Origin of the grains

This study should also serve to better understand the planetary systems observed around stars other than the sun. Astronomers put forward theories about the very origins of these hot dust grains that are behind this luminous diffusion. For stars that are similar to our Sun, the presence of exo-zodiacal hot dust seems to be linked to the presence of cold dust, notably detected by the ESA Herschel satellite and situated in external belts similar to the Kuiper belt, a residue from the formation of the solar system. According to Olivier Absil, “this correlation suggests the existence of an essential condition for the hot dust, the fact that it is intimately linked to the cold dust which would therefore constitute enormous external reservoirs of dust and small bodies situated within the confines of these stellar systems that maintain the phenomenon”. The supply of dust emanates from a sustained injection of comets into the internal system from the external belt. As this scenario requires important disturbances of the external belt to precipitate the small bodies into the internal system, the researchers have possibly uncovered indirect proof of the existence of planets around these nearby stars. “If there is exo-zodiacal light”, continues Olivier Absil, “there is hot dust, but the reservoir of this hot dust must be supplied by cold dust, a mechanism which is probably due to the gravitational influence of planets in their environment. The presence of this light is therefore a clue to the presence of exoplanets”.