Spiral galaxy

A spiral galaxy is a galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the Nebulae” and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk of stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters.
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Noun
1. a galaxy having a spiral structure; arms containing younger stars spiral out from old stars at the center
(synonym) spiral nebula
(hypernym) galaxy, extragalactic nebula
(hyponym) Andromeda galaxy

Any galaxy in which a central bulge of older stars is surrounded by a flattened galactic disc containing a spiral pattern of young, hot stars. First photographs of spirals were taken by James Edward Keeler using the 36-inch reflector of the Lick Observatory in 1900. Their whirlpool structure was evident and from 1924 Edwin Hubble, using the 100-inch Mount Wilson, showed the enormous aggregation of billions of stars proving they were not nebulae but galaxies.   See spiral arms , Hubble tuning fork diagram .

Eng: spiral galaxy
Urdu: لولبی سحابیہ ۔ حَلزُونی کہکشاں