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The Period-Radius Relation for Pulsating Variable Stars.

1964; IOP Publishing; Volume: 140; Linguagem: Inglês

10.1086/148053

1538-4357

J. D. Fernie,

History and Developments in Astronomy

view Abstract Citations (30) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Period-Radius Relation for Pulsating Variable Stars. Fernie, J. D. Abstract A collection of radius determinations by Wesselink's method and others for twenty-five pulsating variables is made from the literature. The majority of classes of pulsating variables are represented, and the range in period extends from DQ Herculis of period 1 minute to Mira of period almost 1 year. It is found that all these variables closely obey a relation of the form P R2. The variables fall clearly into two groups, those still in the pre-red-giant stage of evolution (Group I), and those in the post-red-giant stage of evolution (Group II). The latter group includes the RR Lyrae and W Virginis stars as well as old Population I stars such as the Scuti stars and DQ Herculis. In Group II the constant of proportion- ality in the P R2 relation is 10 + 2 times as great as for Group I. As a consequence of these findings it is shown that P /p = Q cannot be a universal number, in agreement with Kraft's earlier suggestion, but increases with period and mass. The reason that classical Cepheids and long-period variables have nearly the same value of Q is explained. Substitution of the period-radius relation into the L = relation allows the prediction of detailed period-luminosity-color relations for all classes of pulsating variables for which the relations between bolometric correction, effective temperature, and color are known. These predicted relations are made for the classical Cepheids, Cephei stars, Scuti stars, and RR Lyrae stars. Satisfactory agreement with observation is obtained in all cases. In particular, the predicted relation for classical Cepheids is tested on nine Cepheids with periods between 5 and 45 days, and the average residual between observed and predicted absolute magnitude is 0.1 mag., compared to 0 2 mag. obtained using Kraft's P-L-C law. Evidence is given that the ratio of total to selective absorption for Cepheids is more nearly 3.4 than 3.0. Among the RR Lyrae stars the Bailey type-c variables obey the same P-L-C relation as types a and b. Further partia] tests of abso]ute magnitude predictions are carried out on Mira and a W Virginis star in the globular cluster MS. Satisfactory agreement with observation is obtained. Publication: The Astrophysical Journal Pub Date: November 1964 DOI: 10.1086/148053 Bibcode: 1964ApJ...140.1482F full text sources ADS | data products SIMBAD (32)