Variations of the interstellar dust distribution in the heliosphere

Abstract

Cosmic dust is a significant ingredient in the interstellar environment of the Sun. Information about this solid phase of matter in interstellar space comes from the measurement of the extinction, and polarization of starlight, from emission spectra in the infrared, from the analysis of the isotopic composition of presolar grains in primitive meteorites, and from in situ measurements taken by dust detectors on board interplanetary spacecraft. During the more than 10 years of in situ data coverage, our solar system has traveled less than 0.3×10-4 pc, only a tiny fraction of the local interstellar cloud that surrounds the Sun. Therefore we do not expect any change in the flux of interstellar dust through the solar system. And, indeed, the observed variation of the local interstellar dust flux can fully be accounted for by the modulation of the interstellar dust stream and by its interaction with the heliospheric magnetic field. Modelling the current interaction between interstellar dust and the heliosphere provides an excellent laboratory for investigating the consequences of an encounter of the Sun with a much denser interstellar cloud that also should contain a higher concentration of dust grains. If the heliosphere is sufficiently compressed such that the planets are exposed to interstellar material, the small interstellar dust grains, which are currently excluded from the heliosphere, would create an increased amount of secondary dust particles when they collide with asteroids and comets. This would lead to a more dusty interplanetary environment with higher accretion rates of dust onto planetary atmospheres. © 2006 Springer. All Rights Reserved.