Supercluster
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- See Supercluster (genetic) for use of the word in genetics.
Superclusters are large groupings of smaller galaxy groups and clusters, and are among the largest structures of the cosmos. The existence of superclusters indicates that the galaxies in our Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to 50 galaxies and clusters up to several thousand. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.
Once thought to be the largest structures in nature, superclusters are now understood to be subordinate to enormous walls or sheets, sometimes called "supercluster complexes", that can span a billion light-years in length, more than 5% of the observable universe. Given their large size and the typical speed of a galaxy of ∼1000 km/s, the hubble constant implies galaxies can only move ∼10 Mpc/h. Therefore, when we observe superclusters today, we are learning about the condition of the universe when these superclusters were created. The alignment and rotational axes of galaxies within superclusters gives us insight into the formation process of galaxies early in the history of the Universe.[1]
Superclusters can range in size up to several 108 light years. No clusters of superclusters are known, but the existence of structures larger than superclusters is debated (see Galaxy filament). Interspersed among superclusters are large voids of space in which few galaxies exist. Even though superclusters are the largest structures confirmed, the total number of superclusters leave possibilities for structural distribution; the total number of superclusters in the universe is believed to be close to 10 million.
Superclusters are frequently subdivided into groups of clusters called galaxy clouds.
Superclusters are the largest structure in the Universe with scales up to ∼100–150 Mpc. They are in largely unrelaxed state. At a typical velocity of ∼1000 km s−1, galaxies can move only ∼10 h−1Mpc within the Hubble time (Hubble constant H0=100h km s−1 Mpc−1). Accordingly, the superclusters seen today tell us the condition of the Universe when these largest structures were formed (Oort, 1983; Bahcall, 1988). The dynamical ’fossil’ nature of the alignment of rotational axes of galaxies in superclusters provides us with the information on the formation process of galaxies at the early epoch (Djorgovski, 1987).
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[edit] Nearby superclusters
- Local Supercluster: contains the Local Group with our galaxy, the Milky Way. It also contains the Virgo cluster near its center, and is sometimes called the Virgo Supercluster.
- Hydra-Centaurus Supercluster
- Hydra Supercluster
- Centaurus Supercluster
- Perseus-Pisces Supercluster
- Pavo-Indus Supercluster
- Coma Supercluster
- Sculptor Superclusters
- Hercules Superclusters
- Leo Supercluster
- Shapley Supercluster
- Pisces-Cetus Supercluster
- Bootes Supercluster
- Horologium Supercluster
- Corona Borealis Supercluster
- Columba Supercluster
[edit] See also
- Large-scale structure of the cosmos
- Galaxy filament
- Galaxy cloud
- Galaxy cluster
- Galaxy subcluster
- Galaxy
[edit] External links
[edit] References
- ^ Hu, F. X.; Wu, G. X.; Song, G. X.; Yuan, Q. R.; Okamura, S. (2006). "Orientation of Galaxies in the Local Supercluster: A Review". Astrophysics and Space Science 302 (1-4): 43-59.
