1112.0368 (S. M. Lawler et al.)

Debris Disks in Kepler Exoplanet Systems    [PDF]

S. M. Lawler, B. Gladman

The Kepler Mission recently identified systems hosting candidate extrasolar planets, many of which are super-Earths. Realizing these rocky planetary systems are candidates to host extrasolar asteroid belts, we use mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) to search for emission from dust in these systems. We find excesses around eight stars, indicating the presence of warm to hot dust (~100-500 K), corresponding to orbital distances of 0.1-10 AU for these solar-type stars. The strongest detection, KOI 1099, demands ~500 K dust interior to the orbit of its exoplanet candidate. One star, KOI 904, may host very hot dust (~1200 K, corresponding to 0.02 AU). We find the fraction of these exoplanet-bearing stars with warm excesses (~3%) is consistent with the fraction found for solar-type field stars. It is difficult to explain the presence of dust so close to the host stars, corresponding to dust rings at radii <0.3 AU; both the collisional and Poynting-Robertson drag timescales to remove dust from the system are hundreds of years or less at these distances. Assuming a steady-state for these systems implies large mass consumption rates with these short removal timescales, meaning that the dust production mechanism in these systems must almost certainly be episodic in nature. Possible dust production mechanisms include comets with low perihelia, catastrophic collisions between planetesimals, or even impact ejecta from the exoplanets, which are located at similar orbital distances.

View original: http://arxiv.org/abs/1112.0368