Spitzer24 μm Survey of Debris Disks in the Pleiades

Abstract

We performed a 24 μm 2° × 1° survey of the Pleiades cluster, using the MIPS instrument on Spitzer. Fifty-four members ranging in spectral type from B8 to K6 show 24 μm fluxes consistent with bare photospheres. All Be stars show excesses attributed to free-free emission in their gaseous envelopes. Five early-type stars and four solar-type stars show excesses indicative of debris disks. We find a debris disk fraction of 25% for B-A members and 10% for F-K3 ones. These fractions appear intermediate between those for younger clusters and for the older field stars. They indicate a decay with age of the frequency of the dust production events inside the planetary zone, with similar timescales for solar-mass stars as have been found previously for A stars.