Sherry, William

Contact Email: wsherry@mail.ess.sunysb.edu
Institute: SUNY Stony Brook
First Coauthor: Frederick Walter
Institute: SUNY Stony Brook
Second Coauthor: Scott Wolk
Research URL:http://sbast3.ess.sunysb.edu/wsherry/plan.html
Presenting Thesis: Yes
Subject Area: Brown Dwarfs & Extrasolar Planets
Waveband: Multi-wavelength
Technique: Photometry
Presentation: Poster Display
Title: Very Low-Mass Stars and Candidate Brown Dwarfs in the Orion OB1b Sub-Association
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 2 sq. degrees of the association identify about 1000 candidate PMS stars per sq. degree. We expect that roughly 50% to 70% are in fact members of the association. We estimate masses by comparing PMS models with our BVRI photometry and with 2MASS JHK photometry. We find a relatively flat low-mass IMF with a slope of about -0.6 for masses between 0.1 and 1.0 solar masses. Roughly 100 of our objects are well fit by brown dwarf models.