active galactic nucleus

American

[ak-tiv-guh-lak-tik noo-klee-uhs, nyoo-klee-uhs] / ˈæk tɪv gəˈlæk tɪk ˈnu kli əs, ˈnyu kli əs /

noun

Astronomy. a large, extremely bright region at the center of a galaxy, its brightness thought to come from the huge amounts of radiant energy emitted by dust particles and gases falling into a massive black hole within the region.

active galactic nucleus Scientific

/ ăk′tĭv /

See under galactic nucleus

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.

De Graaff and her colleagues tested a wide range of galaxy and active galactic nucleus models against the object's spectrum, attempting to reproduce its features.

From Science Daily • Nov. 29, 2025

Furthermore, the study advanced quantitative understanding of gas flows around the active galactic nucleus.

From Science Daily • Nov. 6, 2023

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

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