Seismological Analysis of the Stars γ Serpentis and ι Leonis: Stellar Parameters and Evolution

Abstract

In order to assess the information that will be available from targets of the Microvariability and Oscillations of Stars (MOST) satellite, we explore the possible evolutionary status and perform preliminary seismological analysis of two targets: the stars gamma Ser and iota Leo, which show solar-like oscillations. Taking into account the astrometric observational constraints on the stars, we find that gamma Ser is in the main-sequence phase of evolution, while iota Leo has two distinct solutions that match well with observations: main-sequence models and post-main-sequence models. The evolutionary tracks cover the following ranges of mass and initial metallicity: gamma Ser, 1.15-1.20 M-circle dot and Z = 0.0135 +/- 0.003; iota Leo, 1.62-1.70 M-circle dot and Z = 0.024 +/- 0.002 (for values of the Galactic helium enrichment ratio Delta Y/Delta Z in the range 0 - 2). By combining stellar models with observational constraints, we determine age ranges of 3.2 +/- 0.6 Gyr for gamma Ser and 1.7 +/- 0.2 Gyr for iota Leo. The results show that the masses and ages of the stars are very sensitive to metallicity and evolutionary phase. Furthermore, we find that models with overshooting from a convective core predict a larger age for a given mass. Finally, we discuss future prospects for constraining stellar models with the help of asteroseismic observations.