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Nonlinear Radiative RR Lyrae Models: A Search for Double-Mode Behavior

Published online by Cambridge University Press:  15 February 2018

Joyce A. Guzik  and
Arthur N. Cox
Joyce A. Guzik
Affiliation:
Los Alamos National Laboratory, Los Alamos, New Mexico, USA
Arthur N. Cox
Affiliation:
Los Alamos National Laboratory, Los Alamos, New Mexico, USA

Extract

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Cox (1991), Kovacs, Buchler, and Marom (1991), and Kovacs et al. (1992) showed that opacity changes indicated by the Livermore OPAL opacities increase the pulsation masses of double-mode RR Lyrae variables. We calculated limiting amplitude solutions for radiative RR Lyrae models of 0.75 M⊙, 51 L⊙, and Z=0.0001 (Oosterhoff II) to investigate the effects of the mass increase and opacity changes suggested by the OPAL opacities. In particular, we modified the Stellingwerf analytical fit (1975) to the Cox-Tabor (1976) tables to decrease the opacity by 20% between 20,000 and 30,000 K. The Stellingwerf periodic relaxation method was used to converge the models to a limit cycle, and the Floquet matrix analysed to search for a tendency of the fundamental mode to grow from the full-amplitude overtone solution, and the overtone to grow from the full-amplitude fundamental mode solution, thereby predicting double-mode behavior.

Type
Theoretical Breakthroughs
Information
International Astronomical Union Colloquium , Volume 139: New Perspectives on Stellar Pulsation and Pulsating Variable Stars , 1993 , pp. 266
Copyright
Copyright © Cambridge University Press 1993

References

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