Virgo Cluster

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Virgo Cluster
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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]
See also: Galaxy groups, Galaxy clusters, List of galaxy clusters

The Virgo Cluster (VC) 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 (LG) is an outlying member. However, the LG experiences the mass of the VC Supercluster as the Virgocentric flow. It is estimated that the VC'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.[5]

The cluster subtends a maximum arc of approximately 8 degrees centered in the constellation Virgo. Many of the member galaxies of the cluster are visible with a small telescope. Its brightest member is the elliptical galaxy Messier 49; however its most famous member is the also elliptical galaxy Messier 87, that unlike the former is located in the center of the cluster.

Characteristics

The cluster is a fairly heterogeneous mixture of spirals and ellipticals.[6] As of 2004, it is believed that the spirals 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.[7] The elliptical galaxies are more centrally concentrated than the spiral galaxies.

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, that surrounds 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.[8]

Of all of them, Virgo A, formed by a mixture of elliptical, lenticular, and -usually- gas-poor spiral galaxies,[9] is the dominant one, with a mass of approximately 1014 M☉, which is approximately an order of magnitude larger than the other two subclumps.[10]

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[10] 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,[11] 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.[12] This strongly suggests the Virgo cluster is a dynamically young cluster that is still forming.[11]

Other two nearby aggregations known as M Cloud, W Cloud, and W' Cloud[8] seem to be background systems independent of the main cluster.[11]

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.

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 Kelvin that emits X-Rays.[13] Within the imtracluster medium are found a large number of intergalactic stars[14] (up to 10% of the stars in the cluster),[15] including some planetary nebulae,[16] that it is theorized were expelled from their home galaxies on interactions with other galaxies,[15] as well as some globular clusters,[17][18][19] possibly stripped off dwarf galaxies,[19] and even at least one star formation region.[20]

Bright or notable galaxies of the Virgo Cluster

File:Virgo cluster 052012 overlay.jpg
Virgo Cluster of galaxies.

Below is given a table of bright or notable objects in the Virgo Cluster and the cluster's subunit where they're located. Note that in some cases a galaxy may be considered in one subunit or in another (sources:[8][11][21][22])

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
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
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

See also

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References

  1. ↑ 1.0 1.1 1.2 1.3 Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ See Virgo Cluster.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 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. (see M91.)
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 8.2 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 The Virgo Super Cluster: home of M87 (with frames)
  11. ↑ 11.0 11.1 11.2 11.3 Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ 15.0 15.1 Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ 19.0 19.1 Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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

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