M81 group
The M81 group is a group of galaxies that is in close proximity to the Local Group . In addition to the Milky Way , the local group also includes the Andromeda Galaxy . The best-known members of the M81 group are the two galaxies Messier 81 (M81), from which the name is derived, and Messier 82 (M82). In total, around 60 galaxies belong to this group, with seven large galaxies among them.
Discovery story
The first members of the M81 group were already known towards the end of the 18th century. The group's two best-known galaxies, M81 and M82, were discovered on December 31, 1774 by the German astronomer Johann Elert Bode . Irrespective of this, both galaxies were found in August 1779 by Pierre Méchain , who had them included in his catalog by Charles Messier . All NGC objects in the M81 group were sighted and cataloged by Wilhelm Herschel between 1788 and 1801 .
morphology
The M81 group extends over the constellations Great Bear and Giraffe and has an angular extent of about 40 ° × 20 °, which corresponds to about 1.8 × 0.9 megaparsecs or 5.87 × 2.93 million light years .
The distance from our sun to the center of the galaxy cluster is about 12 million light years . This makes the M81 group of our local group the second closest galaxy cluster. A little closer are parts of the Sculptor group , a galaxy cluster whose center is also about 12 million light years away.
The M81 group and the local group belong with some other galaxy groups to the Virgo supercluster , the center of which is the Virgo galaxy cluster . Due to the small redshift of the members of the M81 group, it can be assumed that the M81 group, like the local group, is moving towards the center of the Virgo galaxy cluster. The center of the M81 group is formed by the galaxies M81, M82 and NGC 3077, as well as a few other spiral and irregular dwarf galaxies .
The mass of visible matter including the calculated mass of dark matter is (1.6 ± 0.3) · 10 12 M ☉ .
Galaxies in the M81 group
Surname | Other names |
Type | Rect. ( J2000.0 ) | Dec. ( J2000.0 ) | Distance to the sun (million ly ) |
Helligk. m |
Red shift ( km / s ) |
Apparent diameter |
Absolute diameter light years |
Mass [ M ☉ ] |
---|---|---|---|---|---|---|---|---|---|---|
M81 | NGC 3031 | SA (s) from | 09h55m33s | + 69 ° 03'55 " | 11.84 | +6.9 | −34 ± 4 | 26.9 '× 14.1' | 95,000 | |
NGC 2403 | SAB (s) cd | 07h36m51s | + 65 ° 36'09 " | 10.76 | +8.93 | 131 ± 3 | 21.9 'x 12.3' | 75,000 | ||
NGC 4236 | SB (s) dm | 12h16m42s | + 69 ° 27'45 " | 14.51 | +10.05 | 0 ± 4 | 21.9 'x 7.2' | 75,000 | ||
IC 2574 | SAB (s) m | 10h28m23s | + 68 ° 24'44 " | 13.11 | +10.8 | 57 ± 2 | 13.2 'x 5.4' | 45,000 | ||
M82 | NGC 3034 | I0 | 09h55m52s | + 69 ° 40'47 " | 11.51 | +9.3 | 203 ± 4 | 11.2 '× 4.3' | 40,000 | |
NGC 2366 | IB (s) m | 07h28m55s | + 69 ° 12'57 " | 10.40 | +10.91 | 80 ± 1 | 8.1 '× 3.3' | 30,000 | ||
UGC 4305 | Holmberg II | in the | 08h19m05s | + 70 ° 43'12 " | 11.06 | +11.1 | 142 ± 1 | 7.9 '× 6.3' | 30,000 | |
NGC 2976 | SAc | 09h47m15s | + 67 ° 54'59 " | 11.61 | +10.82 | 3 ± 5 | 5.9 'x 2.7' | 20,000 | ||
