Stellar Membership and Dusty Debris Disks in the alpha Persei Cluster

TL;DR

This study identifies members of the alpha Persei cluster and reports the discovery of dusty debris disks around some stars, notably V488 Per, revealing insights into planetary formation processes.

Contribution

It provides the first infrared survey of alpha Persei with WISE, identifying stars with dusty debris disks and characterizing their properties, especially around V488 Per.

Findings

11-12 cluster members have excess infrared emission due to debris disks.

V488 Per exhibits the largest IR excess among main sequence stars.

Dust around V488 Per is at ~800 K, close to the star, likely from planetary collisions.

Abstract

Because of proximity to the Galactic plane, reliable identification of members of the alpha Persei cluster is often problematic. Based primarily on membership evaluations contained in six published papers, we constructed a mostly complete list of high-fidelity members of spectral type G and earlier that lie within 3 arc degrees of the cluster center. Alpha Persei was the one nearby, rich, young open cluster not surveyed with the Spitzer Space Telescope. We examined the first and final data releases of the Wide Field Infrared Survey Explorer (WISE) and found 11, or perhaps 12, alpha Per cluster members that have excess mid-infrared emission above the stellar photosphere attributable to an orbiting dusty debris disk. The most unusual of these is V488 Per, a K-type star with an excess IR luminosity 16% (or more) of the stellar luminosity; this is a larger excess fraction than that of any other known dusty main sequence star. Much of the dust that orbits V488 Per is at a temperature of ~800 K; if these grains radiate like blackbodies, then they lie only ~0.06 AU from the star. The dust is probably the aftermath of a collision of two planetary embryos or planets with small semimajor axes; such orbital radii are similar to those of many of the transiting planets discovered by the Kepler satellite.