Pulsation Constants and Densities for Double Mode Variables in the Cepheid Instability Strip

Pulsation constants and period ratios are given for the first six radial pulsation modes of a set of seven polytropes with indices ranging from n = 2.25 to n = 4.00. The polytrope results are combined with published theoretical data from stellar model pulsation calculations and observational data on thirteen double mode variables in the Cepheid instability strip to obtain four interpolation formulae relating fundamental periods Po, pulsation constants Qo, and period ratios P1 /P0 and P2 /P1. The derived relations are used to obtain accurate densities for the thirteen observed variables, which include six dwarf Cepheids or AI Vel stars, one S Sct star, one RR Lyr star, and five Cepheids. Approximate masses and luminosities are obtained for some of these stars. The probable connection between mass- luminosity ratios and the existence of double mode variables is discussed.This title from the Steward Observatory Preprints collection is made available by the Steward Observatory Parker Library and the University Libraries, The University of Arizona. If you have questions about titles in this collection, please contact Parker Library librarian Betty Fridena, bfridena@as.arizona.edu