Planetary Nebula

In this image of the Stingray, the youngest known planetary nebula (a certain type of dying star), the bright central star is centered in the green ring of gas, with a companion star above it at 10 o'clock. The reddish lines represent bright gas heated by a "shock" caused when the central star's wind hits the gas bubble walls. These are the actual colors emitted by nitrogen (red), oxygen (green) and hydrogen (blue).

Photo by Matt Bobrowsky (Challenger Center for Space Science Education) and NASA.