Credit & Copyright: Anglo-Australian Telescope BoardExplanation: This strange structure is what can result when a normal star runs out of nuclear fuel in its core. At that time, the center condenses into a white dwarf while the outer atmospheric layers are expelled into space and appear as a planetary nebula. This particular planetary nebula, designated Shapley 1 after the famous astronomer Harlow Shapley, has a very apparent annular ring like structure. Although some of these nebula appear like planets on the sky (hence their name), they actually surround stars far outside our solar system.
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Publications with keywords: annular - planetary nebula - Shapley 1
Publications with words: annular - planetary nebula - Shapley 1