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Astron. Astrophys. 328, 253-260

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Do T Tauri stars rotate differentially?

M. Küker1 and G. Rüdiger1

Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany

Received 14 April 1997 / Accepted 29 July 1997


We compute the rotation profile of a T Tauri star from the balance between the different components of the Reynolds stress and the meridional circulation. We first use a simple model to study the influence of the meridional flow on the differential rotation and vice versa. A more realistic model is then presented, which includes the stratification of the turbulence derived from a stellar model. We find that for a strictly spherical star without any latitudinal gradients in temperature, density and pressure the rotation is very close to the rigid-body state. We conclude that the stellar magnetic field must be generated by an $\alpha^2$- rather than an $\alpha \Omega$-dynamo. It must thus have non-axisymmetric geometry and will not show cyclic behaviour.

Key words: hydrodynamics - turbulence - stars: magnetic fields - stars: pre-main sequence - stars: rotation

Send offprint requests to: M. Küker

© European Southern Observatory (ESO) 1997

Online publication: October 30, 1997
Last change: March 24, 1998