Extraplanar gas

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Extraplanar gas is cold atomic hydrogen which has been discovered slowly rotating around some spiral galaxies and located well outside their thin disk regions. [1] It was discovered by using radio telescopes to observe the distribution of atomic hydrogen around galaxy disks. [1] Galaxies which have shown evidence of extraplanar gas include NGC 891, NGC 2403, UGC 7321, NGC 4559 and NGC 3198. [1] [2]

Possible explanations for the presence of this gas include ionised gas being swept up by stellar winds and supernova explosions and, upon cooling, falling back into the galactic plane and the accretion of intergalactic primordial gas. [1] [3]

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NGC 3109 galaxy

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NGC 4216 galaxy

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NGC 2976 spiral galaxy in the constellation Ursa Major

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NGC 1808 galaxy

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NGC 613 galaxy

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NGC 3198 galaxy

NGC 3198, also known as Herschel 146 is a barred spiral galaxy in the constellation Ursa Major. It was discovered by William Parsons, 3rd Earl of Rosse, sometime before 1850.

NGC 4203 Galaxy in the constellation Coma Berenices

NGC 4203 is the New General Catalogue identifier for a lenticular galaxy in the northern constellation of Coma Berenices. It was discovered on March 20, 1787 by English astronomer William Herschel, and is situated 5.5° to the northwest of the 4th magnitude star Gamma Comae Berenices and can be viewed with a small telescope. The morphological classification of NGC 4203 is SAB0−, indicating that it has a lenticular form with tightly wound spiral arms and a weak bar structure at the nucleus.

NGC 7013 galaxy

NGC 7013 is a relatively nearby spiral or lenticular galaxy estimated to be around 37 to 41.4 million light-years away from Earth in the constellation of Cygnus. NGC 7013 was discovered by English astronomer William Herschel on July 17, 1784 and was also observed by his son, astronomer John Herschel on September 15, 1828.

NGC 4522 galaxy

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NGC 3883 galaxy

NGC 3883 is a large low surface brightness spiral galaxy located about 330 million light-years away in the constellation Leo. NGC 3883 has a prominent bulge but does not host an AGN. The galaxy also has flocculent spiral arms in its disk. It was discovered by astronomer William Herschel on April 13, 1785 and is a member of the Leo Cluster.

NGC 759 galaxy

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NGC 973 galaxy

NGC 973 is a giant spiral galaxy located in the constellation Triangulum. It is located at a distance of circa 200 million light years from Earth, which, given its apparent dimensions, means that NGC 973 is about 230,000 light years across. It was discovered by Lewis Swift on October 30, 1885.

NGC 765 galaxy

NGC 765 is an intermediate spiral galaxy located in the constellation Aries. It is located at a distance of circa 220 million light years from Earth, which, given its apparent dimensions, means that NGC 765 is about 195,000 light years across. It was discovered by Albert Marth on October 8, 1864. The galaxy has an extensive hydrogen (HI) disk with low surface brightness, whose diameter is estimated to be 240 kpc.

NGC 4294 Barred spiral galaxy in Virgo

NGC 4294 is a barred spiral galaxy with flocculent spiral arms located about 55 million light-years away in the constellation Virgo. The galaxy was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.

NGC 4298 galaxy

NGC 4298 is a flocculent spiral galaxy located about 53 million light-years away in the constellation Coma Berenices. The galaxy was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.

NGC 4299 galaxy

NGC 4299 is a spiral galaxy located about 55 million light-years away in the constellation Virgo. It was discovered by astronomer William Herschel on March 15, 1784 and is a member of the Virgo Cluster.

NGC 4302 galaxy

NGC 4302 is an edge-on spiral galaxy located about 55 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.

References

  1. 1 2 3 4 Bertin, Giuseppe (2014). Dynamics of Galaxies (2 ed.). Cambridge University Press. pp. 177–80. ISBN   9781107782747.
  2. Gentile, G.; et al. (2013). "HALOGAS: Extraplanar gas in NGC 3198". Astronomy & Astrophysics. 554: A125. arXiv: 1304.4232 . Bibcode:2013A&A...554A.125G. doi:10.1051/0004-6361/201321116. S2CID   56047203.
  3. Kunth, D. (1996-01-01). Interconnexion Entre la Formation D'étoiles Massives, Le Milieu Interstellaire Et L'évolution Des Galaxies. Atlantica Séguier Frontières. ISBN   978-2-86332-194-2.