The role of negative buoyancy in convective Cepheid models. Double-mode pulsations revisited

TL;DR

This paper investigates how negative buoyancy influences the modeling of double-mode pulsations in classical Cepheid stars, revealing that neglecting these effects leads to artificial double-mode behavior.

Contribution

The study clarifies the impact of negative buoyancy in pulsation models, showing that including these effects prevents the artificial double-mode pulsations previously observed.

Findings

Negative buoyancy effects are crucial for accurate Cepheid pulsation modeling.

Neglecting negative buoyancy leads to spurious double-mode solutions.

Inclusion of negative buoyancy effects eliminates non-physical double-mode behavior.

Abstract

The longstanding problem of modeling double-mode behaviour of classical pulsators was solved with the incorporation of turbulent convection into pulsation hydrocodes. However, the reasons for the computed double-mode behaviour were never clearly identified. In our recent papers (Smolec & Moskalik 2008a,b) we showed that the double-mode behaviour results from the neglect of negative buoyancy effects in some of the hydrocodes. If these effects are taken into account, no stable non-resonant double-mode behaviour can be found. In these proceedings we focus our attention on the role of negative buoyancy effects in classical Cepheid models.