Virgo Cluster

The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc)[2] away in the constellation Virgo. Comprising approximately 1300 (and possibly up to 2000) member galaxies,[3] the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group (containing the Milky Way galaxy) is an outlying member. The Local Group actually experiences the mass of the Virgo Supercluster as the Virgocentric flow. It is estimated that the Virgo Cluster's mass is 1.2×1015 M out to 8 degrees of the cluster's center or a radius of about 2.2 Mpc.[4]

Many of the brighter galaxies in this cluster, including the giant elliptical galaxy Messier 87, were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier's catalogue of non-cometary fuzzy objects. Described by Messier as nebulae without stars, their true nature was not recognized until the 1920s.[A]

The cluster subtends a maximum arc of approximately 8 degrees centered in the constellation Virgo. Although some of the cluster's most prominent members can be seen with smaller instruments, a 6 inch telescope will reveal about 160 of the cluster's galaxies on a clear night. Its brightest member is the elliptical galaxy Messier 49; however its most famous member is the elliptical galaxy Messier 87, which is located in the center of the cluster.[6]

Virgo Cluster
ESO-M87
Virgo Cluster showing the diffuse light between member galaxies. Messier 87 is the largest galaxy (lower left).
Observation data (Epoch J2000)
Constellation(s) Virgo & Coma Berenices
Right ascension 12h 27m[1]
Declination +12° 43′[1]
Brightest member Messier 49
Number of galaxies ~1500[1]
Bautz-Morgan classification III[1]

Characteristics

The cluster is a fairly heterogeneous mixture of spirals and ellipticals.[7] As of 2004, it is believed that the spiral galaxies of the cluster are distributed in an oblong prolate filament, approximately four times as long as it is wide, stretching along the line of sight from the Milky Way.[8] The elliptical galaxies are more centrally concentrated than the spiral galaxies.[9]

The cluster is an aggregrate of at least three separate subclumps: Virgo A, centered on M87, a second centered on the galaxy M86, and Virgo B, centered on M49, with some authors including a Virgo C subcluster, centered on the galaxy M60 as well as a LVC (Low Velocity Cloud) subclump, centered on the large spiral galaxy NGC 4216.[10]

Of all of the subclumps, Virgo A, formed by a mixture of elliptical, lenticular, and (usually) gas-poor spiral galaxies,[11] is the dominant one, with a mass of approximately 1014 M, which is approximately an order of magnitude larger than the other two subclumps.[12]

14-296-GalaxyClusters-PerseusVirgo-ChandraXRay-20141027
Turbulence may prevent galaxy clusters from cooling (Chandra X-ray).

The three subgroups are in the process of merging to form a larger single cluster[12] and are surrounded by other smaller galaxy clouds, mostly composed of spiral galaxies, known as N Cloud, S Cloud, and Virgo E that are in the process of infalling to merge with them,[13] plus other farther isolated galaxies and galaxy groups (like the galaxy cloud Coma I) that are also attracted by the gravity of Virgo to merge with it in the future.[14] This strongly suggests the Virgo cluster is a dynamically young cluster that is still forming.[13]

Other two nearby aggregations known as M Cloud, W Cloud, and W' Cloud[10] seem to be background systems independent of the main cluster.[13]

The large mass of the cluster is indicated by the high peculiar velocities of many of its galaxies, sometimes as high as 1,600 km/s with respect to the cluster's center.

The Virgo cluster lies within the Virgo Supercluster, and its gravitational effect slows down the nearby galaxies. The large mass of the cluster has the effect of slowing down the recession of the Local Group from the cluster by approximately ten percent.

