The solitary g-mode frequencies in early B-type stars

TL;DR

This paper explores the excitation of gravity modes in early B-type main sequence stars, analyzing observational data and modeling to understand the origin of these pulsations, including effects of metallicity, opacity, and potential binary interactions.

Contribution

It demonstrates that modifications in metallicity or opacity profiles can selectively excite gravity modes while damping pressure modes in stellar models.

Findings

Gravity modes are observed in three early B-type stars from BRITE data.

Adjusting metallicity or opacity can explain the presence of gravity modes.

Pulsations may also originate from a lower mass companion.

Abstract

We present possible explanations of pulsations in early B-type main sequence stars which arise purely from the excitation of gravity modes. There are three stars with this type of oscillations detected from the BRITE light curves: $\kappa$ Cen, a Car, $\kappa$ Vel. We show that by changing metallicity or the opacity profile it is possible in some models to dump pressure modes keeping gravity modes unstable. Other possible scenario involves pulsations of a lower mass companion.