Cepheid Mass Loss and the Pulsation–Evolutionary Mass Discrepancy

Abstract

I investigate the discrepancy between the evolution and pulsation masses for Cepheid variables. A number of recent works have proposed that noncanonical mass loss can account for the mass discrepancy. This mass loss would be such that a 5 M☉ star loses approximately 20% of its mass by arriving at the Cepheid instability strip; a 14 M☉ star, none. Such findings would pose a serious challenge to our understanding of mass loss. I revisit these results in light of the Padova stellar evolutionary models and find evolutionary masses are (17 ± 5)% greater than pulsation masses for Cepheids between 5 < M/M☉ < 14. I find that mild internal mixing in the main-sequence progenitor of the Cepheid are able to account for this mass discrepancy.