Cool Stars 14 - Submitted Abstract # 134
This version created on 05 October 2006

New Very Low Mass Binaries in the Taurus Star-Forming Region


Quinn M. Konopacky, UCLA
Andrea M. Ghez, UCLA
Emily L. Rice, UCLA

We observed thirteen very low mass (VLM) objects in the Taurus
star-forming region using near-infrared diffraction-limited imaging
techniques on the W.M.  Keck I 10  m telescope.  Of these thirteen,
five were found to be binary, with separations ranging from 0.04" to
0.6" and flux ratios from 1.4 to 3.7.  In all cases, the companions
are highly likely to be physically associated (probability <4 sigma).
Using the theoretical models of Baraffe et al.  (1998), we find that
all five new companions, as well as one of the primaries, are likely
substellar.  The discovery of these systems therefore increases the
total number of known, young VLM binaries by over 50%.  These new
systems, along with other young VLM binaries from the literature, have
properties that differ significantly from older field VLM binaries in
that the young systems have wider separations and lower mass ratios,
supporting the idea that VLM binaries undergo significant dynamical
evolution ~5 - 10  Myr after their formation.  Additionally, the range
of separations of these binaries, four of which are over 30  AU,
argues against the ejection scenario of brown dwarf formation.

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