At red-giant-phase end, stars with less than eight solar masses blow away outer layers {planetary nebula}|, at 10 km/s increasing to 1000 km/s, during 100,000 to 1,000,000 years. Gas rings fluoresce by ultraviolet light from remaining hotter star layers. Magnetic fields and companion stars shape planetary nebulae. Faster winds can push into slower winds to make gas rings {interacting stellar winds hypothesis}, but most nebula do not follow this model. Planetary nebula include Ant, Blue Snowball, Bug, Calabash, Cat's Eye, Dandelion Puff Ball, Egg, Hubble's Double Bubble, Red Rectangle, Ring, Southern Crab, Stingray, Starfish twins, and Twin Jet.
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Date Modified: 2022.0224