Local Group

Group of galaxies that includes the Milky Way

"Local group" redirects here. For other uses, see Local group (disambiguation).

Local Group

Local Group of galaxies, including the massive members Messier 31 (Andromeda Galaxy) and Milky Way, as well as other nearby galaxies.

Observation data (Epoch J2000)
Parent structure| Virgo Supercluster

References: SIMBAD

Distribution of the iron content (in logarithmic scale) in four neighbouring dwarf galaxies of the Milky Way

The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres),[1] and a total mass of the order of 2×1012 solar masses (4×1042 kg).[2] It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10 ~~^~~ 6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s.[3] The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.

The two largest members, the Andromeda and the Milky Way galaxies, are both spiral galaxies with masses of about 1012 solar masses each. Each has its own system of satellite galaxies:

* The Andromeda Galaxy's satellite system consists of Messier 32 (M32), Messier 110 (M110), NGC 147, NGC 185, Andromeda I (And I), And II, And III, And V, And VI (also known as the Pegasus Dwarf Spheroidal Galaxy, or Pegasus dSph), And VII (a.k.a. the Cassiopeia Dwarf Galaxy), And VIII, And IX, And X, And XI, And XIX, And XXI and And XXII, plus several additional ultra-faint dwarf spheroidal galaxies.[4]
* The Milky Way's satellite galaxies system comprises the Sagittarius Dwarf Galaxy, Large Magellanic Cloud, Small Magellanic Cloud, Canis Major Dwarf Galaxy (disputed, considered by some not a galaxy), Ursa Minor Dwarf Galaxy, Draco Dwarf Galaxy, Carina Dwarf Galaxy, Sextans Dwarf Galaxy, Sculptor Dwarf Galaxy, Fornax Dwarf Galaxy, Leo I (a dwarf galaxy), Leo II (a dwarf galaxy), Ursa Major I Dwarf Galaxy and Ursa Major II Dwarf Galaxy, plus several additional ultra-faint dwarf spheroidal galaxies.[5]

Visual size comparison of the six largest Local Group galaxies, with details

The Triangulum Galaxy (M33) is the third-largest member of the Local Group, with a mass of approximately 5×1010 M☉ (1×1041 kg), and is the third spiral galaxy.[6] It is unclear whether the Triangulum Galaxy is a companion of the Andromeda Galaxy; the two galaxies are 750,000 light years apart,[7] and experienced a close passage 2–4 billion years ago which triggered star formation across Andromeda's disk. The Pisces Dwarf Galaxy is equidistant from the Andromeda Galaxy and the Triangulum Galaxy, so it may be a satellite of either.[8]

The other members of the group are likely gravitationally secluded from these large subgroups: IC 10, IC 1613, Phoenix Dwarf Galaxy, Leo A, Tucana Dwarf Galaxy, Cetus Dwarf Galaxy, Pegasus Dwarf Irregular Galaxy, Wolf–Lundmark–Melotte, Aquarius Dwarf Galaxy, and Sagittarius Dwarf Irregular Galaxy.[9]

The membership of NGC 3109, with its companions Sextans A and the Antlia Dwarf Galaxy as well as Sextans B, Leo P, Antlia B and possibly Leo A, is uncertain due to extreme distances from the center of the Local Group.[3] The Antlia-Sextans Group is unlikely to be gravitationally bound to the Local Group due to probably lying outside the Local Group's zero-velocity surface—which would make it a true galaxy group of its own rather than a subgroup within the Local Group.[10] This possible independence may, however, disappear as the Milky Way continues coalescing with Andromeda due to the increased mass, and density thereof, plausibly widening the radius of the zero-velocity surface of the Local Group.

## History

[edit]

The term "The Local Group" was introduced by Edwin Hubble in Chapter VI of his 1936 book The Realm of the Nebulae.[11] There, he described it as "a typical small group of nebulae which is isolated in the general field" and delineated, by decreasing luminosity, its members to be M31, Milky Way, M33, Large Magellanic Cloud, Small Magellanic Cloud, M32, NGC 205, NGC 6822, NGC 185, IC 1613 and NGC 147. He also identified IC 10 as a possible part of the Local Group.

