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

1. 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 /

1. See under galactic nucleus

---

Example Sentences

The active galactic nucleus heats the surrounding gas envelope in a way that resembles how fusion heats the outer layers of a star, producing a similar outward appearance.

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