Amplitudes of low-frequency modes in rotating B-type stars

Umin Lee

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Using the weakly non-linear theory of oscillation, we estimate the amplitudes of low-frequency modes in a slowly pulsating B star, taking account of the effects of rotation on the modes. Applying the formulation by Schenk et al., we compute the non-linear coupling coefficient between the low-frequency modes and estimate the equilibrium amplitudes of the modes excited in the star, assuming the amplitudes of the unstable modes are saturated as a result of non-linear coupling with stable modes, i.e. as a result of parametric instability expected between one unstable mode and two stable modes. We use the traditional approximation to calculate adiabatic and non-adiabatic oscillations in a rotating star. We find r-modes in a rapidly rotating star play a significant role in the amplitude determination through non-linear coupling. We also find that for low-m modes, the fractional amplitudes of the radiative luminosity caused by the low-frequency modes are of order 10 -4 to 10 -3 at the surface.

Original languageEnglish
Pages (from-to)2387-2398
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 2012 Mar


  • Instabilities
  • Stars: Early-type
  • Stars: Oscillations
  • Stars: Rotation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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