Beryllium abundances in stars with planets : extending the sample

Abstract

Context : Chemical abundances of light elements such as beryllium in planet-host stars allow us to study the planet formation scenarios and/or investigate possible surface pollution processes. Aims : We present here an extension of previous beryllium abundance studies. The complete sample consists of 70 stars that host planets and 30 stars without known planetary companions. The aim of this paper is to further assess the trends found in previous studies with fewer objects. This will provide more information on the processes of depletion and mixing of light elements in the interior of late-type stars, and will provide possible explanations for the abundance differences between stars that host planets and "single" stars. Methods : Using high-resolution UVES spectra, we measure beryllium abundances of 26 stars that host planets and one "single" star mainly using the lambda 3131.065 angstrom Be II line, by fitting synthetic spectra to the observational data. We also compile beryllium abundance measurements of 44 stars hosting planets and 29 "single" stars from the literature, resulting in a final sample of 100 objects. Results : We confirm that the beryllium content is roughly the same in stars hosting planets and in "single" stars at temperatures T-eff greater than or similar to 5700 K. The sample is still small for T-eff less than or similar to 5500 K, but it seems that the scatter in Be abundances of dwarf stars is slightly higher at these cooler temperatures. Conclusions : We search for distinctive characteristics of planet hosts through correlations of Be abundance versus Li abundance, age, metallicity, and oxygen abundance. These could provide some insight into the formation and evolution of planetary systems, but we did not find any clear correlation.