Chemical composition of stars with massive planets

Abstract

ABSTRACT Stellar parameters of 25 planet-hosting stars and abundances of Li, C, O, Na, Mg, Al, S, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Zn, Y, Zr, Ba, Ce, Pr, Nd, Sm, and Eu were studied based on homogeneous high-resolution spectra and uniform techniques. The iron abundance [Fe/H] and key elements (Li, C, O, Mg, Si) indicative of the planet formation, as well as the dependences of [El/Fe] on Tcond, were analysed. The iron abundances determined in our sample stars with detected massive planets range within –0.3 < [Fe/H] < 0.4. The behaviour of [C/Fe], [O/Fe], [Mg/Fe], and [Si/Fe] relative to [Fe/H] is consistent with the Galactic Chemical Evolution trends. The mean values of C/O and [C/O] are $\langle$C/O$\rangle$ = 0.48 ± 0.07 and $\langle$[C/O]$\rangle$ = –0.07 ± 0.07, which are slightly lower than solar ones. The Mg/Si ratios range from 0.83 to 0.95 for four stars in our sample and from 1.0 to 1.86 for the remaining 21 stars. Various slopes of [El/Fe] versus Tcond were found. The dependences of the planetary mass on metallicity, the lithium abundance, the C/O and Mg/Si ratios, and also on the [El/Fe]–Tcond slopes were considered.