Sagittarius A*

Sagittarius A, abbreviated Sgr A* is a bright and very compact astronomical radio source at the Galactic Center of the Milky Way. It is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, visually close to the Butterfly Cluster and Shaula. Sagittarius A* is the location of a supermassive black hole, similar to massive objects at the centers of most, if not all, spiral and elliptical galaxies. The observations of several stars orbiting Sagittarius A*, particularly star S2, have been used to determine the mass and upper limits on the radius of the object. Based on mass and increasingly precise radius limits, astronomers have concluded that Sagittarius A* is the Milky Way's central supermassive black hole. The current value of its mass is slightly in excess of 4 million solar masses.

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