Tech & Science : Hypervelocity star ejected from centre of the Milky Way by supermassive black hole - - PressFrom - Australia
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Tech & Science Hypervelocity star ejected from centre of the Milky Way by supermassive black hole

16:30  12 november  2019
16:30  12 november  2019 Source:   abc.net.au

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/ Massive hypervelocity star esc NASA graphic showing the structure of the Milky Way . Since such an environment does not play host to a supermassive black hole , the team had to consider other extreme gravitational events that could have led to so massive a star being ejected from our galaxy.

The monster black hole at the Milky Way 's heart isn't the only celestial beast capable of booting stars out of the galaxy, a new study suggests. They found that the star , known as LAMOST-HVS1, got its speed kick in the Milky Way 's disk, not near the galactic core where the supermassive black hole

a star filled sky: An artist's impression of S5-HSV1 being ejected from the centre of our galaxy. (Supplied: James Josephides/Swinburne Astronomy Productions)© Provided by Australian Broadcasting Corporation An artist's impression of S5-HSV1 being ejected from the centre of our galaxy. (Supplied: James Josephides/Swinburne Astronomy Productions)

Forget dejected suitors being sent packing from The Bachelorette finale — a breakup of more cosmic proportions has just been discovered by scientists.

An international team of researchers have found a hypervelocity star that's been ejected from the centre of our galaxy by the resident supermassive black hole, Sagittarius A*.

The star — with the catchy moniker S5-HSV1 — is now travelling at over six million kilometres per hour (or 1700km/s).

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Gravitation from supermassive black holes in the center of many galaxies is thought to power active objects such as Seyfert galaxies and quasars. Inferred orbits of 6 stars around supermassive black hole candidate Sagittarius A* at the Milky Way galactic center [43].

That's because hypervelocity stars are thought to form when the supermassive black hole at the center of a galaxy devours one star in a binary system and ejects its twin, flinging it They found 130 stars on the edges of the Milky Way 's central black hole that had traveled a remarkable distance.

But the breakup happened five million years ago when it was half of a binary star system that strayed too close to the black hole.

The two stars were in a very tight orbit around each other, until the black hole cruelly wrenched them apart, capturing one and flinging S5-HSV1 at extremely high speed away from its companion and ejecting it from the centre of our galaxy.

Could we compare this to a romantic breakup, a la "you didn't receive a rose" Bachelorette-style?

"If the breakup was sufficient that one party got a lot of energy, I guess so," said astronomer and Emeritus Professor Gary Da Costa of the Australian National University, who is one of the co-authors of the paper published in the Monthly Notices of the Royal Astronomical Society.

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A fast-moving star may have been ejected from the Milky Way 's stellar disk by a cluster of young stars , according to researchers Because there's evidence that there is a supermassive hole at the center of the Milky Way , many astronomers believe that the majority of hypervelocity stars were

Proposed mechanisms for the ejection of intergalactic stars by supermassive black holes . The way these stars arise is still a mystery, but several They argue that these stars are hypervelocity (intergalactic) stars that were ejected from the Milky Way 's galactic center . These stars are red

The ejected star got enough energy from the interaction with the black hole that it will be leaving the Milky Way entirely in about 100 million years, and sailing off into the emptiness of intergalactic space never to return, Professor Da Costa said.

While we've discovered hypervelocity stars before now, we've never been able to unambiguously establish that one has been ejected by the black hole in the centre of the galaxy.

However S5-HSV1 is relatively close to Earth, a distance of only 29,000 light years away, which has allowed the researchers to trace back its orbit much more accurately.

"This one, I'll put my hand on my heart and say it comes from the centre of the galaxy," Professor Da Costa said.

We can use this "exquisite orbit of S5-HSV1" and the fact that it's coming from the centre of the Milky Way as a sort of ruler to measure the galaxy, said lead author of the paper Sergey Koposov of Carnegie Mellon University.

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Scientists have discovered that the fastest stars in the Milky Way —which travel at over two million miles per hour—originally came from other galaxies, having Astronomers had initially thought hypervelocity stars were spewed out of the center of the Milky Way by a supermassive black hole .

Their study, titled “Constraining Milky Way Mass with Hypervelocity Stars “, was recently published in the journal Astronomy and Astrophysics. These stars are thought to have been ejected from the center of our galaxy thanks to the interactions of binary stars with the supermassive black hole

"If we find more such stars, that should allow us to not only measure the galaxy better, but also measure the mass distribution in the galaxy," Dr Koposov said, including the mysterious dark matter.

While S5-HSV1 is the first hypervelocity star where we know it came from the galactic centre, it's not the only way such stars can be created, said astrophysicist Holger Baumgardt of the University of Queensland, who wasn't involved in the study.

When one of the stars in a binary system goes supernova, it can accelerate its companion star to a very high velocity.

"There's also a breakup involved … the star is set free, but it is a different process," Dr Baumgardt said.

Let's hope Angie Kent's suitors have better luck on The Bachelorette.

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