Ursa Minor Dwarf

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Ursa Minor Dwarf
Observation data (J2000 epoch)
Constellation Ursa Minor
Right ascension 15h 09m 08.5s[1]
Declination +67° 13′ 21″[1]
Redshift -247 ± 1 km/s[1]
Distance 200 ± 30 kly (60 ± 10 kpc)[2][3]
Type E[1]
Apparent dimensions (V) 30′.2 × 19′.1[1]
Apparent magnitude (V) 11.9[1]
Notable features Satellite galaxy of Milky Way
Other designations
UGC 9749,[1] PGC 54074,[1] DDO 199,[1] UMi Dwarf[1]
See also: Galaxy, List of galaxies

The Ursa Minor Dwarf dwarf spheroidal galaxy was discovered by A.G. Wilson of the Lowell Observatory in the Palomar Sky Survey in 1955.[4] It is part of the Ursa Minor constellation, and a satellite galaxy to the Milky Way. The galaxy consists mainly of older stars and there appears to be little to no ongoing star formation in the Ursa Minor Dwarf galaxy. Its centre is around 225,000 light years distant from Earth.[5]

Evolutionary history[edit]

In 1999, Kenneth Mighell and Christopher Burke used the Hubble Space Telescope to confirm that the Ursa Minor dwarf galaxy had a straightforward evolutionary history with a single burst of star formation that lasted around 2 billion years and took place around 14 billion years ago,[6] and that the galaxy was probably as old as the Milky Way itself.[7]

See also[edit]


  1. ^ a b c d e f g h i j "NASA/IPAC Extragalactic Database". Results for Ursa Minor Dwarf. Retrieved 2006-11-29. 
  2. ^ I. D. Karachentsev; V. E. Karachentseva; W. K. Hutchmeier; D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905. 
  3. ^ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. 
  4. ^ Bergh, Sidney (2000). The Galaxies of the Local Group. Cambridge, United Kingdom: Cambridge University Press. p. 257. ISBN 9781139429658. 
  5. ^ Grebel, Eva K.; Gallagher, John S., III; Harbeck, Daniel. "The Progenitors of Dwarf Spheroidal Galaxies". The Astronomical Journal 125 (4): 1926–39. Bibcode:2003AJ....125.1926G. doi:10.1086/368363. 
  6. ^ van den Bergh, Sidney (April 2000). "Updated Information on the Local Group". The Publications of the Astronomical Society of the Pacific 112 (770): 529–36. arXiv:astro-ph/0001040. Bibcode:2000PASP..112..529V. doi:10.1086/316548. 
  7. ^ Mighell, Kenneth J.; Burke, Christopher J. (1999). "WFPC2 Observations of the Ursa Minor Dwarf Spheroidal Galaxy". The Astronomical Journal 118 (366). doi:10.1086/300923. 

External links[edit]

Coordinates: Sky map 15h 09m 08.5s, +67° 13′ 21″