Study of the effects of magnetic braking on the lithium abundances of the Sun and solar-type stars

TL;DR

This study investigates how magnetic braking and rotation influence lithium depletion in Sun-like stars, revealing that magnetic fields can reduce lithium destruction and affect stellar evolution models.

Contribution

It provides new insights into the combined effects of rotational mixing and magnetic braking on lithium abundances during stellar evolution.

Findings

Rotational effects increase lithium depletion in models.

Magnetic braking reduces lithium depletion, especially with stronger magnetic fields.

Magnetic fields influence the size of the convective zone and stellar temperature.

Abstract

The study of lithium (Li) surface abundance in the Sun and young stellar globular clusters which are seemingly anomalous in present-day scenarios, as well as the influence of rotation and magnetic braking (MB) on its depletion during pre-main sequence (PMS) and main sequence (MS). In this work, the effects of rotational mixing and of the rotational hydrostatic effects on Li abundances are studied by simulating several grids of PMS and MS rotating and non-rotating models. Those effects are combined with the additional impact of the MB (with magnetic field intensities ranging between 3.0 and 5.0 G). The data obtained from simulations are confronted by comparing different stellar parameters. The results show that the surface Li abundance for the Sun like models at the end of the PMS and throughout the MS decreases when rotational effects are included, i.e. the Li depletion rate for rotating models is higher than for non-rotating ones. This effect is attenuated when the MB produced by a magnetic field is present. This physical phenomena impacts also the star effective temperature ($T_{\mathrm{eff}}$) and its location in the HR diagram. The impact of MB in Li depletion is sensitive to the magnetic field intensity: the higher it is, the lower the Li destruction. A direct link between the magnetic fields and the convective zone (CZ) size is observed: stronger magnetic fields produce shallower CZ's. This result suggests that MB effect must be taken into consideration during PMS if we aim to reproduce Li abundances in young clusters.