What have we learnt from pulsations of B-type stars?

TL;DR

This review summarizes seismic studies of B-type main sequence pulsators, highlighting the need for increased opacity at certain depths, constraints on overshooting, and rotation effects, based on multiple space and ground observations.

Contribution

It provides new insights into stellar interior physics by demonstrating the necessity of modifying opacity profiles and constraining overshooting and rotation from seismic data.

Findings

Significant opacity increase (~200%) at log T=5.46 needed in models.

Overshooting parameter below 0.3 from seismic constraints.

Deeper interior rotation rates vary among stars.

Abstract

We review the main results obtained from our seismic studies of B-type main sequence pulsators, based on the ground-based, MOST, Kepler and BRITE observations. Important constraints on stellar opacities, convective overshooting and rotation are derived. In each studied case, a significant modification of the opacity profile at the depths corresponding to the temperature range $\log{T}\in (5.0-5.5)$ is indispensable to explain all pulsational properties. In particular, a huge amount of opacity (at least 200\%) at the depth of the temperature $\log T = 5.46$ (the "nickel" opacity) has to be added in early B-type stellar models to account for low frequencies which correspond to high-order g modes. The values of the overshooting parameter, $\alpha_{\rm ov}$, from our seismic studies is below 0.3. In the case of a few stars, the deeper interiors have to rotate faster to get the g-mode instability in the whole observed range.