The Age and Interior Rotation of Stars from Asteroseismology

TL;DR

This paper reviews how asteroseismology enables precise stellar age determination and provides insights into stellar interior rotation, revealing discrepancies with models and emphasizing the need for improved physical understanding.

Contribution

It summarizes recent advances in measuring stellar interior rotation profiles and highlights the challenges in modeling core-envelope coupling in stellar evolution.

Findings

Stellar ages can be determined with 10-20% precision using asteroseismology.

Core-to-envelope rotation rates in red giants are lower than predicted by models.

Young massive stars show low core-to-envelope rotation ratios.

Abstract

We provide a status report on the determination of stellar ages from asteroseismology for stars of various masses and evolutionary stages. The ability to deduce the ages of stars with a relative precision of typically 10 to 20% is a unique opportunity for stellar evolution and also of great value for both galactic and exoplanet studies. Further, a major uncalibrated ingredient that makes stellar evolution models uncertain, is the stellar interior rotation frequency $\Omega(r)$ and its evolution during stellar life. We summarize the recent achievements in the derivation of $\Omega(r)$ for different types stars, offering stringent observational constraints on theoretical models. Core-to-envelope rotation rates during the red giant stage are far lower than theoretical predictions, pointing towards the need to include new physical ingredients that allow strong and efficient coupling between the core and the envelope in the models of low-mass stars in the evolutionary phase prior to the core helium burning. Stars are subject to efficient mixing phenomena, even at low rotation rates. Young massive stars with seismically determined interior rotation frequency reveal low core-to-envelope rotation values.