Messier objects: The Andromeda Galaxy M31 and its satellites M32 and M110, as well as the Triangulum Galaxy M33.
Other members (over 30 in all) include our Milky Way Galaxy, the Large and the Small Magellanic Cloud (LMC and SMC), which have been known before the invention of the telescope, as well as several smaller galaxies which were discovered more recently. These galaxies are spread in a volume of nearly 10 million light years diameter, centered somewhere between the Milky Way and M31. Membership is not certain for all these galaxies, and there are possible other candidate members.
Of the Local Group member galaxies, the Milky Way and M31 are by for the most massive, and therefore dominant members. Each of these two giant spirals has accumulated a system of satellite galaxies, where
The other members cannot be assigned to one of the main subgroups, and float quite alone in the gravitational field of 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 have probably been once part of our galaxy group.
As this shows, the Local Group is not isolated, but in gravitional interaction, and member exchange, with the nearest surrounding groups, notably:
A table of the currently known Local Group member galaxies follows. While the positions are known very acurately, the distances are only very vaguely known for some members, and the sources even disagree for the most prominent members such as M31 and M33. If interested, look at our compilation of distances from various sources. Please note that this table is currently under review, as new data (Hipparcos distances, discovery of new members) keep our knowledge in flow.
Galaxy | RA | Dec | Type | m_v | dim | RV | Dist |
---|---|---|---|---|---|---|---|
WLM | 00:02.0 | -15:28 | IB(s) IV-V | 10.9 | 12 x 4 | - 42 | 4200 |
IC 10 | 00:20.4 | +59:18 | KBm? | 10.3 | 7.3 x 6.4 | - 83 | 4200: |
Cet dw | 00:26.1 | -11:02 | dSph/E4 | 3000: | |||
NGC 147 | 00:33.2 | +48:31 | dE5 pec | 9.5 | 15.0 x 9.4 | + 89 | 2400: |
And III | 00:35.4 | +36:31 | dSph/E2 | 13.5p | 2900: | ||
NGC 185 | 00:39.0 | +84:20 | dE3 pec | 9.2 | 14.5 x 12.5 | + 39 | 2500: |
M110 | 00:41.3 | +41:41 | E5 pec | 8.5 | 19.5 x 12.5 | - 1 | 2900 |
And IV | 00:42.5 | +40:34 | Irr ? | 2900: | |||
M 32 | 00:42.7 | +40:52 | E2 (cE2) | 8.1 | 11.0 x 7.3 | + 35 | 2900 |
M 31 | 00:42.7 | +41:16 | SA(s)b I-II | 3.4 | 185.0 x 75.0 | - 59 | 2900 |
And I | 00:45.7 | +38:00 | dSph/E3 pec ? | 13.2 | 2900: | ||
SMC | 00:51.7 | -73:14 | SB(s)m pec | 2.3 | 280 x 160 | - 30 | 210 |
Scl dw | 01:00.0 | -33:42 | dSph/E3 pec | 10.5p | +162 | 300: | |
LGS 3 | 01:03.8 | +21:53 | Irr | 15.4p | 2 | 3000: | |
IC 1613 | 01:05.1 | +02:08 | IAB(s)m V | 9.2 | 20.0 x 18.5 | -125 | 2900: |
And V | 01:10.3 | +47:38 | dSph | 2900: | |||
And II | 01:16.4 | +33:27 | dSph/E0 | 13: | 2900: | ||
M 33 | 01:33.9 | +30:39 | SA(s)cd II-III | 5.7 | 67.0 x 41.5 | + 3 | 3000 |
Phe dw | 01:49.0* | -44:42* | Irr | 1600: | |||
For dw | 02:39.9 | -34:32 | dSph/E2 | 8.1 | 12.0 x 10.2 | 530: | |
UGCA 86 | 03:59.9 | +67:08 | Irr ? S0 ? | +262 | | ||
UGCA 92 | 04:27.4 | +63:30 | Irr ? S0 ? | + 66 | 3000: | ||
LMC | 05:19.7 | -68:57 | SB(s)m | 0.1 | 650 x 550 | + 13 | 179 |
Car dw | 06:14.6 | -50:58 | dSph/E3 | 20.9p | 300: | ||
