On the shape of core overshooting in stellar model computations, and asteroseismic tests

TL;DR

This paper investigates how g-mode pulsations in SPB stars can reveal the internal structure and extent of core overshooting layers, using Kepler data to improve stellar models.

Contribution

It demonstrates the use of mode trapping analysis of multiple g-modes in a Kepler SPB star to constrain the properties of core overshooting layers.

Findings

Mode trapping provides insights into the chemical stratification near the core boundary.

Analysis of 19 g-modes constrains the extent of the overshooting layer.

Results improve understanding of stellar evolution in massive stars.

Abstract

Slowly pulsating B stars (SPB) and $\gamma$ Dor stars pulsate in high-order gravity (g-) modes. The frequencies of g-modes are sensitive to the detailed structure and evolution history of stars having convective cores. Receding convective cores in OB-type stars leave behind a chemically inhomogenous $\nabla_\mu>0$ radiative zone. Once a g-mode has radial nodes near the boundaries of these layers, the mode gets trapped and its period deviates from asymptotic period spacing. Careful study of such trapped modes allows constraining the extent of such layers by fitting individual pulsation frequencies. We employ 19 consecuitve dipole g-modes of a very rich Kepler SPB pulsator, KIC 10526294, to demonstrate the power of mode trapping in B-stars in studying the thermal and chemical stratification in the overshooting layer.