2MASS J06164006-6407194: The First Outer Halo L Subdwarf
Abstract
We present the serendipitous discovery of an L subdwarf in the Two Micron All Sky Survey (2MASS) J06164006-6407194, in a search of the 2MASS for T dwarfs. Its spectrum exhibits features indicative of both a cool and metal poor atmosphere including a heavily pressure-broadened K I resonant doublet, Cs I and Rb I lines, molecular bands of CaH, TiO, CrH, FeH, and H2O, and enhanced collision induced absorption of H2. We assign 2MASS J0616-6407 a spectral type of sdL5 based on a comparison of its red optical spectrum to that of near solar-metallicity L dwarfs. Its high proper motion (μ = 1farcs405 ± 0.008 yr-1), large radial velocity (V rad = 454 ± 15 km s-1), estimated u, v, w velocities (94, -573, 125) km s-1 and Galactic orbit with an apogalacticon at ~29 kpc are indicative of membership in the outer halo making 2MASS J0616-6407 the first ultracool member of this population.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2009
- DOI:
- 10.1088/0004-637X/696/1/986
- arXiv:
- arXiv:0902.1059
- Bibcode:
- 2009ApJ...696..986C
- Keywords:
-
- infrared: stars;
- stars: individual: 2MASS J0164006-6407194;
- stars: low-mass;
- brown dwarfs;
- subdwarfs;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for publication in ApJ