A Classical Cepheid in a LMC eclipsing binary: evidence of shortcomings in current stellar evolutionary models?

TL;DR

This study uses a newly analyzed Cepheid in an eclipsing binary to test stellar evolution models, finding they accurately predict the star's properties and resolving previous mass discrepancy issues.

Contribution

It demonstrates that current stellar evolution models can accurately match observed properties of a Cepheid in an eclipsing binary without fine-tuning.

Findings

Models match observed mass, radius, and temperature simultaneously.

No discrepancy between dynamical and evolutionary masses for the Cepheid.

Challenges previous claims of mass overestimation by models.

Abstract

The recent discovery and analysis of a classical Cepheid in the well detached, double-lined, eclipsing binary OGLE-LMC-CEP0227, has provided the first determination of the dynamical mass of a classical Cepheid variable to an unprecedented 1% accuracy. We show here that modern stellar evolution models widely employed to study Galactic and extragalactic stellar systems, are able to match simultaneously mass and radius (and effective temperature) of the two components with a single value for the age of the system, without any specific fine-tuning. Our conclusion is that there is no discrepancy between dynamical and evolutionary masses for the Cepheid star in this system, contrary to previous claims of an overestimate of the Cepheid mass by stellar evolution theory.