NGC 3077 | I0 | 10h03m19s | + 68 ° 44'02 " | 12.46 | +10.61 | 14 ± 4 | 5.4 'x 4.5' | 20,000 | ||
NGC 4605 | SB (s) c | 12h39m59s | + 61 ° 36'33 " | 16.96 | +10.1 | 143 ± 5 | 5.8 'x 2.2' | 20,000 | ||
UGC 5139 | Holmberg I. | IAB (s) m | 09h40m32s | + 71 ° 10'56 " | 12.52 | +13 | 139 ± 0 | 3.6 '× 3' | 15,000 | 5.5 · 10 8 |
NGC 5204 | SA (s) w | 13h29m37s | + 58 ° 25'07 " | 14.51 | +11.73 | 201 ± 1 | 5 '× 3' | 15,000 | ||
NGC 3738 | Insane | 11h35m49s | + 54 ° 31'26 " | 15.49 | +12.13 | 229 ± 4 | 2.5 'x 1.9' | 10,000 | ||
UGC 5336 | Holmberg IX | in the | 09h57m32s | + 69 ° 02'45 " | 12.06 | +14.3 | 46 ± 6 | 2.5 '× 2' | 10,000 | |
UGC 5692 | DDO 82 | Sm | 10h30m35s | + 70 ° 37'07 " | 13.05 | +13.47 | 56 ± 3 | 3.2 '× 1.8' | 10,000 | |
UGC 5918 | DDO 87 | in the | 10h49m37s | + 65 ° 31'50 " | 24.14 | +15.1 | 340 ± 1 | 2.4 '× 2.4' | 10,000 | |
UGC 8201 | DDO 165 | in the | 13h06m25s | + 67 ° 42'25 " | 14.91 | +12.8 | 31 ± 0 | 3.5 '× 1.9' | 10,000 | |
UGCA 133 | DDO 44 | in the | 07h34m11s | + 66 ° 53'10 " | 10.40 | +15.64 | 3 '× 2' | 10,000 | ||
PGC 23521 | M81 dwarf A, KDG 52 | I. | 08h23m56s | + 71 ° 01'45 " | 11.58 | +16.5 | 133 ± 0 | 1.3 '× 0.7' | 5,000 | |
PGC 30664 | DDO 78 | in the | 10h26m27s | + 67 ° 39'16 " | 12.13 | +15.8 | 55 ± 10 | 2 '× 2' | 5,000 | |
UGC 3794 | Sm | 07h22m51s | + 77 ° 48'23 " | +16.5 | 2656 ± 4 | 1.5 '× 1.3' | 5,000 | |||
UGC 4459 | DDO 53 | in the | 08h34m07s | + 66 ° 10'54 " | 11.61 | +14.48 | 20 ± 0 | 1.5 '× 1.3' | 5,000 | |
UGC 4483 | BCG | 08h37m03s | + 69 ° 46'31 " | 10.47 | +15.12 | 156 ± 0 | 1.4 'x 0.7' | 5,000 | ||
UGC 4945 | UGCA 158 | in the | 09h22m25s | + 75 ° 45'57 " | 17.29 | +17 | 659 ± 1 | 1.3 '× 1.1' | 5,000 | |
UGC 5423 | M81 dwarf B | in the | 10h05m31s | + 70 ° 21'52 " | +15.19 | 347 ± 1 | 0.9 '× 0.6' | 5,000 | ||
UGC 5428 | DDO 71 | in the | 10h05m06s | + 66 ° 33'32 " | 11.42 | +18 | −129 ± 0 | 0.9 '× 0.9' | 5,000 | |
UGC 5442 | KDG 64 | in the | 10h07m02s | + 67 ° 49'39 " | 12.07 | +18 | −18 ± 14 | 1.8 'x 0.9' | 5,000 | |
UGC 6456 | 11h27m60s | + 78 ° 59'39 " | 14.16 | +14.5 | −103 ± 0 | 1.4 '× 0.8' | 5,000 | |||
UGCA 220 | in the | 10h49m23s | + 64 ° 43'20 " | +16.9 | 1.7 'x 1.2' | 5,000 | ||||
UGCA 105 | in the | 05h14m15s | + 62 ° 34'48 " | 10.63 | +13.9 | 111 ± 5 | 5.5 '× 3.5' | |||
NGC 4144 | SAB (s) cd | 12h09m59s | + 46 ° 27'26 " | 31.96 | +12.05 | 265 ± 1 | 6 '× 1.3' | |||
Cam A | Insane | 04h25m16s | + 72 ° 48'21 " | 12.33 | +14.84 | −46 ± 1 | 3.7 '× 2.1' | |||
IKN | 10h08m06s | + 68 ° 23'57 " | 12.09 | +17 | 2.7 '× 2.3' | |||||
NGC 4068 | IC 757 | I am | 12h04m01s | + 52 ° 35'18 " | 17.29 | +13 | 210 ± 3 | 3.3 '× 1.7' | ||
F8D1 | dE | 09h44m47s | + 67 ° 26'19 " | 12.3 | +13.85 | 2.2 '× 2' | ||||
KK 77 | dSph | 09h50m11s | + 67 ° 30'24 " | 11.35 | +16.2 | 2.4 '× 1.8' | ||||
PGC 28759 | Arp's Loop, A0952 | 09h57m33s | + 69 ° 17'00 " | 12.62 | +16.08 | 99 ± 0 | 1.8 '× 1.6' | |||
NGC 2537 | SB (s) w | 08h13m15s | + 45 ° 59'23 " | 22.51 | +12.32 | 431 ± 1 | 1.7 'x 1.5' | |||
Cam B | Insane | 04h53m07s | + 67 ° 05'57 " | 10.8 | +16.1 | 77 ± 0 | 2.2 '× 1.1' | |||
UGC 4426 | DDO 52 | in the | 08h28m28s | + 41 ° 51'24 " | 18.59 | +15 | 397 ± 4 | 2 '× 1' | ||
