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Paper: Oscillating Blue Stragglers in Galactic globular clusters
Volume: 256, Observational Aspects of Pulsating B and A Stars
Page: 249
Authors: Bono, G.; Caputo, F.; Marconi, M.; Santolamazza, P.
Abstract: Preliminary results based on a few nonlinear, convective models of oscillating blue stragglers (SX Phe stars) suggest that both the modal stability and the pulsation amplitudes are somehow affected by the He content. As a matter of fact, we found that a He-enhanced (Y=0.30), second overtone model centrally located in the instability strip presents a mixed-mode behavior at limit cycle stability, whereas the canonical model (Y=0.24) attains a pure second overtone asymptotic behavior. Interestingly enough, we also found that a model constructed by adopting the same He-enhancement and an increase of 0.13 dex in the luminosity attains pulsation amplitudes that are smaller than the canonical ones. These findings support the evidence that the pulsation properties of cluster SX Phe stars can supply useful hints concerning the He content of the envelope, and in turn on the puzzling nature of blue stragglers.
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