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A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group, which in turn is part of the Virgo Supercluster, which is part of the Laniakea Supercluster, which is part of the Pisces–Cetus Supercluster Complex. The large size and low density of superclusters means that they, unlike clusters, expand with the Hubble expansion. The number of superclusters in the observable universe is estimated to be 10 million.
The Local Supercluster is a formerly defined supercluster containing the Virgo Cluster and Local Group, which itself contains the Milky Way and Andromeda galaxies, as well as others. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs. The Virgo SC is one of about 10 million superclusters in the observable universe and is in the Pisces–Cetus Supercluster Complex, a galaxy filament.
The Great Attractor is a region of gravitational attraction in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster of galaxies that includes the Milky Way galaxy, as well as about 100,000 other galaxies.
Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.
In the fields of Big Bang theory and cosmology, reionization is the process that caused electrically neutral atoms in the universe to reionize after the lapse of the "dark ages".
Redshift quantization, also referred to as redshift periodicity, redshift discretization, preferred redshifts and redshift-magnitude bands, is the hypothesis that the redshifts of cosmologically distant objects tend to cluster around multiples of some particular value.
APM 08279+5255 is a very distant, broad absorption line quasar located in the constellation Lynx. It is magnified and split into multiple images by the gravitational lensing effect of a foreground galaxy through which its light passes. It appears to be a giant elliptical galaxy with a supermassive black hole and associated accretion disk. It possesses large regions of hot dust and molecular gas, as well as regions with starburst activity.
The Pavo–Indus Supercluster is a neighboring supercluster located about 60–70 Mpc (196–228 Mly) away in the constellations of Pavo, Indus, and Telescopium. The supercluster contains three main clusters, Abell 3656, Abell 3698, and Abell 3742.
In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50/h to 80/h megaparsecs —with the largest found to date being the Hercules-Corona Borealis Great Wall at around 3 gigaparsecs (9.8 Gly) in length—and form the boundaries between voids. Due to the accelerating expansion of the universe, the individual clusters of gravitationally bound galaxies that make up galaxy filaments are moving away from each other at an accelerated rate; in the far future they will dissolve.
In astronomy, the velocity dispersion (σ) is the statistical dispersion of velocities about the mean velocity for a group of astronomical objects, such as an open cluster, globular cluster, galaxy, galaxy cluster, or supercluster. By measuring the radial velocities of the group's members through astronomical spectroscopy, the velocity dispersion of that group can be estimated and used to derive the group's mass from the virial theorem. Radial velocity is found by measuring the Doppler width of spectral lines of a collection of objects; the more radial velocities one measures, the more accurately one knows their dispersion. A central velocity dispersion refers to the σ of the interior regions of an extended object, such as a galaxy or cluster.
Lyman-break galaxies are star-forming galaxies at high redshift that are selected using the differing appearance of the galaxy in several imaging filters due to the position of the Lyman limit. The technique has primarily been used to select galaxies at redshifts of z = 3–4 using ultraviolet and optical filters, but progress in ultraviolet astronomy and in infrared astronomy has allowed the use of this technique at lower and higher redshifts using ultraviolet and near-infrared filters.
The thick disk is one of the structural components of about 2/3 of all disk galaxies, including the Milky Way. It was discovered first in external edge-on galaxies. Soon after, it was proposed as a distinct galactic structure in the Milky Way, different from the thin disk and the halo in the 1983 article by Gilmore & Reid. It is supposed to dominate the stellar number density between 1 and 5 kiloparsecs above the galactic plane and, in the solar neighborhood, is composed almost exclusively of older stars. Its stellar chemistry and stellar kinematics are also said to set it apart from the thin disk. Compared to the thin disk, thick disk stars typically have significantly lower levels of metals—that is, the abundance of elements other than hydrogen and helium.
Cosmic voids are vast spaces between filaments, which contain very few or no galaxies. In spite of their size, most galaxies are not located in voids. This is because most galaxies are gravitationally bound together, creating huge cosmic structures known as galaxy filaments. The cosmological evolution of the void regions differs drastically from the evolution of the Universe as a whole: there is a long stage when the curvature term dominates, which prevents the formation of galaxy clusters and massive galaxies. Hence, although even the emptiest regions of voids contain more than ~15% of the average matter density of the Universe, the voids look almost empty to an observer.
NGC 4598 is a barred lenticular galaxy located in the constellation Virgo. NGC 4598 was discovered by astronomer William Herschel on April 15, 1784. The distance to NGC 4598 has not been accurately determined; measurements vary from 64 to 102 million light-years. According to the NASA/IPAC Extragalactic Database, its redshift based distance is 102 Mly (31.3 Mpc) while its redshift independent based distance is 88.71 Mly (27.200 Mpc). Also, according to SIMBAD, its distance is 63.7 Mly (19.54 Mpc). NGC 4598's average distance is 84.8 Mly (26.0 Mpc). NGC 4598 is usually considered to be a member of the Virgo Cluster. However, P. Fouqu´e et al. suggests it may be a background galaxy independent of the main cluster.
References
- ↑ Rosati, P.; et al. (1999). "An X-Ray-Selected Galaxy Cluster at z = 1.26". The Astronomical Journal . 118 (1): 76–85. arXiv: astro-ph/9903381 . Bibcode:1999AJ....118...76R. doi:10.1086/300934. S2CID 2560006.
- ↑ "Lynx Supercluster". SIMBAD .
- ↑ Nakata, F.; et al. (2004). "Discovery of a large-scale clumpy structure of the Lynx supercluster at z~1.27". Proceedings of the International Astronomical Union . 2004. Cambridge University Press: 29–33. Bibcode:2004ogci.conf...29N. doi: 10.1017/S1743921304000080 (inactive 1 November 2024). ISBN 0-521-84908-X.
{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link) - ↑ Ohta, K.; et al. (2003). "Optical Identification of the ASCA Lynx Deep Survey: An Association of Quasi-Stellar Objects and a Supercluster at z = 1.3?". The Astrophysical Journal . 598 (1): 210–215. arXiv: astro-ph/0308066 . Bibcode:2003ApJ...598..210O. doi:10.1086/378690. S2CID 117171639.
- ↑ Kim, Jae-Woo; Im, Myungshin; Lee, Seong-Kook; Edge, Alastair C.; Hyun, Minhee; Kim, Dohyeong; Choi, Changsu; Jueun Hong; Jeon, Yiseul (2016). "Discovery of a Supercluster at z 0.91 and Testing the ΛCDM Cosmological Model". The Astrophysical Journal Letters. 821 (1): L10. arXiv: 1604.03254 . Bibcode:2016ApJ...821L..10K. doi: 10.3847/2041-8205/821/1/L10 . ISSN 2041-8205. S2CID 118568359.
- ↑ Nakata, F.; Kodama, T.; Shimasaku, K.; Doi, M.; Furusawa, H.; Hamabe, M.; Kimura, M.; Komiyama, Y.; Miyazaki, S. (2005-03-11). "Discovery of a large-scale clumpy structure around the Lynx supercluster at z 1.27". Monthly Notices of the Royal Astronomical Society. 357 (4): 1357–1362. arXiv: astro-ph/0412460 . Bibcode:2005MNRAS.357.1357N. doi: 10.1111/j.1365-2966.2005.08756.x . ISSN 0035-8711. S2CID 15053608.
