Second Overtone Pulsators Among Delta Scuti Stars

Abstract

We investigate the modal stability of stellar models at masses and luminosity levels corresponding to post main sequence luminous delta scuti pulsators. The envelope models have been computed at fixed mass value, luminosity level and chemical composition (Y=0.28, Z=0.02). According to a nonlinear approach to radial oscillations the present investigation predicts the occurrence of stable second overtone pulsators for the first time. The shape of both light and velocity curves are presented and discussed, providing a useful tool for the identification of second overtone pulsators among the known groups of radially pulsating stars. The period ratios of mixed mode pulsators obtained by perturbing the first and the second overtone radial eigenfunctions are in agreement with observative values. Finally, the physical structure and the dynamical properties of second overtone pulsators are discussed in detail. The role played by the nodal lines in the destabilization of second overtone pulsators is also pointed out.

20 pages, 11 Postscript figures, uses aaspp4.sty and tighten.sty

References in corpus (3)

• The MACHO Project LMC Variable Star Inventory: I. Beat Cepheids - Conclusive Evidence for the Excitation of the Second Overtone in Classical Cepheids
• Double-mode RR Lyrae Variables: Pulsational Masses Revisited
• Metallicity Effects on RR Lyrae Variables

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• The Carina Project. VI. The helium burning variable stars
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• A photometric monitoring of bright high-amplitude delta Scuti stars. I. The double-mode pulsation of V567 Ophiuchi
• Search for pulsation among suspected A-type binaries and the new multiperiodic Delta Scuti star HD217860
• Analysis of a selected sample of RR Lyrae stars in LMC from OGLE III