Coma I

Not to be confused with Coma Cluster.

The Coma I Group is a group of galaxies^[3][1] located about 14.5 Mpc (47.3 Mly)^[7] away in the constellation Coma Berenices. The brightest member of the group is NGC 4725. The Coma I Group is rich in spiral galaxies while containing few elliptical and lenticular galaxies. Coma I lies in the foreground of the more distant Coma and Leo clusters and is located within the Virgo Supercluster.^[3]

Coma I Group
NGC 4414, a flocculent spiral galaxy in the Coma I Group
Observation data (Epoch J2000)
Constellation(s)	Coma Berenices & Ursa Major
Right ascension	12h 22m 19.4s[1][2]
Declination	29° 53′ 47″[1][2]
Brightest member	NGC 4725[3]
Number of galaxies	22–34[3][4][2][5][6]
Velocity dispersion	307 km/s[7]
Redshift	0.002418 (724 km/s)[1]
Distance	14.52 Mpc (47.4 Mly)[7]
Binding mass	2.5×1012 [3] M☉
X-ray luminosity	1.6×1043 erg/s [8]
Other designations
Coma I Group,[9] NGC 4274 Group,[1] NGC 4062 Group, NGC 4565 Group, NGC 4631 Group, LGG 279, LGG 291, LGG 294[4] NBGG 14-01,[1][5] NBGG 14-02, NBGG 14 -2 +1,[9][5] NGC 4203 Group, NOGG H 611, NOGG P1 631, NOGG P2 642, NOGG P2 641[2]

The Coma I Group is currently infalling into the Virgo Cluster and will eventually merge with it.^[10]

Structure

The Coma I Group appears to consist of two main subgroups, a denser subgroup centered on NGC 4274^[11] and NGC 4278, and looser one surrounding NGC 4565 as suggested by De Vaucouleurs.^[12] However, Gregory and Thompson (1977) found no clear evidence for two distinct subgroups in Coma I. They noted a slight density enhancement around NGC 4274 with the rest of the members of Coma I uniformly distributed to the southeast of this density enhancement. They also noted a central bar-like structure with a minor axis of 0.9 Mpc (2.9 Mly) and a major axis of 2.3 Mpc (7.5 Mly).^[3] P. Fouque et al. and A. M. Garcia et al. both list the Coma I group consisting of two subgroups centered on NGC 4274 and NGC 4565.^[6][4] Additionally, Gibson et al. suggests that another association, the Coma II Group which is centered on NGC 4725 is associated with the Coma I Group.^[9] In 2000, Ferrarese et al. defined the Coma II Group as containing 5 galaxies, namely NGC 4494, NGC 4562, NGC 4565, NGC 4725, and NGC 4747. Also, it was found that these 5 galaxies which make up the Coma II Group have radial velocities in the narrow range of 1190 to 1395 km/s which is larger than the range of galaxies that are part of the Coma I group which have ranges of 600 to 1000 km/s.^[13]

The nearby NGC 4631 Group is sometimes listed in some catalogs as being part of the Coma I Group,^[4][2][14] while other catalogs list the group as being separate from the Coma I Group.^[5][6]

Members

The table below lists galaxies that have been commonly and consistently identified as group members in the Nearby Galaxies Catalog,^[5] the survey of Fouque et al.,^[6] the Lyons Groups of Galaxies (LGG) Catalog,^[4] and the three group lists created from the Nearby Optical Galaxy sample of Giuricin et al.^[2]

Members of the Coma I Group

Name	Type[15]	R.A. (J2000)[15]	Dec. (J2000)[15]	Redshift (km/s)[15]	Apparent Magnitude[15]
NGC 4020	SBd?	11h 58m 56.7s	+30° 24′ 43″	760	13.1
NGC 4062	SA(s)c	12h 04m 03.8s	+31° 53′ 45″	758	12.5
NGC 4136	SAB(r)c	12h 09m 17.7s	+29° 55′ 39″	609	11.69
NGC 4173	SBd	12h 12m 21.4s	+29° 12′ 25″	1127	13.59
NGC 4203	SAB0^-?	12h 15m 05.0s	+33° 11′ 50″	1086	11.8
NGC 4245	SB0/a?(r)	12h 17m 36.8s	+29° 36′ 29″	884	12.31
NGC 4251	SB0?	12h 18m 08.2s	+28° 10′ 31″	1066	11.58
NGC 4274	(R)SB(r)ab	12h 19m 50.6s	+29° 36′ 52″	930	11.34
NGC 4278	E1-2	12h 20m 06.8s	+29° 16′ 51″	620	11.20
NGC 4283	E0	12h 20m 20.8s	+29° 18′ 39″	1056	13.10
NGC 4310 (NGC 4338)	(R')SAB0^+(r)?	12h 22m 26.3s	+29° 12′ 33″	913	13.22
NGC 4314	SB(rs)a	12h 22m 31.8s	+29° 53′ 45″	963	11.43
NGC 4359	SB(rs)c?	12h 24m 11.2s	+31° 31′ 19″	1253	13.6
NGC 4393	SABd	12h 25m 51.2s	+27° 33′ 42″	755	12.7
NGC 4414	SA(rs)c?	12h 26m 27.1s	+31° 13′ 25″	716	10.96
NGC 4448	SB(r)ab	12h 28m 15.4s	+28° 37′ 13″	661	12.00
NGC 4494	E1-2	12h 31m 24.1s	+25° 46′ 31″	1342	10.71
NGC 4525	Scd?	12h 33m 51.1s	+30° 16′ 39″	1172	13.4
NGC 4559	SAB(rs)cd	12h 35m 57.6s	+27° 57′ 36″	807	10.46
NGC 4562	SB(s)dm?	12h 35m 34.8s	+25° 51′ 00″	1353	13.9
NGC 4565	SA(s)b?	12h 36m 20.8s	+25° 59′ 16″	1230	10.42
NGC 4725	SAB(r)ab pec	12h 50m 26.6s	+25° 30′ 03″	1206	10.11
NGC 4747	SBcd? pec	12h 51m 45.9s	+25° 46′ 37″	1190	12.96