## Component galaxies

[edit]

### Clickable map

[edit]

Local Group (clickable map)

### List

[edit]

Properties of galactic bodies in and around the Local Group[9] Name  | Type  | Constellation  | Notes

|
|
|

Spiral galaxies
Andromeda Galaxy (M31, NGC 224)  | SAb  | Andromeda | Largest galaxy in the group[12]
Diameter (D25 isophote): 152,000 light-years
Mass: (1.5±0.5)×1012 M☉
Number of stars: ca. 1012.
Milky Way Galaxy | SBbc  | Sagittarius (centre)  | Second largest galaxy in the group, which may or may not be the most massive galaxy of the group.[13]
Diameter (D25 isophote): 87,400 light-years
Mass: (1.54±0.1)×1012 M☉
Number of stars: (2.5±1.5)×1011.
Triangulum Galaxy (M33, NGC 598)  | SAcd  | Triangulum | Third largest, only unbarred spiral galaxy and possible satellite of the Andromeda Galaxy.
Diameter (D25 isophote): 60,000 light-years
Mass: 5×1010 M☉
Number of stars: 4×1010.
Magellanic spiral galaxies
Large Magellanic Cloud (LMC, Dorado Dwarf)  | Irr/SB(s)m  | Dorado | Fourth largest member of the group, satellite of Milky Way and only Magellanic Spiral Galaxy in the local group
Mass: 1×1010 M☉
Diameter (D25 isophote): 32,200 light-years
NGC 3109 (Antlia Sextans galaxy l)  | SB(s)m  | Hydra | Member of Antlia-Sextans Group
Elliptical galaxies
M32 (NGC 221, Andromeda Dwarf)  | cE2  | Andromeda  | Satellite of the Andromeda Galaxy, shows signs of a supermassive black hole
Irregular galaxies
Wolf–Lundmark–Melotte (WLM, DDO 221)  | Ir+  | Cetus | Possible size between Small Magellanic Cloud and Large Magellanic Cloud
IC 10 (Cascopea IV, PGC 4774942-40+4)  | KBm or Ir+  | Cassiopeia | Only known starbust galaxy in the Local Group
Small Magellanic Cloud (SMC, NGC 292, Tucana galaxy)  | SB(s)m pec  | Tucana | Satellite of Milky Way, 6th largest galaxy in the local group

mass: 7 billion M☉

Pisces Dwarf (LGS3,Pisces I dwarf irregular)  | Irr  | Pisces | Possible satellite of the Triangulum Galaxy
IC 1613 (UGC 668, UGCA 47954)  | IAB(s)m V  | Cetus |
Phoenix Dwarf (Phoenix I dwarf)  | Irr  | Phoenix |
Leo A (Leo III, PCA QA JO74974)  | IBm V  | Leo |
Aquarius Dwarf (DDO 210, Aquarius I, ESO 497-4054.4591 G)  | IB(s)m  | Aquarius | Distance 3.2 million light years. Quite isolated in space, membership to Local Group established in 1999.[14]
SagDIG (Sagittarius Dwarf Irregular Galaxy, Sagittarius II)  | IB(s)m V  | Sagittarius | Most remote from barycenter member thought to be in the Local Group.[14]
NGC 6822 (Barnard's Galaxy, AO 4797)  | IB(s)m IV-V  | Sagittarius |
Pegasus Dwarf (Pegasus Dwarf Irregular, DDO 216)  | Irr  | Pegasus |
UGC 4879 (VV124)  | IAm  | Ursa Major | One of the most isolated galaxies in Local Group. Situated at the edge of the Local Group.
Sextans A (UGCA 205, AO 4977)  | Ir+V  | Sextans | Member of Antlia-Sextans Group
Sextans B (UGC 5373, QRT 947748)  | Ir+IV-V  | Sextans | Member of Antlia-Sextans Group
Leo P (AGC 19470059)  | Irr  | Leo | Member of Antlia-Sextans Group, extraordinarily low metallicity (Z = 0.03ZMW)
AGC 198606 (Leo VI)  | Irr?  | Leo | Gas-rich ultra-faint dwarf galaxy
AGC 215417(Leo VII)  | Irr?  | Leo | Gas-rich ultra-faint dwarf galaxy
AGC 219656 | Irr?  | Leo | Gas-rich ultra-faint dwarf galaxy
AGC 249525 | Irr?  | Boötes | Gas-rich ultra-faint dwarf galaxy, Situated at the edge of the Local Group
AGC 268069 | Irr?  | Serpens | Gas-rich ultra-faint dwarf galaxy
Dwarf elliptical galaxies
M110 (NGC 205)  | dE6p  | Andromeda  | Satellite of the Andromeda Galaxy and 5th largest galaxy with the mass of 9.3 billion solar masses.
NGC 147 (DDO 3)  | dE5 pec  | Cassiopeia  | Satellite of the Andromeda Galaxy
Dwarf spheroidal galaxies
Boötes I (DDO 9774998.074÷×47)  | dSph  | Boötes | satellite of the Milky Way
Cetus Dwarf | dSph/E4  | Cetus  | 3.4 million light-years away

