Theoretical instability strips of γ-Doradus stars including the effect of the metallicity and rotation

Abstract

Recent space missions such as have provided large-scale observations of the γ-Doradus instability strips (IS), which can be used to constrain models and explore their limitations. One persistent limitation is the prediction of the blue edge of the γ-Doradus IS, where a significant number of γ-Doradus stars are observed. Despite these observational advances, no systematic study has explored the effects of different physical processes on the γ-Doradus IS. Kepler Our aim is to systematically explore the theoretical γ-Doradus IS with modern tools, accounting for the effects of rotation and metallicity, and providing a large grid of models and their oscillation parameters for the scientific community. We investigated the non-adiabatic pulsation properties of stars in a grid of stellar models with masses between 1.35,M_⊙ and 2.5,M_⊙, metallicities between Z=0.01 and Z=0.025, and solid-body rotation rates ranging from Ω=0 to crit , where Ω_ crit denotes the critical rotation rate. We find that, across all computations, the theoretical γ-Doradus IS agrees well with the observed IS, except in the extended blue region. In terms of radial orders, our models consistently reproduce excited modes in broad agreement with observations for the ell=1, ell=2, and Rossby modes. We also show that the range of excited radial orders is strongly dependent on the effective temperature. The range of excited radial orders can be used to constrain the position of a star within the γ-Doradus IS and may provide insight into the physical mechanisms responsible for the discrepancies observed in the blue region. We have made all computed grids available, including those containing mode damping and growth rates for γ-Doradus stars calculated using a time-dependent treatment of the convection–oscillation interaction.