Excitation of pressure modes in common envelopes

Noam Soker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We study the excitation of oscillatory modes by a low-mass star orbiting inside a common envelope with a more massive star. We treat adiabatic high spherical harmonic degree (l Gt; 1) modes propagating outward in the envelope. The dominant oscillatory modes are those for which the spherical harmonic order is large m ∼ l, and thus the amplitudes are large close to the equatorial plane and small closer to the poles. A secondary of mass ∼1% of the primary mass excites modes with relative surface amplitudes of a few × 10%. Even a Jupiter-like brown dwarf when it is very deep in the envelope of an asymptotic giant branch star can cause perturbations of relative surface amplitudes of ∼ 10% near the equatorial plane. If mass loss is influenced by oscillation then this mechanism can lead to higher mass loss in the equatorial plane. In case of an asymptotic giant branch primary this might lead to the formation of an elliptical planetary nebulae. Oscillation excitation by a low-mass secondary might also be relevant to the formation of the ring around SN 1987A.

Original languageEnglish
Pages (from-to)190-196
Number of pages7
JournalAstrophysical Journal
Issue number1
StatePublished - 1992
Externally publishedYes


  • Binaries: general
  • Stars: individual (sn 1987a)
  • Stars: mass loss
  • Stars: oscillations

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