2MASS 22344161+4041387AB: A wide, young, accreting, low-mass binary in the LkHα233 group

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

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We report the discovery of a young, 016 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 (1 Myr old). A comparison of the T eff and age of 2M2234+4041AB to evolutionary models indicates that the mass of each component is 0.10+0.075 -0.04 M . Emission lines of Hα in the composite optical spectrum of the system and Brγ 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 15 from the well-studied Herbig Ae/Be star, LkHα233. The distance to LkHα233 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 LkHα233 group and find a value of 325 +72 -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 LkHα233 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.

Original languageEnglish (US)
Pages (from-to)824-835
Number of pages12
JournalAstrophysical Journal
Issue number1
StatePublished - 2009
Externally publishedYes


  • Binaries: visual
  • Infrared: stars
  • Stars: formation
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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