ON THE INFLUENCE OF CORPUSCULAR EVAPORATION ON THE CONCENTRATION DISTRIBUTION OF DUST GRAINS IN THE SOLAR-SYSTEM

It is shown that by taking into account corpuscular evaporation, i.e., the evaporation of grain molecules under the impact of solar wind par ticles, the power index of the classical law for the radial distributi on of dust grains n(r) is-proportional-to r-1.0 is changed. The power index becomes less than one by gamma almost-equal-to 0.03mu(s)Y(s), wh ere mu(s) is the mean molecular weight of the dust and Y(s) is the net evaporation factor calculated under the assumption that solar wind co nsists of protons and alpha-particles. For the silica dust of zodiacal light, gamma almost-equal-to 0.03 and for ice, gamma almost-equal-to 1. The constant flux of dust independent of the heliocentric distance was discovered in the experiments of Pioneer-10 and Pioneer-11 and can be explained by the effect of dust evaporation if the dust particles are covered by ice or by other materials with similar Y(s). The ''flat '' distribution of the dust concentration n(r) is-proportional-to r-0. 5, found by Natta et al. [1] near the star Lk Halpha198, can also be i nterpreted as being a result of corpuscular evaporation.