Deflection of the local interstellar dust flow by solar radiation pressure.

Abstract

Interstellar dust grains intercepted by the dust detectors on the Ulysses and Galileo spacecrafts at heliocentric distances from 2 to 4 AU show a deficit of grains with masses from 1×10^-17 to 3×10^-16kg relative to grains intercepted outside 4 AU. To divert grains out of the 2- to 4-AU region, the solar radiation pressure must be 1.4 to 1.8 times the force of solar gravity. These figures are consistent with the optical properties of spherical or elongated grains that consist of astronomical silicates or organic refractory material. Pure graphite grains with diameters of 0.2 to 0.4 μm experience a solar radiation pressure force as much as twice the force of solar gravity.