Editing Dwarf galaxy (section)

==Local dwarf galaxies==
[[File:An explosive phoenix - Phoenix Dwarf.jpg|thumb|The [[Phoenix Dwarf|Phoenix Dwarf Galaxy]] is a dwarf irregular galaxy, featuring younger stars in its inner regions and older ones at its outskirts.<ref>
{{cite web
 |date=24 October 2011
 |title=Hubble Sizes up a Dwarf Galaxy
 |url=http://spacetelescope.org/images/potw1143a/
 |publisher=[[European Space Agency|ESA]]/[[Hubble Space Telescope|Hubble]]
 |access-date=2011-10-25
}}</ref>]]

There are many dwarf galaxies in the [[Local Group]]; these small galaxies frequently orbit larger galaxies, such as the [[Milky Way]], the [[Andromeda Galaxy]] and the [[Triangulum Galaxy]]. A 2007 paper<ref>
{{cite journal
 |last1=Metz |first1=M.
 |last2=Kroupa |first2=P.
 |date=2007
 |title=Dwarf-spheroidal satellites: are they of tidal origin?
 |journal=[[Monthly Notices of the Royal Astronomical Society]]
 |volume=376 |issue=1 |pages=387–392
 |arxiv=astro-ph/0701289
 |bibcode=2007MNRAS.376..387M
 |doi=10.1111/j.1365-2966.2007.11438.x
|doi-access=free
 |s2cid=16426005
 }}</ref> has suggested that many dwarf galaxies were created by [[galactic tide]]s during the early evolutions of the Milky Way and Andromeda. Tidal dwarf galaxies are produced when galaxies collide and their gravitational [[Interacting galaxy|masses interact]]. Streams of galactic material are pulled away from the parent galaxies and the halos of [[dark matter]] that surround them.<ref>
{{cite web
 |date=18 February 2009
 |title=New Recipe for Dwarf Galaxies: Start with Leftover Gas
 |url=http://newswise.com/articles/view/549307/
 |work=Newswise.com
 |access-date=2009-02-20
}}</ref> A 2018 study suggests that some local dwarf galaxies formed extremely early, during the [[Dark Ages (cosmology)|Dark Ages]] within the first billion years after the [[Big Bang]].<ref>{{cite news |last1=Rincon |first1=Paul |title=Earliest galaxies found 'on our cosmic doorstep' |url=https://www.bbc.com/news/science-environment-45198764 |access-date=17 August 2018 |work=BBC News |date=16 August 2018}}</ref>

More than 20 known dwarf galaxies orbit the Milky Way, and recent observations<ref>
{{cite journal
 |last1=Noyola |first1=E.
 |last2=Gebhardt |first2=K.
 |last3=Bergmann |first3=M.
 |year=2008
 |title=Gemini and Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in ω Centauri
 |journal=[[The Astrophysical Journal]]
 |volume=676 |issue=2 |pages=1008–1015
 |arxiv=0801.2782
 |bibcode=2008ApJ...676.1008N
 |doi=10.1086/529002
|s2cid=208867075
 }}</ref> have also led astronomers to believe the largest [[globular cluster]] in the Milky Way, [[Omega Centauri]], is in fact the core of a dwarf galaxy with a [[black hole]] at its centre, which was at some time absorbed by the Milky Way.