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Ireland, M. J; Kraus, A; Martinache, F; Lloyd, J. P; Tuthill, P. G
The Astrophysical journal, 05/2008, Volume: 678, Issue: 1Journal Article
We report a dynamical measurement of the mass of the brown dwarf GJ 802B using aperture-masking interferometry and astrometry. In addition, we report the discovery that GJ 802A is itself a close spectroscopic noneclipsing binary with a 19 hr period. We find the mass of GJ 802B to be image. GJ 802 has kinematics inconsistent with a young star and more consistent with the thick-disk population, implying a system age of image10 Gyr. However, model evolutionary tracks for GJ 802B predict system ages of image2 Gyr, suggesting that brown dwarf evolutionary models may be underestimating luminosity for old brown dwarfs.
