Spectroscopic parameters for a sample of metal-rich solar-type stars

¹ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal e-mail: sousasag@astro.up.pt
² Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
³ Departamento de Matemática Aplicada, Faculdade de Ciências da Universidade do Porto, Portugal
⁴ Observatoire de Genève, 51 Ch. des Mailletes, 1290 Sauverny, Switzerland
⁵ Centro de Geofísica de Évora, Colégio Luis Antonio Verney, Évora, Portugal
⁶ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain

Received: 22 May 2006

Abstract

Aims.To date, metallicity is the only parameter of a star that appears to clearly correlate with the presence of planets and their properties. To check for new correlations between stars and the existence of an orbiting planet, we determine accurate stellar parameters for several metal-rich solar-type stars. The purpose is to fill the gap of the comparison sample presented in previous works in the high metal-content regime.

Methods.The stellar parameters were determined using an LTE analysis based on equivalent widths (EW) of iron lines and by imposing excitation and ionization equilibrium. We also present a first step in determining these stellar parameters in an automatic manner by using the code DAOSPEC for the EW determination.

Results.Accurate stellar parameters and metallicities are obtained for our sample composed of 64 high metal-content stars not known to harbor any planet. This sample will in the future give us the possibility of better exploring the existence of differences in the chemical abundances between planet-host stars and stars without known planets in the metal-rich domain. We also report stellar parameters for some recently discovered planet-host stars. Finally, we present an empirical calibration for DAOSPEC based on the comparison between its EW measurements and the standard “hand made” measurements for the FEROS sample presented in this paper.