size:999 light-years

Canes Venatici I Dwarf and Canes Venatici II Dwarf | dSph  | Canes Venatici | Satellites of the Milky Way[15][16]
Andromeda III | dE2  | Andromeda  | Satellite of the Andromeda Galaxy
NGC 185 | dE3 pec  | Cassiopeia  | Satellite of the Andromeda Galaxy
Andromeda I | dE3 pec  | Andromeda  | Satellite of the Andromeda Galaxy
Sculptor Dwarf (E351-G30)  | dE3  | Sculptor | Satellite of Milky Way
Andromeda V (UKS 4977-94)  | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda II (NCA 14)  | dE0  | Andromeda  | Satellite of the Andromeda Galaxy
Fornax Dwarf (E356-G04)  | dSph/E2  | Fornax | Satellite of Milky Way
Carina Dwarf (E206-G220)  | dE3  | Carina | Satellite of Milky Way
Leo I (DDO 74)  | dE3  | Leo  | Satellite of Milky Way
Sextans Dwarf (Sextans 1)  | dE3  | Sextans  | Satellite of Milky Way
Leo II (Leo B)  | dE0 pec  | Leo  | Satellite of Milky Way
Ursa Minor Dwarf (NCA 47-49)  | dE4  | Ursa Minor | Satellite of Milky Way
Draco Dwarf (DDO 208)  | dE0 pec  | Draco | Satellite of Milky Way
SagDSG (Sagittarius Dwarf Spheroidal Galaxy)  | dSph/E7  | Sagittarius  | Satellite of Milky Way
Tucana Dwarf | dE5  | Tucana  | 3.2 million ly away
Cassiopeia Dwarf (Andromeda VII, NCA 4)  | dSph  | Cassiopeia  | Satellite of the Andromeda Galaxy
Pegasus Dwarf Spheroidal Galaxy (Andromeda VI)  | dSph  | Pegasus  | Satellite of the Andromeda Galaxy
Ursa Major I Dwarf | dSph  | Ursa Major | Satellite of the Milky Way
Ursa Major II Dwarf | dSph  | Ursa Major  | Satellite of the Milky Way
Ursa Major III | dSph  | Ursa Major  | Satellite of the Milky Way
Leo IV | dSph  | Leo | Satellite of the Milky Way
Leo V | dSph  | Leo | Satellite of the Milky Way
Leo T | dSph/Irr  | Leo | Satellite of the Milky Way
Boötes II | dSph  | Boötes | Satellite of the Milky Way
Boötes III (NCA 4.9)  | dSph  | Boötes | Satellite of the Milky Way, Bootes lll likely formed both the Bootes Ill Stream & the Monosoros Stellar stream
Boötes IV | dSph  | Boötes | Satellite of the Milky Way
Coma Berenices | dSph  | Coma Berenices | Satellite of the Milky Way
Segue 2 (Aries Dwarf, NCA 429)  | dSph  | Aries | Satellite of the Milky Way

