Stellar Pollution in the Solar Neighborhood

We study spectroscopically determined iron abundances of 642 solar-type starsto search for the signature of accreted iron-rich material. We find that themetallicity [Fe/H] of a subset of 466 main sequence stars, when plotted as afunction of stellar mass, mimics the pattern seen in lithium abundances in openclusters. Using Monte Carlo models we find that, on average, these stars haveaccreted about 0.4 Earth masses of iron while on the main sequence. A muchsmaller sample of 19 stars in the Hertzsprung gap, which are slightly evolvedand whose convection zones are significantly more massive, have lower average[Fe/H], and their metallicity shows no clear variation with stellar mass. Thesefindings suggest that terrestrial-type material is common around solar typestars.Comment: 33 pages, 11 figures. Submitted to Ap