Abstract

Nano dust particles with sizes roughly 1 to 100 nm are intermediate between molecules and bulk materials. Their properties are often peculiar, being qualitatively different from those of bulk materials. Clusters of nano particles reveal strongly variable, size-dependent properties such as geometric and electronic structure, binding energy and dielectric function, which determine their interaction with surrounding gas and electromagnetic radiation. Interstellar nano dust dominates the far ultraviolet extinction as well as the near- and mid-infrared emission of the interstellar medium of the Milky Way and external galaxies. Nanometre-sized or smaller polycyclic aromatic hydrocarbons (PAHs), C60, and diamonds are observed in astrophysical regions through their characteristic vibrational spectral features. The presence of nano dust leads to the heating of the surrounding plasma and dusty plasma effects, like waves and instabilities. For many years nano dust has been detected with in-situ instruments from spacecraft in different regions of the solar system. In the Earth’s upper atmosphere it forms from the re-condensation of metallic compounds produced from ablating meteoroids. This re-condensed dust is implicated in the formation and chemistry of clouds, also in the atmospheres of e.g. Mars, Venus and Titan. Nano dust is also observed in comets. Volcanic plumes and impacts on planetary objects are sources of nano dust in the vicinity of planets and small solar system objects, e.g. near the Moon. This Focus Meeting brings together researchers from astronomy, space and astrophysics to combine knowledge of nano dust under a wide range of conditions and to progress our understanding.