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

Title: A Transient Transit Signature Associated with the Young Star RIK-210

Abstract

We find transient transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial resolution imaging revealed that the star is single and radial velocity monitoring indicated that the dimming events cannot be due to an eclipsing stellar or brown dwarf companion. Archival and follow-up photometry suggest the dimming events are transient in nature. The variable morphology of the dimming events suggests they are not due to a single spherical body. The ingress of each dimming event is always shallower than egress, as one would expect for an orbiting body with a leading tail. The dimming events are periodic and synchronous with the stellar rotation. However, we argue it is unlikely the dimming events could be attributed to anything on the stellar surface based on the observed depths and durations. Variable obscuration by a protoplanetary disk is unlikely on the basis that the star is not actively accreting and lacks the infrared excess associated with an inner disk. Rather, we explore the possibilities that the dimming events are due to magnetospheric clouds, a transiting protoplanet surrounded by circumplanetary dustmore » and debris, eccentric orbiting bodies undergoing periodic tidal disruption, or an extended field of dust or debris near the corotation radius.« less

Authors:
; ; ;  [1]; ;  [2]; ;  [3];  [4];  [5];  [6];  [7];  [8]; ;  [9]; ;  [10]
  1. Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)
  3. NASA Ames Research Center, Mountain View, California 94035 (United States)
  4. SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS (United Kingdom)
  5. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  6. Institute for Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States)
  7. Department of Astronomy, University of California, Berkeley, California 94720 (United States)
  8. National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States)
  9. Astrophysics Group, Keele University, Staffordshire, ST5 5BG (United Kingdom)
  10. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
Publication Date:
OSTI Identifier:
22663953
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DUSTS; ECLIPSE; INTERACTIONS; MAGNETIC FIELDS; MONITORING; PERIODICITY; PHOTOMETRY; PLANETS; PROTOPLANETS; RADIAL VELOCITY; ROTATION; SPATIAL RESOLUTION; SPHERICAL CONFIGURATION; STARS; SURFACES; TRANSIENTS

