galactic nucleus
Americannoun
-
The center of a galaxy, usually small, very bright, and containing a high density of stars and other objects.
-
◆ 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.
Other Word Forms
Noun Inflected Forms
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Some galaxies host an active galactic nucleus, an intensely bright region powered by a supermassive black hole that is actively pulling in surrounding matter.
From Science Daily • Jan. 19, 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
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
