galactic nucleus

American  

[guh-lak-tik noo-klee-uhs] / gəˈlæk tɪk ˈnu kli əs /

noun

plural

galactic nuclei

1. Astronomy. the region at the center of a galaxy, such as the Milky Way; often contains one or more black holes.

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galactic nucleus Scientific  

1. The center of a galaxy, usually small, very bright, and containing a high density of stars and other objects.

2. ◆ An active galactic nucleus is a nucleus that emits more radiation than can be explained in terms of stars alone. Blazars and quasars are thought to be active galactic nuclei; the nuclei of Seyfert galaxies are also active, and are thought to contain an extremely massive black hole.

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Example Sentences

"It is the only galactic nucleus close enough to Earth for us to study in such fine detail," Barnes explains.

From Science Daily • Mar. 5, 2026

A quasar is an active galactic nucleus that is believed to be energized by a supermassive black hole.

From Salon • Jul. 4, 2023

The second theory is that they result from the activities of an active galactic nucleus, with radio jets spewing particles to create the ORC’s shape.

From Scientific American • Mar. 29, 2022

Active galactic nucleus activity in a GRB host galaxy is rarely observed, but is not unprecedented58 in nearby short GRBs.

From Nature • Oct. 15, 2017

How does the presence of an active galactic nucleus in a starburst galaxy affect the starburst process?

From Textbooks • Oct. 13, 2016