2004/05/21 by M. Di Criscienzo, Di Criscienzo M., M. Marconi +1 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Scientific Research and Discoveries #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/422742
published as Astrophys.J. 612 (2004) 1092-1106 · 23 pages, 17 postscript figures, accepted for publication on ApJ
arxiv created 2004/05/21 · openalex publication_date 2004/09/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
The results of nonlinear, convective models of RR Lyrae pulsators with metal content Z = 0.0001-0.006 are discussed and several predicted relations connecting pulsational (period and amplitude of pulsation) and evolutionary parameters (mass, absolute magnitude, and color of the pulsator) are derived. These relations, when linked with the average mass of RR Lyrae stars, as suggested by horizontal-branch evolutionary models, provide a "pulsational" route to the determination of the distance modulus, both apparent and intrinsic, of RR Lyrae-rich globular clusters. Based on a preliminary set of synthetic horizontal-branch simulations, we compare the predicted relations with observed variables in selected globular clusters (M2, M3, M5, M15, M55, M68, NGC 1851, NGC 3201, NGC 5466, NGC 6362, NGC 6934, and IC 4499). We show that the distance moduli inferred by the various theoretical relations are mutually consistent within the errors, provided that the value of the mixing-length parameter slightly increases from the blue to the red edge of the pulsation region. Moreover, we show that the relative "pulsational" distance moduli fit well previous empirical results and that the parallax of the prototype variable RR Lyr, as inferred by the predicted period-Wesenheit relation, is in close agreement with the Hubble Space Telescope astrometric measurement.