AAS 200th meeting, Albuquerque, NM, June 2002
Session 11. Nearby Stars and Low Mass Dwarfs
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[11.05] Three Binary T Dwarfs Identified with HST and Keck

A. J. Burgasser (UCLA), J. D. Kirkpatrick (Caltech/IPAC), M. E. Brown (Caltech)

We present the discovery of three T dwarf binaries, two (2MASS 1225-2739AB and 2MASS 1534-2952AB) identified using WF/PC2 on HST and one (2MASS 1553-1532AB) identified using NIRC on Keck. Companionship for the HST binaries is established by their uniquely red F814W-F1042M colors, caused by the heavily pressure-broadened K I doublet at 7665 & 7699 Å. Companionship for 2MASS 1553-1532AB is based on its Ks-CH4 color, also unique for T dwarfs. The separations of these systems are 0''28, 0''07, and 0''27, implying physical separations of 2.8, 1.0, and 3.0 AU. These values are similar to those found in previous brown dwarf binary searches, and are adequate for orbital mapping over the coming decade. 2MASS 1225-2739AB has a flux ratio (f2/f1) of 0.20 at 0.8 microns and 0.36 at 1.0 microns, 2MASS 1534-2952 has f2/f1 = 1.0 at both 0.8 and 1.0 microns, and 2MASS 1553-1532AB has f2/f1 = 0.72 at 2.2 microns. The flux ratio of 2MASS 1225-2739AB implies that it is likely composed of a T6 primary and T8 secondary. The binary fraction of our HST sample, 20±6%, is consistent with results obtained for L dwarfs.

Portions of the data presented herein were obtained at the W. M. Keck Observatory which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

If you would like more information about this abstract, please follow the link to http://www.astro.ucla.edu/~adam/homepage/research/tdwarf/index.html. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

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

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.