A monster black hole called Sagittarius A* lies at the heart of the Milky Way, about 26,000 light-years away from Earth. The footage, taken during a 26-year-long observation campaign, revealed that a small group of stars orbit this gravitational monster at high speed.
Using the VLTee, astronomers followed one of these stars, known as S2, as it passed close to the black hole during May 2018. Their observations showed that, at its closest approach, this star was less than 12 billion miles (20 billion kilometers) from the black hole and moving at a speed of 15.5 million mph (25 million km/h). [Images: Black Holes of the Universe]
Traveling at nearly 3 percent of the speed of light, S2 is an ideal test object for studying very strong gravitational fields and testing Einstein's theory of general relativity, ESO officials said in a statement.
"This is the second time that we have observed the close passage of S2 around the black hole in our galactic center. But this time, because of much improved instrumentation, we were able to observe the star with unprecedented resolution," Reinhard Genzel, lead researcher from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, said in the statement. "We have been preparing intensely for this event over several years, as we wanted to make the most of this unique opportunity to observe general relativistic effects."
The last time S2 made its closest approach to the black hole was 16 years ago, and the resolution of the measurements taken using other instruments wasn't good enough to pick up the effects of relativity, according to the statement.
The new infrared observations were made using the GRAVITY, SINFONI and NACO instruments on ESO's VLT. Astronomers compiled the recent observations to make a time-lapse video of their findings, as well as an animation that simulates the orbits of the tight group of stars circling the Milky Way's black hole and S2's close approach.
"ESO has worked with Reinhard Genzel and his team and collaborators in the ESO Member States for over a quarter of a century," Xavier Barcons, ESO's director general, said in the statement. "It was a huge challenge to develop the uniquely powerful instruments needed to make these very delicate measurements and to deploy them at the VLT in Paranal."