NGC 3923

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NGC 3923
NGC 3923.png
Observation data (J2000 epoch)
ConstellationHydra
Right ascension 11h 51m 01.7s[1]
Declination−28° 48′ 22″[1]
Redshift0.005801 +/- 0.00003 km/s[1]
Distance71 ± 23 Mly (21.6 ± 7.0 Mpc)[1]
Apparent magnitude (V)9.6
Characteristics
TypeE4-5 [1]
Apparent size (V)5′.9 × 3′.9[1]
Notable featuresShell galaxy
Other designations
ESO 440- G 017, AM 1148-283, MCG -05-28-012, PGC 37061[1]
See also: Galaxy, List of galaxies

NGC 3923 is an elliptical galaxy located in the constellation Hydra. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 3923 is about 155,000 light years across. NGC 3923 is an example of a shell galaxy where the stars in its halo are arranged in layers, it has more than twenty shells.[2] It was discovered by William Herschel on March 7, 1791.

Characteristics[edit]

NGC 3923 is an example of a shell galaxy where the stars in its halo are arranged in layers. NGC 3923 has up to 42 shells, the highest number among all shell galaxies,[3] and its shells are much more subtle than those of other shell galaxies; the shells of this galaxy are also symmetrical, while other shell galaxies are more skewed. Concentric shells of stars enclosing a galaxy are quite common and are observed in many elliptical galaxies. In fact, every tenth elliptical galaxy exhibits this onion-like structure, which has never been observed in spiral galaxies; the shell-like structures are thought to develop as a consequence of galactic cannibalism, when a larger galaxy ingests a smaller companion. As the two centers approach, they initially oscillate about a common center, and this oscillation ripples outwards forming the shells of stars just as ripples on a pond spread when the surface is disturbed.[2]

With deep imaging were also detected a stream extending from the core of NGC 3923 and a small elliptical galaxy on its axis, which is a probable progenitor of some the shells. Another stream lies south of the core of NGC 3923, and a hook like structure lies at the northwest.[3]

Based on the velocity dispersion of the globular clusters of NGC 3923 the mass of the supermassive black hole of the galaxy was estimated to be (5.3±2.5)×108 M.[4]

Supernovae[edit]

One supernova has been detected in NGC 3923, SN 2018aoz, a type Ia supernova with peak magnitude 12.7. It was discovered on April 2, 2018.[5]

Nearby galaxies[edit]

NGC 3923 is the brightest galaxy in a galaxy group known as the NGC 3923 galaxy group. Within 25 arcminutes from NGC 3923 have being detected seven dwarf elliptical galaxies. NGC 3904 is located 37 arcminutes away.[6] Other galaxies in the group include NGC 3885, ESO 440-27, and ESO440-011. Other nearby galaxies include NGC 3617, NGC 3673, NGC 3717, NGC 3936, and NGC 4105.[7]

References[edit]

  1. ^ a b c d e f g "NASA/IPAC Extragalactic Database". Results for NGC 3923. Retrieved 2016-01-18.
  2. ^ a b "Hubble Spots the Layers of NGC 3923". NASA. May 15, 2015.
  3. ^ a b Bílek, M.; Cuillandre, J.-C.; Gwyn, S.; Ebrová, I.; Bartošková, K.; Jungwiert, B.; Jílková, L. (22 March 2016). "Deep imaging of the shell elliptical galaxy NGC 3923 with MegaCam". Astronomy & Astrophysics. 588: A77. arXiv:1505.07146. Bibcode:2016A&A...588A..77B. doi:10.1051/0004-6361/201526608.
  4. ^ Sadoun, Raphael; Colin, Jacques (11 October 2012). "-σ relation between supermassive black holes and the velocity dispersion of globular cluster systems". Monthly Notices of the Royal Astronomical Society: Letters. 426 (1): L51–L55. arXiv:1204.0144. Bibcode:2012MNRAS.426L..51S. doi:10.1111/j.1745-3933.2012.01321.x.
  5. ^ "List of supernovae sorted by Magnitude for 2018".
  6. ^ Sandage, A., Bedke, J. (1994). The Carnegie Atlas of Galaxies. Carnegie Institution of Washington.CS1 maint: Multiple names: authors list (link)
  7. ^ Makarov, Dmitry; Karachentsev, Igor (21 April 2011). "Galaxy groups and clouds in the local (z∼ 0.01) Universe". Monthly Notices of the Royal Astronomical Society. 412 (4): 2498–2520. arXiv:1011.6277. Bibcode:2011MNRAS.412.2498M. doi:10.1111/j.1365-2966.2010.18071.x.
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External links[edit]