Cepheid Mass-loss and the Pulsation – Evolutionary Mass Discrepancy

I investigate the discrepancy between the evolution and pulsation masses for Cepheid variables. A number of recent works have proposed that non-canonical mass-loss can account for the mass discrepancy. This mass-loss would be such that a 5M⊙ star loses approximately 20% of its mass by arriving at the Cepheid instability strip; a 14M⊙ 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. Subject headings: Cepheids:pulsation stellar:evolution