The Local Group is a small cluster of more than 50 galaxies located in the outskirts of the Virgo Supercluster. Its gravitational field is somewhere between the Milky Way and Andromeda galaxy.
The biggest galaxy of the cluster is the Andromeda Galaxy, an unbarred spiral galaxy, closely followed by our own Milky Way. The last major galaxy in the local group is the Triangulum Galaxy, all others are Dwarf Galaxies.
Description
The group is around 10 Mly in (3.1 Mpc) in diameter. It has a binary distribution with two concentrations of objects at either end. It is a section of the Laniakea Supercluster, also known as the Local Supercluster, which contains the neighboring Virgo Cluster. The two largest galaxies, Andromeda and the Milky Way, are both spiral galaxies, with systems of satellite galaxies. (Dwarf galaxies)
Members
Map
Galactic Bodies
| Spiral galaxies | |||
|---|---|---|---|
| name | type | constellation | notes |
| Milky Way | SBbc | Sagittarius (centre) | Where we reside; the second largest galaxy in the group.[1] |
| Andromeda Galaxy (M31, NGC 224) | SA(s)b | Andromeda | With ~220 kly in diameter, it is the largest and most massive galaxy in the group. |
| Triangulum Galaxy (M33, NGC 598) | SA(s)cd | Triangulum | Third largest, only unbarred spiral galaxy and possible satellite of the Andromeda Galaxy. |
| Elliptical galaxies | |||
| name | type | constellation | notes |
| M32 (NGC 221) | E2 | Andromeda | satellite of the Andromeda Galaxy |
| Irregular galaxies | |||
| name | type | constellation | notes |
| Wolf–Lundmark–Melotte (WLM, DDO 221) | Ir+ | Cetus | |
| IC 10 | KBm or Ir+ | Cassiopeia | |
| Small Magellanic Cloud (SMC, NGC 292) | SB(s)m pec | Tucana | satellite of Milky Way |
| Canis Major Dwarf | Irr | Canis Major | satellite of Milky Way |
| Pisces Dwarf (LGS3) | Irr | Pisces | satellite of the Triangulum Galaxy? |
| IC 1613 (UGC 668) | IAB(s)m V | Cetus | |
| Phoenix Dwarf | Irr | Phoenix | |
| Large Magellanic Cloud (LMC) | Irr/SB(s)m | Dorado | Fourth largest member of the group, satellite of Milky Way |
| Leo A (Leo III) | IBm V | Leo | |
| Sextans B (UGC 5373) | Ir+IV-V | Sextans | |
| NGC 3109 | Ir+IV-V | Hydra | |
| Sextans A (UGCA 205) | Ir+V | Sextans | |
| Dwarf elliptical galaxies | |||
| name | type | constellation | notes |
| M110 (NGC 205) | dE6p | Andromeda | satellite of the Andromeda Galaxy |
| NGC 147 (DDO 3) | dE5 pec | Cassiopeia | satellite of the Andromeda Galaxy |
| SagDIG (Sagittarius Dwarf Irregular Galaxy) | IB(s)m V | Sagittarius | Most remote from barycenter member thought to be in the Local Group.[2] |
| NGC 6822 (Barnard's Galaxy) | IB(s)m IV-V | Sagittarius | |
| Pegasus Dwarf (Pegasus Dwarf Irregular, DDO 216) | Irr | Pegasus | |
| Dwarf spheroidal galaxies | |||
| name | type | constellation | notes |
| Boötes I | dSph | Boötes | |
| Cetus Dwarf | dSph/E4 | Cetus | |
| Canes Venatici I Dwarf and Canes Venatici II Dwarf | dSph | Canes Venatici | |
| KKs 3 | dSph | ||
| 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 | dSph | Andromeda | satellite of the Andromeda Galaxy |
| Andromeda II | 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 |
| Antlia Dwarf | dE3/dSph/Irr? | Antlia | |
