DISCOVERY OF A HIGH PROPER MOTION L DWARF BINARY: 2MASS J152002244422419AB

We report the discovery of the wide L1.5+L4.5 binary 2MASS J152002244422419AB, identified during spec-troscopic follow-up of high proper motion sources selected from the Two Micron All Sky Survey. This source was independently identified by Kendall et al. in the SuperCOSMOS Sky Survey. Resolved JHK photometry and low-resolution near-infrared spectroscopy demonstrate that this system is composed of two well-separated (1:17400 0:01600) L dwarfs. Component classifications are derived using both spectral ratios and comparison to the near-infrared spectra of previously classified field L dwarfs. Physical association for the pair is deduced from the large common proper motion of the components ( 0:7300 0:0300 yr1) and their similar spectrophotometric distances (19 2 pc). The projected separation of the binary, 22 2 AU, is consistent with maximum separation/total system-mass trends for very lowmass binaries. The 2MASS J15204422 system exhibits both large tangential (66 7 km s1) and radial velocities (70 18 km s1), and its motion in the local standard of rest suggests that it is an old member of the Galactic disk population. This system joins a growing list of well-separated (>0.500), very low mass binaries, and is an excellent target for resolved optical spectroscopy to constrain its age, as well as trace activity/rotation trends near the hydrogen-burning limit. Subject headinggs: binaries: visual — stars: individual (2MASS J152002244422419) — stars: low-mass, brown dwarfs Online material: color figures 1