A T8.5 Brown Dwarf Member of the ξ Ursae Majoris System
Abstract
The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighborhood (8 pc) quadruple star system—ξ Ursae Majoris. The angular separation is 8.'5, and the projected physical separation is ≈4000 AU. The sub-solar metallicity and low chromospheric activity of ξ UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and color of the brown dwarf suggests the mass of this companion ranges between 14 and 38 M J for system ages of 2 and 8 Gyr, respectively.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 2013
- DOI:
- 10.1088/0004-6256/145/3/84
- arXiv:
- arXiv:1203.5764
- Bibcode:
- 2013AJ....145...84W
- Keywords:
-
- brown dwarfs;
- infrared: stars;
- solar neighborhood;
- stars: late-type;
- stars: low-mass;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- AJ in press, 12 pages LaTeX with 6 figures. More astrometric data and a laser guide star adaptive optics image added