Detailed theoretical models for extra-solar planet-host stars

The “red stragglers” HD 37124 and HD 46375

¹ Grupo de Astrofísica da Universidade de Coimbra, Observatório Astronómico da Universidade de Coimbra, Santa Clara, 3000 Coimbra, Portugal
² Departamento de Matemática, FCTUC, Largo D. Dinis, Portugal e-mail: jmfernan@mat.uc.pt
³ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, Lisboa, Portugal
⁴ Observatoire de Genève, 51 ch. Des Maillettes, 1290 Sauverny, Switzerland e-mail: nuno.santos@oal.ul.pt

Received: 22 April 2004
Accepted: 16 July 2004

Abstract

In this paper we analyse and discuss the HR Diagram position of two extra-solar planet-host stars – HD 37124 and HD 46375 – by means of theoretical stellar evolution models. This work was triggered by the results obtained by Laws et al. ([CITE]) who found that these stars were in contradiction to the expectation based on their high metallicity. Fixing the age of both stars with the value based on their chromospheric activity levels and computing our own evolutionary models using the CESAM code, we are able to reproduce the observed luminosity, effective temperature and metallicity of both stars for a set of stellar parameters that are astrophysically reliable even if it is non-trivial to interpret the absolute values for these parameters. Our results are discussed in the context of the stellar properties of low mass stars.