Banyan. X. Discovery of a Wide, Low-gravity L-type Companion to a Fast-rotating M3 Dwarf

Abstract

We report the discovery of a substellar-mass co-moving companion to 2MASS J22501512+2325342, an M3 candidate member of the young (130-200 Myr) AB Doradus Moving Group (ABDMG). This L3 β companion was discovered in a 2MASS search for companions at separations of 3″-18″ from a list of 2812 stars suspected to be young (≲500 Myr) in the literature, and was confirmed with follow-up astrometry and spectroscopy. Evolutionary models yield a companion mass of {30}_-4⁺¹¹ {M}_{Jup} at the age of ABDMG. The 2MASS J22501512+2325342 AB system appears to be a spatial outlier to the bulk of ABDMG members, similarly to the young 2MASS J22362452+4751425 AB system. Future searches for young objects around these two systems would make it possible to determine whether they are part of a spatial extension of the known ABDMG distribution.

Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientique of France, and the University of Hawaii.