On the magnetic fields of upper main sequence stars.

The distribution of magnetic flux density of a centrally condensed fossil field in steady exponential decay in the presence of steady large scale circulation in upper main sequence stars is discussed. In the models studied, the distribution of flux density inside the star is determined by the ratio of the circulation speed to the magnetic resistivity, and it is found that the ratio of the flux density at the surface to that at the inner boundary of the radiative envelope decreases sharply with increasing ratio of circulation speed to magnetic resistivity. The results imply that in rapidly rotating stars the surface flux density will be negligible; for medium rotation speeds, the maximum surface fields will be of the order of 1 to 10 Gauss, while in slow rotators, the surface flux densities may reach 1,000 or 10,000 Gauss.