The Galactic Center
The center of the Milky Way is the only galactic nucleus that can be observed at resolutions down to a few light hours or even minutes. The Galactic center offers thus unique insights into the nuclear stellar cluster and the immediate surroundings of a supermassive black hole. It also allow us to study the conditions for star formation in an extreme environment.
The central supermassive black hole, Sgr A*
At the beginning of the 1970s, right at the heart of the Milky Way, the nonthermal radio point-source Sagittarius A* (Sgr A*) was discovered. Shortly after, the possibility was considered that Sgr A* is the manifestation of a supermassive black hole. The gas and stellar velocities increase toward the position of Sgr A* indicating the presence of a large compact mass. The evidences for a dark central massive object in the Galactic Center have been steadily growing over the past two decades from observations of the dynamics of gas and stars in its vicinity . Currently, with a determined mass of 4.15 million solar masses, and a maximum charge of 300 millon coulombs, SgrA* is the very best candidate for a supermassive black hole.