving the highest honor the U.S. government can bestow on an outstanding scientist in the early stages of his research career.

  11. DOSFAC2 user`s guide Young, M.L.; Chanin, D. 56 BIOLOGY AND MEDICINE...

    Office of Scientific and Technical Information (OSTI)

    and (3) a users guide. 20 refs., 5 tabs. INIS; OSTI as TI97008490 Nuclear Regulatory Commission, Washington, DC (United States). Div. of Systems Technology; Sandia...

  12. Dust around young stars. Observations of the polarization of UX Ori in deep minima

    SciTech Connect (OSTI)

    Voshchinnikov, N.V.; Grinin, V.P.; Kiselev, N.N.; Minikulov, N.K.

    1988-09-01

    Photometric and polarimetric monitoring observations of UX Ori begun in 1986 in the Crimea and Bolivia have resulted in the observation of two deep minima of the brightness during which a growth of the linear polarization (to approx. =7%) was observed, together with a tendency for the circular polarization to increase (up to approx. =1%). Analysis of the observational data shows that the main source of the polarized radiation in the deep minima is the emission of the star scattered by grains of circumstellar dust. On the basis of Mie's theory for a polydisperse graphite-silicate mixtures of particles the optical properties of ellipsoidal dust envelopes have been calculated and a model of the Algol-like minimum constructed.

  13. Extra-nuclear starbursts: young luminous Hinge clumps in interacting galaxies

    SciTech Connect (OSTI)

    Smith, Beverly J.; Giroux, Mark L.; Soria, Roberto; Struck, Curtis; Swartz, Douglas A.; Yukita, Mihoko E-mail: girouxm@etsu.edu E-mail: curt@iastate.edu

    2014-03-01

    Hinge clumps are luminous knots of star formation near the base of tidal features in some interacting galaxies. We use archival Hubble Space Telescope (HST) UV/optical/IR images and Chandra X-ray maps along with Galaxy Evolution Explorer UV, Spitzer IR, and ground-based optical/near-IR images to investigate the star forming properties in a sample of 12 hinge clumps in five interacting galaxies. The most extreme of these hinge clumps have star formation rates of 1-9 M {sub ?} yr{sup 1}, comparable to or larger than the 'overlap' region of intense star formation between the two disks of the colliding galaxy system the Antennae. In the HST images, we have found remarkably large and luminous sources at the centers of these hinge clumps. These objects are much larger and more luminous than typical 'super star clusters' in interacting galaxies, and are sometimes embedded in a linear ridge of fainter star clusters, consistent with star formation along a narrow caustic. These central sources have FWHM diameters of ?70 pc, compared to ?3 pc in 'ordinary' super star clusters. Their absolute I magnitudes range from M{sub I} ? 12.2 to 16.5; thus, if they are individual star clusters they would lie near the top of the 'super star cluster' luminosity function of star clusters. These sources may not be individual star clusters, but instead may be tightly packed groups of clusters that are blended together in the HST images. Comparison to population synthesis modeling indicates that the hinge clumps contain a range of stellar ages. This is consistent with expectations based on models of galaxy interactions, which suggest that star formation may be prolonged in these regions. In the Chandra images, we have found strong X-ray emission from several of these hinge clumps. In most cases, this emission is well-resolved with Chandra and has a thermal X-ray spectrum, thus it is likely due to hot gas associated with the star formation. The ratio of the extinction-corrected diffuse X-ray luminosity to the mechanical energy rate (the X-ray production efficiency) for the hinge clumps is similar to that in the Antennae galaxies, but higher than those for regions in the normal spiral galaxy NGC 2403. Two of the hinge clumps have point-like X-ray emission much brighter than expected for hot gas; these sources are likely 'ultra-luminous X-ray sources' due to accretion disks around black holes. The most extreme of these sources, in Arp 240, has a hard X-ray spectrum and an absorbed X-ray luminosity of ?2 10{sup 41} erg s{sup 1}; this is above the luminosity expected by single high mass X-ray binaries (HMXBs), thus it may be either a collection of HMXBs or an intermediate mass black hole (?80 M {sub ?}).

  14. STEM Mentoring Café- Engaging Young Women in an Authentic Mentoring

    Energy Savers [EERE]

    Café Hits the Midwest STEM Café Hits the Midwest July 27, 2015 - 2:38pm Addthis Aerial view of STEM Mentoring Café table in Chicago: Photo Courtesy of Argonne National Aerial view of STEM Mentoring Café table in Chicago: Photo Courtesy of Argonne National Erin Twamley Project and Web Manager, Education & Workforce Development In the heart of the Midwest, the Museum of Science and Industry Chicago is helping to engage STEM professionals and middle school students. As part of the Energy

  15. NREL's Romero Chosen Top Young Professional in U.S. - News Releases...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Work on PV Power Yields Recognition from International Group Two scientists from NREL were honored by the Utility Variable-Generation Integration Group for their pioneering work in ...