Citation Formats

David, Trevor J., Hillenbrand, Lynne A., Howard, Andrew W., Wang, Ji, Petigura, Erik A., Benneke, Björn, Cody, Ann Marie, Howell, Steve B., Cameron, Andrew Collier, Stauffer, John R., Fulton, B. J., Isaacson, Howard T., Everett, Mark E., Hellier, Coel, Anderson, David R., West, Richard G., and Pollacco, Don, E-mail: tjd@astro.caltech.edu. A Transient Transit Signature Associated with the Young Star RIK-210. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/168.
David, Trevor J., Hillenbrand, Lynne A., Howard, Andrew W., Wang, Ji, Petigura, Erik A., Benneke, Björn, Cody, Ann Marie, Howell, Steve B., Cameron, Andrew Collier, Stauffer, John R., Fulton, B. J., Isaacson, Howard T., Everett, Mark E., Hellier, Coel, Anderson, David R., West, Richard G., & Pollacco, Don, E-mail: tjd@astro.caltech.edu. A Transient Transit Signature Associated with the Young Star RIK-210. United States. doi:10.3847/1538-4357/835/2/168.
David, Trevor J., Hillenbrand, Lynne A., Howard, Andrew W., Wang, Ji, Petigura, Erik A., Benneke, Björn, Cody, Ann Marie, Howell, Steve B., Cameron, Andrew Collier, Stauffer, John R., Fulton, B. J., Isaacson, Howard T., Everett, Mark E., Hellier, Coel, Anderson, David R., West, Richard G., and Pollacco, Don, E-mail: tjd@astro.caltech.edu. Wed . "A Transient Transit Signature Associated with the Young Star RIK-210". United States. doi:10.3847/1538-4357/835/2/168.
@article{osti_22663953,
title = {A Transient Transit Signature Associated with the Young Star RIK-210},
author = {David, Trevor J. and Hillenbrand, Lynne A. and Howard, Andrew W. and Wang, Ji and Petigura, Erik A. and Benneke, Björn and Cody, Ann Marie and Howell, Steve B. and Cameron, Andrew Collier and Stauffer, John R. and Fulton, B. J. and Isaacson, Howard T. and Everett, Mark E. and Hellier, Coel and Anderson, David R. and West, Richard G. and Pollacco, Don, E-mail: tjd@astro.caltech.edu},
abstractNote = {We find transient transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial resolution imaging revealed that the star is single and radial velocity monitoring indicated that the dimming events cannot be due to an eclipsing stellar or brown dwarf companion. Archival and follow-up photometry suggest the dimming events are transient in nature. The variable morphology of the dimming events suggests they are not due to a single spherical body. The ingress of each dimming event is always shallower than egress, as one would expect for an orbiting body with a leading tail. The dimming events are periodic and synchronous with the stellar rotation. However, we argue it is unlikely the dimming events could be attributed to anything on the stellar surface based on the observed depths and durations. Variable obscuration by a protoplanetary disk is unlikely on the basis that the star is not actively accreting and lacks the infrared excess associated with an inner disk. Rather, we explore the possibilities that the dimming events are due to magnetospheric clouds, a transiting protoplanet surrounded by circumplanetary dust and debris, eccentric orbiting bodies undergoing periodic tidal disruption, or an extended field of dust or debris near the corotation radius.},
doi = {10.3847/1538-4357/835/2/168},
journal = {Astrophysical Journal},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}
  • Recently a repeating fast radio burst (FRB) 121102 has been confirmed to be an extragalactic event and a persistent radio counterpart has been identified. While other possibilities are not ruled out, the emission properties are broadly consistent with Murase et al. that theoretically proposed quasi-steady radio emission as a counterpart of both FRBs and pulsar-driven supernovae. Here, we constrain the model parameters of such a young neutron star scenario for FRB 121102. If the associated supernova has a conventional ejecta mass of M {sub ej} ≳ a few M {sub ⊙}, a neutron star with an age of t {submore » age} ∼ 10–100 years, an initial spin period of P{sub i} ≲ a few ms, and a dipole magnetic field of B {sub dip} ≲ a few × 10{sup 13} G can be compatible with the observations. However, in this case, the magnetically powered scenario may be favored as an FRB energy source because of the efficiency problem in the rotation-powered scenario. On the other hand, if the associated supernova is an ultra-stripped one or the neutron star is born by the accretion-induced collapse with M {sub ej} ∼ 0.1 M {sub ⊙}, a younger neutron star with t {sub age} ∼ 1–10 years can be the persistent radio source and might produce FRBs with the spin-down power. These possibilities can be distinguished by the decline rate of the quasi-steady radio counterpart.« less
  • Stellar rotation is a strong function of both mass and evolutionary state. Missions such as Kepler and CoRoT provide tens of thousands of rotation periods, drawn from stellar populations that contain objects at a range of masses, ages, and evolutionary states. Given a set of reasonable starting conditions and a prescription for angular momentum loss, we address the expected range of rotation periods for cool field stellar populations (∼0.4-2.0 M{sub ☉}). We find that cool stars fall into three distinct regimes in rotation. Rapid rotators with surface periods less than 10 days are either young low-mass main sequence (MS) stars,more » or higher mass subgiants which leave the MS with high rotation rates. Intermediate rotators (10-40 days) can be either cool MS dwarfs, suitable for gyrochronology, or crossing subgiants at a range of masses. Gyrochronology relations must therefore be applied cautiously, since there is an abundant population of subgiant contaminants. The slowest rotators, at periods greater than 40 days, are lower mass subgiants undergoing envelope expansion. We identify additional diagnostic uses of rotation periods. There exists a period-age relation for subgiants distinct from the MS period-age relations. There is also a period-radius relation that can be used as a constraint on the stellar radius, particularly in the interesting case of planet host stars. The high-mass/low-mass break in the rotation distribution on the MS persists onto the subgiant branch, and has potential as a diagnostic of stellar mass. Finally, this set of theoretical predictions can be compared to extensive datasets to motivate improved modeling.« less
  • Germline alterations in DNA repair genes are implicated in cancer predisposition and can result in characteristic mutational signatures. However, specific mutational signatures associated with base excision repair (BER) defects remain to be characterized. Here, by analysing a series of colorectal cancers (CRCs) using exome sequencing, we identified a particular spectrum of somatic mutations characterized by an enrichment of C > A transversions in NpCpA or NpCpT contexts in three tumours from a MUTYH-associated polyposis (MAP) patient and in two cases harbouring pathogenic germline MUTYH mutations. In two series of adrenocortical carcinomas (ACCs), we identified four tumours with a similar signaturemore » also presenting germline MUTYH mutations. Altogether, these findings demonstrate that MUTYH inactivation results in a particular mutational signature, which may serve as a useful marker of BER-related genomic instability in new cancer types.« less