Overshooting

TL;DR

This paper reviews the phenomenon of convective overshoot in stars, especially the Sun, highlighting its implications for stellar magnetic field generation and discussing recent numerical simulation results.

Contribution

It provides a comprehensive review of convective overshoot properties and introduces recent findings from advanced 2-D and 3-D simulations.

Findings

Overshoot depends subtly on thermal diffusion.

Recent DNS results reveal detailed overshoot dynamics.

Implications for solar dynamo models.

Abstract

Overshooting occurs in stars when convective elements penetrate into adjacent radiative zones. In the Sun, it leads to the so-called `tachocline' at the base of the outer convection zone and this region is becoming a key ingredient of the standard solar dynamo model as strong toroidal magnetic fields may be generated there. However this overshoot is not predicted by the mixing-length theory of convection where convective elements must stop at the border of a convectively unstable region. I will review the main properties of this convective overshoot in stellar interiors, with in particular its subtle dependence with the thermal diffusion, and will present the most recent results obtained from 2-D and 3-D direct numerical simulations (DNS) of penetrative convection.