Physical properties of the dust in the Solar System and its interrelation with small bodies

Abstract

Dust particles in the solar system are produced from the small bodies: asteroids, comets, meteoroids and Kuiper belt objects. A further source of dust is provided by the warm interstellar medium that the Sun is currently embedded in and that streams into the solar system. We review the physical properties of solar system dust and trace back its interrelation with the small solar system bodies. Comets contain relatively pristine material that they transport to the inner solar system. The alteration of dust in the vicinity of comets is complex and connected to the gas evolution, but a significant part of the organic dust material survives these alterations. The optical properties of cometary dust are best described with a mixture of silicate and carbon bearing materials. As far as the darkness of the cometary material is concerned, according to recent models, this is not a result of the porosity, but rather of the darkness of the carbon bearing component. This does not contradict the observation of silicate features in the thermal emission brightness of cometary dust, since porous mixtures of silicate and carbon bearing dust can produce the observed polarization and albedo characteristics, as well as the silicate features. The carbon-bearing component is most likely an organic refactory component. The relative contributions of different sources change within the solar system dust cloud and depend as well on the measurement technique considered. In particular, the dust from asteroids, which provides a large component of the dust near Earth orbit, is also preferably seen with most of the detection methods. The majority of dust inward from 1 AU is produced from cometary dust and meteoroids. Dust material evaporation induced by collisions inward from 1 AU produces a minor heavy ion component in the solar wind plasma known as inner source pick-up ions.