Paper

The Contour Method: a new approach to finding modes of non-adiabatic stellar pulsations

Townsend, R H D, Goldstein, J

2020

Overview

The contour method is a new approach to calculating the non-adiabatic pulsation frequencies of stars. These frequencies can be found by solving for the complex roots of a characteristic equation constructed from the linear non-adiabatic stellar pulsation equations. A complex-root solver requires an initial trial frequency for each non adiabatic root. A standard method for obtaining initial trial frequencies is to use a star's adiabatic pulsation frequencies, but this method can fail to converge to non-adiabatic roots, especially as the growth and/or damping rate of the pulsations becomes large. The contour method provides an alternative way for obtaining initial trial frequencies that robustly converges to non-adiabatic roots, even for stellar models with extremely non-adiabatic pulsations and thus large growth/damping rates. We describe the contour method implemented in the GYRE stellar pulsation code and use it to calculate the non-adiabatic pulsation frequencies of \\(10\\,\\rm{M_{\\odot}}\\) and \\(20\\,\\rm{M_{\\odot}}\\) \\(\\beta\\) Cephei star models, and of a \\(0.9\\,\\rm{M_{\\odot}}\\) extreme helium star model.

• Publisher: Cornell University Library, arXiv.org
• Subject: Adiabatic flow / Astronomical models / Contours / Convergence / Damping / Eigenvalues / Eigenvectors / Pulsation / Shape / Stellar models