AAS 199th meeting, Washington, DC, January 2002
Session 61. Stars: Dwarfs and Companions
Display, Tuesday, January 8, 2002, 9:20am-6:30pm, Exhibit Hall

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[61.08] T Dwarfs and the Substellar Mass Function

A. J. Burgasser (UC Los Angeles), 2MASS Rare Objects Team

The recent sky surveys 2MASS, SDSS, and DENIS have unveiled a vast population of substellar objects in the Solar Neighborhood, and have appended two new spectral classes onto the familiar MK system: L and T dwarfs. With hundreds of these objects now known, we can address one of the fundamental questions that initiated the search for brown dwarfs in the first place - what is their contribution to the Galactic mass budget? I present results on the field substellar mass function, based on a sample of T dwarfs identified in the 2MASS survey. Using the evolutionary models of Burrows et al. and a Monte Carlo simulation of the Solar Neighborhood, I show that the number of T dwarfs identified in this sample is consistent with a shallow power-law mass function, 0.5 < \alpha < 1.0, similar to values derived from young clusters but inconsistent with previous estimates in the field. I discuss possible reasons for this discrepancy, and ways in which we may improve our census of nearby brown dwarfs.

Support for this work was provided by NASA through a Hubble Fellowship grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incoporated, under NASA contract NAS5-26555.

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The author(s) of this abstract have provided an email address for comments about the abstract: adam@astro.ucla.edu

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