New M Dwarf Debris Disk Candidates in NGC 2547
First Author:
Jan Forbrich
Email: jforbrich AT cfa.harvard.edu
Harvard-Smithsonian CfA
60 Garden St, MS 72
Cambridge, MA 02138
Coauthors:
Lada, Charles J., CfA
Muench, August A., CfA
Teixeira, Paula S., CfA
Abstract
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 per pixel. Among sources selected from a previously published membership list, we identify nine new M dwarfs with excess emission at 24 micron 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. In addition to the imaging data, we also discuss mid-infrared spectroscopic data of one of these sources, acquired with Spitzer-IRS.
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