Radial and nonradial oscillations of massive supergiants

Hideyuki Saio

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


Stability of radial and nonradial oscillations of massive supergiants is discussed. The kappa-mechanism and strange-mode instability excite oscillations having various periods in wide ranges of the upper part of the HR diagram. In addition, in very luminous (log L/L ≳ 5.9) models, monotonously unstable modes exist, which probably indicates the occurrence of optically thick winds. The instability boundary is not far from the Humphreys-Davidson limit. Furthermore, it is found that there exist low-degree (ℓ=1, 2) oscillatory convection modes associated with the Fe-opacity peak convection zone, and they can emerge to the stellar surface so that they are very likely observable in a considerable range in the HR diagram. The convection modes have periods similar to g-modes, and their growth-times are comparable to the periods. Theoretical predictions are compared with some of the supergiant variables.

Original languageEnglish
Title of host publicationActive OB stars
Subtitle of host publicationstructure, evolution, mass loss, and critical limits
PublisherCambridge University Press
Number of pages6
ISBN (Print)9780521198400
Publication statusPublished - 2010 Jul
Externally publishedYes

Publication series

NameProceedings of the International Astronomical Union
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221


  • Convection
  • Instabilities
  • Stars: oscillations (including pulsations)
  • Supergiants

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science


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