Fig12_6 Supermassive blackhole at center of Milky Way

Fig12_6 Supermassive blackhole at center of Milky Way

Fig. 12.6 . Stars slowly revolve about an unseen center, whose gravity controls their motions. This diagram portrays the orbits of infrared stars near the center of our Milky Way. The annual positions of seven stars have been determined over a fifteen-year period (colored dots), determining their curved trajectories and inferring the mass of the invisible center. These orbits indicate that a super-massive black hole is located at the center of the Milky Way; it has a mass of 4.1 million times the mass of the Sun. The display covers the central 1.0 x 1.0 seconds of arc, which at a distance of about 27,700 light-years corresponds to a width of about 0.13 light-years or 1,140 light-hours. (Courtesy of Andrea M. Ghez/UCLA galactic center group.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University