M81 Group

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M81 Group
Messier 81 HST.jpg
Observation data (Epoch J2000)
Constellation(s) Ursa Major/Camelopardalis
Other designations
NGC 3031 Group
See also: Galaxy groups, Galaxy clusters, List of galaxy clusters

The M81 Group is a galaxy group in the constellations Ursa Major and Camelopardalis that includes the well-known galaxies Messier 81 and Messier 82, as well as several other galaxies with high apparent brightnesses.[1] The approximate center of the group is located at a distance of 3.6 Mpc, making it one of the nearest groups to the Local Group.[1] The group is estimated to have a total mass of (1.03 ± 0.17)×1012M.[2] The M81 Group, the Local Group, and other nearby groups all lie within the Virgo Supercluster (i.e. the Local Supercluster).[3]



Members[edit]

The table below lists galaxies that have been identified as associated with the M81 Group by I. D. Karachentsev.[1]

Members of the M81 Group
Name Type[4] R.A. (J2000)[4] Dec. (J2000)[4] Redshift (km/s)[4] Apparent Magnitude[4]
Arp's Loop 09h 57m 32.6s +69° 17′ 00″ 99 16.1
DDO 78 Im 10h 26m 27.4s +67° 39′ 16″ 55 ± 10 15.8
F8D1 dE 09h 44m 47.1s +67° 26′ 19″ 13.9
FM1 dSph 09h 45m 10.0s +68° 45′ 54″ 17.5
HIJASS J1021+6842 10h 21m 00.0s +68° 42′ 00″ 46 20
HS 117 I 10h 21m 25.2s +71° 06′ 51″ -37 16.5
Holmberg I IAB(s)m 09h 40m 32.3s +71° 10′ 56″ 139 ± 0 13.0
Holmberg II Im 08h 19m 05.0s +70° 43′ 12″ 142 ± 1 11.1
Holmberg IX Im 09h 57m 32.0s +69° 02′ 45″ 46 ± 6 14.3
IC 2574 SAB(s)m 10h 28m 23.5s +68° 24′ 44″ 57 ± 2 13.2
IKN 10h 08m 05.9s +68° 23′ 57″ 17.0
KKH 57 dSph 10h 00m 16.0s +63° 11′ 06″ 18.5
Messier 81 SA(s)ab 09h 55m 33.2s +69° 03′ 55″ -34 ± 4 7.9
Messier 81 Dwarf A I 08h 23m 56.0s +71° 01′ 45″ 113 ± 0 16.5
Messier 82 I0 09h 55m 52s +69° 40′ 47″ 203 ± 4 9.3
NGC 2366 IB(s)m 07h 28m 54.7s +69° 12′ 57″ 80 ± 1 11.4
NGC 2403 SAB(s)cd 07h 36m 51.4s +65° 36′ 09″ 131 ± 3 8.9
NGC 2976 SAc pec 09h 47m 15.5s +67° 54′ 59″ 3 ± 5 10.8
NGC 3077 I0 pec 10h 03m 19.1s +68° 44′ 02″ 14 ± 4 10.6
NGC 4236 SB(s)dm 12h 16m 42s +69° 27′ 45″ 0 ± 4 10.1
PGC 28529 Im 09h 53m 48.5s +68° 58′ 08″ -40 17.1
PGC 28731 dE 09h 57m 03.1s +68° 35′ 31″ -135 ± 30 15.6
PGC 29231 dE 10h 04m 41.1s +68° 15′ 22″ 16.7
PGC 31286 dSph 10h 34m 29.8s +66° 00′ 30″ 16.7
PGC 32667 Im 10h 52m 57.1s +69° 32′ 58″ 116 ± 1 14.9
UGC 4459 Im 08h 34m 07.2s +66° 10′ 54″ 20 ± 0 14.5
UGC 4483 08h 37m 03.0s +69° 46′ 31″ 156 ± 0 15.1
UGC 5428 Im 10h 05m 06.4s +66° 33′ 32″ -129 ± 0 18
UGC 5442 Im 10h 07m 01.9s +67° 49′ 39″ -18 ± 14 18
UGC 5692 13.5 10h 30m 35.0s +70° 37′ 07.2″ 56 ± 3 13.5
UGC 6456 Pec 11h 27m 59.9s +78° 59′ 39″ -103 ± 0 14.5
UGC 7242 Scd 12h 14m 08.4s +66° 05′ 41″ 68 ± 2 14.6
UGC 8201 Im 13h 06m 24.9s +67° 42′ 25″ 31 ± 0 12.8
UGCA 133 Im 07h 34m 11.4s +66° 53′ 10″ 15.6

Note that the object names used in the above table differ from the names used by Karachentsev. NGC, IC, UGC, and PGC numbers have been used in many cases to allow for easier referencing.

Interactions within the group[edit]

Messier 81, Messier 82, and NGC 3077 are all strongly interacting with each other.[5] The gravitational interactions have stripped some hydrogen gas away from all three galaxies, leading to the formation of filamentary gas structures within the group.[5] Moreover, the interactions have also caused some interstellar gas to fall into the centers of Messier 82 and NGC 3077, which has led to strong starburst activity (or the formation of many stars) within the centers of these two galaxies.[5]

External links[edit]

References[edit]

  1. ^ a b c I. D. Karachentsev (2005). "The Local Group and Other Neighboring Galaxy Groups". Astronomical Journal 129 (1): 178–188. arXiv:astro-ph/0410065. Bibcode:2005AJ....129..178K. doi:10.1086/426368. 
  2. ^ 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. 
  3. ^ R. B. Tully (1982). "The Local Supercluster". Astrophysical Journal 257: 389–422. Bibcode:1982ApJ...257..389T. doi:10.1086/159999. 
  4. ^ a b c d e "NASA/IPAC Extragalactic Database". Results for various galaxies. Retrieved 2007-02-09. 
  5. ^ a b c M. S. Yun, P. T. P. Ho, K. Y. Lo (1994). "A high-resolution image of atomic hydrogen in the M81 group of galaxies". Nature 372 (6506): 530–532. Bibcode:1994Natur.372..530Y. doi:10.1038/372530a0. PMID 7990925.