Detailed theoretical models for extra-solar planet-host stars. The ``red stragglers'' HD 37124 and HD 46375

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. (2003) 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.