Stellar Orbits around the Galactic Center

The UCLA Galactic Center Group has been tracking specific stars orbiting the proposed black hole at the center of our Galaxy for more than 20 years Keck Telescopes on Mauna Kea in Hawaii. These stellar orbits, and a simple application of Kepler’s Laws of motion, provide the best evidence yet for a supermassive black hole, which has a mass 4 million times the mass of the Sun. Particularly important is the short period star S0-2, which has been observed for more than a full orbital period (orbital period ~ 16 years) and puts limits on how massive and far away the supermassive black hole is to Earth.

This animation is created from actual 2.2 micron images taken of the center of the galaxy with the W. M. Keck Telescopes on Mauna Kea. The images are aligned at the position of Sgr A*, located in the center of the images. Sgr A* is the radio counterpart associated with the supermassive black hole at the center of the galaxy. The star S0-2 went through its closest approach to the black hole in 2018, and it and its measured orbit are labeled in the images.

Credit: Abhimat Gautam, Keck/UCLA Galactic Center Group