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Title: 2MASS J06164006-6407194: THE FIRST OUTER HALO L SUBDWARF

Journal Article · · Astrophysical Journal
;  [1]; ;  [2];  [3];  [4]; ;  [5]
  1. Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  2. Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Building 37, Room 664B, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
  3. Infrared Processing and Analysis Center, M/S 100-22, California Institute of Technology, Pasadena, CA 91225 (United States)
  4. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794 (United States)
  5. Department of Astronomy, Caltech, MC 105-24, Pasadena, CA 91125 (United States)

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 H{sub 2}O, and enhanced collision induced absorption of H{sub 2}. 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 ({mu} = 1.''405 {+-} 0.008 yr{sup -1}), large radial velocity (V {sub rad} = 454 {+-} 15 km s{sup -1}), estimated u, v, w velocities (94, -573, 125) km s{sup -1} and Galactic orbit with an apogalacticon at {approx}29 kpc are indicative of membership in the outer halo making 2MASS J0616-6407 the first ultracool member of this population.

OSTI ID:
21296181
Journal Information:
Astrophysical Journal, Vol. 696, Issue 1; Other Information: DOI: 10.1088/0004-637X/696/1/986; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
Country of Publication:
United States
Language:
English