Friday , August 19 2022

This star was thrown out of the Milky Way. She knows what she did.



[ad_1]

Every bit, the Milky Way throws out a star. An ejected star is usually evicted from a chaotic area in the center of the galaxy, where our super massive black hole (SMBH) lives. But at least one of them was thrown out of a relatively quiet galactic disc, the discovery that astronomers question this phenomenon of star eviction.

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


Monica Valluri, Research Professor, Department of Astronomy at the U-M College of Literature, Science and Art.

The star concerned is a rapid-moving star, or what is still called a hyperlocal star. Stars of hyperlocality are rare in our galaxy. The first was discovered in 2005, and so far researchers have discovered less than 30 of them. They travel with more than one million kilometers per hour, or 500 kilometers 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, look at the overall structure of the Milky Way.

Structure of the Milky Way. Image credit: ESA
Structure of the Milky Way. Image credit: ESA

The galactic protuberance is at the center, and deep in the heart of this bulge is the SMBH of our Sagittarius A * (Sagittarius A-Star). Of less importance in this research are stellar halo and globular clusters.

When a star is thrown out of the galaxy, it is usually one star from a binary pair. Scientists believe that the binary pair is too close to the SMBH and that its strong gravity, the hole affects one of the stars. The second star was thrown into the universe in a "gravity mole." The black holes must be super-massive because only they have a strong force of gravity to accelerate these escaped stars to such high speeds.

However, researchers at the University of Michigan have identified a hypervelocyte star that appears to have been discarded from a star disk rather than a galactic protuberance.

Monica Valluri and Kohei Hattori followed the star of hyperlocality
LAMOST-HVS1, a hypervelokation star that is closer to the Sun. They used one of Magellan's telescopes to measure the speed and position of the star. They then teamed up with other colleagues to combine their data with ESA Gaia mission data to track the path of the hypervelock back to its origin. They were surprised when the star's origin was not a protuberance, but a galactic disc.

"This discovery dramatically changes our view of the origin of fast stars," said Monica Valluri, professor of research at the Department of Astronomy at the U-M Library, Science and Art. "The fact that the paths of this massive moving star originate from the disc, and not in the Galactic Center, suggests that the very extreme environments needed to eject fast-moving stars can occur in places that are not around the supermassive black holes"

"We must consider other possibilities for the emergence of a star."

Kohei Hattori, postdoctoral researcher, University of Michigan.

"We thought this star came from the Galactic Center. But if you look at her path, it's clear that this is not related to the Galactic Center, "Hattori said. "We must consider other possibilities for the emergence of a star."

What would be the possibilities?

Authors are not sure at this point. One possibility is meeting another type. The escaped star may have encountered a whole group of other massive stars, and was thrown out by a complex interaction of gravity.

This type of encounter created the escaped stars in the past. But nothing that travels as fast as LAMOST-HVS1. Defending stars with stars were measured at 40-100 km / s (25-62 miles / second), but none came close to 500 km / second in which this star travels.

Star clusters like the trapezoid cluster in Orion are embedded in gas and dust in the galactic disk and are very difficult to see. It is possible that there is a cluster similar to this in the spiral arm Norm, the origin of the hypervelocative star LAMOST-HVS1. Image Credit: NASA / CKSC / Penn State / E.Feigelson & K.Getman et al. - http: //chandra.harvard.edu/photo/2007/orion/, Public Domain, https: //commons.vikimedia.org/v/index.php? curid = 38576885
Star clusters like the trapezoid cluster in Orion are embedded in gas and dust in the galactic disk and are very difficult to see. It is possible that there is a cluster similar to this in the spiral arm Norm, the origin of the hypervelocative star LAMOST-HVS1. Image Credit: NASA / CKSC / Penn State / E.Feigelson & K.Getman et al. – http: //chandra.harvard.edu/photo/2007/orion/, Public Domain, https: //commons.vikimedia.org/v/index.php? curid = 38576885

Another, more exotic feature is a black hole. There may also be a second, medium black hole in the galactic disk with enough gravity to throw a star into space. But that's a bit more than speculation.

If it's a star that has been ejected by LAMOST-HVS1, then it's still nobody. The hyper-velocity star came from Norm's spiral arm, an area that was not associated with any known massive stars of the stars. However, this area is well-shelled by dust. There could be a group with enough mass to throw a star.

If astronomers could find a massive cluster there, then it could have shown that all hypervelocational stars were thrown out of the clash with massive clusters, and SMBH has nothing to do with it. Or, carry me here, a massive stellar cluster could have a middle black hole at its center, strong enough to throw out the star.

For now, however, the origin of LAMOST-HVS1 remains uncertain.

Sources:

[ad_2]
Source link