PLANETS AROUND LOW-MASS STARS (PALMS). V. AGE-DATING LOW-MASS COMPANIONS TO MEMBERS AND INTERLOPERS OF YOUNG MOVING GROUPS

Brendan P. Bowler*, Evgenya L. Shkolnik, Michael C. Liu, Joshua E. Schlieder, Andrew W. Mann, Trent J. Dupuy, Sasha Hinkley, Justin R. Crepp, John Asher Johnson, Andrew W. Howard, Laura Flagg, Alycia J. Weinberger, Kimberly M. Aller, Katelyn N. Allers, William M. J. Best, Michael C. Kotson, Benjamin T. Montet, Gregory J. Herczeg, Christoph Baranec, Reed RiddleNicholas M. Law, Eric L. Nielsen, Zahed Wahhaj, Beth A. Biller, Thomas L. Hayward

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (similar to 10-100 M-Jup) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892-0929121 C (40-60 M-Jup) shows. clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the similar to 40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (less than or similar to 100 AU) configuration. In addition, LiI lambda 6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (less than or similar to 200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (

Original languageEnglish
Article number62
Number of pages36
JournalAstrophysical Journal
Volume806
Issue number1
DOIs
Publication statusPublished - 10 Jun 2015

Keywords

  • binaries: spectroscopic
  • brown dwarfs
  • stars: individual (2MASS J02155892, 0929121, 2MASS J15594729+4403595, HD 23514)
  • TW-HYDRAE ASSOCIATION
  • DIGITAL SKY SURVEY
  • VERY-LOW MASS
  • BRIGHT SOURCE CATALOG
  • X-RAY SOURCES
  • SOUTHERN SPECTROPHOTOMETRIC STANDARDS
  • CANDIDATE SUBSTELLAR COMPANION
  • SUPERNOVA FACTORY OBSERVATIONS
  • FINDING CAMPAIGN DISCOVERY
  • EXTRASOLAR GIANT PLANETS

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