Observations of the black hole in the center of the Galaxy and its closest neighbors, the stars, have helped scientists find the first hints of how the "Einstein" relativistic effects generated by it can change the orbits of the stars, according to an article published in the Astrophysical Journal.
“The Galactic Center is arguably the best laboratory for studying how stars move in a relativistic environment. I was delighted that we were able to apply the methods that we developed for studying the behavior of stars in virtual reality, to calculate the orbits of real stars orbiting at high speed around a black hole,”says Marzieh Parsa of the University of Cologne. Germany).
In the center of the Milky Way, and presumably all other galaxies in the universe, an unusually large black hole lives. In our case, it is about four million times heavier than the Sun and is located 26 thousand light years from Earth.
This black hole, which astronomers call Sgr A *, is surrounded by several dozen stars and several large clouds of gas that periodically approach and pass at a dangerous distance from it.
Such encounters and related relativistic effects, as predicted by Einstein's theory of relativity, will have a special effect on the orbit of a star, forcing it to move in a slightly different course after it "escapes" from the gravitational embrace of the black hole.
Parsa and her colleagues proved that this is actually the case by observing S2, the closest star to Sgr A *, for 20 years using the VLT telescope and a number of other ground and space observatories. During this time, the star managed to complete one complete revolution around the black hole, which allowed scientists to track how it moves around Sgr A * and compare the real data with the orbit calculated in accordance with Newtonian physics and Kepler's laws.
As it turned out, Einstein was right again - the star S2, a blue giant with a mass of 15 Suns, did change its orbit after approaching the black hole in 2003. Its orbit, as shown by the calculations of scientists, became less elongated and shifted to the side after the rendezvous with Sgr A * by approximately the same values that are predicted by the theory of relativity.
Whether this is really so, scientists plan to check again during the next approach of S2 to a black hole, which will happen very soon, in April or June 2018, depending on how much mass Sgr A * has. During this rendezvous, the strength of the relativistic effects will be at their maximum, and astronomers will measure it by observing how the black hole's gravity bends and stretches the star's light. This will help scientists calculate the exact mass of the black hole and find out many of its other secrets.
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