A joint research team led by Professor Ren Bin from the Department of Astronomy at Xiamen University and Astronomer Paul Kalas from the University of California, Berkeley, has identified a second planetesimal collision in the Fomalhaut star system.
Their study, titled "A second planetesimal collision in the Fomalhaut system", was published in Science.
Fomalhaut, located approximately 25 light-years from the sun, first drew attention in 2008 when Kalas and his colleagues reported the discovery of a circumstellar object, Fomalhaut b, using 2004 and 2006 data from the Hubble Space Telescope's coronagraph. To determine whether Fomalhaut b persisted, Kalas' team conducted long-exposure Hubble observations after 2023, which revealed that Fomalhaut b was no longer detectable, but a new object was identified within the star's debris disk.
The presence of this new source, confirmed by Kalas and Professor Ren through four independent data-processing methods, indicates that it emerged after 2014, as earlier observations show no sign of it. Following consultation with the International Astronomical Union, the original object was renamed Fomalhaut cs1 (circumstellar source 1) and the new object Fomalhaut cs2 (circumstellar source 2).
The roughly 20-year interval between the detections of cs1 and cs2 provides the first direct observational evidence for the frequency of planetesimal collisions. This allows astronomers to estimate the sizes of collision progenitors and offers insights into planetary system formation, including Earth's early development.