  16. Norwegian Young Sea Ice Experiment (N-ICE) Field Campaign Report

    Office of Scientific and Technical Information (OSTI)

    ... Since these low water clouds observed in springsummer are optically thick, they are the ... The solution was to simply perform a "hard reboot" of the computer. 4.0 Results Data ...

  17. Calling all Young Entrepreneurs: Deadline for Energy Department Business Plan Competition Approaching

    Broader source: Energy.gov [DOE]

    If you’re a university student interested in low-carbon technologies and entrepreneurship, then this is the premier opportunity for you to pitch your idea. The Regional Clean Energy Business Plan Competition is accepting business plan submissions from today until March 2, 2012.

  18. YIA1 - Chen > Young Investigator Program > Research > The Energy Materials

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Center at Cornell Using a microfluidic device to synthesize bimetallic nanoparticle catalysts with desired phase and size: An improvement of the nanoparticle-KCl matrix method With efforts from Hao Chen (DiSalvo), Deli Wang (Abruña) and Joshua Tokuda (Pollack), this research is looking to improve the nanoparticle-KCl matrix method. A great effort at emc2 has been focused on synthesizing bimetallic nanoparticle (Np) catalysts for oxygen reduction reactions. Recently, we developed a Np-KCl

  19. YIA2 - Rodríguez-Calero > Young Investigator Program > Research > The

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Materials Center at Cornell Three Dimensionally Integrated Architecture for Ultra-High Rate Li-Ion Batteries Gabriel Rodríguez-Calero (Abruña) and Joerg Werner (Wiesner) are taking a closer look at Li-Ion batteries. Conventional lithium ion batteries (LIBs) are built in a macroscopically layered structure consisting of an anode, an electrolyte/separator and a cathode with dimensions of the order of microns. One of the main constraints for fast charge/discharge is the diffusion

  20. YIA3 - Rodriguez-López > Young Investigator Program > Research > The

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Materials Center at Cornell Tuning the ORR Electrocatalytic Activity via Controllably Induced Strain With Joaquin Rodriguez-López (Abruña) and Manuel Plaza (Brock), proposed is a novel approach consisting on the use of a piezoelectric platform on which thin epitaxial layers of Pt and Ru will be grown and strained in order to manipulate their electrocatalytic properties towards the Oxygen Reduction Reaction. We anticipate the applied strain will impact the electronic structure of the

  1. YIA4 - Hernández-Burgos > Young Investigator Program > Research > The

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy Materials Center at Cornell In Situ Characterization of the Electrolyte-Anode Interface in Magnesium Ion Batteries With Kenneth Hernández-Burgos (Abruña), Nicole Ritzert (Abruña) and Xin Huang (Brock) this research will look at a the rechargeable magnesium ion battery. A main limitation in the development of rechargeable magnesium ion batteries is failure due to the decomposition of the electrolyte, causing the formation of a non-conductive, passivating film on the anode. We

  2. YIA5 - Khurana > Young Investigator Program > Research > The Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Materials Center at Cornell Single-Ion Gel Polymer Electrolytes for Lithium-Ion and Lithium Metal Secondary Batteries Rachna Khurana (Coates) and Jennifer Schaefer (Archer) hope to find new materials and design rules for creating single-ion conducting polymer membranes suitable for application in lithium-ion and lithium metal batteries with improved performance and safety. Mobile anions produced from dissociation of binary salt in traditional Li-ion electrolytes lead to ionic concentration

  3. YIA6 - Potash > Young Investigator Program > Research > The Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Materials Center at Cornell Liquid Power: Utilizing Redox Active Liquids as Active Material in Redox Flow Batteries Rebecca Potash (Abruña) and Samanvaya Srivastava (Archer) are researching a new spin on RFBs. Redox flow batteries (RFB) are currently gaining attention for large-scale grid load-leveling applications. Contemporary technology is based primarily on aqueous salt electrode solutions that are limited by low operating salt concentrations, limiting the energy density of the cell.

  4. White Matter Fractional Anisotropy Correlates With Speed of Processing and Motor Speed in Young Childhood Cancer Survivors

    SciTech Connect (OSTI)

    Aukema, Eline J.; Oudhuis, Nienke; Vos, Frans M.; Reneman, Liesbeth; Last, Bob F.; Grootenhuis, Martha A.

