Possible Stellar Metallicity Enhancements from the Accretion of Planets

Open Access
Publisher Website
Google Scholar
Abstract
A number of recently discovered extrasolar planet candidates have surprisingly small orbits, which may indicate that considerable orbital migration takes place in protoplanetary systems. A natural consequence of orbital migration is for a series of planets to be accreted, destroyed, and then thoroughly mixed into the convective envelope of the central star. We study the ramifications of planet accretion for the final main-sequence metallicity of the star. If maximum disk lifetimes are on the order of ~10 Myr, stars with masses near 1.0 M are predicted to have virtually no metallicity enhancement. On the other hand, early F- and late A-type stars with masses M* ≈ 1.5-2.0 M can experience significant metallicity enhancements due to their considerably smaller convection zones during the first 10 Myr of pre-main-sequence evolution. We show that the metallicities of an aggregate of unevolved F stars are consistent with an average star accreting ~2 Jupiter-mass planets from a protoplanetary disk having a 10 Myr dispersal time.
All Related Versions