Rotational mixing in low-mass stars : I Effect of the mu-gradients in main sequence and subgiant Pop I stars

TL;DR

This study models the impact of mu-gradients on rotational mixing in low-mass Population I stars, highlighting their significance in shaping internal rotation profiles and chemical mixing during main sequence and subgiant phases.

Contribution

It introduces a comprehensive model including mu-gradients in the analysis of rotational mixing, emphasizing their role in stellar evolution of low-mass stars.

Findings

Mu-gradients significantly influence rotation profiles.

Rotation-induced mixing explains Li dip features.

Mu-gradients affect later evolutionary stages.

Abstract

We present a first set of results concerning stellar evolution of rotating low-mass stars. Our models include fully consistent transport of angular momentum and chemicals due to the combined action of rotation induced mixing (according to Maeder & Zahn 1998) and element segregation. The analysis of the effects of local variations of molecular weight due to the meridional circulation on the transport of angular momentum and chemicals are under the scope of this study. We apply this mechanism to low mass main sequence and subgiant stars of population I. We show that the so-called $\mu$-currents are of major importance in setting the shape of the rotation profile, specially near the core. Furthermore, as shown by Talon & Charbonnel (1998) and Charbonnel & Talon (1999) using models without $\mu$-currents, we confirm that rotation-induced mixing in stars braked via magnetic torquing can explain the blue side of the Li dip, as well as the low Li abundances observed in subgiants even when $\mu$-currents are taken into account. We emphasize that $\mu$ variations are not to be neglected when treating rotation-induced mixing, and that they could be of great importance for latter evolutionary stages.