Are beryllium abundances anomalous in stars with giant planets?^*

¹ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal e-mail: Nuno.Santos@oal.ul.pt
² Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
³ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez s/n, 38206, La Laguna, Tenerife, Spain
⁵ Consejo Superior de Investigaciones Científicas, Spain
⁶ INAF/Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy

Received: 24 March 2004
Accepted: 22 July 2004

Abstract

In this paper we present beryllium (Be) abundances in a large sample of 41 extra-solar planet host stars, and for 29 stars without any known planetary-mass companion, spanning a large range of effective temperatures. The Be abundances were derived through spectral synthesis done in standard Local Thermodynamic Equilibrium, using spectra obtained with various instruments. The results seem to confirm that overall, planet-host stars have “normal” Be abundances, although a small, but not significant, difference might be present. This result is discussed, and we show that this difference is probably not due to any stellar “pollution” events. In other words, our results support the idea that the high-metal content of planet-host stars has, overall, a “primordial” origin. However, we also find a small subset of planet-host late-F and early-G dwarfs that might have higher than average Be abundances. The reason for the offset is not clear, and might be related either to the engulfment of planetary material, to galactic chemical evolution effects, or to stellar-mass differences for stars of similar temperature.