The Virgo cluster's thermal conduction follows magnetic field lines, so magnetic fields strongly shape the cluster’s thermal history; that some have not since cooled and collapsed is a mystery. Recent observations of Virgo cluster spiral galaxies imply ridges of strong, coherent magnetic fields offset from their center. This observation can be explained by galaxies sweeping up field lines as they orbit inside the cluster. This magnetic drape is then lit up with cosmic rays from the galaxies’ stars, generating coherent polarized emission at the galaxies’ leading edges. This immediately presents a technique for probing local orientations and characteristic length scales of cluster magnetic fields. The first application of this technique, mapping the field of the Virgo cluster, gives a startling result: outside a central region, the magnetic field is preferentially oriented radially as predicted by the magnetothermal instability. The results strongly suggest a mechanism for maintaining some clusters in a ‘non-cooling-core’ state.[15]

Intracluster medium

As with many other rich galaxy clusters, Virgo's intracluster medium is filled with a hot, rarefied plasma at temperatures of 30 million kelvins that emits X-Rays.[16] Within the intracluster medium (ICM) are found a large number of intergalactic stars[17][18] (up to 10% of the stars in the cluster),[19] including some planetary nebulae.[20] It is theorized that these were expelled from their home galaxies by interactions with other galaxies.[19] The ICM also contains some globular clusters,[21][22][23] possibly stripped off dwarf galaxies,[23] and even at least one star formation region.[24]

Galaxies

Virgo cluster 052012 overlay
Virgo Cluster of galaxies

Below is given a table of bright or notable objects in the Virgo Cluster and the subunit of the cluster in which they are located. Note that in some cases a galaxy may be considered in a different subunit by other researchers (sources:[10][13][25][26])

Column 1: The name of the galaxy.
Column 2: The right ascension for epoch 2000.
Column 3: The declination for epoch 2000.
Column 4: The blue apparent magnitude of the galaxy.
Column 5: The galaxy type: E=Elliptical, S0=Lenticular, Sa,Sb,Sc,Sd=Spiral, SBa,SBb,SBc,SBd=Barred spiral, Sm,SBm,Irr=Irregular.
Column 6: The angular diameter of the galaxy (arcminutes).
Column 7: The diameter of the galaxy (thousands of light years).
Column 8: The recessional velocity (km/s) of the galaxy relative to the cosmic microwave background.
Column 9: Subcluster where the galaxy is located.
Cluster members
Designation Coordinates (Epoch 2000) Apparent
magnitude

(blue)
Type Angular size Diameter
(kly)
RV
(km/s)
Subcluster
RA Dec
Messier 98 12 13.8 14 54 10.9 SBb 9.8′ 150 184 Virgo A or N Cloud
NGC 4216 12 15.9 13 09 10.9 SBb 7.9′ 120 459 Virgo A, N Cloud, or LVC.
Messier 99 12 18.8 14 25 10.4 Sc 5.4′ 80 2735 Virgo A or N Cloud
NGC 4262 12 19.5 14 53 12.4 S0 1.9′ 30 1683 Virgo A
NGC 4388 12 25.5 12 39 11.8 SAb 6.2′ 85 2845 Virgo A
Messier 61 12 21.9 04 28 10.2 SBbc 6.2′ 100 1911 S Cloud
Messier 100 12 22.9 15 49 10.1 SBbc 7.6′ 115 1899 Virgo A
Messier 84 12 25.1 12 53 10.1 E1 6.0′ 90 1239 Virgo A
Messier 85 12 25.4 18 11 10.0 S0 7.1′ 105 1056 Virgo A
Messier 86 12 26.2 12 57 9.9 E3 10.2′ 155 37 Virgo A or own subgroup.
NGC 4435 12 27.7 13 05 11.7 S0 3.0′ 45 1111 Virgo A
NGC 4438 12 27.8 13 01 11.0 Sa 8.7′ 130 404 Virgo A
NGC 4450 12 28.5 17 05 10.9 Sab 5.1′ 80 2273 Virgo A
Messier 49 12 29.8 08 00 9.3 E2 9.8′ 150 1204 Virgo B
Messier 87 12 30.8 12 23 9.6 E0-1 9.8′ 150 1204 Virgo A
Messier 88 12 32.0 14 25 10.3 Sb 6.8′ 100 2599 Virgo A
NGC 4526 12 32.0 07 42 10.6 S0 7.1′ 105 931 Virgo B
NGC 4527 12 34.1 02 39 12.4 Sb 4.6′ 69 1730 S Cloud
NGC 4536 12 34.4 02 11 11.1 SBbc 7.2′ 115 2140 S Cloud
Messier 91 12 35.4 14 30 11.0 SBb 5.2′ 80 803 Virgo A
NGC 4550 12 35.5 12 13 12.5 S0 3.2′ 50 704 Virgo A
Messier 89 12 35.7 12 33 10.7 E0 5.0′ 75 628 Virgo A
NGC 4567 12 36.5 11 15 12.1 Sbc 2.8′ 40 2588 Virgo A
NGC 4568 12 36.6 11 14 11.7 Sbc 4.4′ 65 2578 Virgo A
Messier 90 12 36.8 13 10 10.2 SBab 10.5′ 160 87 Virgo A
NGC 4571 12 36.9 14 13 11.9 Sc 3.7′ 55 659 Virgo A
Messier 58 12 37.7 11 49 10.6 SBb 5.6′ 85 1839 Virgo A
Messier 59 12 42.9 11 39 10.8 E5 5.0′ 75 751 Virgo A or Virgo E
Messier 60 12 43.7 11 33 9.8 E2 7.2′ 110 1452 Virgo A, Virgo E, or Virgo C
NGC 4651 12 43.7 16 24 11.4 Sc 4.0′ 60 1113
NGC 4654 12 43.9 13 08 11.1 SBc 5.0′ 75 1349 Virgo A

