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ESO / Wikimedia
Sagittarius A *
Several researchers, including the Portuguese, discovered, for the first time, that one of the stars around a “ supermassive ” black hole in the center of the Milky Way is moving as predicted in Einstein’s Theory of General Relativity. , was released today.
The star is S2, which is part of a star cluster that exists around the black hole. Sagittarius A, located 26,000 light years from the Sun and which will have four million solar masses.
According to the European Southern Observatory, which operates the telescope in Chile with which the observations were made and which today released the results of the investigation in a statement, the orbit of this star rosette shaped and not an ellipse, as predicted by the classical theory of gravitation of the physicist Isaac Newton, from 1687.
“We discovered that the movement of a star around this black hole is not a closed orbit, that is, it is not a path where the end and the beginning are the same point, periodically described,” one of the Portuguese researchers involved told Lusa. . in the study, Paulo García, from the Center for Astrophysics and Gravitation (Centra) of the Instituto Superior Técnico, in Lisbon.
According to Paulo García, who also teaches at the Faculty of Engineering at the University of Porto, the S2 star’s orbit “is a rosette-like path”, an “open orbit, compatible with general relativity “ published by physicist Albert Einstein in 1915.
The results of the research, which involved making accurate measurements of the star’s orbit for approximately 30 years from observations made with the VLT telescope, were published in the journal Astronomy & Astrophysics. The work mobilized an international scientific team, namely from Portugal, France and Germany.
In addition to Paulo García, researchers from Centra António Amorim and Vítor Cardoso were also involved.
The Portuguese team participated in more than 330 measurements of the position of the star, which completes an orbit in the vicinity of Sagittarius after 16 years, but also in the “design and construction” of a component of a VLT telescopic instrument that allows “Take pictures of the environment near the black hole”António Amorim said, quoted in a Centra statement.
Paulo García explained to Lusa that the orbit of the star S2, one of the closest to the Sagittarius A black hole, “is associated with the physical mechanism called precession”, which, in this case, “It is linked to the deformation of space-time by the black hole”.
Einstein’s Theory of General Relativity describes the deformation of space-time caused by a black hole, an extremely dense and dark body in the center of galaxies from which nothing escapes, not even light.
“The effect of the warping of space-time is ‘pure’ and gives the star an extra pull at the closest approach point to the black hole, causing the orbit not to return to the starting point and causing the figure of the rosette, “said Paulo García.
According to the professor, the classical theory of gravitation, unlike Einstein’s modern one, “is unable to explain this phenomenon without invoking a third body (which would be a second black hole) or a cloud of massive dark matter that is unknown. “
However, for the researcher, “as spectacular as General Relativity is, most physicists believe that this is not the latest theory of gravity.”
“Test the theory [de Einstein] at the limit of the immense curvature of space-time which is the region near the horizon of the “supermassive” black hole [Sagitário A] in the center of the galaxy [Via Láctea] is a way to get to this new physics“, Held.
Therefore, the scientists intend to deepen their studies, measuring the S2 star’s orbit more precisely, searching for stars in orbits closer to Sagittarius A, and analyzing what triggers the explosions around the black hole.
