New M Dwarf Debris Disk Candidates in NGC 2547

With only six known examples, M dwarf debris disks are rare, even though M dwarfs constitute the majority of stars in the Galaxy. After finding a new M dwarf debris disk in a shallow mid-infrared observation of NGC 2547, we present a considerably deeper Spitzer MIPS image of the region, with a maximum exposure time of 15 minutes pixel-1. Among sources selected from a previously published membership list, we identify nine new M dwarfs with excess emission at 24 μm tracing warm material close to the snow line of these stars, at orbital radii of less than 1 AU. We argue that these are likely debris disks, suggesting that planet formation is under way in these systems. Interestingly, the estimated excess fraction of M stars appears to be higher than that of G and K stars in our sample.