Ultra diffuse galaxy

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An ultra diffuse galaxy (UDG) is an extremely-low-density galaxy. Such a galaxy may have the same size as the Milky Way but a visible star count of only 1%. Their lack of luminosity is due to the lack of star-forming gas in the galaxy. This results in old stellar populations.[1][2]

One example is of an UDG is DragonFly 44.[2] Some UDGs found in the Coma Cluster have diameters of 60 kly (18 kpc) (more than half the size of our galaxy) with 1% of the stars of the Milky Way Galaxy.[3] The distribution of ultra diffuse galaxies in the Coma Cluster is the same as luminous galaxies, this suggests that the cluster environment strips the gas from the galaxies, while allowing them to populate the cluster the same as more luminous galaxies. The similar distribution in the higher tidal force zones suggest a larger dark matter fraction to hold the galaxies together under the higher stress.[1]

Further reading

  • Pieter G. van Dokkum; Aaron J. Romanowsky; Roberto Abraham; Jean P. Brodie; Charlie Conroy; Marla Geha; Allison Merritt; Alexa Villaume; Jielai Zhang (6 February 2015). "Spectroscopic Confirmation of the Existence of Large, Diffuse Galaxies in the Coma Cluster". The Astrophysical Journal Letters. 804 (1). American Astronomical Society (published 1 May 2015). arXiv:1504.03320. Bibcode:2015arXiv150403320V. doi:10.1088/2041-8205/804/1/L26. {{cite journal}}: Unknown parameter |publicationdate= ignored (|publication-date= suggested) (help)
  • Koda, Jin; Yagi, Masafumi; Yamanoi, Hitomi; Komiyama, Yutaka (4 June 2015). "Approximately A Thousand Ultra Diffuse Galaxies in the Coma cluster". The Astrophysical Journal Letters. arXiv:1506.01712. Bibcode:2015arXiv150601712K.

References

  1. ^ a b "Astronomers discover 854 ultra-dark galaxies in the famous Coma Cluster". Science Daily. 22 June 2015.
  2. ^ a b "Scientists discover the fluffiest galaxies". phys.org. 14 May 2015.
  3. ^ "Scientists at Keck Discover the Fluffiest Galaxies". Space Daily. 18 May 2015.

See also


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