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| Paper: |
Observational tests for stellar evolution and pulsation theory - The Sandage period-shift effect |
| Volume: |
11, Confrontation Between Stellar Pulsation and Evolution |
| Page: |
22 |
| Authors: |
Caputo, Filippina |
| Abstract: |
By demanding a full agreement among some key observables of RR Lyrae stars in globular clusters, a rather constant value is derived for parameter A, at variance with the correlation A-(Fe/H) found by Sandage. Alternatively were the Sandage effect actually present, some significant changes are needed in the currently used theoretical instability strip. In this latter case, the comparison with theoretical RGB and HB star evolution leads to exclude the anticorrelation of Y with (Fe/H), in favor of the requirement for an anticorrelation of DeltaMc (the enhancement of He-core mass with respect to the canonical one) and metallicity. |
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