| Advertisement |
April 16 (UPI) -- The orbital pattern of star dancing around the supermassive black hole at the center of the Milky Way looks like a rosette -- the pattern predicted by Einstein's general theory of relativity. The discovery, made possible by three decades of observations by the European Southern Observatory's Very Large Telescope, was announced Thursday in the journal Astronomy and Astrophysics.
Advertisement
Newton's theory of gravity predicted the orbit of a star around a supermassive black hole would take the shape of an ellipse. The latest research suggests Newton was wrong and Einstein was right.
"Einstein's general relativity predicts that bound orbits of one object around another are not closed, as in Newtonian gravity, but precess forwards in the plane of motion," study co-author Reinhard Genzel, director at the Max Planck Institute for Extraterrestrial Physics in Germany, said in a news release. "This famous effect -- first seen in the orbit of the planet Mercury around the Sun -- was the first evidence in favor of general relativity."
"One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the center of the Milky Way," Genzel said. "This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the sun."
The close proximity of Sagittarius A* and its neighbors to the center of the Milky Way has offered scientists a unique opportunity to study the effects of extreme gravity on stellar behavior. One of the stars within the cluster surrounding Sagittarius A* follows an extremely elliptical orbit, swinging within 12.4 billion miles of the supermassive black hole upon its closest approach. During its approach, the star, S2, reaches speeds approximating 3 percent of the speed of light. The star completes an orbit of the black hole every 16 years.
"After following the star in its orbit for over two and a half decades, our exquisite measurements robustly detect S2's Schwarzschild precession in its path around Sagittarius A*," said study co-author Stefan Gillessen, an astrophysicist at MPE.
Unlike the elliptical orbits of most stars and planets, the orbital path of S2 and the positioning of its closest approach shift with each new lap around around the supermassive black hole. As such, its repeated orbits create a rosette pattern -- a phenomenon called the Schwarzschild precession.
Though predicted by Einstein's general relativity, such an orbital precession had never been measured before. The ability to precisely track S2's unique orbital path was made possible by the VLT Interferometer, an instrument that combines the light of all four 8-meter VLT telescopes.
Scientists suggest the three decades worth of observations will help them begin to understand the formation and evolution of supermassive black holes. And in the near future, astronomers expect to have even more precise data to work with.
"If we are lucky, we might capture stars close enough that they actually feel the rotation, the spin, of the black hole," said researcher Andreas Eckart, an astronomer at Cologne University in Germany. "That would be again a completely different level of testing relativity,"
