Research Papers in Physics and Astronomy


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THE ASTROPHYSICAL JOURNAL, 343: L17-L20, 1989 August 1


Copyright 1989 The American Astronomical Society. All rights reserved. Printed in U.S.A.


Some results are given from the comparison with observations of a large number of hydrodynamic pulsation models: (1) Linear pulsation calculations are adequate for the determination of the masses of RRd stars; (2) the Fourier phase parameter ϕ31 measures the luminosity-to-mass ratio L/M1.81 for RRc stars; (3) most of the Ѡ Cen RRc stars seem to be evolved, as has previously been suggested; (4) the masses of the w Cen RRc stars agree with the masses of RRd stars in other clusters; and (5) a hint emerges of a mass-helium abundance relation among the RRc stars in Ѡ Cen. New CCD observations will be needed to extend our analysis to additional globular clusters.