Discovery of an Extremely Nearby Brown Dwarf Pair

Large proper motion suggested that the object detected with NASA’s Wide-field Infrared Survey Explorer satellite, WISE J104915.57-531906, is nearby, with parallax measurements confirming its distance of only about 2pc. This is the closest stellar system found in a century, and the third closest overall. Subsequent observations with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South showed, unexpectedly, that the target is in fact a binary system. The spectroscopic observations also demonstrate that the brighter member is a type L8 brown dwarf. The other member is only about half a magnitude fainter, which suggests that it is near the L/T transition. Kevin Luhman (Penn State University) rapidly utilized GMOS spectroscopy obtained on February 23, 2013, with the bonus of discovering the binary (separated by 1.5 arcseconds, which corresponds to 3AU) in the acquisition image. This work will appear in The Astrophysical Journal Letters. A preprint and more information from Gemini and Penn State University are available now.