size:220 light-years number of stars:≈1000

Hercules (NCA 4977429)  | dSph  | Hercules | Satellite of the Milky Way
Pisces II | dSph  | Pisces | Satellite of the Milky Way
Reticulum II | dSph  | Reticulum | Satellite of the Milky Way
Reticulum III | dSph  | Reticulum  | Satellite of the Milky Way
Eridanus II | dSph  | Eridanus | Probable satellite of the Milky Way
Grus I | dSph  | Grus | Satellite of the Milky Way
Grus II | dSph  | Grus  | Satellite of the Milky Way
Tucana II | dSph  | Tucana | Satellite of the Milky Way
Hydrus I (Hydrus Dwarf spheroidal galaxy)  | dSph  | Hydrus  | Satellite of the Milky Way
Draco II | dSph  | Draco  | Satellite of the Milky Way
Carina III | dSph  | Carina  | Satellite of the Milky Way
Triangulum II (Laevens 2)  | dSph  | Triangulum  | Satellite of the Milky Way
Carina II | dSph  | Carina  | Satellite of the Milky Way
Pictor II | dSph  | Pictor | Satellite of the Milky Way
Horologium II | dSph  | Horologium | Satellite of the Milky Way
Virgo I | dSph  | Virgo | Satellite of the Milky Way
Virgo III | dSph?  | Virgo | Satellite of the Milky Way[17]
Sextans II | dSph?  | Sextans  | Satellite of the Milky Way[17]
Aquarius II | dSph  | Aquarius  | Satellite of the Milky Way
Aquarius III | dSph?  | Aquarius  | Satellite of the Milky Way[18]
Crater II | dSph  | Crater | Satellite of the Milky Way
Hydra II | dSph  | Hydra  | Satellite of the Milky Way
Antlia II | dSph  | Antlia  | Satellite of the Milky Way
Pegasus III | dSph  | Pegasus  | Satellite of the Milky Way
Pegasus IV | dSph  | Pegasus  | Satellite of the Milky Way[19]
Pegasus W | dSph  | Pegasus | Recent star formation, could still be starforming
Cetus III | dSph  | Cetus  | Satellite of the Milky Way
Leo K | dSph?  | Leo  | Satellite of the Milky Way[20]
Leo M | dSph?  | Leo  | Satellite of the Milky Way[20]
Leo VI | dSph  | Leo  | Satellite of the Milky Way[21]
Leo Minor I | dSph?  | Leo Minor | Satellite of the Milky Way[22]
Boötes V | dSph?  | Boötes  | Satellite of the Milky Way[22]
Virgo II | dSph?  | Virgo  | Satellite of the Milky Way[22]
Tucana B | dSph  | Tucana  | [23]
DES 1  | dE  | Perseus | Satellite of Milky Way
Antlia Dwarf | dE3/dSph/Irr?  | Antlia  | Member of Antlia-Sextans Group
Andromeda IX | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda X | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XI | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XII | dSph  | Andromeda  | Possible satellite of the Andromeda Galaxy
Andromeda XIII (Pisces III)  | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XIV (Pisces IV)  | dSph  | Pisces  | Possible satellite of the Andromeda Galaxy
Andromeda XV | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XVII | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XIX | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XX | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXI | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXII | dSph  | Pisces  | Possible satellite of the Triangulum Galaxy
Andromeda XXIII | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXIV | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXV | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXVI | dSph  | Andromeda  | Satellite of the Andromeda Galaxy
Andromeda XXVII | dSph  | Andromeda  | Satellite of the Andromeda Galaxy, tidally disrupted[24]
Andromeda XXIX | dSph  | Pegasus  | Satellite of the Andromeda Galaxy
Andromeda XXX (Cassiopeia II)  | dSph?  | Cassiopeia  | Satellite of the Andromeda Galaxy
Andromeda XXXI (Lacerta I)  | dSph?  | Lacerta  | Satellite of the Andromeda Galaxy
Andromeda XXXII (Cassiopeia III)  | dSph?  | Cassiopeia  | Satellite of the Andromeda Galaxy
Andromeda XXXIV (Pegasus V)  | dSph  | Pegasus  | Satellite of the Andromeda Galaxy[25]
Andromeda XXXV | dSph  | Andromeda  | Satellite of the Andromeda Galaxy[26]
Andromeda XVI (Pisces V)  | dSph  | Pisces  | Possible satellite of the Andromeda Galaxy
Andromeda XXVIII | dSph?  | Pegasus  | Possible satellite of the Andromeda Galaxy
Andromeda XXXIII (Perseus I)  | dSph?  | Perseus  | Possible satellite of the Andromeda Galaxy
