On the Nearby Binary Brown Dwarf WISE J104915.57-531906.1 (Luhman 16)

Abstract: I report some observations and calculations related to the new nearby brown dwarf at d = 2 pc discovered by Luhman (2013, ApJ Letters, in press; arXiv:1303.2401). I report archival astrometry and photometry of the new object from IRAS (epoch 1983.5; IRAS Z10473-5303), AKARI (epoch 2007.0; AKARI J1049166-531907), and the Guide Star Catalog (epoch 1995.304; GSC2.2 S11132026703, GSC2.3 S4BM006703). A SuperCOSMOS scan of a plate taken with the ESO Schmidt Telescope (epoch 1984.169) shows the source as elongated (PA = 138 deg). Membership of the binary to any of the known nearby young groups within 100 pc appears unlikely based on the available astrometry and photometry. Based on the proper motion and parallax, a Monte Carlo simulation of thin disk/thick disk/halo stars is suggestive that the binary is, unsurprisingly, most likely a thin disk star (~96%), with a ~4% chance that it is a thick disk (and negligible chance that it is a halo star). I suggest that this important new nearby binary be called by either its provisional Washington Double Star catalog identifier ("Luhman 16"), or perhaps "Luhman-WISE 1", either of which is easier to remember than the WISE identifier.