UGC 8508 | I am | 13h30m44s | + 54 ° 54'36 " | 8.35 | +14.4 | 62 ± 5 | 1.7 '× 1' | |||
UGC 7242 | Scd | 12h14m08s | + 66 ° 05'41 " | 14.03 | +14.6 | 68 ± 2 | 1.9 'x 0.8' | |||
UGC 6541 | Insane | 11h33m29s | + 49 ° 14'14 " | 12.92 | +14.5 | 250 ± 1 | 1.2 '× 0.7' | |||
HS 117 | Ir | 10h21m25s | + 71 ° 06'51 " | 12.07 | +16.5 | −37 ± 0 | 1.5 'x 0.9' | |||
PGC 28731 | KDG 61 | dE | 09h57m03s | + 68 ° 35'31 " | 11.74 | +15.6 | −135 ± 30 | 1.2 '× 1' | ||
VKN | 08h40m09s | + 68 ° 26'23 " | 11.09 | +17.7 | 0.9 '× 0.9' | |||||
PGC 31286 | BK6N | dSph | 10h34m30s | + 66 ° 01'00 " | 12.56 | +16.7 | 1 '× 0.8' | |||
UGC 7298 | in the | 12h16m30s | + 52 ° 13'39 " | 13.6 | +15 | 173 ± 0 | 1.3 '× 0.6' | |||
FM1 | dSph | 09h45m10s | + 68 ° 45'54 " | 11.15 | +17.5 | 0.9 '× 0.8' | ||||
PGC 29231 | BK5N | dE | 10h04m41s | + 68 ° 15'22 " | 12.33 | +16.72 | 0.8 '× 0.6' | |||
UGCA 281 | Sm | 12h26m16s | + 48 ° 29'37 " | 18.59 | +15.15 | 281 ± 4 | 0.8 '× 0.6' | |||
KKH 34 | Mailyan 13 | Ir | 05h59m40s | + 73 ° 25'40 " | 16.9 | +17.1 | 110 ± 0 | 0.6 '× 0.5' | ||
KKH 57 | Sph | 10h00m16s | + 63 ° 11'06 " | 12.82 | +18.5 | 0.6 '× 0.5' | ||||
KK 109 | dIrr | 11h47m12s | + 43 ° 40'18 " | 15.33 | +17.5 | 212 ± 1 | 0.6 '× 0.4' | |||
KKH 87 | Ir | 14h15m09s | + 57 ° 05'15 " | 22.18 | +16.5 | 320 ± 1 | 0.8 '× 0.3' | |||
PGC 28529 | BK3N | in the | 09h53m49s | + 68 ° 58'08 " | 13.11 | +17.1 | −40 ± 0 | 0.5 '× 0.4' | ||
PGC 32667 | KDG 73 | in the | 10h52m57s | + 69 ° 32'58 " | 12.07 | +14.9 | 116 ± 1 | 0.6 '× 0.4' | ||
KKH 79 | Ir | 12h19m52s | + 61 ° 31'11 " | 20.87 | +17.5 | 516 ± 1 | 0.44 'x 0.2' | |||
PGC 29167 | Garland | in the | 10h03m42s | + 68 ° 41'36 " | 50 ± 0 | |||||
HIJASS J1021 + 6842 | HI | 10h21m00s | + 68 ° 42'00 " | 12.07 | +20 | 46 ± 0 |
The table is compiled from the information from Atlas of the Universe and The M81 group of Galaxies: New distances, kinematics and structure (2002) . The data for the type, the coordinates, brightness and the apparent diameter are taken from the NASA / IPAC Extragalactic Database . The data can be called up in the NED database using the designations in the Name column (exceptions: KK = KK98, HS = HS98, FM = FM2000). The distances are from Karachentsev's work in 2005 and 2002.
See also
- Structure of the cosmos
- List of the brightest galaxies
- Position of the earth in the universe
- Local group
- Maffei group
- M83 group
- Sculptor group
- Canes Venatici I group
Web links
- Stars and Space, The M81 Group
- Galaxy group M81 in different images
- SEDS Description of the M81 group
- SEDS Messier Galaxy Groups
- Atlas of the Universe
- Inventory of the known dwarf galaxies in the M81 group
- Ursa Major A, M82 (history)
- The M81 group of galaxies: New distances, kinematics and structure (2002), bibcode : 2002A & A ... 383..125K
- The Local Group and Other Neighboring Galaxy Groups, Karachentsev 2005, bibcode : 2005AJ .... 129..178K
- Nearby Groups of Galaxies
- M81 group in NASA / IPAC EXTRAGALACTICAL DATABASE
- Spektrum.de : Collection of amateur recordings from Messier 81 , 82 & surroundings