    2009-07-01

    Purpose: To determine whether childhood medulloblastoma and acute lymphoblastic leukemia (ALL) survivors have decreased white matter fractional anisotropy (WMFA) and whether WMFA is related to the speed of processing and motor speed. Methods and Materials: For this study, 17 patients (6 medulloblastoma, 5 ALL treated with high-dose methotrexate (MTX) (4 x 5 g/m{sup 2}) and 6 with low-dose MTX (3 x 2 g/m{sup 2})) and 17 age-matched controls participated. On a 3.0-T magnetic resonance imaging (MRI) scanner, diffusion tensor imaging (DTI) was performed, and WMFA values were calculated, including specific regions of interest (ROIs), and correlated with the speed of processing and motor speed. Results: Mean WMFA in the patient group, mean age 14 years (range 8.9 - 16.9), was decreased compared with the control group (p = 0.01), as well as WMFA in the right inferior fronto-occipital fasciliculus (IFO) (p = 0.03) and in the genu of the corpus callosum (gCC) (p = 0.01). Based on neurocognitive results, significant positive correlations were present between processing speed and WMFA in the splenium (sCC) (r = 0.53, p = 0.03) and the body of the corpus callosum (bCC) (r = 0.52, p = 0.03), whereas the right IFO WMFA was related to motor speed (r = 0.49, p < 0.05). Conclusions: White matter tracts, using a 3.0-T MRI scanner, show impairment in childhood cancer survivors, medulloblastoma survivors, and also those treated with high doses of MTX. In particular, white matter tracts in the sCC, bCC and right IFO are positively correlated with speed of processing and motor speed.

  5. A SEARCH FOR YOUNG STARS IN THE S0 GALAXIES OF A SUPER-GROUP AT z = 0.37

    SciTech Connect (OSTI)

    Just, Dennis W.; Zaritsky, Dennis; Tran, Kim-Vy H.; Gonzalez, Anthony H.; Kautsch, Stefan J.; Moustakas, John

    2011-10-20

    We analyze Galaxy Evolution Explorer UV data for a system of four gravitationally bound groups at z = 0.37, SG1120, which is destined to merge into a Coma-mass cluster by z = 0, to study how galaxy properties may change during cluster assembly. Of the 38 visually classified S0 galaxies, with masses ranging from log (M{sub *})[M{sub sun}] {approx} 10-11, we detect only one in the near-UV (NUV) channel, a strongly star-forming S0 that is the brightest UV source with a measured redshift placing it in SG1120. Stacking the undetected S0 galaxies (which generally lie on or near the optical red sequence of SG1120) still results in no NUV/far-UV (FUV) detection (<2{sigma}). Using our limit in the NUV band, we conclude that for a rapidly truncating star formation rate, star formation ceased at least {approx}0.1-0.7 Gyr ago, depending on the strength of the starburst prior to truncation. With an exponentially declining star formation history over a range of timescales, we rule out recent star formation over a wide range of ages. We conclude that if S0 formation involves significant star formation, it occurred well before the groups were in this current pre-assembly phase. As such, it seems that S0 formation is even more likely to be predominantly occurring outside of the cluster environment.

  6. THREE-DIMENSIONAL SIMULATIONS OF THE THERMAL X-RAY EMISSION FROM YOUNG SUPERNOVA REMNANTS INCLUDING EFFICIENT PARTICLE ACCELERATION

    SciTech Connect (OSTI)

    Ferrand, Gilles; Safi-Harb, Samar; Decourchelle, Anne E-mail: samar@physics.umanitoba.ca

    2012-11-20

    Supernova remnants (SNRs) are believed to be the major contributors to Galactic cosmic rays. The detection of non-thermal emission from SNRs demonstrates the presence of energetic particles, but direct signatures of protons and other ions remain elusive. If these particles receive a sizeable fraction of the explosion energy, the morphological and spectral evolution of the SNR must be modified. To assess this, we run three-dimensional hydrodynamic simulations of a remnant coupled with a nonlinear acceleration model. We obtain the time-dependent evolution of the shocked structure, impacted by the Rayleigh-Taylor hydrodynamic instabilities at the contact discontinuity and by the back-reaction of particles at the forward shock. We then compute the progressive temperature equilibration and non-equilibrium ionization state of the plasma, and its thermal emission in each cell. This allows us to produce the first realistic synthetic maps of the projected X-ray emission from the SNR. Plasma conditions (temperature and ionization age) can vary widely over the projected surface of the SNR, especially between the ejecta and the ambient medium owing to their different composition. This demonstrates the need for spatially resolved spectroscopy. We find that the integrated emission is reduced with particle back-reaction, with the effect being more significant for the highest photon energies. Therefore, different energy bands, corresponding to different emitting elements, probe different levels of the impact of particle acceleration. Our work provides a framework for the interpretation of SNR observations with current X-ray missions (Chandra, XMM-Newton, and Suzaku) and with upcoming X-ray missions (such as Astro-H).

