POSTER PAPER 2.14
Very Low-Mass Stars and Candidate Brown Dwarfs in the Orion OB1b Sub-Association
W. H. Sherry, F. M. Walter, S. J. Wolk
Institute: SUNY Stony Brook
Institute: CfA
Contact Email: wsherry@mail.ess.sunysb.edu
Abstract:
We are conducting a large scale, multiwavelength survey of 5 sq.
degrees of the Orion OB1b sub-association (Walter et al. 2000), a
2Myr old fossil OB association 440pc from the Sun. Young fossil OB
associations are especially good sites to study the very low-mass
end of the initial mass function (IMF) because low-mass stars and
brown dwarfs are brightest during their pre-main-sequence (PMS)
phase and brown dwarfs are still relatively hot. We identify
candidate PMS stars by their position in the PMS locus of the color
magnitude diagram traced by X-ray selected PMS stars. Our results
for the first 2 sq. degrees of the association identify about 800
candidate PMS stars per sq. degree. Roughly 40% are in fact
members of the association. We estimate masses by comparing PMS
models with our BVRI photometry and with 2MASS JHK photometry. We
have found 23 objects that are well fit by brown dwarf models.
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Manuscript submitted: 2001-Sep-08
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.