Let’s set the scene: We are transported to the center of the Milky Way. There lies Sagittarius A* (Sgr A*), a supermassive black hole 4.6 million times the mass of our own Sun. It is orbited by a fair number of young stars, the S-Cluster, including one called S50. Researchers have now observed for the first time how this star is interacting with the complex environment surrounding the black hole.
Researchers report in The Astrophysical Journal on the twenty years of observation of a peculiar feature around Sagittarius A* called X7. It is a bow shock – the collision between supersonic material and the interstellar plasma that surrounds the supermassive black hole. Researchers have worked out that X7 is the circumstellar envelope of the star S50.
The exciting thing is that the shape of X7 is changing over time. Having the data to actually observe this rare dynamic interaction is very important, as it is providing us with clues about what exactly is going in at the very center of our galaxy.
“For the first time, we have observed the interaction of a young star with the environment of the supermassive black hole Sgr A*. This interaction is unexpected and underlines the uniqueness of the cluster (or S-cluster),” lead author Dr Florian Peißker from the University of Cologne, told IFLScience.
“In the future, it can help to understand the star formation process and activity close to a supermassive black hole. In addition, we do find that the dusty shell of the young star seems to detach. Such a dynamic process on this scale was never observed in this region. This finding will help understand the evolution of young stellar objects in the Galactic center.”
The team believes that the change in shape is due to wind. This is not your regular wind that you might experience outside, but a stream of charged particles. The source of this could be the region closest to the supermassive black hole itself if energetic processes are taking place. Another option is that the wind comes from a group of mass-losing hot stars known as IRS 16, and that the black hole is just channeling that wind towards X7 due to its enormous mass.
“There are two possibilities: either the black hole is bending the space-time and influences the direction of the stellar winds from IRS16.” Dr Peißker explained to IFLScience. “Or, Sgr A* itself is creating the wind that causes the shape. Hence, we need more information to see how the X7/S50 system behaves.”
Sgr A* is located about 26,700 light-years from Earth, and over the last decades, we have begun to learn so much about the stars that orbit it and even test general relativity with it. Continuous observations with current instruments, the data from the Event Horizon Telescope, and upcoming observatories will help crack its mysteries even more.