Antisolar differential rotation of slowly rotating cool stars
Abstract
Rotating stellar convection transports angular momentum towards the equator, generating the characteristic equatorial acceleration of the solar rotation while the radial flux of angular momentum is always inwards. New numerical box simulations for the meridional crosscorrelation ⟨u_{θ}u_{ϕ}⟩, however, reveal the angular momentum transport towards the poles for slow rotation and towards the equator for fast rotation. The explanation is that for slow rotation a negative radial gradient of the angular velocity always appears, which in combination with a sofar neglected rotationinduced offdiagonal eddy viscosity term ν_{⊥} provides "antisolar rotation" laws with a decelerated equator. Similarly, the simulations provided positive values for the rotationinduced correlation ⟨u_{r}u_{θ}⟩, which is relevant for the resulting latitudinal temperature profiles (cool or warm poles) for slow rotation and negative values for fast rotation. Observations of the differential rotation of slowly rotating stars will therefore lead to a better understanding of the actual stressstrain relation, the heat transport, and the underlying model of the rotating convection.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 October 2019
 DOI:
 10.1051/00046361/201935280
 arXiv:
 arXiv:1902.04172
 Bibcode:
 2019A&A...630A.109R
 Keywords:

 stars: solartype;
 convection;
 stars: rotation;
 turbulence;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 9 pages, 8 figures