Sagittarius A (place)
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|The name given to the galactic center of the Milky Way. The center is mostly just a bright spot that appears in the Sagittarius constellation.|
Most astrophysicists believe that at its center there is a super-massive black hole that holds the galaxy together. It acts as an engine for the galaxy's evolution. But this isn't the entire story to the center of the galaxy.
The core isn't just a black hole with a bright ovoid around it as it is often portrayed in movies and popular science artistry. The center of our galaxy is a bar with arms streaming out at either end. This has a number of interesting effects on the orbits of stellar matter in the galaxy. Orbits where the bar points to the minor axis of the ellipse tend to be typical orbital ellipses. But orbits that have the bar pointing along the major axis of the ellipse tend to cusp at the points. As we go further out from the center the cusps turn into retrograde turns that have the orbits of stars turning in on themselves.
Because of this, when cold stellar matter such as nebulae pass through these orbits they become densely packed and lose momentum. Creating large clusters of big stars which fall toward the center of the galaxy to be eaten in the dark maw of Sag A.
This is cause for some concern because astrophysicists find that when this occurs those large clusters fall toward the center of the galaxy, feel even pressured by the closeness of the galactic black hole and explode all at once. Several million suns exploding, each turning a mass equal to that of Sol into energy, could cause a situation not unlike the one in Ringworld where a rapid core explosion will reach our part of the galaxy after 20,000 years.