This fluff-ball in space is E0102, the debris left over from a massive stellar explosion in the Small Magellanic Cloud. It's located 190,000 light years away in the constellation Tucana, and it's a favourite target of NASA's Chandra X-Ray Observer.
E0102 was one of the first objects Chandra looked at, mere months after the telescope first launched in 1999, and revisited during the 10-year anniversary in 2009. The image is a composite of X-ray and optical wavelengths. Breaking it into the component images, E0102 looks like this:
The highest-energy X-rays are in blue, fading into cyan at the intermediate energy levels, and down to orange-and-yellow for the coolest material at the center of the ring. This later analysis helped determine that the circle isn't a sphere of gas, but a cylinder. Some of the gas is moving towards us, and some away, red-shifting or blue-shifting the light by the Doppler effect.
For more on supernova structure, consider this exploration into where carefully-layered shells end up, or this downright weird supernova remnant that keeps getting bigger.