Leo A | 09:59.4 | +30:45 | IBm V | 7000: | |||
Sex B | 10:00.0 | +05:20 | Ir+ IV-V | 4000: | |||
NGC 3109 | 10:03.1 | -26:09 | Ir+ IV-V | 10. p | 16.0 x 2.9 | +131 | 4100: |
Ant dw | 10:04.1 | -27:20 | dSph/E3 | 14.8 | 4100: | ||
Leo I | 10:05.5 | +12:19 | dE3 | 9.8 | 880: | ||
Sex A | 10:11.1 | -04:43 | Ir+ V | 4000: | |||
Sex dw | 10:13.2 | -01:37 | dSph/E3 | 300: | |||
Leo II | 11:13.5 | +22:10 | dSph/E0 pec | 800: | |||
GR 8 | 12:58.7 | +14:13 | Im V | 14.5 | 1.2 x 1.1 | +165 | 5000: |
UMi dw | 15:08.8 | +67:12 | dSph/E4 | 10.9 | 41.0 x 26.0 | 240: | |
Dra dw | 17:20.1 | +57:55 | dSph/E0 pec | 9.9 | 51.0 x 31.0 | 280 | |
Milky Way | 17:45.6 | -28:56 | SAB(s)bc I-II ? | - | 0 | 28 | |
SagDEG | 18:55 | -30:30 | dSph/E7 | 80 | |||
SagDIG | 19:30.1 | -17:42 | IB(s)m V | 15: | 2000: | ||
NGC 6822 | 19:44.9 | -14:49 | IB(s)m IV-V | 9 | + 66 | 1700: | |
Aqr dw | 20:46.8 | -12:51 | Im V | 13.9 | 2.3 x 1.2 | 2000: | |
IC 5152 | 22:06.1 | -51:17 | IAB(s)m IV | 10.6 | 4.9 x 3.0 | + 30 | 3000: |
Tuc dw | 22:41.7 | -64:25 | dSph/E5 | 3000: | |||
And VII | 23:27.8 | +50:35 | dSph | 2900: | |||
Peg dw | 23:28.6 | +14:45 | Im V | 6000: | |||
And VI | 23:51.7 | +24:36 | dSph | 2900: |
Below we list some nearby but probably non-member field galaxies (which are also not members of one of the neighboring groups listed above), in the same format as above:
Galaxy | RA | Dec | Type | m_v | dim | RV | Dist |
---|---|---|---|---|---|---|---|
NGC 404 | 01:09.4 | +35:43 | E0 | 10.1 | 4.4 x 4.1 | +178 | 8000: |
Argo dw | 07:04.5* | -58:27* | Irr | 12000: | |||
2318-42 | 23:18.1* | -42:00* | Irr | | |||
UKS2323-326 | 23:23.8* | -32:40* | Irr | 4500: |
Key:
Galaxy | Other name | R | Diam | Mass |
---|---|---|---|---|
WLM | (*) | 8 | ? | |
IC 10 | | |||
Cet dw | | |||
NGC 147 | DDO 3 | | ||
And III | | |||
NGC 185 | | |||
M 110 | NGC 205 | 17 | 10000 | |
And IV | (*) | | ||
M 32 | NGC 221 | 8 | 3000 | |
M 31 | NGC 224 | 195 | 400000 | |
And I | | |||
SMC | NGC 292 | 25 | 6000 | |
Scl dw | E351-G30 | | ||
LGS 3 | Psc dw | (*) | | |
IC 1613 | DDO 8 | | ||
And V | | |||
And II | | |||
M 33 | NGC 598 | 60 | 25000 | |
Phe dw | (I) | | ||
For dw | E356-G04 | | ||
UGCA 86 | (?) | | ||
UGCA 92 | EGB0427+63 | (I) | | |
LMC | 30 | 20000 | ||
Car dw | E206-G220 | | ||
Leo A | Leo III | (?) | | |
Sex B | DDO 70 | (I) | | |
NGC 3109 | (I) | | ||
Ant dw | (I) | 5 | | |
Leo I | Regulus G. | | ||
Sex A | DDO 75 | | ||
Sex dw | | |||
Leo II | Leo B | | ||
GR 8 | DDO 155 | (?) | | |
UMi dw | DDO 199 | | ||
Dra dw | DDO 208 | | ||
Milky Way | 100 | 750000 | ||
SagDEG | Sgr dShp | (*) | | |
SagDIG | Sgr dw | (*) | | |
NGC 6822 | Barnard's | | ||
Aqr dw | DDO 210 | (?) | | |
IC 5152 | (?) | | ||
Tuc dw | | |||
And VII | Cas dSph | | ||
Peg dw | DDO 216 | | ||
And VI | Peg dSph | |
Key:
Various sources have listed other Local Group candidates which however have not been confirmed:
Galaxy | listed | Rem |
---|---|---|
1010-27 | McGraw | (= Ant dw ?) |
DDO 187 | McGraw | |
UMa dw | LGAA | |
Sex C | LGAA | |
Jeff Bondono has compiled a comprehensive list of Local Group member and member candidate galaxies.
This page has been used in the sci.astro FAQ
Last Modification: 31 Dec 1999, 17:00 MET