New M dwarf debris disk candidates in NGC 2547

TL;DR

This study identifies nine new M dwarf debris disk candidates in NGC 2547 using deep infrared imaging, indicating active planet formation around these common stars.

Contribution

It reports the discovery of multiple new M dwarf debris disks in a young cluster, significantly increasing known examples and suggesting higher debris disk occurrence in M dwarfs.

Findings

Nine new M dwarf debris disk candidates identified.

Higher debris disk fraction in M dwarfs compared to G and K stars.

Debris disks found close to the snow line, implying ongoing planet formation.

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.