Hostname: page-component-77c89778f8-9q27g Total loading time: 0 Render date: 2024-07-18T22:21:45.990Z Has data issue: false hasContentIssue false
  • English
  • Français

The Oblique Pulsator Model for the Blazhko Effect in RR Lyrae Stars. Theory of Amplitude Modulation I

Published online by Cambridge University Press:  12 April 2016

Hiromoto Shibahashi
Hiromoto Shibahashi*
Affiliation:
Department of Astronomy, University of Tokyo, Tokyo 113-0033, Japan

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

By assuming that RR Lyrae stars have fairly strong dipole magnetic fields with symmetry axis oblique to the rotation axis of the star, I show that the oscillation mode which would be a pure radial oscillation in absence of the magnetic field has a quadrupole component, whose symmetry axis coincides with the magnetic axis. The aspect angle of the quadrupole component changes due to the stellar rotation, and this apparent amplitude variation is interpreted as the Blazhko effect in RR Lyrae stars. It is shown that, in the case of off-axis magnetic field, phase modulation is expected. I list up some theoretical predictions based on this model, which would observationally examine this hypothesis.

Type
Part 4. Blazhko Phenomenon
Information
International Astronomical Union Colloquium , Volume 176: The Impact of Large-Scale Surveys on Pulsating Star Research , 2000 , pp. 299 - 306
Copyright
Copyright © Astronomical Society of the Pacific 2000

References

Borkowski, K.J. 1980, Acta Astron., 30, 393 Google Scholar
Christy, R.F. 1966, ApJ, 144, 108 CrossRefGoogle Scholar
Cousens, A. 1983, MNRAS, 203, 1171 CrossRefGoogle Scholar
Kolenberg, K., Aerts, C., Chadid, M., & Gillet, D. 2000, in these proceedings, p. 286Google Scholar
Kovács, G. 1995, A&A, 295, 693 Google Scholar
Kurtz, D.W. 1982, MNRAS, 200, 807 Google Scholar
Kurtz, D.W. and the MACHO collaboration 2000, in these proceedings, p. 291Google Scholar
Romanov, Yu.S., Udovichenko, S.N., & Frolov, M.S. 1987, Soviet Ast. Letters, 13, 29 Google Scholar
Shibahashi, H. 1986, in Hydrodynamic and Magnetohydrodynamic Problems in the Sun and Stars, ed. Osaki, Y. (Tokyo: Univ. of Tokyo), 195 Google Scholar
Shibahashi, H. 1995, in ASP Conf. Ser. Vol. 76, GONG ’94: Helio- and Asteroseismology from the Earth and Space, ed. Ulrich, R.K., Rhodes, E.J. Jr., & Däppen, W. (San Francisco: ASP), 618 Google Scholar
Shibahashi, H., & Takata, M. 1995, in ASP Conf. Ser. Vol. 83, Astrophysical Applications of Stellar Pulsation, ed. Stobie, R. & Whitelock, P. (San Francisco: ASP), 42 Google Scholar
Smith, H., Matthews, J.M., Lee, K.M., Williams, J., Silberman, N.A., & Bolte, M. 1994, AJ, 107, 679 Google Scholar
Szeidl, B. 1988, in Multi-mode Stellar Pulsations, ed. Kovács, G., Szabados, L., & Szeidl, B. (Budapest: Konkoly Observatory), 45 Google Scholar
Unno, W., Osaki, Y., Ando, H., Saio, H., & Shibahashi, H. 1989, Nonradial Oscillations of Stars (Tokyo: Univ. of Tokyo Press)Google Scholar