Three newly discovered M-dwarf companions of solar neighborhood stars

We present low-resolution spectroscopy of newly discovered candidate companions to three stars in the solar neighborhood. All three companions are M dwarfs, with spectral types ranging from M4 to M9.5. In two cases, G85-55B (M6) and G87-9B (M4), we have circumstantial evidence from spectroscopy, photometry, and limited astrometry that the systems are physical binaries; in the third, G216-7B (M9.5), comparison of POSS II IIIaF plate material and the 2MASS image indicates common proper motion. The primary star in this system, G216-7A (M0), is itself an unresolved, nearly equal-mass binary. All three low-mass companions are highly likely to be stellar in nature, although G216-7B lies very close to the hydrogen-burning limit.