Inventory of the Galactic Center 

How do we study the center of the Galaxy? At the distance of the Galactic Center, 1" is about 0.05 parsecs.

What do we see?

In the infrared: A rising density of stars towards the center: ρ(r) ~  r-2 from 1 parsec to 0.1 parsec. Stars are very close together, so close interactions are common.

In the radio: Lots of non-thermal synchrotron radio emission showing ionized gas and magnetic fields:

(Picture spans ~ 60 pc across)

The brightest radio source is called Sagittarius A (Sgr A). Sgr A is not a single object, but a complex region at the center of the Galaxy:

VLA radio image (Farhad-Zadeh & Morris)