The gemini nici planet-finding campaign: Discovery of a substellar L dwarf companion to the nearby young M dwarf CD-35 2722

Zahed Wahhaj, Michael C. Liu, Beth A. Biller, Fraser Clarke, Eric L. Nielsen, Laird M. Close, Thomasl Hayward, Eric E. Mamajek, Michael Cushing, Trent Dupuy, Matthias Tecza, Niranjan Thatte, Mark Chun, Christ Ftaclas, Markus Hartung, I. Neill Reid, Evgenya L. Shkolnik, Silvia H.P. Alencar, Pawel Artymowicz, Alan BossElisabethe De Gouveia Dal Pino, Jane Gregorio-Hetem, Shigeru Ida, Marc Kuchner, Douglas N.C. Lin, Douglas W. Toomey

Research output: Contribution to journalArticle

83 Scopus citations

Abstract

We present the discovery of a wide (67AU) substellar companion to the nearby (21pc) young solar-metallicity M1 dwarf CD-35 2722, a member of the ≈100Myr AB Doradus association. Two epochs of astrometry from the NICI Planet-Finding Campaign confirm that CD-35 2722B is physically associated with the primary star. Near-IR spectra indicate a spectral type of L4 ± 1 with a moderately low surface gravity, making it one of the coolest young companions found to date. The absorption lines and near-IR continuum shape of CD-35 2722B agree especially well the dusty field L4.5 dwarf 2MASS J22244381-0158521, while the near-IR colors and absolute magnitudes match those of the 5Myr old L4 planetary-mass companion, 1RXS J160929.1-210524 b. Overall, CD-35 2722B appears to be an intermediate-age benchmark for L dwarfs, with a less peaked H-band continuum than the youngest objects and near-IR absorption lines comparable to field objects. We fit Ames-Dusty model atmospheres to the near-IR spectra and find T eff= 1700-1900K and log(g)= 4.5 ± 0.5. The spectra also show that the radial velocities of components A and B agree to within ±10kms-1, further confirming their physical association. Using the age and bolometric luminosity of CD-35 2722B, we derive a mass of 31 ± 8 M Jup from the Lyon/Dusty evolutionary models. Altogether, young late-M to mid-L type companions appear to be overluminous for their near-IR spectral type compared with field objects, in contrast to the underluminosity of young late-L and early-T dwarfs.

Original languageEnglish (US)
Article number139
JournalAstrophysical Journal
Volume729
Issue number2
DOIs
StatePublished - Mar 10 2011

Keywords

  • brown dwarfs
  • instrumentation: adaptive optics
  • planetary systems
  • planets and satellites: detection
  • stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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