Is there a mass discrepancy in the Cepheid binary OGLE-LMC-CEP0227?
Abstract
Context. The Cepheid mass discrepancy, the difference between masses predicted from stellar evolution and stellar pulsation calculations, is a challenge for the understanding of stellar astrophysics. Recent models of the eclipsing binary Cepheid OGLE 0227 have suggested that the discrepancy may be resolved.
Aims: We explore for what physical parameters do stellar evolution models agree with the measured properties of OGLE-LMC-CEP0227 and compare to canonical stellar evolution models assuming no convective core overshooting.
Methods: We construct state-of-the-art stellar evolution models for varying mass, metallicity, and convective core overshooting and compare the stellar evolution predictions with the observed properties.
Results: The observed mass, effective temperature, and radius of the two stars in the binary system are well fit by numerous combinations of physical parameters, suggesting a Cepheid mass discrepancy of 10-20% relative to canonical stellar evolution models.
Conclusions: The properties of the observed binary Cepheid suggest that the Cepheid mass discrepancy is still a challenge and requires more specific observations, such as the rate of period change, to better constrain and understand the necessary physics for stellar evolution models to resolve the discrepancy.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- January 2012
- DOI:
- 10.1051/0004-6361/201117829
- arXiv:
- arXiv:1110.6657
- Bibcode:
- 2012A&A...537A..26N
- Keywords:
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- stars: evolution;
- stars: variables: Cepheids;
- binaries: eclipsing;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 5 pages, 3 figures, A&