A near-infrared, wide-field, proper-motion search for brown dwarfs

A common proper-motion survey of M dwarf stars within 8 pc of the Sun reveals no new stellar or brown dwarf companions at wide separations (similar to100-1400 AU). This survey tests whether the brown dwarf desert extends to large separations around M dwarf stars and further explores the census of the solar neighborhood. The sample includes 66 stars north of -30degrees and within 8 pc of the Sun. Existing first-epoch images are compared with new J-band images of the same fields an average of 7 yr later to reveal proper-motion companions within a similar to4' radius of the primary star. No new companions are detected to a J-band limiting magnitude of similar to16.5, corresponding to a companion mass of similar to40 Jupiter masses for an assumed age of 5 Gyr at the mean distance of the objects in the survey, 5.8 pc.