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A galaxy consisting of a rotating flattened disk with a central bulge made up mostly of old stars, from which extend two or more spiral arms made up mostly of younger stars and large amounts of interstellar gas and dust.
(Astronomy) a galaxy consisting of an ellipsoidal nucleus of old stars from opposite sides of which arms, containing younger stars, spiral outwards around the nucleus. In a barred spiral, the arms originate at the ends of a bar-shaped nucleus
a galaxy having a spiral structure. Compare elliptical galaxy.
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|Noun||1.||spiral galaxy - a galaxy having a spiral structure; arms containing younger stars spiral out from old stars at the center|
extragalactic nebula, galaxy - (astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust; "`extragalactic nebula' is a former name for `galaxy'"
Andromeda galaxy - a spiral galaxy in the constellation of Andromeda that is visible to the naked eye