How Anti-Solar Rotation Laws can be produced
Leonid Kitchatinov (Inst. Solar-Terrestrial Physics, Irkutsk)
Guenther Ruediger (Astrophysical Institute Potsdam)
There are observational claims of detecting
anti-solar differential rotation laws with the stellar equator
rotating slower than the poles. We thus discuss the theoretical possibilities for
the origin of
equatorial deceleration. The standard hydrodynamical models
for global circulation in convection zones do always produce
solar-like differential rotation with equatorial acceleration. We argue that the antisolar
rotation can be produced though if the meridional flow is
amplified by any additional driver which is not included in the standard
formulation. Both magnetic polar spots or tidal forcing from a close
companion are possible amplifiers of the meridional circulation.
Theoretical estimations and first results of numerical simulations
for polar spots as the reason for the
equatorial deceleration are reported. Observers should be motivated to find the peculiarities of the stars with anti-solar rotation laws.