Untitled #351 / Sagittarius A

In the center of our galaxy from 1992 through 2003 astronomers were able to observe a star, orbiting compact radio source Sagittarius A. The star had an orbit with average radius 1.4x1014 m and period 15 years. From this information astronomers estimated the mass of Sagittarius A. v = 2π(1.4x1014)/(15x365x24x60x60) = 1.86x106 m/s a = (1.86x106)2/(1.4x1014) = 0.0247 m/s2 0.0247 = (6.673x10-11)M/(1.4x1014)2 M = 7.24x1036 kg 7.24x1036/(1.989x1030) = 3.6 million suns! Astronomers infer that Sag. A is a supermassive black hole (it cannot be seen)! OH LITTLE STAR