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arXiv · 0902.1059

2MASS J06164006-6407194: The First Outer Halo L Subdwarf

M. C. Cushing·D. Looper·A. J. Burgasser·J. D. Kirkpatrick·J. Faherty·K. Cruz·A. Sweet·R. E. Sanderson
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Abstract

We present the serendipitous discovery of an L subdwarf, 2MASS J06164006-6407194, in a search of the Two Micron All Sky Survey for T dwarfs. Its spectrum exhibits features indicative of both a cool and metal poor atmosphere including a heavily pressured-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 0616-6407 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 arcsec yr-1), large radial velocity (Vrad = 454+-15 km s-1), estimated uvw 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 0616-6407 the first ultracool member of this population.

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M. C. Cushing, D. Looper, A. J. Burgasser, J. D. Kirkpatrick, J. Faherty, K. Cruz, A. Sweet, R. E. Sanderson. 2009-02-06. 2MASS J06164006-6407194: The First Outer Halo L Subdwarf. https://doi.org/10.1088/0004-637x/696/1/986

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