Evolution of the magnetic fields of main-sequence CP-stars. II

The average surface magnetic fields Bs of about 120 CP stars are reduced to the time of luminosity class V. These fields are constantly changing because of increases owing to simplification of the surface structure and simultaneous reductions as the radius evolves. The dependence of the corrected values of Bs on the age logt of the stars corresponds to an assumed field damping time of τ ~ 10⁹ −10¹⁰ years consistent with ohmic dissipation of the field. Over essentially the entire time magnetic stars are present on the Main sequence the total magnetic flux remains constant. The variation in the surface magnetic field owing to the evolutionary change in the radius most likely does not follow a cubic dependence, but is slower because the internal structures deviate from a “dipole” form. In terms of the distribution of the stars in plots of Bs as a function of age, the magnetic stars with different types of peculiarity differ greatly, presumably because of features of their formation from magnetized protostar clouds.