Fainter galaxies within the cluster are usually known by their numbers in the Virgo Cluster Catalog, particularly members of the numerous dwarf galaxy population.[27]

Hubble Constant

The nearest large groups of elliptical galaxies, in the Virgo and Fornax clusters, play a central role in determinations of the Hubble constant, H0, and hence the cosmological rate of expansion. Because the relative distances between these two clusters and more remote clusters are well known, absolute distance determinations to Virgo and Fornax should establish the Hubble constant for the local Universe. In addition, elliptical galaxies reside predominantly in the cores of clusters, so distance calibrations for ellipticals should minimize the uncertainties due to the possibly large extent of the clusters along the line of sight. A powerful and direct way of establishing such distances is to use the brightest red-giant stars, which have nearly uniform luminosities.[28][29] The direct observation of old red-giant stars in a dwarf elliptical galaxy in the Virgo cluster was reported in a paper in Nature. It was determined that the distance to this galaxy, and thus to the core of the Virgo cluster, was 15.7 ± 1.5 megaparsecs, from which they estimated a Hubble constant of H0 = 77 ± 8 km s−1 Mpc−1. Under the assumption of a low-density Universe with the simplest cosmology, they estimated the age of the Universe to be no more than 12–13 billion years; not bad for a paper written twenty years ago.[30]

See also

Notes

  1. ^ Following the entry for M91 in the Connoissance des Temps for 1784, Messier added the following note:
    The constellation of Virgo, & especially the northern Wing is one of the constellations which encloses the most Nebulae: this Catalog contains thirteen which have been determined: viz. Nos. 49, 58, 59, 60, 61, 84, 85, 86, 87, 88, 89, 90, & 91. All these nebulae appear to be without stars: one can see them only in a very good sky, & near their meridian passage. Most of these nebulae have been pointed to me by Mr. Méchain.[5]