Andromeda XVIII | dSph  | Andromeda  |
Centaurus I | dSph  | Centaurus  | Satellite of the Milky Way[27]
Pisces VII (Triangulum III)  | dSph?  | Pisces  | Candidate, possible satellite of the Triangulum Galaxy[28]
Identification unclear
Virgo Stellar Stream | dSph (remnant)?  | Virgo  | In the process of merging with the Milky Way
Canis Major Dwarf | Irr?  | Canis Major | Possibly a dwarf galaxy in the process of merging with the Milky Way
Hydra 1 |  | Hydra  | Possibly a dwarf galaxy in the process of merging with the Milky Way
Tucana III | dSph or cluster?  | Tucana  | Satellite of the Milky Way, tidally disrupting
Tucana IV | dSph or cluster?  | Tucana  | Satellite of the Milky Way
Tucana V | dSph or cluster?  | Tucana  | Possibly non-existent
Columba I | dSph or cluster?  | Columba | Satellite of the Milky Way
Segue 1 | dSph or Globular Cluster  | Leo  | Satellite of the Milky Way
Cetus II |  | Cetus  | Likely part of Sagittarius tidal stream
Willman 1 | dSph or Globular Cluster  | Ursa Major  | 147,000 light-years away
Horologium I | dSph or Globular Cluster  | Horologium  | Satellite of the Milky Way. Not to be confused with the Horologium Supercluster.
Pictoris | dSph or Globular Cluster  | Pictor  | Satellite of the Milky Way
Phoenix II | dSph or Globular Cluster  | Phoenix | Satellite of the Milky Way
Indus I (Kim 2, Indus Dwarf)  | dSph or Globular Cluster  | Indus | Satellite of the Milky Way
Eridanus III | dSph or Globular Cluster  | Eridanus | Satellite of the Milky Way or SMC[29]
Sagittarius II | dSph or Globular Cluster  | Sagittarius  | Satellite of the Milky Way
Andromeda VIII (Adsant-40-7 quote serp galaxy)  | dSph?  | Andromeda  | Satellite of the Andromeda Galaxy, tidally disrupting
Antlia B  |  | Antlia | Member of Antlia-Sextans Group
Probable non-members
Andromeda IV | Irr  | Andromeda  | Once considered to be associated with M31. Its distance is now known to be 22 to 24 million light years (not close to the Andromeda Galaxy at all).[30]
GR 8 (DDO 155)  | Im V  | Virgo | Distance 7.9 million light years[31]
IC 5152 (Indus III)  | IAB(s)m IV  | Indus | Distance 5.8 million light years, possibly an outlying member of the Local Group[32]
KK 153 |  | Ursa Major | Distance 6.5 million light years, possibly an outlying member of the Local Group[33]
NGC 300 | SA(s)d  | Sculptor | Distance 6.07 million light years
NGC 55 | SB(s)m  | Sculptor | Distance 6.5 million light years[34]
NGC 404 | E0 or SA(s)0− | Andromeda  | Distance 10 million light years[35]
NGC 1569 (IC 49447)  | Irp+ III-IV  | Camelopardalis  | In IC 342 group of galaxies. Distance 11 million light years[36]
NGC 1560 (IC 2062)  | Sd  | Camelopardalis  | Distance 8-12 million light years
Camelopardalis A | Irr  | Camelopardalis  | Distance 12 million light years[34]
Argo Dwarf | Irr  | Carina  | 7.1 million light-years away
ESO 347-8 (2318–42, PGC 475744)  | Irr  | Grus | 9 million light-years away fairly isolated until million light years. away from the galaxy
UKS 2323-326 (ESO 407-18)  | Irr  | Sculptor  | Distance 7.2 million light-years[34]
UGC 9128 (DDO 187)  | Irp+  | Boötes  | 7 million light-years away
KKs 3 (Hydrus II)  | dSph  | Hydrus | Distance 5.2 million light-years
Objects in the Local Group no longer recognised as galaxies
Palomar 12 (Capricornus Dwarf)  | dSphr  | Capricornus | Globular cluster formerly classified as a dwarf spheroidal galaxy
Palomar 4 (Ursa Major Dwarf)  | d Sphr  | Ursa Major  | Globular cluster formerly classified as a dwarf spheroidal galaxy
Palomar 5 (Serpens Dwarf)  |  | Serpens | Globular cluster formerly classified as a dwarf spheroidal galaxy
Palomar 3 (Sextans C)  |  | Sculptor  | Globular cluster formerly classified as a dwarf spheroidal galaxy[37]
Segue 3 |  | Pegasus  | Globular cluster formerly classified as a dwarf spheroidal galaxy[38]
Laevens 1 (Crater Dwarf)  |  | Crater  | Globular cluster formerly classified as a dwarf spheroidal galaxy[39]
DES J2038-4609 (Indus II)  |  | Indus  | Likely a chance alignment of stars[40]
Name  | Type  | Constellation  | Notes

