Confirm the strange-mode nature of the unstable modes

Determine whether the candidate strange-mode instabilities identified in the radial models of the O-type supergiant HD 152249 are in fact strange modes by applying the Non-Adiabatic-Reversible approximation.

Background

The study identifies several unstable radial modes in envelope models representing the O-type supergiant HD 152249, with mode crossings, strong non-adiabatic behavior, and growth rates suggestive of strange-mode instabilities. However, the analysis presented does not definitively classify these modes as strange modes.

The authors specify that confirmation requires the Non-Adiabatic-Reversible approximation, which was not carried out within the study. Establishing the modes’ nature would clarify whether the calculated instabilities belong to the strange-mode class and would strengthen the interpretation of the associated envelope inflation, finite-amplitude pulsation, and possible mass loss.