M81 Group

M81 Group
Messier 81 HST.jpg
Observation data (Epoch J2000)
Constellation(s)Ursa Major/Camelopardalis
Brightest memberM81[1] (pictured)
Number of galaxies34[1]
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 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[]

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 6.9
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[]

Messier 81, Messier 82, and NGC 3077 are all strongly interacting with each other.[5] Observations of the 21-centimeter hydrogen line indicate how the galaxies are connected.[6] 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] Bridges of neutral hydrogen have been shown to connect M81 with M82 and NGC 3077.[6][7] 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] Computer simulations of tidal interactions have been used to show how the current structure of the group could have been created.[8]

Gallery[]

External links[]

References[]

  1. ^ a b c d e 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.
  6. ^ a b Chynoweth, Katie M.; et al. (2008). "Neutral Hydrogen Clouds in the M81/M82 Group". The Astronomical Journal. 135 (2008 June): 1983–1992. doi:10.1088/0004-6256/135/6/1983.
  7. ^ Hulst, J. M. van der (1978). "The Structure and Kinematics of the Neutral Hydrogen Bridge Between M 81 and NGC 3077". Astronomy and Astrophysics. 75 (1–2): 97–111.
  8. ^ Yun, M. S. (1999). "Tidal Interactions in M81 Group". Galaxy Interactions at Low and High Redshift, Proceedings of IAU Symposium. 186.
  9. ^ "The mysteries of UGC 8201". Retrieved 18 June 2015.