Cepheid in the Eclipsing Binary System OGLE-LMC-CEP1812 is a Stellar Merger
Classical Cepheids and eclipsing binary systems are powerful probes for measuring stellar fundamental parameters and constraining stellar astrophysics. A Cepheid in an eclipsing binary system is even more powerful, constraining stellar physics, the distance scale and the Cepheid mass discrepancy. However, these systems are rare, only three have been discovered. One of these, OGLE-LMC-CEP1812, presents a new mystery: where the Cepheid component appears to be younger than its red giant companion. In this work, we present stellar evolution models and show that the Cepheid is actually product of a stellar merger during main sequence evolution that causes the Cepheid to be a rejuvenated star. This result raises new questions into the evolution of Cepheids and their connections to smaller-mass anomalous Cepheids.
Neilson, Hilding; and Ignace, Richard. 2014. Cepheid in the Eclipsing Binary System OGLE-LMC-CEP1812 is a Stellar Merger. American Astronomical Society, 224th AAS Meeting, #314.03.