In 2011, astronomers were happy to discover a large cloud of gas rushing towards a supermassive black hole located in the center of the Milky Way. But at the beginning of this year, astronomers also discovered that not far from the absorption area of a black hole, which is located in a radio-emitting region called Sagittarius A, a cloud of gas flashed near the gravitational giant.
There were all signs that the cosmic cloud, called “G2”, was to be absorbed by the black hole, creating bright flashes, as the gas interacts with its accretion disk. Now, thanks to research by astronomers from the University of California at Los Angeles (UCLA), we have the answer to why there were no galactic fireworks.
In July, it looked a bit strange, since G2 did nothing to predict. At this time, frustrated astronomers studying data using the Very Large Telescope European telescope, located in the southern observatory in Chile, watched gas jets retract into a black hole, creating a subtle effect on the horizon of Strelets A. Instead of reaching a black hole in the form of bunches that were supposed to be drawn into the event horizon and generate powerful flashes, the material flows smoothly approached the black hole without causing any significant radiation. Recent observations have shown that G2 actually survived, continuing the journey in its orbit, and was left untouched after a close gravitational approach.
In a new article published in the Astrophysical Journal, Andrea Geza and members of UCLA seem to have found the answer to how this cloud did not become a snack for a black hole.
"G2 survived and continued its journey in orbit. Just a gas cloud would not do anything like that," said Geza. "G2 was essentially not affected by the black hole. There were no fireworks."
Assuming why G2 survived, Geza identified the mystical object as a star surrounded by a gas and dust envelope that are held together by the star’s gravity. But this is no ordinary star.
Our galaxy is filled with double star systems. In fact, the Sun is rare in the sense that it does not have a stellar partner locked in a gravitational embrace. The sun is a loner. However, most other stars are not so antisocial. Binary star systems are systems in which stars rotate around a common center of gravity. It is also possible to have three or more stars. But under extreme conditions surrounding a supermassive black hole, binary stars risk destabilizing when they pass too close to the horizon of a black hole's event, which leads to binary merging.
Using a powerful 10-meter optical / infrared telescope located at the Keck Observatory on Mauna Kea, Hawaii, the researchers were able to study G2 in more detail and believe that this star is experiencing a period of binary fusion. Keck's double telescopes use adaptive optics to adjust atmospheric turbulence, revealing to astronomers what violent dynamic processes occur in the center of our galaxy.
"This can happen much more often than we think. The stars in the center of the galaxy are more massive and mostly binary," said Geza. "It is possible that many of the stars that we are seeing may be the end product of a star merger."
