Abstract
AbstractThe solar tachocline is an internal region of the Sun possessing strong radial and latitudinal shears straddling the base of the convective envelope. Based on helioseismic inversions, the tachocline is known to be thin (less than 5% of the solar radius). Since the first theory of the solar tachocline in 1992, this thinness has not ceased to puzzle solar physicists. In this review, we lay out the grounds of our understanding of this fascinating region of the solar interior. We detail the various physical mechanisms at stake in the solar tachocline, and put a particular focus on the mechanisms that have been proposed to explain its thinness. We also examine the full range of MHD processes including waves and instabilities that are likely to occur in the tachocline, as well as their possible connection with active region patterns observed at the surface. We reflect on the most recent findings for each of them, and highlight the physical understanding that is still missing and that would allow the research community to understand, in a generic sense, how the solar tachocline and stellar tachocline are formed, are sustained, and evolve on secular timescales.
Funder
DIM-ACAV+ ANAIS2 project
ERC Whole Sun Synergy grant
ERC STARS2 starting grant
ANR Toupies
ANR STORMGE-NESIS
INSU/PNST
Solar Orbiter
PLATO CNES
Grand Équipement National De Calcul Intensif
Royal Society
National Center for Atmospheric Research
National Aeronautics and Space Administration
Stanford’s COFFIES Phase II NASA-DRIVE Center
Publisher
Springer Science and Business Media LLC
Subject
Space and Planetary Science,Astronomy and Astrophysics