Traditional Approximation for Low-Frequency Modes in Rotating Stars and A Working Hypothesis About Episodic Mass Loss in Be Stars

Chapter
Part of the Astrophysics and Space Science Proceedings book series (ASSSP, volume 31)

Abstract

The so-called traditional approximation is reasonably good for very low frequency modes of rotating stars. In this approximation, the angular dependence of eigenfunction is expressed in terms of the Hough functions, and the radial dependence is expressed in a form similar to the case of non-rotating stars with only the replacement of the spherical degree with the eigenvalue of the Hough function. Paying attention to the non-zero surface temperature, we point out that very low frequency oscillations become leaky waves. A working hypothesis is then proposed to explain mass loss in Be stars as episodic wave leakage associated with gradual angular-momentum transport due to prograde modes.

Keywords

Leaky Wave Angular Momentum Transport Angular Momentum Flux Rotating Star Nonradial Oscillation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

This research was partially supported by the Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C) 23540260.

References

  1. 1.
    Aprilia, Lee, U., Saio, H.: Stability of g modes in rotating B-type stars. MNRAS 412, 2265–2276 (2011)Google Scholar
  2. 2.
    Balona, L.A.: Rotational modulation in Be stars. In: Suárez, J.C., Garrido, R., Balona, L.A., Christensen, J. (eds.) Stellar Pulsations. Springer, Heidelberg (2012)Google Scholar
  3. 3.
    Bildsten, L., Ushomirsky, G., Cutler, C.: Ocean g-modes on rotating neutron stars. ApJ 460, 827–831 (1996)ADSCrossRefGoogle Scholar
  4. 4.
    Eckart, C.: Hydrodynamics of Oceans and Atmospheres. Pergamon Press, Oxford (1960)MATHGoogle Scholar
  5. 5.
    Lee, U., Saio, H.: Low-frequency nonradial oscillations in rotating stars. I. Angular dependence. ApJ 491, 839–845 (1997)Google Scholar
  6. 6.
    Osaki, Y.: Nonradial pulsation theory of massive stars. PASP 98, 30–32 (1986)ADSCrossRefGoogle Scholar
  7. 7.
    Pantillon, F.P., Talon, S., Charbonnel, C.: Angular momentum transport by internal gravity waves III. Wave excitation by core convection and the Coriolis effect. A&A 474, 155–163 (2007)Google Scholar
  8. 8.
    Rivinius, T.: Be stars: Rapidly rotating pulsators. In: Suárez, J.C., Garrido, R., Balona, L.A., Christensen, J. (eds.) Stellar Pulsations. Springer, Heidelberg (2012)Google Scholar
  9. 9.
    Unno, W., Osaki, Y., Ando, H., Saio, H., Shibahashi, H.: Nonradial Oscillations of Stars. University of Tokyo Press, Tokyo (1989)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Department of AstronomyUniversity of TokyoTokyoJapan

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