References

  1. ^ a b c d "NASA/IPAC Extragalactic Database". Results for Virgo Cluster. Retrieved 2006-10-19.
  2. ^ Mei, Simona; Blakeslee, John P.; Côté, Patrick; Tonry, John L.; West, Michael J.; Ferrarese, Laura; Jordán, Andrés; Peng, Eric W.; Anthony, André; Merritt, Davi (2007). "The ACS Virgo Cluster Survey. XIII. SBF Distance Catalog and the Three-dimensional Structure of the Virgo Cluster". The Astrophysical Journal. 655 (1): 144–162. arXiv:astro-ph/0702510Freely accessible. Bibcode:2007ApJ...655..144M. doi:10.1086/509598.
  3. ^ "Virgo Cluster". Cosmos. Swinburne University of Technology.
  4. ^ Fouqué, P.; Solanes, J. M.; Sanchis, T.; Balkowski, C. (2001). "Structure, mass and distance of the Virgo cluster from a Tolman-Bondi model". Astronomy and Astrophysics. 375 (3): 770–780. arXiv:astro-ph/0106261Freely accessible. Bibcode:2001A&A...375..770F. doi:10.1051/0004-6361:20010833.
  5. ^ "Messier 91 — Observations and Descriptions". SEDS.
  6. ^ "Virgo Cluster | Messier Objects". www.messier-objects.com. Retrieved 2018-06-24.
  7. ^ Côté, Patrick; Blakeslee, John P.; Ferrarese, Laura; Jordán, Andrés; Mei, Simona; Merritt, David; Milosavljević, Miloš; Peng, Eric W.; Tonry, John L.; et al. (July 2004). "The ACS Virgo Cluster Survey". The Astrophysical Journal. 153 (1): 223–242. arXiv:astro-ph/0404138Freely accessible. Bibcode:2004ApJS..153..223C. doi:10.1086/421490.
  8. ^ M. Fukugita; S. Okamura; N. Yasuda (1993). "Spatial distribution of spiral galaxies in the Virgo Cluster from the Tully-Fisher relation". Astrophysical Journal. 412: L13–L16. Bibcode:1993ApJ...412L..13F. doi:10.1086/186928.
  9. ^ "Virgo Cluster". ned.ipac.caltech.edu. Retrieved 2018-06-24.
  10. ^ a b c Boselli, A.; Voyer, E.; Boissier, S.; Cucciati, O.; Consolandi, G.; Cortese, L.; Fumagalli, M.; Gavazzi, G.; Heinis, S.; Roehlly, Y.; Toloba, E. (2014). "The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). IV. The role of the cluster environment on galaxy evolution". Astronomy & Astrophysics. 570: A69. arXiv:1407.4986Freely accessible. Bibcode:2014A&A...570A..69B. doi:10.1051/0004-6361/201424419. A69.
  11. ^ Chamaraux, P.; Balkowski, C.; Gerard, E. (1980). "The H I deficiency of the Virgo cluster spirals". Astronomy & Astrophysics. 83 (1–2): 38–51. Bibcode:1980A&A....83...38C.
  12. ^ a b The Virgo Super Cluster: home of M87 (with frames)
  13. ^ a b c d Gavazzi, G.; Boselli, A.; Scodeggio, M.; Pierini, D.; Belsole, E. (1999). "The 3D structure of the Virgo cluster from H-band Fundamental Plane and Tully-Fisher distance determinations". Monthly Notices of the Royal Astronomical Society. 304 (3): 595–610. arXiv:astro-ph/9812275Freely accessible. Bibcode:1999MNRAS.304..595G. doi:10.1046/j.1365-8711.1999.02350.x.
  14. ^ Tully, R. B.; Shaya, E. J. (1984). "Infall of galaxies into the Virgo cluster and some cosmological constraints". Astrophysical Journal. 281: 31–55. Bibcode:1984ApJ...281...31T. doi:10.1086/162073.
  15. ^ Pfrommer, Christoph; Dursi, Jonathan (2010-05-16). "Detecting the orientation of magnetic fields in galaxy clusters". Nature Physics. 6 (7): 520–526. doi:10.1038/nphys1657. ISSN 1745-2473.
  16. ^ Lea, S. M.; Mushotzky, R.; Holt, S. S. (1982). "Einstein Observatory solid state spectrometer observations of M87 and the Virgo cluster". Astrophysical Journal. 262 (1): 24–32. Bibcode:1982ApJ...262...24L. doi:10.1086/160392.
