Star falls exist, but they are not what people are used to seeing in the night sky.

Many people have seen short-lived bright flashes in the night sky, commonly referred to as “star falls”. In fact, in most cases, this effect occurs when small rocks coming from space burn up in the atmosphere. However, there are real star falls in the universe, as astrophysicist Idan Ginsburg from Georgia State University in the USA told in his article.


Image source: NASA / ESA / G. Bacon (STScI), CC BY

Between 2005 and 2014, astrophysicists conducted a monumental observation program. It included the Sloan Digital Sky Survey (a large-scale study of multispectral images and redshift spectra of stars and galaxies using a 2.5-meter wide-angle telescope at the Apache Point Observatory in New Mexico), and work with telescopes by the Observatory. Whipple in Arizona. As a result, scientists have confirmed the existence of a new class of stars that move at incredible speeds, enough to escape the gravitational field of their home galaxies. At present, not everything is known to the science of these falling stars, or so-called hyper-velocity stars, which rush through outer space at speeds of thousands of kilometers per second.

The story of hyper-velocity stars began in 1988, when Jack Gilbert Hills, a scientist at the Los Alamos National Laboratory, wondered what would happen if a binary star system (consisting of two stars connected by gravity and rotating around a common center of mass) would fly past it. massive black hole in the middle of the Milky Way. Hill’s calculations showed that under the influence of a solid black hole, the system would collapse and one of the objects would be thrown into space at high speed. He also suggested that the impact of a black hole could give a star enough speed to escape its galaxy.

After Hills published his calculations, the astronomical community treated hyper-velocity stars as an exciting theory that was not supported by actual observations. The situation changed dramatically in 2005, when a group of researchers from the MMT Observatory in Arizona stumbled upon something unexpected. In fact, they could observe a star leaving the Milky Way galaxy at a speed of about 3.2 million km / h. Later, this object was named Outcast Star and became the first hyper-speed star.

The observations have helped astrophysicists learn more about hyper-velocity stars, but so far scientists do not have all the answers. For example, it is still not known exactly what happens to the other object in the binary system after a star is launched into space at high speed. Simulations have shown that in such cases the other star can remain relatively close to the black hole and orbit it, much like the earth orbits the sun. The simulations also showed that star collisions can sometimes occur, resulting in two objects merging into one massive star.

We also note that scientists have simulated the passage of a binary system, one of the elements of which is a planet, near a solid black hole. It turned out that in this case, the impact of a black hole can cause the planet to be ejected from the Milky Way at a speed that is approximately equal to 5% of the speed of light. At present, no hyper-velocity planets have been discovered yet, but that does not mean that they do not exist in the universe. It is possible that in the future astronomers will be able to observe such objects.

Since the discovery of the first hyper-velocity star, astronomers have been able to discover several more objects of this type. It was also found that not all stars in the universe that move at high speed can be considered as hyper-speed. This suggests that the circumstances under which stars receive strong acceleration may be different. Further studies of fallout will help researchers answer a number of important questions. For example, scientists can get a clue to nature and the distribution of dark matter in the universe. In addition, hyper-velocity stars may provide an answer to the question of the possibility of more than one black hole in the center of a galaxy.

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