skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS

Abstract

We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central {approx}300 pc region of the Milky Way. We obtained IRS spectra over 5-35 {mu}m using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 {mu}m shoulder on the absorption profile of 15 {mu}m CO{sub 2} ice, suggestive of CO{sub 2} ice mixed with CH{sub 3}OH ice on grains. This 15.4 {mu}m shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO{sub 2}, C{sub 2}H{sub 2}, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23 M{sub sun}, which generallymore » agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of {approx}0.07 M{sub sun} yr{sup -1} at the GC.« less

Authors:
 [1]; ;  [2];  [3];  [4]; ;  [5];  [6];  [7];  [8]
  1. Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of)
  2. NASA Exoplanet Science Institute, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125 (United States)
  3. Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
  4. CRESST/UMBC/GSFC, Code 665, NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)
  5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  6. Observatoire de Besancon, 41bis, avenue de l'Observatoire, 25000 Besancon (France)
  7. SETI Institute, 515 North Whisman Road, Mountain View, CA 94043 (United States)
  8. Spitzer Science Center, California Institute of Technology, Mail Code 220-6, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
21578202
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/133; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABSORPTION SPECTROSCOPY; CARBON DIOXIDE; GALAXY NUCLEI; HYDROCYANIC ACID; ICE; INFRARED SPECTRA; METHANOL; STARS; ALCOHOLS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; INORGANIC ACIDS; INORGANIC COMPOUNDS; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; SORPTION; SPECTRA; SPECTROSCOPY

Citation Formats

An, Deokkeun, RamIrez, Solange V., Boogert, A. C. Adwin, Sellgren, Kris, Arendt, Richard G., Robitaille, Thomas P., Smith, Howard A., Schultheis, Mathias, Cotera, Angela S., and Stolovy, Susan R., E-mail: deokkeun@ewha.ac.kr. MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/133.
An, Deokkeun, RamIrez, Solange V., Boogert, A. C. Adwin, Sellgren, Kris, Arendt, Richard G., Robitaille, Thomas P., Smith, Howard A., Schultheis, Mathias, Cotera, Angela S., & Stolovy, Susan R., E-mail: deokkeun@ewha.ac.kr. MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS. United States. doi:10.1088/0004-637X/736/2/133.
An, Deokkeun, RamIrez, Solange V., Boogert, A. C. Adwin, Sellgren, Kris, Arendt, Richard G., Robitaille, Thomas P., Smith, Howard A., Schultheis, Mathias, Cotera, Angela S., and Stolovy, Susan R., E-mail: deokkeun@ewha.ac.kr. Mon . "MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS". United States. doi:10.1088/0004-637X/736/2/133.
@article{osti_21578202,
title = {MASSIVE YOUNG STELLAR OBJECTS IN THE GALACTIC CENTER. I. SPECTROSCOPIC IDENTIFICATION FROM SPITZER INFRARED SPECTROGRAPH OBSERVATIONS},
author = {An, Deokkeun and RamIrez, Solange V. and Boogert, A. C. Adwin and Sellgren, Kris and Arendt, Richard G. and Robitaille, Thomas P. and Smith, Howard A. and Schultheis, Mathias and Cotera, Angela S. and Stolovy, Susan R., E-mail: deokkeun@ewha.ac.kr},
abstractNote = {We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central {approx}300 pc region of the Milky Way. We obtained IRS spectra over 5-35 {mu}m using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 {mu}m shoulder on the absorption profile of 15 {mu}m CO{sub 2} ice, suggestive of CO{sub 2} ice mixed with CH{sub 3}OH ice on grains. This 15.4 {mu}m shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO{sub 2}, C{sub 2}H{sub 2}, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23 M{sub sun}, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of {approx}0.07 M{sub sun} yr{sup -1} at the GC.},
doi = {10.1088/0004-637X/736/2/133},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}