Paper: astro-ph/0505205
Date: Tue, 10 May 2005 18:01:26 GMT (122kb)

Title: Astrometric Discovery of GJ 802b: In the Brown Dwarf Oasis?

Authors: Steven H. Pravdo, Stuart B. Shaklan, James Lloyd
Comments: 13 pages, 6 figures, accepted for publication in ApJ on May 9, 2005
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The Stellar Planet Survey is an ongoing astrometric search for giant planets
and brown dwarfs around a sample of about 30 M-dwarfs. We have discovered
several low-mass companions by measuring the motion of our target stars
relative to their reference frames. The lowest mass discovery thus far is GJ
802b, a companion to the M5-dwarf GJ 802A. The orbital period is 3.14 +/- 0.03
y, the system mass is 0.214 +/- 0.045 Msolar, and the semi-major axis is 1.28
+/- 0.10 AU or 81 +/- 6 mas. Imaging observations indicate that GJ 802b is
likely to be a brown dwarf with the astrometrically determined mass 0.058 +/-
0.021 Msolar (one sigma limits). The remaining uncertainty in the orbit is the
eccentricity that is now loosely constrained. We discuss how the system age
limits the mass and the prospects to further narrow the mass range when e is
more precisely determined.

\\ ( http://arXiv.org/abs/astro-ph/0505205 , 122kb)