Sagittarius A
This feature is about 25 light-years wide. It looks like a remnant from a supernova explosion that happened between 35,000 and 100,000 years ago. However, it would take 50 to 100 times more energy than a standard supernova explosion to create a structure of this size and energy. Sgr A East might be the remains of a star that exploded as it was gravitationally squashed approaching the central black hole.