  17. ^ Ferguson, H. (1997). "Intergalactic Stars in the Virgo Cluster". HST proposal: 7411. Bibcode:1997hst..prop.7411F.
  18. ^ Ferguson, Henry C.; Tanvir, Nial R.; von Hippel, Ted (1998-01). "Detection of intergalactic red-giant-branch stars in the Virgo cluster". Nature. 391 (6666): 461–463. doi:10.1038/35087. ISSN 0028-0836. Check date values in: |date= (help)
  19. ^ a b Ferguson, Henry C.; Tanvir, Nial R.; von Hippel, Ted (1998). "Detection of intergalactic red-giant-branch stars in the Virgo cluster". Nature. 391 (6666): 461–463. arXiv:astro-ph/9801228Freely accessible. Bibcode:1998Natur.391..461F. doi:10.1038/35087.
  20. ^ Feldmeier, J.; Ciardullo, R.; Jacoby, G. (1998). "Intracluster Planetary Nebulae in the Virgo Cluster. I. Initial Results". Astrophysical Journal. 503: 109–117. arXiv:astro-ph/9803062Freely accessible. Bibcode:1998ApJ...503..109F. doi:10.1086/305981.
  21. ^ Takamiya, Marianne; West, Michael; Côté, Patrick; Jordán, Andrés; Peng, Eric; Ferrarese, Laura (2009). "IGCs in the Virgo Cluster". Globular Clusters - Guides to Galaxies, Eso Astrophysics Symposia, Volume. Eso Astrophysics Symposia: 361–365. Bibcode:2009gcgg.book..361T. doi:10.1007/978-3-540-76961-3_83. ISBN 978-3-540-76960-6.
  22. ^ Durrell, Patrick R.; Accetta, K.; Feldmeier, J. J.; Mihos, J. C.; Ciardullo, R.; Peng, E. W.; Members of the NGVS team (2010). "Searching for Intracluster Globular Clusters in the Virgo Cluster". Bulletin of the American Astronomical Society. 42: 567. Bibcode:2010AAS...21547814D.
  23. ^ a b Lee, Myung Gyoon; Park, Hong Soo; Hwang, Ho Seong (2010). "Detection of a Large-Scale Structure of Intracluster Globular Clusters in the Virgo Cluster". Science. 328 (5976): 334–. arXiv:1003.2499Freely accessible. Bibcode:2010Sci...328..334L. doi:10.1126/science.1186496. PMID 20223950.
  24. ^ Gerhard, Ortwin; Arnaboldi, Magda; Freeman, Kenneth C.; Okamura, Sadanori (2002). "Isolated Star Formation: A Compact H II Region in the Virgo Cluster". The Astrophysical Journal. 580 (2): L121–L124. arXiv:astro-ph/0211341Freely accessible. Bibcode:2002ApJ...580L.121G. doi:10.1086/345657.
  25. ^ "Galaxy On Line Database Milano Network". GOLDMine. Retrieved 2012-08-06.
  26. ^ "The Virgo Cluster". Retrieved 2013-04-06.
  27. ^ Binggeli, Bruno; Sandage, Allan; Tammann, Gustav (1985). "Studies of the Virgo Cluster. II – A Catalog of 2096 Galaxies in the Virgo Cluster Area". Astronomical Journal. American Astronomical Society. 90: 1681–1759. Bibcode:1985AJ.....90.1681B. doi:10.1086/113874. Retrieved 30 November 2016.
  28. ^ Lee, Myung Gyoon; Freedman, Wendy L.; Madore, Barry F. (1993-11). "The Tip of the Red Giant Branch as a Distance Indicator for Resolved Galaxies". The Astrophysical Journal. 417: 553. doi:10.1086/173334. ISSN 0004-637X. Check date values in: |date= (help)
  29. ^ Mould, J.; Kristian, J. (1986-6). "The stellar population in the halos of M31 and M33". The Astrophysical Journal. 305: 591–599. doi:10.1086/164273. ISSN 0004-637X. Check date values in: |date= (help)
  30. ^ Harris, William E.; Durrell, Patrick R.; Pierce, Michael J.; Secker, Jeff (1998-09). "Constraints on the Hubble constant from observations of the brightest red-giant stars in a Virgo-cluster galaxy". Nature. 395 (6697): 45–47. doi:10.1038/25673. ISSN 0028-0836. Check date values in: |date= (help)

External links

Coordinates: Sky map 12h 27m 00s, 12° 43′ 00″

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