WHAT SUSTAINS THE ANGULAR MOMENTUM TRANSPORT IN THE ROTATING SUN ?
National Astronomical Observatory of Japan
Mercredi 08/04/2009, 11:00
Bat 709, salle 3 (salle Cassini, Rdc), CEA Saclay, Orme des Merisiers
One important unsolved issue in the solar physics is the evolution history of the solar internal rotation (e.g., Thompson et al. 2003). The physical mechanism for sustaining both rigid rotation in the radiative core and differential rotation in the convective envelope, which are observationallyfound by the helioseismology, are not fully understood in the existing theoretical framework.
The key physics for understanding the rotation law of the sun is the angular momentum transport in its interior. Tayler-Spruit Dynamo has been recently focused as the promising candidate for the dominant mechanism of the angular momentum transport (particularly in radiative core: Acheson 1978; Spruit 1999, 2002). This dynamo process is believed to be driven by Pitts&Tayler instability (kink-type instability) + differential rotation, and strongly
related to the amplification process of the solar internal magnetic field. There are some theoretical and numerical works for verifying this dynamo process under the realistic condition of the solar interior (c.f., Braithwaite 2006; Zahn, Brun & Mathis 2007). However, its presence is not settled yet.
In the talk, we focus on the linear evolutionary phase of the Tayler-Spruit Dynamo and analyse the stability of the differentially rotating system with the toroidal magnetic field. Finally, the condition for the Tayler-Spruit Dynamo being efficient is discussed under the physical condition of the solar interior.