THE STELLAR METALLICITY GIANT PLANET CONNECTION

The parent stars of the recently announced planetary system candidates are far from typical in terms of their chemical compositions. In this study we report on spectroscopic abundance analyses of upsilon And an d tau Boo. Both stars are metal-rich relative to the Sun, with a mean [Fe/H] value near 0.25. These findings follow the trend set by two oth er planetary system candidates, rho(1) 55 Cnc and 51 Peg, which also d isplay metallicities much higher than the average for nearby dwarfs. I n addition, their companions share similar orbital characteristics. Gi ven these observations, we propose that the current metallicities of t hese four stars are not representative of that of the original interst ellar clouds from which they formed but, rather, are the result of sel f-pollution during the planet formation epoch early in their histories .