Modeling epsilon Eri and Asteroseismic Tests of Element Diffusion

Abstract

Taking into account the helium and metal diffusion, we explore the possible evolutionary status with a seismic analysis, of the MOST (Microvariability and Oscillations of STars) target: the star epsilon Eri. We adopt different input parameters to construct models to fit the available observational constraints in, e.g., T-eff, L, R and [Fe/H]. From the computation we obtain the average large spacings of epsilon Eri to be about 194 +/- 1 mu Hz. The age of the diffused models was found to be about 1 Gyr, which is younger than the age determined previously by models without diffusion. We found that the effect of pure helium diffusion on the internal structure of the young low-mass star is slight, but that of metal diffusion is obvious. The metal diffusion leads the models to have much higher temperature in the radiative interior, and, correspondingly a higher sound speed there, hence a larger frequency and spacings.