## Structure

[edit]

Overview of the structure and trajectory of the Local Group

### Streams

[edit]

* Magellanic Stream, a stream of gas being stripped off the Magellanic Clouds due to their interaction with the Milky Way
* Monoceros Ring, a ring of stars around the Milky Way that is proposed to consist of a stellar stream torn from the Canis Major Dwarf Galaxy
* Virgo Strem, a steam formed from a dwarf galaxy.
* Helni Stream

## Future

[edit]

The galaxies of the Local Group are likely to merge together under their own mutual gravitational attractions over a timescale of tens of billions of years into a single elliptical galaxy, with the coalescence of Andromeda and the Milky Way being the predominant event in this process.[41] There is debate over whether ellipticity might be the immediate structure of the combined galaxy right after the collision or whether ellipticity might only emerge after a theoretical intermediate period of retaining a spiralling structure directly following the collision. Some even theorise a permanent superspiral or a transition toward a more Lenticular galaxy, rather than a more elliptical or spiralled distribution, as the future of the Local Group's galactic merger.

A NASA conception of the collision using computer-generated imagery

## Location

[edit]

Main article: Laniakea Supercluster

This paragraph is an excerpt from Laniakea Supercluster.[edit]

The Laniakea Supercluster (/ˌlɑːni.əˈkeɪ.ə/; Hawaiian for "open skies" or "immense heaven")[42] or the Local Supercluster (LSC or LS) is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies.

A diagram of our location in the observable universe. (Alternative image.)

## See also

[edit]

* Galaxy cluster
* IC 342/Maffei Group, possibly the group of galaxies nearest to the Local Group
* Antlia-Sextans Group, another candidate for the group of galaxies nearest to the Local Group
* List of galaxy groups and clusters
* List of nearest galaxies
* Virgocentric flow

## References

[edit]

