On the effect of turbulent anisotropy on pulsation stability of stars

TL;DR

This study investigates how turbulent anisotropy influences the stability of stellar pulsations, finding minimal impact on low-order modes and robustness against calibration errors in anisotropic parameters.

Contribution

It provides a detailed analysis of turbulent anisotropy effects on stellar pulsation stability within a non-local convection framework, highlighting its limited influence on certain modes.

Findings

Anisotropy has little effect on g modes and low-order p modes.

High-order p modes are more affected by anisotropy.

Stability calculations are insensitive to the anisotropic parameter $c_3$.

Abstract

Within the framework of non-local time-dependent stellar convection theory, we study in detail the effect of turbulent anisotropy on stellar pulsation stability. The results show that anisotropy has no substantial influence on pulsation stability of g modes and low-order (radial order $n_\mathrm{r}<5$) p modes. The effect of turbulent anisotropy increases as the radial order increases. When turbulent anisotropy is neglected, most of high-order ($n_\mathrm{r}>5$) p modes of all low-temperature stars become unstable. Fortunately, within a wide range of the anisotropic parameter $c_3$, stellar pulsation stability is not sensitive to the specific value of $c_3$. Therefore it is safe to say that calibration errors of the convective parameter $c_3$ do not cause any uncertainty in the calculation of stellar pulsation stability.