Virgo Supercluster
Virgo Supercluster | |
---|---|
Doppler shift | |
Binding mass | ~1.48 × 1015[1] M☉ |
Luminosity (specify) | 3×1012 L☉[1] (total) |
Other designations | |
Local Supercluster, LSC, LS | |
The Virgo Supercluster (Virgo SC) or the Local Supercluster (LSC or LS) is a mass concentration of
A 2014 study indicates that the Virgo Supercluster is only a lobe of an even greater supercluster, Laniakea, a larger, competing referent of the term Local Supercluster centered on the Great Attractor.[2]
Background
Beginning with the first large sample of nebulae published by William and John Herschel in 1863, it was known that there is a marked excess of nebular fields in the constellation Virgo, near the north galactic pole. In the 1950s, French–American astronomer Gérard de Vaucouleurs was the first to argue that this excess represented a large-scale galaxy-like structure, coining the term "Local Supergalaxy" in 1953, which he changed to "Local Supercluster" (LSC[3]) in 1958. Harlow Shapley, in his 1959 book Of Stars and Men, suggested the term Metagalaxy.[4]
Debate went on during the 1960s and 1970s as to whether the Local Supercluster (LS) was actually a structure or a chance alignment of galaxies.[5] The issue was resolved with the large redshift surveys of the late 1970s and early 1980s, which convincingly showed the flattened concentration of galaxies along the supergalactic plane.[6]
Structure
In a comprehensive 1982 paper, R. Brent Tully presented the conclusions of his research concerning the basic structure of the LS. It consists of two components: an appreciably flattened disk containing two-thirds of the supercluster's luminous galaxies, and a roughly spherical halo containing the remaining one-third.[7] The disk itself is a thin (~1 Mpc) ellipsoid with a long axis / short axis ratio of at least 6 to 1, and possibly as high as 9 to 1.[8] Data released in June 2003 from the 5-year Two-degree-Field Galaxy Redshift Survey (2dF) has allowed astronomers to compare the LS to other superclusters. The LS represents a typical poor (that is, lacking a high density core) supercluster of rather small size. It has one rich galaxy cluster in the center, surrounded by filaments of galaxies and poor groups.[1]
The Local Group is located on the outskirts of the LS in a small filament extending from the Fornax Cluster to the Virgo Cluster.[6] The Virgo Supercluster's volume is very approximately 7,000 times that of the Local Group, or 100 billion times that of the Milky Way.
Galaxy distribution
The
Of the luminous galaxies located in the disk, one third are in the Virgo Cluster. The remainder are found in the Canes Venatici Cloud and Virgo II Cloud, plus the somewhat insignificant NGC 5643 Group.
The luminous galaxies in the halo are concentrated in a small number of clouds (94% in 7 clouds). This distribution indicates that "most of the volume of the supergalactic plane is a great void."
Cosmology
Large-scale dynamics
Since the late 1980s it has been apparent that not only the Local Group, but all matter out to a distance of at least 50 Mpc is experiencing a bulk flow on the order of 600 km/s in the direction of the Norma Cluster (Abell 3627).[11] Lynden-Bell et al. (1988) dubbed the cause of this the "Great Attractor". The Great Attractor is now understood to be the center of mass of an even larger structure of galaxy clusters, dubbed "Laniakea", which includes the Virgo Supercluster (including the Local Group) as well as the Hydra-Centaurus Supercluster, the Pavo-Indus Supercluster, and the Fornax Group.
The Great Attractor, together with the entire supercluster, is found to be moving toward Shapley Supercluster, with center of Shapley Attractor.[12]
Dark matter
The LS has a total mass M ≈ 1015 M☉ and a total optical luminosity L ≈ 3×1012 L☉.[1] This yields a mass-to-light ratio of about 300 times that of the solar ratio (M☉/L☉ = 1), a figure that is consistent with results obtained for other superclusters.[13][14] By comparison, the mass-to-light ratio for the Milky Way is 63.8 assuming a solar absolute magnitude of 4.83,[15] a Milky Way absolute magnitude of −20.9,[16] and a Milky Way mass of 1.25×1012 M☉.[17] These ratios are one of the main arguments in favor of the presence of large amounts of dark matter in the universe; if dark matter did not exist, much smaller mass-to-light ratios would be expected.
Maps
Diagrams
See also
References
- ^ a b c d
Einasto, M.; et al. (December 2007). "The richest superclusters. I. Morphology". Astronomy and Astrophysics. 476 (2): 697–711. S2CID 15004251.
- S2CID 205240232.
- ^ cfa.harvard.edu, The Geometry of the Local Supercluster, John P. Huchra, 2007 (accessed 12-12-2008)
- ^ Shapley, Harlow Of Stars and Men (1959)
- ^
de Vaucouleurs, G. (March 1981). "The Local Supercluster of Galaxies". Bulletin of the Astronomical Society of India. 9: 6 (see note). Bibcode:1981BASI....9....1D.
- ^ a b
Klypin, Anatoly; et al. (October 2003). "Constrained Simulations of the Real Universe: The Local Supercluster". The Astrophysical Journal. 596 (1): 19–33. S2CID 1830859.
- ^
Hu, F. X.; et al. (April 2006). "Orientation of Galaxies in the Local Supercluster: A Review". Astrophysics and Space Science. 302 (1–4): 43–59. S2CID 18837475.
- ^ a b
Tully, R. B. (15 Jun 1982). "The Local Supercluster". Astrophysical Journal. 257 (1): 389–422. doi:10.1086/159999.
- ^
Carroll, Bradley; Ostlie, Dale (1996). An Introduction to Modern Astrophysics. New York: ISBN 0-201-54730-9.
- ^
Fairall, A. P.; Vettolani, G.; Chincarini, G. (May 1989). "A wide angle redshift survey of the Hydra-Centaurus region". Astronomy and Astrophysics Supplement Series. 78 (2): 270. ISSN 0365-0138.
- ^ Plionis, Manolis; Valdarnini, Riccardo (March 1991). "Evidence for large-scale structure on scales about 300/h MPC". Monthly Notices of the Royal Astronomical Society. 249: 46–61. .
- ^ "What is the Great Attractor?". 14 July 2014.
- ^
Small, Todd A.; et al. (Jan 1998). "The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster". Astrophysical Journal. 492 (1): 45–56. S2CID 119451873.
- ^
Heymans, Catherine; et al. (April 2008). "The dark matter environment of the A901 abell A901/902 supercluster: a weak lensing analysis of the HST STAGES survey". S2CID 59057342.
- ^ Williams, D. R. (2004). "Sun Fact Sheet". NASA. Retrieved 2012-03-17.
- ^ Jerry Coffey. "Absolute Magnitude". Retrieved 2010-04-09.
- S2CID 119100616
Further reading
- Tully, Brent (1982). "The Local Supercluster". Astrophys. J. 257: 389–422. doi:10.1086/159999.
- Lynden-Bell, D.; et al. (1988). "Spectroscopy and photometry of elliptical galaxies. V — Galaxy streaming toward the new supergalactic center". Astrophysical Journal. 326: 19–49. doi:10.1086/166066.
External links
- The Atlas of the Universe, a website created by astrophysicist Richard Powell that shows maps of our local universe on a number of different scales (similar to above maps).