AIP astronomy picture of the month

(previous pictures of the month)

How long can a star rotate differentially?


(credit: Rainer Arlt, AIP)

The Sun and probably many stars rotate differentially - the angular velocity depends on the location. On the other hand, a small magnetic field can turn such a diffrential-rotation flow into turbulence (magnetorotational instability). The turbulent flow will -- sooner or later -- equalize the rotation profile. The present numerical investigations show that this process is very fast and is expected to destroy differential rotation on the rotational time-scale.

The spectral spherical MHD code of Rainer Hollerbach was adapted for this model. The film shown here is one of the first successful simulations. Right now, results from higher-resolution runs are becoming available.

 

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