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Pulsation Period Change & Classical Cepheids: Probing the Details of Stellar Evolution

Published online by Cambridge University Press:  23 January 2015

Hilding R. Neilson
Affiliation:
East Tennessee State University email: [email protected]
Alexandra C. Bisol
Affiliation:
Villanova University
Ed Guinan
Affiliation:
Villanova University
Scott Engle
Affiliation:
Villanova University
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Abstract

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Measurements of secular period change probe real-time stellar evolution of classical Cepheids making these measurements powerful constraints for stellar evolution models, especially when coupled with interferometric measurements. In this work, we present stellar evolution models and measured rates of period change for two Galactic Cepheids: Polaris and l Carinae, both important Cepheids for anchoring the Cepheid Leavitt law (period-luminosity relation). The combination of previously-measured parallaxes, interferometric angular diameters and rates of period change allows for predictions of Cepheid mass loss and stellar mass. Using the stellar evolution models, We find that l Car has a mass of about 9 M consistent with stellar pulsation models, but is not undergoing enhanced stellar mass loss. Conversely, the rate of period change for Polaris requires including enhanced mass-loss rates. We discuss what these different results imply for Cepheid evolution and the mass-loss mechanism on the Cepheid instability strip.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2015 

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