Seismology of stars in the Hyades and M67 open clusters : theoretical constraints on the mixing length parameter

Abstract

The mixing length parameter is a free parameter governing convective energy transport in current stellar models, and is poorly constrained by current photometric observations. Theoretical nonradial pulsation spectra have been calculated for main-sequence stars in the Hyades and M67 open clusters. It is shown that the major eigenfrequency spacing is sensitive to the mixing length parameter, and relatively insensitive to uncertainties in stellar metallicity, age, and helium abundance. Given the predicted uncertainties in observing the major eigenfrequency spacing of stars in the Hyades and M67 clusters, it is shown that proposed seismological studies of these clusters (Gilliland et al. 1993; Appourchaux et al. 1991) could determine the mixing length parameters for member stars to within ± 0.2. The determination of the mixing length parameter for a number of different, well-characterized stars would allow for the parameterization of convective properties as a function of other stellar characteristics. Such a parameterization would be beneficial to current efforts to numerically simulate stellar convection from first principles (Demarque 1996; Kim et al. 1996).