Internal rotation and inclinations of slowly pulsating B stars: Evidence of interior angular momentum transport

TL;DR

This study uses asteroseismology to measure internal rotation in 52 slowly pulsating B stars, revealing core spin-down with age and evidence of angular momentum transport during the main sequence.

Contribution

It provides the first large-scale compilation of asteroseismic rotation measurements for intermediate-mass stars, demonstrating angular momentum transport in stellar interiors.

Findings

Core rotation decreases with stellar age.

Most stars exhibit sub-inertial oscillation regimes.

Inclination angles align with surface cancellation expectations.

Abstract

One of the largest uncertainties in stellar structure and evolution theory is the transport of angular momentum in the stellar interiors. Asteroseismology offers a powerful tool for measuring the internal rotation frequencies of pulsating stars, but the number of such measurements has remained few for $\gtrsim 3\,{\rm M}_\odot$ main-sequence stars. In this work, we compile a list of 52 slowly pulsating B stars for which the interior rotation has been measured asteroseismically. The measurements of the spin parameters, which describe the relative importance of rotation, for the gravito-inertial mode oscillations show that for 40 of the stars the oscillations fall within the sub-inertial regime. We find that the core rotation frequencies of the stars decrease as a function of age, and show evidence of angular momentum transport occurring on the main-sequence. Finally, we derive the inclination angles of the stars, showing that they are generally consistent with the expectations from surface cancellation effects for the given oscillation modes.