Multimode Cepheids in the Large Magellanic Cloud - challenges for theory

TL;DR

This paper compares observational data of multimode Cepheids in the LMC with theoretical models, highlighting discrepancies and challenges in explaining certain pulsation modes, especially double-mode pulsators with specific period ratios.

Contribution

It identifies inconsistencies between observed Cepheid pulsation modes and existing models, and explores nonradial modes to explain unusual period ratios.

Findings

Models match observed radial mode periods but not evolutionary models.

Nonradial modes may explain unusual period ratios.

Double-mode pulsators with period ratios near 0.6 remain unexplained.

Abstract

Data on multimode Cepheids from OGLE-III catalog of the LMC Cepheids are confronted with results from model calculations. Models whose radial mode periods are consistent with observation are not always in agreement with published evolutionary models. Nonradial mode interpretation is considered for the cases of unusual period ratios. The greatest challenge for stellar pulsation theory is explanation of double-mode pulsators with period ratios near 0.6.