Dynamical mass of a Cepheid (CEP-0227)

Relevant publication:

The dynamical mass of a classical Cepheid variable star in an eclipsing binary system

G. Pietrzyński, I. Thompson, W. Gieren, D. Graczyk, G. Bono, A. Udalski, I. Soszyński, D. Minniti, B. Pilecki

2010, Nature, 468, 542-544 (← click to see the publication at ADS/arXiv)

The two ways to determine the Cepheid mass – from stellar pulsation theory and from stellar evolution theory – yield the results different by 30% (the Cepheid mass discrepancy problem). The accuracy of previous efforts to establish a dynamical Cepheid mass from single-lined non-eclipsing binaries was ∼ 15−30%, not good enough to resolve the mass discrepancy problem. The discovery of a classical Cepheid OGLE-LMC-CEP0227 in a well detached, double-lined eclipsing binary allowed to determine the mass of the pulsator to 4.14 M☉ with a precision of 1.2%. This determination agrees with its pulsation mass, providing strong evidence that pulsation theory correctly and precisely predicts the masses of classical Cepheids.