Chemical Composition of Stars with Extrasolar Planetary Systems

In this article we review surface abundances in stars which host planetary systems. Recent spectroscopic studies of stars with and without planetary systems have concluded that stars which host giant planets are more metal-rich than those without planets. We discover more subtle trends of different chemical elements as the number of detected exoplanets continues to grow. In particular, Li seems to be depleted in planet host stars. Knowledge of precise abundances of oxygen and carbon may help to understand the structure of extrasolar planets. However, in most cases, the abundance trends of planet-host stars are very similar to those of the comparison sample. Possible explanations for the abundance anomalies or the correlation between [Fe/H] and the presence of giant planets have certain implications for planetary formation and evolution theory, Galactic chemical evolution, and astrobiology. The latest results indicate that some metals other than iron may also have an important contribution to planet formation if the amount of iron is low. Stars that host terrestrial planets, that can be found at low-iron regime, are mostly enhanced by alpha-elements.