The State of Cepheid Pulsation Theory

TL;DR

This paper reviews the current state of Cepheid pulsation modeling, highlighting successes, key deficiencies, and future challenges in multi-dimensional convection modeling and nonlinear nonradial pulsation analysis.

Contribution

It provides a comprehensive overview of Cepheid modeling progress, identifies main shortcomings, and outlines future research directions in nonlinear and multi-dimensional modeling.

Findings

Successful modeling of some Cepheid properties

Discrepancies in subtle nonlinear effects

Identification of future challenges in modeling

Abstract

We review the current state of Cepheid modeling and discuss its dominant deficiency, namely the use of time dependent mixing length. Notwithstanding, Cepheid modeling has achieved some excellent successes, and we mention some of the most recent ones. Discrepancies between observations and modeling appear not so much in the gross properties of single mode Cepheids, but rather when more subtle nonlinear effects are important, such as in double mode or even triple mode pulsations. Finally we discuss what we consider the most important challenges for the next decade. These are, first, realistic multi dimensional modeling of convection in a pulsating environment, and second, the nonlinear modeling of the nonradial pulsations that have been observed, and, relatedly, of the Blazhko like phenomenon that has recently been observed in Cepheids.