Discovery of a Second L Subdwarf in the Two Micron All Sky Survey

I report the discovery of the second L subdwarf identified in the Two Micron All Sky Survey, 2MASS J16262034+3925190. This high proper motion object (μ = 1 27 ± 0 03 yr -1 ) exhibits near-infrared spectral features indicative of a subsolar metallicity L dwarf, including strong metal hydride and H 2 O absorption bands, pressure-broadened alkali lines, and blue near-infrared colors caused by enhanced collision-induced H 2 absorption. This object is of later type than any of the known M subdwarfs but does not appear to be as cool as the apparently late-type sdL 2MASS 0532+8246. The radial velocity ( V rad = -260 ± 35 km s -1 ) and estimated tangential velocity ( V tan ≈ 90-210 km s -1 ) of 2MASS 1626+3925 indicate membership in the Galactic halo, and this source is likely near or below the hydrogen-burning minimum mass for a metal-poor star. L subdwarfs such as 2MASS 1626+3925 are useful probes of gas and condensate chemistry in low-temperature stellar and brown dwarf atmospheres, but more examples are needed to study these objects as a population as well as to define a rigorous classification scheme.