The Ring Planetary Nebula
The nebula's glow is caused by ultraviolet radiation from a white dwarf that ionizes its gases, the remnants of the central red giant star's jettisoned atmosphere
The Ring Planetary Nebula

The Ring Planetary Nebula
The nebula's glow is caused by ultraviolet radiation from a white dwarf that ionizes its gases, the remnants of the central red giant star's jettisoned atmosphere