| Leo I (DDO 74) | dE3 | Leo | satellite of Milky Way |
| Sextans Dwarf | dE3 | Sextans | satellite of Milky Way |
| Leo II (Leo B) | dE0 pec | Leo | satellite of Milky Way |
| Ursa Minor Dwarf | dE4 | Ursa Minor | satellite of Milky Way |
| Draco Dwarf (DDO 208) | dE0 pec | Draco | satellite of Milky Way |
| SagDEG (Sagittarius Dwarf Elliptical Galaxy) | dSph/E7 | Sagittarius | satellite of Milky Way |
| Tucana Dwarf | dE5 | Tucana | |
| Cassiopeia Dwarf (Andromeda VII) | dSph | Cassiopeia | satellite of the Andromeda Galaxy |
| Pegasus Dwarf Spheroidal Galaxy (Andromeda VI) | dSph | Pegasus | satellite of the Andromeda Galaxy |
| Ursa Major I Dwarf and Ursa Major II Dwarf | dSph | Ursa Major | satellite of 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 | dSph | Boötes | satellite of the Milky Way |
| Coma Berenices | dSph | Coma Berenices | satellite of the Milky Way |
| Segue 2 | dSph | Aries | satellite of the Milky Way |
| Hercules | 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 |
| Eridanus II | dSph | Eridanus | satellite of the Milky Way |
| Grus | dSph | Grus | satellite of the Milky Way |
| Tucana II | dSph | Tucana | satellite of the Milky Way |
| Identification Unclear | |||
| name | type | constellation | notes |
| Virgo Stellar Stream | dSph (remnant)? | Virgo | In the process of merging with the Milky Way |
| Willman 1 | dwarf Spherical galaxy or Globular cluster? |
Ursa Major | 147,000 light-years away |
| Andromeda IV | Irr? | Andromeda | probably not a galaxy |
| UGCA 86 (0355+66) | Irr, dE or S0 | Camelopardalis | |
| UGCA 92 (EGB0427+63) | Irr or S0 | Camelopardalis | |
| Horologium | dSph or Globular Cluster | Horologium | satellite of the Milky Way |
| Pictoris | dSph or Globular Cluster | Pictor | satellite of the Milky Way |
| Phoenix II | dSph or Globular Cluster | Phoenix | satellite of the Milky Way |
| Indus | dSph or Globular Cluster | Indus | satellite of the Milky Way |
| Eridanus III | dSph or Globular Cluster | Eridanus | satellite of the Milky Way |
| Probable non-members | |||
| name | type | constellation | notes |
| GR 8 (DDO 155) | Im V | Virgo | |
| IC 5152 | IAB(s)m IV | Indus | |
| NGC 55 | SB(s)m | Sculptor | |
| Aquarius Dwarf (DDO 210) | Im V | Aquarius | |
| NGC 404 | E0 or SA(s)0− | Andromeda | |
| NGC 1569 | Irp+ III-IV | Camelopardalis | |
| NGC 1560 (IC 2062) | Sd | Camelopardalis | |
| Camelopardalis A | Irr | Camelopardalis | |
| Argo Dwarf | Irr | Carina | |
| ESO 347-8 (2318–42) | Irr | Grus | |
| UKS 2323-326 | Irr | Sculptor | |
| UGC 9128 (DDO 187) | Irp+ | Boötes | |
| Sextans C | |||
| objects in local group no longer recognised as galaxies | |||
| name | type | constellation | notes |
| Palomar 12 (Capricornus Dwarf) | Capricornus | a globular cluster formerly classified as a dwarf spheroidal galaxy | |
| Palomar 4 (originally designated Ursa Major Dwarf) | Ursa Major | a globular cluster formerly classified as a dwarf spheroidal galaxy | |
- ↑ http://www.atlasoftheuniverse.com/galaxies.html
- ↑ (April 2000)"Updated Information on the Local Group". The Publications of the Astronomical Society of the Pacific 112 (770): 529–536. DOI:10.1086/316548.