Vol. 543
In section 10. Planets and planetary systems

Overabundance of alpha-elements in exoplanet-hosting stars

by V.Zh. Adibekyan, N.C. Santos, S.G. Sousa, et al., A&A 543, A89

The authors present a chemical abundance analysis of 12 refractory elements for 1111 nearby stars that have been the target of planet searches with HARPS. Of these stars, 109 are known to harbor high-mass planetary companions and 26 stars host only lower mass Neptunians and super-Earths. Thus the chemical properties of stars with and without planets can be compared. The authors found that abundances of Mg, Al, Si, Sc, and Ti for all stars with known planets are systematically higher than those of comparison stars of similar metallicity but with no known planets. Magnesium shows the largest difference. These results suggest that chemical elements other than Fe may have an important role in planet formation, especially at low [Fe/H]. Moreover, this indicates that chemical composition and not the location of a star determines the likelihood of planet formation.