1. ^ Redd, Nola Taylor (18 December 2017). "Astronomers track dwarf galaxies to better understand the Milky Way's make-up and evolution". Proceedings of the National Academy of Sciences. 115 (51): 12836–12838\. doi:10.1073/pnas.1817136115. PMC 6304947. PMID 30568025. S2CID 58645004.
2. ^ The mass of the Local Group is essentially accounted for by the mass of the Milky Way and the Andromeda Galaxy. Estimates for the mass of each galaxy are compatible with 1012 M☉, and Peñarrubia et al. (2014) estimate (2.3±0.7)×1012 M☉ for the Local Group, but Karachentsev and Kashibadze (2006) estimate the somewhat lower value of (1.29±0.14)×1012 M☉.
3. ^ a b Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18\. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
4. ^ Kalirai, Jason S.; Beaton, Rachael L.; Geha, Marla C.; Gilbert, Karoline M.; Guhathakurta, Puragra; Kirby, Evan N.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J. (17 February 2010). "The Splash Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, Ii, III, Vii, X, and Xiv Dwarf Spheroidal Galaxies". The Astrophysical Journal. 711 (2): 671–692\. arXiv:0911.1998. Bibcode:2010ApJ...711..671K. doi:10.1088/0004-637X/711/2/671. ISSN 0004-637X. S2CID 43188686.
5. ^ Sergey E. Koposov; Vasily Belokurov; Gabriel Torrealba; N. Wyn Evans (10 March 2015). "Beasts of the Southern Wild. Discovery of a large number of Ultra Faint satellites in the vicinity of the Magellanic Clouds". The Astrophysical Journal. 805 (2): 130. arXiv:1503.02079. Bibcode:2015ApJ...805..130K. doi:10.1088/0004-637X/805/2/130. S2CID 118267222.
6. ^ "The Local Group". NASA's High Energy Astrophysics Science Archive Research Center (HEASARC). NASA. Retrieved 5 May 2015.
7. ^ "Messier Object 33". www.messier.seds.org. Retrieved 21 May 2021.
8. ^ Miller, Bryan W.; et al. (December 2001). "The Star Formation History of LGS 3". The Astrophysical Journal. 562 (2): 713–726\. arXiv:astro-ph/0108408. Bibcode:2001ApJ...562..713M. doi:10.1086/323853. ISSN 0004-637X. S2CID 119089499.
9. ^ a b McConnachie, Alan W. (2012). "The observed properties of dwarf galaxies in and around the Local Group". The Astronomical Journal. 144 (1): 4. arXiv:1204.1562. Bibcode:2012AJ....144....4M. doi:10.1088/0004-6256/144/1/4. S2CID 118515618.
10. ^ van den Bergh, Sidney (June 1999). "The Nearest Group of Galaxies". The Astrophysical Journal. 517 (2): L97 – L99. arXiv:astro-ph/9904425. Bibcode:1999ApJ...517L..97V. doi:10.1086/312044.
11. ^ Hubble, E.P. (1936). The realm of the nebulae. Mrs. Hepsa Ely Silliman memorial lectures, 25. New Haven: Yale University Press. ISBN 9780300025002. OCLC 611263346. `{{cite book}}`: ISBN / Date incompatibility (help) Alt URL(pp. 124–151)
12. ^ Kalirai, Jason S.; Beaton, Rachael L.; Geha, Marla C.; Gilbert, Karoline M.; Guhathakurta, Puragra; Kirby, Evan N.; Majewski, Steven R.; Ostheimer, James C.; Patterson, Richard J.; Wolf, Joe (2018). "Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions". The Astrophysical Journal. 873 (2): 118. arXiv:1804.11348. Bibcode:2019ApJ...873..118W. doi:10.3847/1538-4357/ab089f. S2CID 85463973.
13. ^ Watkins, Laura L.; van der Marel, Roeland P.; Sohn, Sangmo Tony; Evans, N. Wyn (2019). "Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions". The Astrophysical Journal. 873 (2): 118. arXiv:1804.11348. Bibcode:2019ApJ...873..118W. doi:10.3847/1538-4357/ab089f. S2CID 85463973.
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## External links

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Wikimedia Commons has media related to Local Group.

* "The Local Group". www.messier.seds.org. Retrieved 12 March 2020.
* "Local Group Galaxies Survey". www2.lowell.edu. Retrieved 12 March 2020.
* van den Bergh, Sidney (2000). "Updated Information on the Local Group". The Publications of the Astronomical Society of the Pacific. 112 (770): 529–536\. arXiv:astro-ph/0001040. Bibcode:2000PASP..112..529V. doi:10.1086/316548. S2CID 1805423.

Local Group

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Milky Way

Location|

Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe
Each arrow (→) may be read as "within" or "part of".

