Fomalhaut is a young star around which thousands of comets could be destroying each day. The Herschel space observatory of the European Space Agency (ESA) has studied the disk of dust that surrounds it and in which a cosmic massacre could be taking place.
The origin of the dust disk surrounding Fomalhaut was quite controversial, as images taken with the Hubble Space Telescope suggest properties that apparently contradict Herschel observations. The latter have made it possible to determine the thermal properties of the powder that makes up the disk, and indicate that it is made up of particles only a few micrometers in diameter. However, the Hubble images indicated a diameter ten times greater than suggested by the space observatory.
The team of researchers from the University of Leuven (Belgium), after analyzing the data obtained by Herschel, has proposed a hypothesis that would solve this paradox. Scientists suggest that the dust particles are actually fluffy aggregates, similar to those left behind by comets in our own Solar System.
This theory would explain the dispersion measured by Hubble and the thermal properties detected by Herschel, but it poses a new problem, and that is that if the particles are as small as they appear, the radiation emitted by the star Fomalhaut would drag them away from the disk quickly. If this is the case, the presence of a high number of particles around the star can only be explained if there is a continuous supply of these elements. This contribution must come from collisions between larger objects that also orbit Fomalhaut.
For the disk to remain stable, an enormous collision rate is required: the equivalent of two 10-kilometer-diameter comets have to be reduced to dust every day . “I was really surprised”, admits Bram Acke, one of the researchers, “it seemed to me an excessively high number”.
“These impressive images taken by Herschel provide us with the information we needed to understand the nature of the dust disk surrounding Fomalhaut,” said Göran Pilbratt, ESA Herschel Project scientist.
