Asteroseismic models for the exoplanet host star HD 19994: A preliminary approach

International audienceWe present preliminary models for HD 19994, a star which is part of a binary system and also harbors an extrasolar planet. We compute evolutionary tracks with the Toulouse-Geneva evo- lution code, using four different metallicity values. Large and small separations are computed, and the echelle diagrams are given for a few models. From the currently known spectroscopic data, we found that HD 19994 could be either an overmetallic main sequence star with a mass range between 1.24 and 1.36 Mȯ or a less massive subgiant star, with a mass range of 1.18-1.28 Mȯ and a solar metallicity. We also found that, in some cases, the small separations can become negative at a given frequency, which is related to the presence of a convective and helium-rich core. This is a preliminary approach: a more precise asteroseismic study of this star, based on recent (November 2007) data from the HARPS spectrograph will be given later