" Gaia is a powerful time machine for these types of studies, as it provides not only star positions but also their motions," explains Timo Prusti, Gaia project scientist at ESA. To look for its home, astronomers had to trace back in time not only the trajectory of the interstellar comet, but also of a selection of stars that might have crossed paths with this object in the past few million years.
The most likely explanation of the tiny variations recorded in its trajectory was that they are caused by gasses emanating from its surface, making it more akin to a comet.īut where in the Milky Way did this cosmic traveller come from?Ĭomets are leftovers of the formation of planetary systems, and it is possible that 'Oumuamua was ejected from its home star's realm while planets were still taking shape there. The discovery last year sparked a large observational campaign: originally identified as the first known interstellar asteroid, the small body was later revealed to be a comet, as further observations showed it was not slowing down as fast as it should have under gravity alone. Using data from ESA's Gaia stellar surveyor, astronomers have identified four stars that are possible places of origin of 'Oumuamua, an interstellar object spotted during a brief visit to our Solar System in 2017.Īrtist's impression of 'Oumuamua. Gaia finds candidates for interstellar 'Oumuamua's home
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