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Local Group





A collection of more than 40 galaxies, spread across a volume of space some 10 million light-years in diameter, of which our own Milky Way Galaxy and the Andromeda Galaxy are the dominant and central members. Both these two giant spirals have retinues of satellite galaxies, which together account for most of the membership of the Local Group.

Local Group

The Milky Way's satellites include: the Large Magellanic Cloud, the Small Magellanic Cloud, the Sagittarius Dwarf Elliptical, the Ursa Minor Dwarf, the Draco Dwarf, the Carina Dwarf, the Sextans Dwarf, the Sculptor Dwarf, the Fornax Dwarf, Leo I, and Leo II. Among the retinue of the Andromeda Galaxy are: M32 , M110, the fainter and more faraway NGCs 147 and 185, the very faint systems And I, And II, And III, and possibly And IV, And V, And VI (the Pegasus Dwarf), and And VII (the Cassiopeia Dwarf). The third-largest galaxy, the Triangulum Galaxy (M33), may or may not be an outlying gravitationally-bound companion of M31, but has itself probably the dwarf LGS 3 as a satellite. The other members of the Local Group, including the Antlia Dwarf and Wolf-Lundmark-Melotte Galaxy, fall outside the main subgroups and float alone in the gravitational seas between the giant group members.

The substructures of the group are probably not stable. Observations and calculations suggest that the group is highly dynamic and has changed significantly in the past. The galaxies around the large elliptical Maffei 1 (see Maffei 1 Group, for example, were probably once part of our galaxy group. Indeed, the Local Group is not isolated but is in gravitational interaction and member exchange with the nearest surrounding groups, notably the Maffei 1 Group, the Sculptor Group, the M81 Group, and the M83 Group. In the future, interaction between the member galaxies and with the cosmic neighborhood will continue to change the Local Group. Some astronomers speculate that the two large spirals, our Milky Way and the Andromeda Galaxy, may collide and merge to form a giant elliptical. Also, there is evidence that our nearest big cluster of galaxies, the Virgo Cluster, will probably stop our cosmological recession away from it, accelerate the Local Group toward itself, and so eventually assimilate the Local Group into its collection.


galaxy R.A. dec. type abs.
mag.
diameter
(lt. yr.)
rad. vel.
(km/s)*
distance
(lt. yr.)
Milky Way Galaxy 17:45.6 -28:56 SBbc I-II -20.6 90,000 0 28,000
Sagittarius Dwarf Elliptical 18:55 -30:30 dSph(E7) -14.0 10,000   78,000
Large Magellanic Cloud 05:19.7 -68:57 Irr III-IV -18.1 30,000 +119 179,000
Small Magellanic Cloud 00:51.7 -73:14 Irr IV-V -16.2 16,000 +34 210,000
Ursa Minor Dwarf 15:08.8 +67:12 dSph -8.9 2,000 -47 215,000
Sculptor Dwarf 01:00.0 -33:42 dSph -10.7 3,000 +115 260,000
Draco Dwarf 17:20.1 +57:55 dSph -8.6 3,000 -87 270,000
Sextans Dwarf 10:13.2 -01:37 dSph -10.0 4,000   280,000
Carina Dwarf 06:14.6 -50:58 dSph -9.92 2,000 +13 330,000
Fornax Dwarf 02:39.9 -34:32 dSph -13.0 6,000 -41 450,000
Leo II 11:13.5 +22:10 dSph -10.2 3,000 +36 670,000
Leo I 10:08.5 +12:18 dE3 -12.0 3,000 +60 820,000
Phoenix Dwarf 01:51.1 -44:27 dIrr/dSph -9.9 2,000   1,450,000
NGC 6822 (Barnard's Galaxy) 19:44.9 -14:49 Irr IV-V -16.4 8,000 +44 1,600,000
Andromeda II 01:16.4 +33:27 dSph -11.7 2,000   1,700,000
NGC 185 00:39.0 +84:20 dSph/dE3 -15.3 8,000 +39 2,000,000
Leo III (Leo A) 09:59.4 +30:45 dIrr -11.7 4,000 -19 2,250,000
Andromeda VII 23:27.8 +50:35 dSph -12.0 2,000   2,250,000
IC 1613 01:05.1 +02:08 Irr V -14.9 10,000 -152 2,300,000
NGC 147 00:33.2 +48:31 dSph/dE5 -14.8 10,000 +28 2,350,000
Andromeda III 00:35.4 +36:31 dSph -10.2 3,000   2,500,000
Cetus Dwarf 00:26.1 -11:02 dSph -10.1 3,000   2,550,000
Andromeda VI 23:51.7 +24:36 dSph -11.3 3,000   2,550,000
Aquarius Dwarf 20:46.8 -12:51 dIrr/dSph 2     -23 2,600,000
M32 00:42.7 +40:52 dE2 -16.4 8,000 -28 2,600,000
Andromeda I 00:45.7 +38:00 dSph -11.7 2,000   2,600,000
Andromeda V 01:10.3 +47:38 dSph -9.1     2,650,000
LGS 3 (Pisces Dwarf) 01:03.8 +21:53 dIrr/dSph -9.7 2,000 -149 2,650,000
Andromeda Galaxy (M31) 00:42.7 +41:16 Sb I-II -21.1 140,000 -121 2,650,000
M110 (NGC 205) 00:41.3 +41:41 dSph/dE5 -16.3 15,000 -60 2,650,000
IC 10 00:20.4 +59:18 dIrr -17.6 8,000 -146 2,700,000
Triangulum Galaxy (M33) 01:33.9 +30:39 Sc II-III -18.9 55,000 -46 2,850,000
Tucana Dwarf 22:41.7 -64:25 dSph -9.6 2,000   2,850,000
Wolf-Lundmark-Mellote 00:02.0 -15:28 Irr IV-V -14.0 10,000 -61 3,000,000
Pegasus Dwarf 23:28.6 +14:45 dIrr/dSph -12.7 2,000 -20 3,100,000
Sagittarius Dwarf Irregular 19:30.1 -17:42 dIrr -11.0 3,000 +8 3,450,000
Antlia Dwarf 10:04.1 -27:20 dSph -10.7 3,000   4,000,000
NGC 3109 10:03.1 -26:09 Irr IV-V -15.8 25,000 +194 4,100,000
UGC-A92 04:27.4 +63:30 dIrr   3,000 +66 4,200,000
UKS 2323-326 23:26.5 -32:23 dIrr -13.1 3,000 +74 4,300,000
Sextans B 10:00.0 +05:20 dIrr -14.4 8,000 +168 4,400,000
Sextans A 10:11.1 -04:43 dIrr -14.3 10,000 +164 4,700,000
IC 5152 22:06.1 -51:17 dIrr   8,000 +80 5,200,000
GR 8 12:58.7 +14:13 dIrr -12.5 2,000 +183 5,200,000

*Radial velocity with respect to center of the Milky Way Galaxy



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   • GALAXIES