Astrophysics and Space Science

, Volume 91, Issue 2, pp 319–325 | Cite as

Effect of variations of opacity and helium-hydrogen ratio on pulsational instability

  • H. S. Gurm
  • H. M. Sukhija
  • J. K. Badalia
Article
Received:

Abstract

An attempt has been made to study the effects of the opacity mechanisms on pulsational instability of some theoretical models having different masses and in different evolutionary stages. Different combinations of the opacity exponentsn, s, and helium-hydrogen ratio,B, have been considered. Based on these combinations, Gamma-mechanism and Kappa-mechanism have been compared. Gamma-mechanism (n=0,s=0) is found to be totally ineffective forB=0.01 in producing a driving force. Even a high value ofB (=0.38) is also not suitable for instability. The combination ofn=0.7,s=2.1, andB=0.25 has been found to give the largest negative dissipation for a 15.6M⊙ star in hydrogen-burning phase although the same does not hold for helium-burning phase. The conditions in which these excitation mechanisms could be most effective have been discussed.

Keywords

Theoretical Model Evolutionary Stage Excitation Mechanism Pulsational Instability Negative Dissipation 
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.
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Copyright information

© D. Reidel Publishing Co 1983

Authors and Affiliations

  • H. S. Gurm
    • 1
  • H. M. Sukhija
    • 1
  • J. K. Badalia
    • 1
  1. 1.Department of Astronomy and Space SciencesPunjabi UniversityPatialaIndia

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