Home / Science / This star has been kicked out of the Milky Way. It knows what it did.

This star has been kicked out of the Milky Way. It knows what it did.



Each Milky Way removes a star. The evicted star is usually ejected from the chaotic area of ​​the center of the galaxy, where our Super Massive Black Hole (SMBH) lives. But at least one of them was expelled from the relatively quiet galactic disc, a discovery that has astronomers reconsider this entire star ejection phenomenon.

"This discovery dramatically changes our view of the origin of fast stars".


Monica Valluri, research professor, Department of Astronomy at U-M's literature, science and art academy.

The current star is a fast-paced star, or it is also called a hyper-city star. Hypervelocity stars are quite rare in our galaxy. The first was discovered in 2005, and so far, researchers have discovered fewer than 30 of them. They travel more than 1

million miles per hour, or 500 km per second, twice as fast as other stars, and it takes a huge amount of energy to drive them to that speed.

To understand what is happening, take a look at the plant's overall structure.

  The structure of the milk. Image Credit: ESA
The structure of the milk. Image Credit: ESA

The galactic bolt is in the middle, and deep in the heart of this bolt is our galaxy's SMBH, Sagittarius A * (Case A-star.) Spread around it is the galactic disk up of the galaxy's spiral arms. Of minor importance in this study are the star halo and the global groups.

When a star is kicked out of the galaxy, it is usually a star from a binary pair. Scientists believe that as a binary couple gets too close to SMBH and its overwhelming gravity, the hole captures one of the stars. The other star is shot into space in a "gravitational stroke." The black hole has to be a super massive, because only they have powerful accuracy to accelerate these passing stars to such high speeds.

But researchers from the University of Michigan have identified a hypervelocity star that appears to have been ejected from the star disk rather than the galactic bolt.

Monica Valluri and Kohei Hattori tracked a hypervelocity star named
LAMOST-HVS1, a hypervelocity star that is closer to the sun someone else. They used one of Magellan's telescopes to measure the star's speed and position. Then they went with other colleagues and combined their data with data from ESA's Gaia mission to trace the path of hyper-velocity back to its origin. They were surprised when the star's origin was not the bolt, but the galactic disc.

"This discovery dramatically changes our perception of the origin of the fast stars," says Monica Valluri, a research professor at the Department of Astronomy at U-M's College of Literature, Science and the Arts. "The fact that the track of this massive fast star originates in the disc, rather that at the Galactic Center indicates that the extreme extreme surroundings needed to eject fast stars can occur elsewhere than around supermassive black holes." [19659013] "We must consider other opportunities for the star's origin."

Kohei Hattori, Postdoctoral Researcher, University of Michigan.

"We thought this star came from the Galactic Center. But if you look at its path, it's obvious that it's not related to the galactic center," Hattori said. "We need to consider other opportunities for the star's origin." 19659005] What Would These Opportunities Be?

The authors are not safe at this point. An opportunity is a meeting of various kinds. The runaway star may have had a meeting with a whole cluster of other massive stars and be expelled by a complicated interplay of gravity.

This type of meeting has created lost stars in the past, but nothing that travels as fast as LAMOST-HVS1. Star-Cluster Runaways has been clocked at 40-100 km / s (25-62 miles / second) , but no one has come close to the 500 km / sec that this star goes on.

  Star clusters such as the Trapezium divide in Orion are embedded in gas and dust in galactic disk and are very difficult to see. the in the Norma spiral alarm, the origin of the hypervelocity star LAMOST-HVS1. Image Credit: By NASA / CXC / Penn State / E.Feigelson & K.Getman et al. - http://chandra.harvard.edu/photo/2007/orion/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=38576885
Star gaps like the Trapezium Gap in Orion is embedded in gas and dust in galactic disc and is very difficult to see. There may be a cluster similar to that in Norma spiral alarm, the origin of the hypervelocity star LAMOST-HVS1. Image Credit: By NASA / CXC / Penn State / E.Feigelson & K.Getman et al. – http://chandra.harvard.edu/photo/2007/orion/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=38576885

Another, more exotic opportunity is one black hole. There may be other intermediate black holes in the galactic disc with sufficient gravity to fly the star into space. But it's a little more than a guess.

If it is a star cluster that knocked out LAMOST-HVS1, then no one has seen it yet. The Hypervel star came from the Norma spiral arm, an area that is not associated with any known massive star clusters. But that area is well darkened by dust. There may be a cluster there with enough mass to eject the star.

If astronomers could find a massive cluster there, then it can show that all hypervelocity stars were ejected from massive cluster meetings, and SMBH has nothing to do with it. Or carry with me here, the massive star club can have an intermediate black hole in the middle, powerful enough to eject the star.

At present, the origin of LAMOST-HVS1 is still uncertain.

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