Stellar pollution in the solar neighborhood

We study spectroscopically determined iron abundances of 640 solar-type sta rs to search for the signature of accreted iron-rich material. We find that the metallicity [Fe/H] of a subset of 466 main-sequence stars, when plotte d as a function of stellar mass, mimics the pattern seen in lithium abundan ces in open clusters. Using Monte Carlo models, we find that, on average, t hese stars appear to have accreted similar to0.5 M-circle plus of iron whil e on the main-sequence. A consistency check is provided by a much smaller s ample of 19 stars in the Hertzsprung gap, which are slightly evolved and th e convection zones of which are significantly more massive; they have lower average [Fe/H], and their metallicity shows no clear variation with stella r mass. We argue that our Sun is likely to have accreted a similar amount o f iron; in this respect, most systems resemble ours rather than the current ly known extrasolar planetary systems. These findings suggest that terrestr ial-type material is common around solar-type stars.