View source for Local Group

[[Image:local.group.arp.600pix.jpg|thumb|A member of the Local Group of galaxies, irregular galaxy [[Sextans A]] is 4.3 million light-years distant. The bright Milky Way foreground stars appear yellowish in this view. Beyond them lie the stars of Sextans A with young blue star clusters clearly visible.]]
[[Image:VLT Shows Milky Way's Neighbouring Galaxies Have Different History.jpg|thumb|Distribution of the [[iron]] content (in logarithmic scale) in four dwarf neighbouring galaxies of the Milky Way.]]

The '''Local Group''' is the [[Galaxy group|group of galaxies]] that includes our [[galaxy]], the [[Milky Way]]. 

The group has more than 50 galaxies (including [[Dwarf galaxy|dwarf galaxies]]).  Its [[center of mass]] is somewhere between the Milky Way and the [[Andromeda galaxy]].  The galaxies of the Local Group cover a 10 million [[light-year]] [[diameter]] and have a binary (dumbbell) shape. The group has a total mass of about (1.29 ± 0.14){{e|12}}[[solar mass|M<sub>s</sub>]].<ref name="Karachentsevetal2006">{{cite journal| author=Karachentsev I.D. & Kashibadze O.G.| title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field| journal=Astrophysics| year=2006| volume=49| issue=1| pages=3–18| bibcode=2006Ap.....49....3K | doi = 10.1007/s10511-006-0002-6| s2cid=120973010}}</ref>
The group itself is part of the [[Virgo Supercluster]] (also called the Local Supercluster).<ref name="tully1982">{{cite journal| author= Tully R.B.| title=The Local Supercluster| url= https://archive.org/details/sim_astrophysical-journal_1982-06-01_257_1/page/n391| journal=Astrophysical Journal| year=1982| volume=257| pages=389–422| bibcode=1982ApJ...257..389T | doi = 10.1086/159999
}}</ref>
== History ==
The term "Local Group" was introduced by [[Edwin Hubble]] in 1936.<ref>Hubble, Edwin 1936. ''The realm of the nebulae'', pages 124–151</ref> He describes it as "a typical small group of nebulae which is isolated in the general field". He listed the galaxies, by decreasing luminosity, as the [[Andromeda galaxy]], the [[Milky Way]], [[Triangulum galaxy]], the [[Large Magellanic Cloud]], the [[Small Magellanic Cloud]] and half-a-dozen others. 

By 2003, the number of known Local Group members has increased from his initial twelve to thirty-six, because of the discovery of almost two dozen low-luminosity galaxies.<ref name="Bergh2003">{{Cite journal
 | last1 = van den Bergh
 | first1 = Sidney
 | authorlink1 =
 | title = History of the Local Group
 | date = 2003
 | journal = In: "The Local Group as an Astrophysical Laboratory"
 | publisher = Cambridge University Press
 | arxiv = astro-ph/0305042
 | bibcode = 2003astro.ph..5042V
 }}</ref>
== Movement of the Local Group ==
[[File:Dipole repeller.svg|thumb|300px|Gravitational attraction induces movement towards more dense areas giving the appearance of galaxies moving away from a less dense area, known as the 'dipole repeller'.]]

The Milky Way, Andromeda, and the whole Local Group are being pulled by the [[gravitational]] attraction of the most massive structure in the observable universe. They are being pulled by the [[Shapley Supercluster|Shapley attractor]], which is a dense supercluster of galaxies some 750 million light years from the Milky Way. {{cn|date=August 2023}}

At the same time, the Local Group is being pushed by an almost empty region of space called the "dipole repeller".<ref>Hoffman Y ''et al'' 2017. The dipole repeller. ''Nature Astronomy'' '''1''', 0036. [https://www.nature.com/articles/s41550-016-0036]</ref><ref>Hoffman Y; Courtois H.M. & Tully R.B. 2015. Cosmic bulk flow and the local motion from Cosmicflows-2. ''Monthly Notices Royal Astron. Soc''. '''449''', 4494–4505. </ref><ref>Tully R.B. ''et al'' 2013. Cosmicflows-2: The data. ''Astron. J''. '''146''', 86. </ref>
== Map ==
<imagemap>
Image:Local_Group.svg|frame|center|Local Group (clickable map)

circle 180 27 20 [[Sextans B]]
circle 130 36 23 [[Sextans A]]
circle 318 239 20 [[Milky Way]]
circle 289 197 16 [[Leo I (dwarf galaxy)]]
circle 334 201 15 [[Canes Dwarf]]
rect 303 185 318 215 [[Leo II (dwarf galaxy)]]
circle 357 289 28 [[NGC 6822]]
circle 288 323 24 [[Phoenix Dwarf]]
circle 248 391 35 [[Tucana Dwarf]]
circle 363 416 20 [[Wolf-Lundmark-Melotte]]
circle 363 383 17 [[Cetus Dwarf]]
circle 369 346 11 [[IC 1613]]
rect 381 335 393 357 [[SagDIG]]
rect 393 335 406 356 [[Aquarius Dwarf]]
circle 417 304 17 [[Triangulum Galaxy]]
circle 417 254 15 [[NGC 185]]
rect 432 237 447 260 [[NGC 147]]
circle 461 229 17 [[IC 10]]
poly 440 282 455 260 511 259 493 285 [[Andromeda Galaxy]]
poly 450 264 434 265 431 280 442 280 [[Messier 110|M110]]
circle 295 110 20 [[Leo A]]
circle 84 128 20 [[NGC 3109]]
circle 109 149 14 [[Antlia Dwarf]]
circle 412 332 12 [[LGS 3]]
circle 460 361 21 [[Pegasus Dwarf Spheroidal Galaxy|Pegasus Dwarf]]
circle 394 272 14 [[Andromeda II]]
rect 427 279 438 294 [[Andromeda III]]
rect 438 282 450 294 [[Andromeda I]]

desc bottom-left
</imagemap>

== Local Group Media ==
<gallery widths='160px' heights='100%' mode='traditional' caption=''>
File:06-Local Group (LofE06240).png|A map of the Local Group with two subgroups of both Milky Way and Andromeda galaxies around its center

File:Local Group Galaxies Comparison.png|Visual size comparison of the five largest Local Group galaxies along with the possible member [[NGC 3109]], with details

File:Thelocalgroup.jpg|Overview of the structure and trajectory of the Local Group

File:Andromeda and Milky Way collision.webm|A [[NASA]] conception of the collision using [[computer-generated imagery]]
</gallery>
== Related pages ==
*[[Galaxy]]
*[[List of galaxies]]
*[[Most distant things]]
*[[Sag DEG]]
== References ==
{{Reflist}}


[[Category:Galaxy clusters]]
[[Category:Local galaxies| ]]