Vol. 579
In section 8. Stellar atmospheres

High-precision abundances of elements in solar twin stars. Trends with stellar age and elemental condensation temperature

by P.E. Nissen, A&A 579, A52


It is known that the Sun appears to have an unusually low ratio between refractory and volatile elements. This has led to the suggestion that the relation between abundance ratios and the elemental condensation temperature can be used as a signature of the existence of terrestrial planets around a star. In this paper the author presents carefully analysed HARPS spectra with high S/N > 600 for 21 solar twin stars and the Sun (observed via reflected light from asteroids) to determine for the first time very precise (σ ∼ 0.01 dex) differential abundances for a range of chemical elements to accurately measure this relation and also to compare it to other parameters such as stellar age. This work confirms that the ratio of refractory and volatile elements is lower in the Sun than in the vast majority of solar twins. The slope of abundance ratios relative to iron as a function of elemental condensation temperature depends, however, on stellar age. For several elements there is an astonishingly tight correlation with stellar age that provides new constraints on supernovae yields and Galactic chemical evolution, and is of interest for discussions of the composition of exoplanets.