On the Pulsation Amplitude of Cepheid Variables

  • Nikola Nikolov
  • Tsvetan Tsvetkov
Conference paper


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 PL relation of cepheids near log P ≈ 1.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Christy, R. F.: Ann. Rev. Astron. Astrophys. 4, 353 (1966).ADSCrossRefGoogle Scholar
  2. Efremov, Yu. N.: Astron. Circ. No. 443 (1967).Google Scholar
  3. Efremov, Yu. N.: Perem. Zvezdy 16, 365 (1968).ADSGoogle Scholar
  4. Efremov, Yu. N.: In “Pulsirujuscije Zvezdy”. Moscow 1970.Google Scholar
  5. Efremov, Yu. N.: Astron. Circ. No. 671 (1972).Google Scholar
  6. Fernie, J. D.: Observatory 85, 185 (1965).ADSGoogle Scholar
  7. Ferme, J. D.: Astrophys. J. 151, 197 (1968).ADSCrossRefGoogle Scholar
  8. Fitch, W. S.: Astrophys. J. 161, 669 (1970).ADSCrossRefGoogle Scholar
  9. Kukarkin, B. V.: Isledovanije stroenija i razvitija zvezdnih sistem. Moscow 1949.Google Scholar
  10. 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
  11. Kurochkin, N. E.: Perem. Zvezdy 16, 10 (1966).ADSGoogle Scholar
  12. Malik, G. M.: Astron. J. 70, 94 (1965).ADSCrossRefGoogle Scholar
  13. Nikolov, N. S.: Astron. Z. 43, 783 (1966a).ADSGoogle Scholar
  14. Nikolov, N. S.: Soviet Astron. 10, 623 (1966b).ADSGoogle Scholar
  15. Nikolov, N. S.: Perem. Zvezdy 16, 312 (1968).ADSGoogle Scholar
  16. Payne-Gaposchkin, C, Gaposchkin, S.: Smithsonian Contr. Astrophys. 9 (1966).Google Scholar
  17. Petit, M.: Comm. 27 IAU Inf. Bull. Var. Stars 455 (1970).Google Scholar

Copyright information

© Springer-Verlag, Berlin, Heidelberg 1974

Authors and Affiliations

  • Nikola Nikolov
    • 1
  • Tsvetan Tsvetkov
    • 1
  1. 1.Department of Astronomy, Faculty of PhysicsUniversity of SofiaBulgaria

Personalised recommendations