![Variability at radio and submillimeter wavelengths](/typo3temp/assets/images/____csm_gclogo4_a53dac0bca_af1c6b712cf3eb96cabd60272b43f6b4.jpg)
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.
![Variability at radio and submillimeter wavelengths](/typo3temp/assets/images/____csm_gclogo4_a53dac0bca_af1c6b712cf3eb96cabd60272b43f6b4.jpg)
![Near-infrared and X-ray variability and polarisation](/typo3temp/assets/images/____csm_gclogo1_84c8c385d1_fe6eec015523e6df29e9e584a0567fc9.jpg)
Near-infrared and X-ray variability and polarisation
![Simulations of orbiting and in-falling matter](/typo3temp/assets/images/____csm_gclogo2o_018cee8e53_bc06defa3e36a5ee511ea504d1302ba4.jpg)
Simulations of orbiting and in-falling matter
The central few parsecs
![The nuclear star cluster](/typo3temp/assets/images/____csm_teaser_nuclear_star_cluster_d70b7b3264_db90b7d9d67408a523a567deb4e238bd.jpg)
The nuclear star cluster
![Warm dust and IR-excess sources](/typo3temp/assets/images/____csm_teaser_GC_2004_Kband_3513192d43_36acbaaff297bc0ca8e8a1d6c365ff02.jpg)