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S.A. Metchev, L.A. Hillenbrand (Caltech)
We present first results from a coronagraphic survey of young nearby stars using the Palomar and Keck adaptive optics systems. The survey targets approximately 100 solar-type (F5--K5) stars at 20--160 pc from the Sun, spanning the 3--500 Myr age range, and is conducted in coordination with the Formation and Evolution of Planetary Systems Spitzer Legacy program. The survey is sensitive to sub-stellar companions at separations >0.5\arcsec from their host stars, with sensitivity extending to planetary-mass (5--15 Mjup) objects at wider (>3\arcsec) separations. From multi-epoch astrometric and spectroscopic observations, we have discovered and confirmed a L4 brown dwarf companion at a projected separation of 44 AU from a star in our sample. Because of its association with a young main sequence star, it is a member of a very limited list of known young (<1 Gyr) L or T dwarfs, and as such can be used to constrain evolutionary models of ultra-cool objects. Over 200 other candidate companions within 13\arcsec (2100 AU) identified from first-epoch direct imaging await confirmation. Based on the single confirmed detection, a preliminary estimate of the frequency of massive (>40 Mjup) brown dwarf companions at 40--200 AU separations is \approx1%. After taking into account the effects of the age and distance distributions of the sample, and of other observational biases, the estimated sub-stellar companion fraction is expected to be a factor of several higher.
The research presented here is supported by funding from NASA and NSF.
The author(s) of this abstract have provided an email address for comments about the abstract: metchev@astro.caltech.edu
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.