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With the help of the most detailed map of the galaxy produced to date, astronomers have spotted more than a dozen high-speed stars that seem to float in our direction – and they do not represent potentially only a fraction of the total number of stars having similar positions.
Interestingly, the study aimed to find high-speed stars moving towards outside of the milky way; instead, the team ended up identifying more people traveling in the opposite direction.
Such itinerant stars over long distances could be crucial clues to what lies in the confines of space, and the history of neighboring galaxies.
When a star is not gravitationally bound to the rotation of a galaxy, astronomers call it an unlinked star.
The fastest of these types of stars – known as hypervelocity stars, traveling at a maximum speed of 700 km / s – are supposed to be ejected from the center of the Milky Way after s & rsquo; Be brushed with the supermassive black hole in the middle. Only a small number of them have already been discovered.
But while looking for potential new stars of hypervelocity, the Leiden University team in the Netherlands instead found a group of candidates for fast and unrelated cosmic bodies heading towards us – Hyper-fleeing stars.
According to the researchers, some of these stars are pulling from the galactic disk inland, but others could even be intergalactic visitors, coming from the Great Magellanic Cloud or beyond.
"Rather than flying out of the galactic center, most of the high-velocity stars we've seen seem to be heading towards him," said one of the team members, Tommaso Marchetti.
"These could be stars from another galaxy, zooming in the Milky Way."
The discovery was made possible thanks to the latest Gaia satellite data dump from the European Space Agency, including information of unprecedented accuracy on about 1.7 billion stars.
Gaia recorded 3D motion data as well as 2D plots for seven million of the brightest stars, and researchers were able to spot 20 new high-speed unrelated star candidates. Seven of them seem to travel from the galactic disk and 13 can not be traced at all until the Milky Way.
If these cosmic immigrants have actually arrived from outside our galaxy, they could tell us about the characteristics of other galaxies that we can not yet see, in the same way that falling meteorites provide us with a mine information about what lies in the depths.
The Milky Way contains more than 100 billion stars, most arranged in the familiar disc form that you may have seen on images. As in other galaxies, in the center of this dense disk is a supermassive black hole, which could explain some of these ultra-fast speeds.
"Stars can be accelerated at high speeds when they interact with a supermassive black hole," said one of the researchers, Elena Maria Rossi. "Thus, the presence of these stars could be a sign of such black holes in neighboring galaxies."
"But the stars may have also been part of a binary system, thrown to the Milky Way when their companion star exploded into supernova.Anyway, their study could tell us more about this type of process in the neighboring galaxies. "
We will need more data to be sure, both from future measurements of Gaia and observations made by telescopes here on Earth.
Another explanation advanced by the researchers is that they come from inside the Milky Way halo – that the remains of dwarf galaxy falls inside our own planet could explain the unusual way they draw in the space. More data on the composition and age of the stars will help us know.
"We are ultimately predicting complete 3D velocity measurements for up to 150 million stars," said one of the astronomers, Anthony Brown, chairman of the board of directors of the company. Gaia Data Processing and Analysis Consortium.
"This will help us find hundreds, even thousands, of hypervelocity stars, to understand their origin in more detail and to use them to study the galactic center's environment and the history of our galaxy."
The study was published in Monthly Notices from the Royal Astronomical Society.
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