Modelling Pulsating Stars

TL;DR

This paper introduces a new, faster version of a hydrodynamic code for modeling pulsating stars, enabling extensive parameter studies and fitting observed data with high accuracy, exemplified by the star SZ Lyn.

Contribution

A novel, efficient version of the Christy hydrodynamic code that allows rapid modeling of pulsating stars and detailed fitting to observational data.

Findings

The new code runs hundreds of models in a day or two.

Best-fit parameters for SZ Lyn were identified from 625 models.

Model results closely match observed light and velocity curves.

Abstract

Pulsating stars have been studied using non-linear hydrodynamic codes since the pioneering work of Robert Christy in the 1960s. Modern codes include improvements such as allowing for convection but there is a penalty in terms of computation speed and for some stars convection is not significant. In this work a new version of the Christy program has been developed which can run hundreds of star models to convergence in a day or two of computer time. This allows overall patterns of behaviour to be studied and suitable models for individual case stars to be identified. The star SZ Lyn was chosen as a test case for the model. Light curve and radial velocity data were obtained for this star using amateur equipment. A run of 625 parameter sets (mass, luminosity, effective temperature and hydrogen fraction) identified the best fit parameters for SZ Lyn. Model results show a good fit to the observed data in terms of amplitude, period and shape of the light and velocity curves. In this paper we report on the model developed by PM and radial velocity observations by RL.