Attempts to reproduce the rotation profile of the red giant KIC 7341231 observed by Kepler

TL;DR

This study attempts to reproduce the observed internal rotation profile of the red giant KIC 7341231 using stellar evolution models, revealing discrepancies that suggest additional angular momentum transport mechanisms are at play.

Contribution

It is the first to compare detailed stellar evolution models with asteroseismic rotation profiles for this star, highlighting gaps in current modeling of angular momentum transport.

Findings

Models with shellular rotation do not match observed rotation profiles.

A discrepancy indicates additional angular momentum extraction mechanisms.

Current models underestimate core angular momentum loss.

Abstract

Thanks to the asteroseimic study of the red giant star KIC 7341231 observed by Kepler, it has been possible to infer its radial differential rotation profile (Deheuvels et al. 2012). This opens new ways to constrain the physical mechanisms responsible of the angular momentum transport in stellar interiors by directly comparing this radial rotation profile with the ones computed using stellar evolution codes including dynamical processes. In this preliminary work, we computed different models of KIC 7341231 with the Geneva stellar evolution code that includes transport mechanisms due to a shellular rotation and the associated large-scale meridional circulation and shear-induced turbulence. Once the global parameters of the star had been established, we modified some of the model's input parameters in order to understand their effects on the predicted rotation profile of the modeled star. As a result, we find a discrepancy between the rotation profile deduced from asteroseismic measurements and the profiles predicted from models including shellular rotation and related meridional flows and turbulence. This indicates that a most powerful mechanism is in action to extract angular momentum from the core of this star.