What is the best evidence that Sagittarius A* is a black hole at the centre of the Milky Way galaxy?
A)Orbits of stars indicate a mass several million times that of the Sun within a very small volume.
B)Sagittarius A* is a powerful radio source.
C)No visible light from Sagittarius A* reaches the Earth.
D)Radio maps of the region around Sagittarius A* show complicated gas structures believed to be related to massive star formation.

Question

Quizplus · Accepted Answer

The orbits of stars in the very small volume around Sagittarius A* indicate a mass that is several million times that of the Sun, which is consistent with a black hole. This evidence strongly supports the presence of a black hole at the center of the Milky Way.  The other options, B, C, and D, are not necessarily unique to black holes and do not provide as strong evidence as the stellar orbits.

What Is the Best Evidence That Sagittarius A* Is a Black