Other possible member galaxies (galaxies listed in only one or two of the lists from the above references) include IC 3215, IC 3247, MCG 5-29- 66, NGC 4080, NGC 4150, NGC 4308, NGC 4455, NGC 4509, NGC 4534, NGC 4627, NGC 4631, NGC 4656, NGC 4670, UGC 6900, UGC 7007, UGC 7300, UGC 7428, UGC 7438, UGC 7673, UGC 7916 and UGCA 294.

Nearby groups

The center of the Virgo Cluster (M87) lies about 3.6 Mpc (11.7 Mly) from the Coma I Group.^[3]

See also

• List of Galaxy Groups
• M94 Group
• M96 Group
• Ursa Major Cluster – Another nearby spiral-rich group within the Virgo Supercluster

References

1. "Coma I Group". Retrieved 2018-05-12.
2. G. Giuricin; C. Marinoni; L. Ceriani; A. Pisani (2000). "Nearby Optical Galaxies: Selection of the Sample and Identification of Groups". Astrophysical Journal. 543 (1): 178–194. arXiv:astro-ph/0001140. Bibcode:2000ApJ...543..178G. doi:10.1086/317070. S2CID 9618325.
3. Gregory, Stephen A.; Thompson, Laird A. (April 1977). "The Coma i Galaxy Cloud". The Astrophysical Journal. 213: 345–350. Bibcode:1977ApJ...213..345G. doi:10.1086/155160. ISSN 0004-637X.
4. A. Garcia (1993). "General study of group membership. II – Determination of nearby groups". Astronomy and Astrophysics Supplement. 100: 47–90. Bibcode:1993A&AS..100...47G.
5. R. B. Tully (1988). Nearby Galaxies Catalog. Cambridge: Cambridge University Press. ISBN 0-521-35299-1.
6. P. Fouque; E. Gourgoulhon; P. Chamaraux; G. Paturel (1992). "Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members". Astronomy and Astrophysics Supplement. 93: 211–233. Bibcode:1992A&AS...93..211F.
7. Boselli, A.; Gavazzi, G. (2009-10-21). "The HI properties of galaxies in the Coma I cloud revisited". Astronomy & Astrophysics. 508 (1): 201–207. arXiv:0909.4140. Bibcode:2009A&A...508..201B. doi:10.1051/0004-6361/200912658. ISSN 0004-6361. S2CID 14049523.
8. Garcia-Barreto, J. A.; Downes, D.; Huchtmeier, W. K. (August 1994). "H I deficiency in the Coma I cloud of galaxies" (PDF). Astronomy and Astrophysics. 288: 705–712. Bibcode:1994A&A...288..705G.
9. Gibson, Brad K.; Hughes, Shaun M. G.; Stetson, Peter B.; Freedman, Wendy L.; Robert C. Kennicutt, Jr.; Mould, Jeremy R.; Bresolin, Fabio; Ferrarese, Laura; Ford, Holland C. (1999). "The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XVII. The Cepheid Distance to NGC 4725". The Astrophysical Journal. 512 (1): 48. arXiv:astro-ph/9810003. Bibcode:1999ApJ...512...48G. doi:10.1086/306762. ISSN 0004-637X. S2CID 117635398.
10. Tully, R. B.; Shaya, E. J. (June 1984). "Infall of galaxies into the Virgo cluster and some cosmological constraints". The Astrophysical Journal. 281: 31–55. Bibcode:1984ApJ...281...31T. doi:10.1086/162073. ISSN 0004-637X.
11. "Nearby Groups of Galaxies". ned.ipac.caltech.edu. Retrieved 2018-05-19.
12. Forbes, Duncan A. (October 1996). "Globular Cluster Luminosity Functions and the Hubble Constant From WFPC Imaging: Galaxies in the Coma I Cloud". The Astronomical Journal. 112: 1409. arXiv:astro-ph/9611139. Bibcode:1996AJ....112.1409F. doi:10.1086/118108. ISSN 0004-6256. S2CID 118922735.
13. Ferrarese, Laura; Ford, Holland C.; Huchra, John; Kennicutt, Robert C. Jr.; Mould, Jeremy R.; Sakai, Shoko; Freedman, Wendy L.; Stetson, Peter B.; Madore, Barry F.; Gibson, Brad K.; Graham, John A. (2000-06-01). "A Database of Cepheid Distance Moduli and Tip of the Red Giant Branch, Globular Cluster Luminosity Function, Planetary Nebula Luminosity Function, and Surface Brightness Fluctuation Data Useful for Distance Determinations". The Astrophysical Journal Supplement Series. 128 (2): 431–459. arXiv:astro-ph/9910501. Bibcode:2000ApJS..128..431F. doi:10.1086/313391. ISSN 0067-0049. S2CID 121612286.
14. Makarov, Dmitry; Karachentsev, Igor (2010-11-29). "Galaxy groups and clouds in the Local (z~0.01) universe". Monthly Notices of the Royal Astronomical Society. 412 (4): 2498–2520. arXiv:1011.6277v1. Bibcode:2011MNRAS.412.2498M. doi:10.1111/j.1365-2966.2010.18071.x. S2CID 119194025.
15. "NASA/IPAC Extragalactic Database". Results for various galaxies. Retrieved 2006-10-15.