M57 is a small-mid mass star that has recently died. During this process all fusion has ceased in the core of the star. Eventually the core of the star became exposed to space, and all the outer layers of the star have started to detach as an expanding gas cloud. Now the core of the star is very hot, and is radiating intense amounts of ultraviolet radiation into the expanding gas cloud, ionizing it. The result of this process causes the surrounding gas cloud to glow. This process will continue for 10,000 years, after which the gas cloud will become invisible, yet continue to expand, and all that will remain is the dead core of the star, which is now a white dwarf star. The stellar remnant resides at 2,600 light years distant and is found in the constellation Lyra.
Credit: Frosty Drew Astronomy Team member, Scott MacNeill