On the Pulsation Amplitude of Cepheid Variables
On the basis of more numerous data a relation log P ΔV/log Δ R (P is the period, ΔR is the amplitude of the radius variation and ΔV is the amplitude of the V-magnitude variation) for cepheid variables (Fernie, 1965) has been established. A linear relation between log ΔV and log ΔR for classical cepheids is found, which perhaps has a break at ΔR = 10 R⊙.
In the log ΔR/log P diagram the s-cepheids (Efremov, 1968) form a distinct sequence. All s-cepheids present a relative variation of the radii ΔR/R≦0.075. Very probably this is in accordance with Efremov’s (1968) hypothesis that these cepheids cross for the first time the instability region in the HR-diagram.
On the basis of the log ΔR/log P diagram one could suppose that cepheids with log P≧1.1 pulsate in the first overtone whereas those with log P≦1.1 pulsate in the fundamental one. If these two groups of cepheids pulsate really differently, they would have a distinct P — L relation, as some investigators have found a break in the P — L relation of cepheids near log P ≈ 1.
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- Efremov, Yu. N.: Astron. Circ. No. 443 (1967).Google Scholar
- Efremov, Yu. N.: In “Pulsirujuscije Zvezdy”. Moscow 1970.Google Scholar
- Efremov, Yu. N.: Astron. Circ. No. 671 (1972).Google Scholar
- Kukarkin, B. V.: Isledovanije stroenija i razvitija zvezdnih sistem. Moscow 1949.Google Scholar
- Kukarkin, B. V., Kholopov, P. N., Efremov, Yu. N., Kukarkina, N. P., Kurochkin, N. E., Medvedeva, G. I., Perova, N. B., Fedorovich, V. P., Frolov, M. S.: General Catalogue of Variable Stars, Third Edition. Moscow 1969.Google Scholar
- Payne-Gaposchkin, C, Gaposchkin, S.: Smithsonian Contr. Astrophys. 9 (1966).Google Scholar
- Petit, M.: Comm. 27 IAU Inf. Bull. Var. Stars 455 (1970).Google Scholar