  7. PROPER MOTIONS OF YOUNG STELLAR OUTFLOWS IN THE MID-INFRARED WITH SPITZER (IRAC). I. THE NGC 1333 REGION

    SciTech Connect (OSTI)

    Raga, A. C.; Noriega-Crespo, A.; Carey, S. J.; Arce, H. G. E-mail: alberto@ipac.caltech.edu E-mail: hector.arce@yale.edu

    2013-02-01

    We use two 4.5 {mu}m Spitzer (IRAC) maps of the NGC 1333 region taken over a {approx}7 yr interval to determine proper motions of its associated outflows. This is a first successful attempt at obtaining proper motions of stellars' outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8, and 10, we find proper motions of {approx}9-13 km s{sup -1}, which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of eight outflows, ranging from {approx}10 to 100 km s{sup -1}. The derived proper motions show that out of these eight outflows, three have tangential velocities {<=}20 km s{sup -1}. This result shows that a large fraction of the observed outflows have low intrinsic velocities and that the low proper motions are not merely a projection effect.

  8. SPITZER DETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND SILICATE FEATURES IN POST-AGB STARS AND YOUNG PLANETARY NEBULAE

    SciTech Connect (OSTI)

    Cerrigone, Luciano; Hora, Joseph L.; Umana, Grazia; Trigilio, Corrado

    2009-09-20

    We have observed a small sample of hot post-asymptotic giant branch (AGB) stars with the Infrared Array Camera (IRAC) and the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. The stars were selected from the literature on the basis of their far-infrared (IR) excess (i.e., post-AGB candidates) and B spectral type (i.e., close to the ionization of the envelope). The combination of our IRAC observations with Two Micron All Sky Survey and IRAS catalog data, along with previous radio observations in the cm range (where available) allowed us to model the spectral energy distributions of our targets and find that in almost all of them at least two shells of dust at different temperatures must be present, the hot dust component ranging up to 10{sup 3} K. In several targets, grains larger than 1 {mu}m are needed to match the far-IR data points. In particular, in IRAS 17423-1755 grains up to 100 {mu}m must be introduced to match the emission in the millimeter range. We obtained IRS spectra to identify the chemistry of the envelopes and found that more than one-third of the sources in our sample have mixed chemistry, showing both mid-IR bands attributed to polycyclic aromatic hydrocarbons (PAHs) and silicate features. The analysis of the PAH features indicates that these molecules are located in the outflows, far away from the central stars. We consider the larger than expected percentage of mixed-chemistry targets as a selection bias toward stars with a disk or torus around them. Our results strengthen the current picture of mixed chemistry being due to the spatial segregation of different dust populations in the envelopes.

  9. INJECTION AND ACCELERATION OF ELECTRONS AT A STRONG SHOCK: RADIO AND X-RAY STUDY OF YOUNG SUPERNOVA 2011dh

    SciTech Connect (OSTI)

    Maeda, Keiichi

    2012-10-20

    In this paper, we develop a model for the radio and X-ray emissions from the Type IIb supernova (SN IIb) 2011dh in the first 100 days after the explosion, and investigate a spectrum of relativistic electrons accelerated at a strong shock wave. The widely accepted theory of particle acceleration, the so-called diffusive shock acceleration (DSA) or Fermi mechanism, requires seed electrons with modest energy with {gamma} {approx} 1-100, and little is known about this pre-acceleration mechanism. We derive the energy distribution of relativistic electrons in this pre-accelerated energy regime. We find that the efficiency of the electron acceleration must be low, i.e., {epsilon}{sub e} {approx}< 10{sup -2} as compared to the conventionally assumed value of {epsilon}{sub e} {approx} 0.1. Furthermore, independent of the low value of {epsilon}{sub e}, we find that the X-ray luminosity cannot be attributed to any emission mechanisms suggested as long as these electrons follow the conventionally assumed single power-law distribution. A consistent view between the radio and X-ray can only be obtained if the pre-acceleration injection spectrum peaks at {gamma} {approx} 20-30 and then only a fraction of these electrons eventually experience the DSA-like acceleration toward the higher energy-then the radio and X-ray properties are explained through the synchrotron and inverse Compton mechanisms, respectively. Our findings support the idea that the pre-acceleration of the electrons is coupled with the generation/amplification of the magnetic field.

  10. Department of Energy Awards $2 Million for National University Clean Energy Business Challenge to Jump Start Young Entrepreneurship

    Broader source: Energy.gov [DOE]

    Washington, D.C. – The U.S. Department of Energy (DOE) recently announced $2 million over three years for six regional awardees to create and administer a network of student-focused business...