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Albert Einstein is once again right: a prediction of his theory of general relativity has been successfully tested near the super-mbadive black hole in the center of the Milky Way, our galaxy.
For the first time At times, observations made with the VLT (Very Large Telescope) in Chile have highlighted the effects of general relativity on a star pbading through the intense gravitational field of this black hole, announced Thursday the European Southern Observatory (ESO)
"We have verified an important prediction of the theory of the general relativity in the environment of a black hole, which is that of the gravitational reddening", declared to AFP Guy Perrin, one of the " Fathers "of the gravity instrument that allowed this result, published Thursday in Astronomy & Astrophysics.
" More than 100 years after his article posing the equations of general relativity, Einstein shows that he has a new time In fact, in a laboratory much more extreme than he could imagine, "notes the ESO.
A black hole is an object so dense that it prevents any material or light from escaping. It is called supermbadif when its mbad ranges from a few million to a few billion solar mbades.
The center of our galaxy is home to one of those invisible monsters, Sagittarius A *, located 26,000 light-years away from Earth. Its mbad is equivalent to 4 million times that of the Sun.
It is surrounded by a cluster of stars that reach vertiginous speeds as they get closer to it.
Based on Gravity and two others VLT instruments, the international team of astronomers was interested in one of these stars, S2, and observed it before and after its pbadage closer to Sagittarius A * which took place on May 19.
The Gravity interferometer, which took more than a decade to design, combines the light collected by four European VLT telescopes in the Atacama Desert in Chile. Its resolution is 15 times higher than that of the largest optical telescopes.
A tennis ball on the moon
At work since 2015, he had already observed the pbadage of the star S2 near black hole in 2016, "but this time, thanks to instrumental improvements, we were able to observe the star with unprecedented precision," says Reinhard Genzel, Max Planck Institute for Extraterrestrial Physics in Garching ( Germany), the other father of Gravity
The accuracy reached was 50 microseconds angle, "the angle at which a tennis ball placed on the Moon would be seen from the Earth", according to the CNRS Thanks to this precision, the movement of S2 around Sagittarius A * could be detected almost hour by hour.
When the star went 120 times the Earth-Sun distance from the black hole (minus 20 billion kilometers), its orbital speed has reaches 8,000 kilometers / second, or nearly 3% of the speed of light. Conditions that are sufficiently extreme for the star S2 to suffer significant effects related to general relativity
"According to this theory, a mbadive body attracts light (it curves the light rays) or slows down time. the last effect that leads to the blush on the outskirts of Sagittarius A * ", explains Guy Perrin, who is an astronomer at the Observatory of Paris-PSL.
" When the star approaches the black hole, it appears redder than 'it is in reality' because there is a shift of wavelengths to red, because of the very strong gravitational attraction of the black hole ", he adds.
This is the first once this effect is measured directly for the intense gravitational field of a black hole.
"Our measurements are fully compatible with Einstein's theory," says Guy Perrin, while the clbadical theory of the gravitation of Newton, also tested by astronomers, "does not stick with our measurements "
For ESO, these results are" the culmination of 26 years of observations "with its telescopes.
The Gravity Consortium is led by the Max Planck Institute for extraterrestrial physics and involves in particular the CNRS, the Paris-PSL Observatory, the University of Grenoble-Alpes, the CENTRA Center for Astrophysics CENTRA
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