Editing Dwarf galaxy (section)

== Formation ==
[[File:NGC 5264 HST.jpg|thumb|Dwarf galaxies like [[NGC 5264]] typically possess around a billion stars.<ref>{{cite web|title=An irregular island|url=http://www.spacetelescope.org/images/potw1634a/|website=www.spacetelescope.org|access-date=25 August 2016}}</ref>]]
One theory states that most galaxies, including dwarf galaxies, form in association with [[dark matter]],<ref>{{Cite journal |last=O'Callaghan |first=Jonathan |date=22 May 2024 |title=Astronomers find long-missing dwarf galaxies—too many of them |journal=Science |volume=384 |issue=6698 |page=836 |doi=10.1126/science.z6r95kt}}</ref> or from gas that contains metals. However, [[NASA]]'s [[Galaxy Evolution Explorer]] [[space probe]] identified new dwarf galaxies forming out of gases  with low [[metallicity]]. These galaxies were located in the [[Leo Ring]], a cloud of [[hydrogen]] and [[helium]] around two massive galaxies in the [[constellation]] [[Leo (constellation)|Leo]].<ref>
{{cite web
 |date=19 February 2009
 |title=New Recipe For Dwarf Galaxies: Start With Leftover Gas
 |url=https://www.sciencedaily.com/releases/2009/02/090218132145.htm
 |work=[[Science Daily]]
 |access-date=2015-07-29
}}</ref>

Because of their small size, dwarf galaxies have been observed being pulled toward and [[Interacting galaxy|ripped]] by neighbouring [[Spiral galaxy|spiral galaxies]], resulting in [[List of stellar streams|stellar streams]] and eventually [[galaxy merger]].<ref>
{{cite web
 |last=Jaggard |first=V.
 |date=9 September 2010
 |title=Pictures: New Proof Spiral Galaxies Eat, Digest Dwarfs
 |url=http://news.nationalgeographic.com/news/2010/09/photogalleries/100909-spiral-galaxies-eat-dwarf-space-science-pictures/
 |archive-url=https://web.archive.org/web/20100912161830/http://news.nationalgeographic.com/news/2010/09/photogalleries/100909-spiral-galaxies-eat-dwarf-space-science-pictures/
 |url-status=dead
 |archive-date=12 September 2010
 |publisher=[[National Geographic Society]]
 |access-date=2012-02-11
}}</ref>