2007ApJ...667..527G

We report the mid- and far-infrared properties of nearby M dwarfs. Spitzer MIPS measurements were obtained for a sample of 62 stars at 24 µm, with subsamples of 41 and 20 stars observed at 70 and 160 µm, respectively. We compare the results with current models of M star photospheres and look for indications of circumstellar dust in the form of significant deviations of K-[24 µm] colors and 70 µm/24 µm flux ratios from the average M star values. At 24 µm, all 62 of the targets were detected; 70 µm detections were achieved for 20 targets in the subsample observed, and no detections were seen in the 160 µm subsample. No clear far-infrared excesses were detected in our sample. The average far-infrared excess relative to the photospheric emission of the M stars is at least 4 times smaller than the similar average for a sample of solar-type stars. However, this limit allows the average fractional infrared luminosity in the M-star sample to be similar to that for more massive stars. We have also set low limits (10^–4 to 10^–9 M_⊕ depending on location) for the maximum mass of dust possible around our stars.