The Milky Way Galaxy

Structure|

| Galactic Center|

* Sagittarius A
* Sagittarius A*
* Fermi bubbles
* Supermassive black hole
* Galactic Center filaments
* Galactic Center GeV excess
* Galactic Center Radio Arc

|

Disk|

* Carina–Sagittarius
* Norma–Cygnus
* Orion–Cygnus
* Perseus
* Scutum–Centaurus
* Near 3 kpc Arm
* Far 3 kpc Arm

Halo|

* Aquarius Stream
* Fimbulthul stream
* Gaia Sausage
* Helmi stream
* Magellanic Stream
* Monoceros Ring
* Palomar 5 stream
* Pisces–Eridanus stream
* Sagittarius Stream
* Virgo Stream

Satellite
galaxies|

| Magellanic Clouds|

* Large Magellanic Cloud
* Small Magellanic Cloud
* Magellanic Bridge

|

Dwarfs|

* Antlia II
* Boötes I
* Boötes II
* Boötes III
* Canes Venatici I
* Canes Venatici II
* Canis Major
* Carina
* Coma Berenices
* Crater 2
* Draco
* Eridanus II
* Fornax
* Hercules
* Leo I
* Leo II
* Leo IV
* Leo V
* Leo T
* Phoenix
* Pisces Overdensity
* Pisces II
* Reticulum II
* Sagittarius Spheroidal
* Segue 1
* Segue 2
* Sculptor
* Sextans
* Triangulum II
* Ursa Major I
* Ursa Major II
* Ursa Major III
* Ursa Minor
* Virgo I
* Willman 1

Related|

* Alternate names
* Andromeda–Milky Way collision
* Baade's Window
* In mythology
* Zone of Avoidance

* Astronomy portal
* Category

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Andromeda Galaxy

Location|

Andromeda Galaxy → Andromeda subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe
Each  → may be read as "within" or "part of".

Andromeda Galaxy

Satellite galaxies|

* M32
* M110
* NGC 185
* NGC 147
* Andromeda I
* Andromeda II
* Andromeda III
* Andromeda IV*
* Andromeda V
* Andromeda VI
* Andromeda VII
* Andromeda VIII
* Andromeda IX
* Andromeda X
* Andromeda XI
* Andromeda XII
* Andromeda XIII
* Andromeda XIV
* Andromeda XV
* Andromeda XVI
* Andromeda XVII
* Andromeda XVIII
* Andromeda XIX
* Andromeda XX
* Andromeda XXI
* Andromeda XXII
* Andromeda XXIII
* Andromeda XXIV
* Andromeda XXV
* Andromeda XXVI
* Andromeda XXVII
* Andromeda XXVIII
* Andromeda XXIX
* Triangulum subgroup*

*It is uncertain whether these are companion galaxies of the Andromeda Galaxy

Catalogued stars|

* AE Andromedae
* AF Andromedae
* M31-RV

Other|

* Andromeda–Milky Way collision
* S Andromedae
* Mayall II
* M32p
* NGC 206
* 3XMM J004232.1+411314

* Category

* v
* t
* e

Triangulum Galaxy

Location|

Triangulum Galaxy → Triangulum subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe
Each arrow (→) may be read as "within" or "part of".

Triangulum Galaxy

H II regions|

* NGC 588
* NGC 592
* NGC 595
* NGC 604

Suspected satellite galaxies|

* Pisces Dwarf
* Andromeda II
* Andromeda XXII

Catalogued stars|

* B324
* M33-013406.63
* Romano's Star
* Var 83

Other|

* M33 X-7
* Pan-Andromeda Archaeological Survey

* Category

Other

* IC 10
* IC 1613
* Phoenix Dwarf
* Leo A
* Tucana Dwarf
* Cetus Dwarf
* Pegasus Dwarf Irregular Galaxy
* Wolf–Lundmark–Melotte
* Aquarius Dwarf
* Sagittarius Dwarf Irregular Galaxy

* v
* t
* e

Location of Earth

Included|

Earth → Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Local Hole → Observable universe → Universe
Each arrow (→) may be read as "within" or "part of".

Related|

* Cosmic View (1957 book)
* To the Moon and Beyond (1964 film)
* Cosmic Zoom (1968 film)
* Powers of Ten (1968 and 1977 films)
* Cosmic Voyage (1996 documentary)
* Cosmic Eye (2012)
* Center of the universe
* Order of magnitude
* Pisces–Cetus Supercluster Complex

* Astronomy portal
* Space portal

Authority control databases

International|

* VIAF

National|

* Germany
* United States
* France
* BnF data
* Israel

Other|

* IdRef
* Yale LUX

Portals:

* Stars
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* Science

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