THE INTERNAL SOLAR ROTATION IN ITS SPIN-DOWN HISTORY

A solar spin-down model is developed with the differential rotation in the convective envelope included. The model works with an internal ma gnetic held in the radiative core. The question is addressed whether t he present profiles in radius and latitude of the angular velocity der ived by helioseismology can be reproduced by following the spin-down o ver the solar lifetime. In spite of the high efficiency of the magneti c transport of the angular momentum, a positive answer is only possibl e if the viscosity is strongly amplified compared to its microscopic v alue. The model is basically insensitive to the amplitude of the inter nal poloidal field when the field strength becomes larger than about 1 0(-3) C. The magnetic held geometry is, however, an important factor. The helioseismology inversions are reproduced only with the poloidal f ield fully contained within the core. The dependence on the initial ro tation rate is also small. After similar to 1 Gyr, the stars with stro ngly different initial rotation rates settle on practically the same s pin-down track.