Interpretation of the BRITE oscillation spectra of the early B-type stars: $\nu$ Eri and $\alpha$ Lup

TL;DR

This paper analyzes the pulsation spectra of early B-type stars, specifically $ u$ Eri and $eta$ Cephei/SPB hybrid $ ext{α}$ Lupi, using seismic models to understand their oscillation modes and the stellar interior properties.

Contribution

It develops complex seismic models that explain observed frequencies and the non-adiabatic parameter, highlighting the need for opacity profile modifications in stellar models.

Findings

Significant opacity profile modifications are required at $ ext{log}T$ between 5.0 and 5.5.

Seismic models successfully reproduce observed frequency ranges and parameters.

$ ext{α}$ Lupi is confirmed as a hybrid $eta$ Cep/SPB pulsator.

Abstract

$\nu$ Eridani is a well known multiperiodic $\beta$ Cephei pulsator which exhibits also the SPB (Slowly Pulsating B-type stars) type modes. Recent frequency analysis of the BRITE photometry of $\alpha$ Lupi showed that the star is also a hybrid $\beta$ Cep/SPB pulsator, in which both high and low frequencies were detected. We construct complex seismic models in order to account for the observed frequency range, the values of the frequencies themselves and the non-adiabatic parameter $f$ for the dominant mode. Our studies suggest, that significant modifications of the opacity profile at the temperature range $\log{T}\in (5.0-5.5)$ are necessary to fulfill all these requirements.