Extension of the Asfgrid for correcting asteroseismic large frequency separations

Abstract

The asteroseismic scaling relation, dnu~rho^{0.5}, linking a star's large frequency separation, dnu, and its mean density, rho, is not exact. Yet, it provides a very useful way to obtain fundamental stellar properties. Common ways to make the relation more accurate is to apply correction factors to it. Because the corrections depend on stellar properties, such as mass, Teff, and metallicity, it is customary to interpolate these properties over stellar model grids that include both dnu, measured from adiabatic frequencies of the models, and the models' stellar density; hence linking both sides of the scaling relation. A grid and interpolation tool widely used for this purpose, known as Asfgrid, was published by Sharma & Stello 2016. Here, we present a significant extension of Asfgrid to cover higher- and lower-mass stars and to increase the density of grid points, especially in the low-metallicity regime.