The metal-rich nature of stars with planets

With the goal of confirming the metallicity "excess" present in stars with planetary-mass companions, we present in this paper a high-precision spectr oscopic study of a sample of dwarfs included in the CORALIE extrasolar plan et survey. The targets were chosen according to the basic criteria that 1) they formed part of a limited volume and 2) they did not present the signat ure of a planetary host companion. A few stars with planets were also obser ved and analysed; namely, HD6434, HD 13445 (Gl 86), HD 16141, HD 17051 (iot a Hor), HD 19994, HD 22049 (epsilon Eri), HD 28185, HD 38529, HD 52265, HD 190228, HD 210277 and HD 217107. For some of these objects there had been n o previous spectroscopic studies. The spectroscopic analysis was done using the same technique as in previous work on the metallicity of stars with planets, thereby permitting a direct comparison of the results. The work described in this paper thus represent s the first uniform and unbiased comparison between stars with and without planetary-mass companions in a volume-limited sample. The results show that 1) stars with planets are significantly metal-rich, and 2) that the source of the metallicity is most probably "primordial". The results presented he re may impose serious constraints on planetary system formation and evoluti on models.