These were the first comets ever observed around a star other than the Sun. Now, an international research team headed by Alain Lecavelier des Etangs, CNRS researcher at the Institut d'Astrophysique de Paris (CNRS/Sorbonne Universite)1 , has discovered 30 such exocomets and determined the size of their nuclei2 , which vary between 3 and 14 kilometres in diameter. The scientists were also able to estimate the size distribution of the objects, i.e. the proportion of small comets to large ones.
This is the first time this distribution has been measured outside our Solar System, and it is strikingly similar to that of comets orbiting the Sun. It shows that, just like the comets of the Solar System, the exocomets of ss Pictoris were shaped by a series of collisions and breakups.
This work sheds new light on the origin and evolution of comets in planetary systems. Since a part of Earth's water probably originated in comets, scientists are seeking to understand their impact on the characteristics of planets.
Their findings, published in Scientific Reports on April 28, 2022, are the outcome of 156 days of observation of the ss Pictoris system using NASA's Transiting Exoplanet Survey Satellite (TESS). Other upcoming observations, in particular with the Hubble and James Webb space telescopes, should enable scientists to find out more in the future.
Research Report:Exocomets size distribution in the ss Pictoris planetary system.
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