Galaxies are gravitationally bound, large-scale astrophysical systems composed primarily of dark matter, stars, stellar remnants, gas, and dust, often embedded in extended dark matter halos. They exhibit diverse morphologies, including spiral, elliptical, and irregular types, and span mass scales from roughly 10⁷ to over 10¹² solar masses. Their internal dynamics are governed by gravity and angular momentum distribution, with baryonic components organized into disks, bulges, and halos, and frequently hosting central supermassive black holes. Galaxies are fundamental units of cosmic structure formation, participating in hierarchical assembly, mergers, and interactions within larger environments such as groups, clusters, and filaments of the cosmic web.
NASA's James Webb Space Telescope captured two nearby dwarf galaxies interacting with each other in this image released on Dec. 2, 2025.
Astronomy
Dec 22, 2025
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Black holes are notorious for gobbling up everything that comes their way, but astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that even supermassive black holes can be picky eaters, ...
Astronomy
Dec 22, 2025
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How galaxies assemble their stars and grow over billions of years remains one of the central questions in astronomy. Recent results from the James Webb Space Telescope (JWST), including reports of surprisingly massive and ...
Astronomy
Dec 18, 2025
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Our universe is filled with galaxies, in all directions as far as our instruments can see. Some researchers estimate that there are as many as 2 trillion galaxies in the observable universe. At first glance, these galaxies ...
Astronomy
Dec 15, 2025
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What could force a supermassive black hole (SMBH) out of its host galaxy? They can have hundreds of millions, even billions of solar masses. What's powerful enough to dislodge one of these behemoths?
Astronomy
Dec 15, 2025
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The Large and Small Magellanic Clouds are irregular dwarf galaxies and satellites of the Milky Way. The LMC is about 163,000 light-years away and the SMC is about 206,000 light-years away, and their close proximity makes ...
Astronomy
Dec 14, 2025
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Most smaller galaxies may not have supermassive black holes in their centers, according to a recent study using NASA's Chandra X-ray Observatory. This contrasts with the common idea that nearly every galaxy has one of these ...
Astronomy
Dec 11, 2025
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By analyzing the data from the PHANGS-MUSE survey, an international team of astronomers has inspected a nuclear star cluster of the nearby large spiral galaxy Messier 74. The new study presented Dec. 3 on the arXiv pre-print ...
Galaxy clusters are the most massive objects in the universe held together by gravity, containing up to several thousand individual galaxies and huge reservoirs of superheated, X-ray-emitting gas. The mass of this hot gas ...
Astronomy
Dec 10, 2025
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Clues about how galaxies like our Milky Way form and evolve and why their stars show surprising chemical patterns have been revealed by a new study.
Astronomy
Dec 8, 2025
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