Editing Galaxy (section)

==== Seyfert galaxy ====
{{Main|Seyfert galaxy}}

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses; but unlike quasars, their host galaxies are clearly detectable.<ref name=Peterson1997>{{cite book |url=http://ned.ipac.caltech.edu/level5/Cambridge/frames.html |title=An Introduction to Active Galactic Nuclei |publisher=[[Cambridge University Press]] |first=Bradley M. |last=Peterson |year=1997 |isbn=978-0-521-47911-0}}</ref> Seen through a telescope, a Seyfert galaxy appears like an ordinary galaxy with a bright star superimposed atop the core. Seyfert galaxies are divided into two principal subtypes based on the frequencies observed in their spectra.<ref>{{Cite journal |last=Peterson |first=Bradley M. |date=2008-08-01 |title=The central black hole and relationships with the host galaxy |url=https://www.jmmc.fr/mirrors/www.vlti.org/events/assets/3/documents/peterson.pdf |journal=New Astronomy Reviews |series=Active Galactic Nuclei at the Highest Angular Resolution: Theory and Observations |volume=52 |issue=6 |pages=240–252 |bibcode=2008NewAR..52..240P |doi=10.1016/j.newar.2008.06.005 |s2cid=121460317 |issn=1387-6473}}</ref>