Editing Andromeda Galaxy (section)

== Nearby and satellite galaxies ==
{{Main|Andromeda's satellite galaxies}}
[[File:M31, the Andromeda Galaxy, Killarney Provincial Park Observatory.jpg|thumb|The Andromeda Galaxy with [[Satellite galaxy|satellite galaxies]] [[Messier 32|M32]] (center left above the [[galactic nucleus]]) and [[Messier 110|M110]] (center right below the galaxy)]]
Like the Milky Way, the Andromeda Galaxy has smaller [[satellite galaxy|satellite galaxies]], consisting of over 20 known [[dwarf galaxy|dwarf galaxies]]. The Andromeda Galaxy's dwarf galaxy population is very similar to the Milky Way's, but the galaxies are much more numerous.<ref>{{cite journal|doi=10.1093/mnras/stab1754|title=Solo dwarfs IV: Comparing and contrasting satellite and isolated dwarf galaxies in the Local Group|year=2021|last1=Higgs|first1=C. R.|last2=McConnachie|first2=A. W.|journal=Monthly Notices of the Royal Astronomical Society|volume=506|issue=2|pages=2766–2779|doi-access=free |arxiv=2106.12649}}</ref> The best-known and most readily observed satellite galaxies are [[Elliptical Galaxy M32|M32]] and [[Elliptical Galaxy M110|M110]]. Based on current evidence, it appears that M32 underwent a close encounter with the Andromeda Galaxy in the past. M32 may once have been a larger galaxy that had its stellar disk removed by M31 and underwent a sharp increase of [[star formation]] in the core region, which lasted until the relatively recent past.<ref name="Bekki et al 2001"/>

M110 also appears to be interacting with the Andromeda Galaxy, and astronomers have found in the halo of the latter a stream of metal-rich stars that appear to have been stripped from these satellite galaxies.<ref name="Ibata et al 2001"/> M110 does contain a dusty lane, which may indicate recent or ongoing star formation.<ref name="Young 2000"/> M32 has a young stellar population as well.<ref name="Rudenko"/>

The [[Triangulum Galaxy]] is a non-dwarf galaxy that lies 750,000 light-years from Andromeda. It is currently unknown whether it is a satellite of Andromeda.<ref>{{cite web |url=http://www.messier.seds.org/m/m033.html |title=Messier 33 |access-date=22 July 2024 |website=SEDS Messier Catalog}}</ref>

In 2006, it was discovered that nine of the satellite galaxies lie in a plane that intersects the core of the Andromeda Galaxy; they are not randomly arranged as would be expected from independent interactions. This may indicate a common tidal origin for the satellites.<ref name="Koch & Grebel 2006"/>