Discovery of a Brown Dwarf Companion to Gliese 570ABC: A 2MASS T Dwarf Significantly Cooler than Gliese 229B

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Published 2000 February 10 © 2000. The American Astronomical Society. All rights reserved. Printed in U.S.A.
, , Citation Adam J. Burgasser et al 2000 ApJ 531 L57 DOI 10.1086/312522

1538-4357/531/1/L57

Abstract

We report the discovery of a widely separated (258farcs3 ± 0farcs4) T dwarf companion to the Gl 570ABC system. This new component, Gl 570D, was initially identified from the Two Micron All-Sky Survey. Its near-infrared spectrum shows the 1.6 and 2.2 μm CH4 absorption bands characteristic of T dwarfs, while its common proper motion with the Gl 570ABC system confirms companionship. Gl 570D (MJ = 16.47 ± 0.07) is nearly a full magnitude dimmer than the only other known T dwarf companion, Gl 229B, and estimates of L = (2.8 ± 0.3) × 10-6 L and Teff = 750 ± 50 K make it significantly cooler and less luminous than any other known brown dwarf companion. Using evolutionary models by Burrows et al. and an adopted age of 2-10 Gyr, we derive a mass estimate of 50 ± 20 MJup for this object.

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10.1086/312522