English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In order to understand the periodic and semiperiodic variations of luminous OBA‐type stars, linear non‐adiabatic stability analyses for radial and non‐radial oscillations have been performed for massive evolutionary models (8–90  M ⊙  ). In addition to radial and non‐radial oscillations excited by the kappa‐mechanism and strange mode instability, we discuss the importance of low‐degree oscillatory convection (non‐adiabatic g  −  ) modes. Although their kinetic energy is largely confined to the convection zone generated by the Fe‐opacity peak near  2 × 10 5  K , the amplitude can emerge into the photosphere and should be observable in a certain effective temperature range. They have periods longer than those of the radial strange modes so that they seem to be responsible for some of the long‐period microvariations of Luminous Blue Variables (LBVs; S Dor variables) and α Cyg variables. Moreover, monotonically unstable radial modes are found in some models whose initial masses are greater than or equal to  60 M ⊙   with   Z = 0.02 . The monotonic instability probably corresponds to the presence of an optically thick wind. The instability boundary roughly coincides with the Humphreys–Davidson limit.

Linear analyses for the stability of radial and non‐radial oscillations of massive stars