Masses of the Double-Mode RR Lyrae Stars

Authors

Norman R. Simon, University of Nebraska - LincolnFollow
Arthur N. Cox, Los Alamos National LaboratoryFollow

Document Type

Article

Date of this Version

1990

Citation

Bulletin of the American Astronomical Society, Vol. 22 (1990), p.1222

Comments

Copyright 1990 American Astronomical Society. Provided by the NASA Astrophysics Data System

Abstract

We re-examine the double-mode RR Lyrae (RR_d) mass determination using both new and previously existing linear pulsation models. The independently written Los Alamos (Cox, et al. 1983. Ap. J. 266, 94) and Aikawa (Aikawa and Simon 1983, Ap. J. 273, 346) pulsation codes both yield "canonical" values for the RR_d masses, i.e., 0.55 M_ʘ for 0o I clusters, and 0.65 M_ʘ for 0o II clusters. These results are essentially independent of reasonable changes in helium abundance, the treatment of convection and the formulation of standard opacities. 'We show that recent contrary results by Petersen (1990. preprint) are almost certainly due' to the use of an adiabatic approximation and inappropriate metallicity. Given this, it is further argued that earlier disorepant results due to Kovacs (1985; Acta Astr. 35. 37) ought not to be given a high weight. Finally, we concur with Petersen's (1990) assertion that the 0o I RR_d masses could be increased provided that Population II metal opacities turn out to be very high.