Warm dust in the terrestrial planet zone of a sun-like Pleiad: collisions between planetary embryos?

TL;DR

This study identifies warm dust around a Pleiades star, suggesting frequent planetary collisions and early terrestrial planet formation in sun-like stars, based on mid-infrared observations of dust emission.

Contribution

It reports the discovery of warm dust around HD 23514, indicating planetary collisions are common during early planet formation stages in sun-like stars.

Findings

Warm dust detected around HD 23514 with a non-standard 9 micron peak.

Presence of dust implies frequent collisions of planetary embryos.

Terrestrial planet formation may be common in young solar-type stars.

Abstract

Only a few solar-type main sequence stars are known to be orbited by warm dust particles; the most extreme is the G0 field star BD+20 307 that emits ~4% of its energy at mid-infrared wavelengths. We report the identification of a similarly dusty star HD 23514, an F6-type member of the Pleiades cluster. A strong mid-IR silicate emission feature indicates the presence of small warm dust particles, but with the primary flux density peak at the non-standard wavelength of ~9 micron. The existence of so much dust within an AU or so of these stars is not easily accounted for given the very brief lifetime in orbit of small particles. The apparent absence of very hot (>~1000 K) dust at both stars suggests the possible presence of a planet closer to the stars than the dust. The observed frequency of the BD+20 307/HD 23514 phenomenon indicates that the mass equivalent of Earth's Moon must be converted, via collisions of massive bodies, to tiny dust particles that find their way to the terrestrial planet zone during the first few hundred million years of the life of many (most?) sun-like stars. Identification of these two dusty systems among youthful nearby solar-type stars suggests that terrestrial planet formation is common.