Astronomers spot star dancing around black hole

PanARMENIAN.Net - For the first time, astronomers have observed a star orbiting the supermassive black hole at the center of our Milky Way galaxy. And the star is dancing to the predicted tune of Albert Einstein's general theory of relativity.

The study published Thursday in the journal Astronomy & Astrophysics.

Observations of the star were made by astronomers using the European Southern Observatory's Very Large Telescope in Chile's Atacama Desert. They saw that the star's orbit is shaped like a rosette.

Isaac Newton's theory of gravity suggested the orbit would look like an ellipse, but it doesn't. The rosette shape, however, holds up Einstein's theory of relativity.

"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," said Reinhard Genzel, in a statement. He is the director at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

Genzel also led a program that demonstrated this result. The initiative strove for increasing the precision of measurements over a 30-year period.

"This famous effect -- first seen in the orbit of the planet Mercury around the Sun -- was the first evidence in favour of general relativity," Genzel said. "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 centre of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the sun."

Sagittarius A* is the supermassive black hole at the center of our galaxy. It's 26,000 light-years from the sun. Our solar system exists on the edge of one of the Milky Way's massive spiral arms.

Dense stars can be found around the black hole. One of them, the star known as S2 in this observation, passes closest to the black hole within less than 20 billion kilometers.