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Using the data from ESA's Gaia star geometer, astronomers have identified four stars that are possible origins of Oumuamua, an interstellar object spotted during a brief visit to our solar system in 2017.
Last year, the discovery sparked a major campaign of observation: originally identified as the first known interstellar asteroid, the small body later revealed to be a comet, d & # 39; Other observations showing that it was not slowing as fast as gravity. The most likely explanation for the tiny variations recorded in its trajectory was that they were caused by gases emanating from its surface, which makes it closer to a comet.
But where did this cosmic traveler come into the Milky Way?
Comets are the remnants of the formation of planetary systems, and it is possible that "Oumuamua was ejected from the realm of its original star while the planets were still taking shape there. To search for his home, astronomers had to go back in time, not only the trajectory of the interstellar comet, but also a selection of stars that could have intersected with this object over the past millions of years .
"Gaia is a powerful time machine for these types of studies, as it not only provides prime positions but also their movements," says Timo Prusti, project scientist Gaia at ESA.
To this end, a team of astronomers led by Coryn Bailer-Jones at the Max Planck Institute for Astronomy in Heidelberg, Germany, plunged into data from the second version of Gaia, rendered public in April.
Gaia's data contains positions, distance indicators, and sky motions for more than a billion stars in our galaxy; more importantly, the dataset includes radial velocities – how fast they move toward or away from us – for a subset of seven million, allowing a complete reconstruction of their trajectories. The team examined these seven million stars, plus 220,000 additional stars for which radial velocities are available in astronomical literature.
As a result, Coryn and his colleagues identified four stars whose orbits were a few light years away from Oumuamua in the near past and whose relative speed was low enough to be compatible with ejection mechanisms. likely.
All four are dwarf stars – with masses similar or inferior to those of our Sun – and have had their "coming together" with the interstellar comet one to seven million years ago. However, none of them is known to harbor planets or to be part of a binary star system; a giant planet or a companion star would be the preferred mechanism for ejecting the small body.
Although future observations of these four stars may shed new light on their properties and potential to be the original system of Oumuamua, astronomers also look forward to future versions of Gaia's data. At least two projects are planned in the 2020s, which will include a much larger sample of radial velocities, allowing them to reconstruct and study the trajectories of many more stars.
"Although it is still too early to identify the original star of Oumuamua, this result illustrates Gaia's power to dive into the history of our galaxy's track. milk, "concludes Timo.
Research report: "Plausible house stars of the interstellar object" Oumuamua found in GaiaDR2 "
Related Links
Gaia at the ESA
Lands Beyond Beyond – Extra Solar Planets – News and Science
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Planet Vulcan Found
Gainesville FL (SPX) Sep 19, 2018
Among the TV series Star Trek, there are many characters and planets. Now, the Dharma Planet Survey, in a new study by astronomer Jian Ge of the University of Florida and the team including astronomers Matthew Muterspaugh and Gregory Henry of Tennessee State University, has shown that science fiction was maybe a little less. The Dharma project has discovered what could be the famous Vulcan planet of Star Trek.
"The new planet is a" super-Earth "orbiting around the HD star 26965, which … read more
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