THE CIRCUMSOLAR DUST COMPLEX AND SOLAR MAGNETIC-FIELD

New model calculations for the dynamical evolution of dust particles a t several solar radii around the Sun are presented. We choose a fracta l aggregate consisting of either silicate or carbon as a representativ e of dielectric and absorbing fluffy particles. We take into account a large array of forces and effects acting on the dust particles-solar gravity, direct solar radiation pressure, Poynting-Robertson effect, s ublimation, and the Lorentz force, with a special emphasis given to th e latter. The Lorentz force was computed on the base of modeled grain' s charges and a model of the actual solar magnetic field from 1976 to 1996. We have investigated the dynamics of individual grains, obtained radial and vertical density profiles of different-sized particles, an d used the computed dust density distributions to calculate the expect ed F-corona brightness during the periods of weak and strong magnetic field. We have found that the solar magnetic field and its variations do not affect the dynamics and spatial distribution of carbon aggregat es, which are thought to produce the peak features of the near-infrare d F-corona brightness that were sometimes observed. On the other hand, the variations of the solar magnetic field may alter the latitudinal distribution of silicate aggregates. However, the effect is not strong enough to account for the observed temporal variations in the brightn ess. Thus we can rule out the correlation between the appearance or di sappearance of a peak feature and the solar activity cycle.