Radial Stellar Pulsation and 3D Convection. I. Numerical Methods and Adiabatic Test Cases

TL;DR

This paper introduces a new 3D radiation hydrodynamics code for simulating stellar pulsation and convection, overcoming previous limitations to achieve full amplitude simulations and validating the method with adiabatic tests.

Contribution

The authors develop a novel coordinate system flow algorithm that maintains constant mass in spherical shells, enabling long-term, full amplitude pulsation simulations in 3D.

Findings

Large amplitude solutions are repeatable over 150 pulsation periods.

The computational method conserves peak kinetic energy per cycle.

The new code successfully simulates adiabatic pulsations with stable, consistent results.

Abstract

We are developing a 3D radiation hydrodynamics code to simulate the interaction of convection and pulsation in classical variable stars. One key goal is the ability to carry these simulations to full amplitude in order to compare them with observed light and velocity curves. Previous 2D calculations were prevented from doing this because of drift in the radial coordinate system, due to the algorithm defining radial movement of the coordinate system during the pulsation cycle. We remove this difficulty by defining our coordinate system flow algorithm to require that the mass in a spherical shell remain constant throughout the pulsation cycle. We perform adiabatic test calculations to show that large amplitude solutions repeat over more than 150 pulsation periods. We also verify that the computational method conserves the peak kinetic energy per period, as must be true for adiabatic pulsation models.