irregular galaxy

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Related to Irregular Galaxies: Elliptical Galaxies, Spiral Galaxies
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irregular galaxy
Messier 82

irregular galaxy

n.
A galaxy that does not have the clearly defined shape and structure of an elliptical, lenticular, or spiral galaxy. Irregular galaxies typically contain large amounts of gas and dust, and their stellar populations are relatively young.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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Based on its amount of hydrogen-alpha emission, a proxy for the rate of star formation, 30 Doradus ranks in the top 1% of 21,000 H II regions in 57 spiral galaxies, and it tops the 614 H II regions found in the study's 13 irregular galaxies by a factor of 10!
And if we leave aside the so-called irregular galaxies, there are the lenticular galaxies, among which are the very unusual but not-so-rare spindle galaxies.
Further out are a number of similarly sized and slightly misshaped dwarf irregular galaxies, which are not gravitationally bound to the Milky Way and may be relative newcomers to our galactic neighborhood.
Intermediate galaxies, as magenta and purple dots, which correspond to irregular galaxies show this change of the slope at z < 2.
Not only are these conditions typical for dwarf irregular galaxies like the SMC, they also mimic ones that would have existed in the early universe.
Irregular galaxies have no particular shape: the Small Magellanic Cloud is an example.
Modern-day galaxies come in three types: spirals with swirling, starlit arms; football-shape ellipticals; and irregular galaxies, which have no organized structure.
Unlike symmetrical spiral and elliptical galaxies, or known irregular galaxies such as the Magellanic Clouds, many of these merging pairs display strange structures such as loops, narrow streamers, and rings.
Skillman, "Evidence for and against galactic wind dominated evolution of dwarf irregular galaxies," Revista Mexicana de Astronomia y Astrofisica Conference Series, vol.
As NASA points out, spiral, elliptical and irregular galaxies can all be seen in the photo of NGC 4866.
The mix of galaxy structures in the early universe is quite different, with a much greater diversity and larger fraction of irregular galaxies, Shapley said.
NGC 2403 has two unusual neighbors--the Magellanic-type dwarf irregular galaxies Holmberg II (6.4[degrees] to the northeast) and NGC 2366 (3.7[degrees] north).