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

[Previous] | [Session 61] | [Next]

[61.10] Age Dependence of the Substellar Luminosity Function

P.R. Allen, D.W. Koerner (University of Pennsylvania), I.N. Reid (University of Pennsylvania/Space Telescope Science Institute), A.J. Burgasser (University of California Los Angeles)

Recent discoveries of low-luminosity objects have now firmly established that the dwarf mass function extends below the minimum-mass hydrogen-burning limit for both field stars and binary companions. However, the exact nature of the mass distribution is difficult to ascertain below this boundary. It is problematic to infer precise brown-dwarf masses from imaging data, since the mass-luminosity relation is heavily dependent on age. We have carried out the mass-luminosity transformation under different assumptions about the distribution of stellar ages with the aid of model atmospheres provided by Burrows et al. from the University of Arizona. Here we present the resultant luminosity and temperature distributions for a wide range of mass functions. We consider age distributions derived in three independent ways: 1) assuming a constant star-formation rate, 2) extrapolating from age diagnostics measured in field F and G dwarfs, and 3) assuming a star-formation rate implied by the luminosity evolution of high-Z galaxies. We use the resulting luminosity functions to refine estimates of the mass distribution of field L and T dwarfs, and to understand the implications of recent companion searches for the substellar companion mass function.

The author(s) of this abstract have provided an email address for comments about the abstract: pallen@copernicus.physics.upenn.edu

[Previous] | [Session 61] | [Next]