32 - Computations of static white dwarf models: A must for asteroseismological studies

Summary

Abstract

We present briefly a new generation of white dwarf models incorporating the latest developments of the constitutive physics. These are static models especially designed for accurate seismological studies.

Introduction

The main goal of asteroseismology is the determination of the internal structure of a pulsating star through the analysis of its observed pulsation properties. One way to fulfill this goal is by producing a stellar model that reproduces to high accuracy the observed periods of oscillation. This is generally not possible through full evolutionary calculations as the parameters of a model must be tuned rather finely to satisfy the requirement of accuracy. However, computations of static models can be used with profit here. We have therefore developed the capacity to rapidly build complete static models of stratified H-rich (DA) or He-rich (DB) white dwarfs, especially suited for asteroseismological studies, by specifying the stellar mass, the H-layer thickness, the He-layer thickness, the convective efficiency and the effective temperature.

Method

To build our models, we integrate with the help of a Runge-Kutta technique the equations of stellar structure and stellar grey atmosphere (see, e.g., Cox & Guili 1968 and Mihalas 1978) from the high atmosphere (ρ ≲ 10⁻¹³) down to the center of the star. We iterate this procedure until we find a model with M_r = 0 at r = 0. To have a good spatial resolution both in the interior and the external regions, we use the integration variable x[≡ ln(r/P)].