The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star then makes the material glow.
The burned-out star, called a white dwarf, appears as a white dot in the center.
Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. Hubble's Wide Field Planetary Camera 2 captured this image of planetary nebula NGC 2440 on Feb. 6, 2007.