The central radio emission consists of three parts:
Sagittarius A East (blue): a hypernova remnant, which was
produced by a violent explosion only several tens of thousands of years
ago. The origin is unknown. Explanations range from a star disrupted
by a black hole to a chain reaction of ordinary supernovae or even a
gamma-ray burst.
Sagittarius A West or Minispiral (red): Gas and
dust streamers ionized by stars and spiraling around the very center,
possibly feeding the nucleus.
Sagittarius A *: A bright and very compact radio point at the intersection of
the arms of the Minispiral (difficult to see in this image)
(Figure: Radio image of Sagittarius A taken with the VLA by Y. Farhad-Zadeh & M. Morris)
