Ursa Minor Dwarf

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Ursa Minor Dwarf
Observation data (J2000 epoch)
ConstellationUrsa Minor
Right ascension15h 09m 08.5s[1]
Declination+67° 13′ 21″[1]
Redshift-247 ± 1 km/s[1]
Distance200 ± 30 kly (60 ± 10 kpc)[2][3]
Apparent magnitude (V)11.9[1]
Apparent size (V)30′.2 × 19′.1[1]
Notable featuresSatellite galaxy of Milky Way
Other designations
UGC 9749,[1] PGC 54074,[1] DDO 199,[1] UMi Dwarf[1]
See also: Galaxy, List of galaxies
Amateur image, 10.7 hr. exposure with Esprit 100 APO Refractor+QHY16200CCD @-20C/ IDAS LP2 filter.

The Ursa Minor Dwarf is a dwarf spheroidal galaxy, discovered by A.G. Wilson of the Lowell Observatory, in the United States, during the Palomar Sky Survey in 1955.[4] It appears in the Ursa Minor constellation, and is a satellite galaxy of the Milky Way. The galaxy consists mainly of older stars and seems to house little to no ongoing star formation. 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. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  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. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  5. Grebel, Eva K.; Gallagher, John S., III; Harbeck, Daniel. "The Progenitors of Dwarf Spheroidal Galaxies". The Astronomical Journal 125 (4): 1926–39. arXiv:astro-ph/0301025. 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). arXiv:astro-ph/9903065. Bibcode 1999AJ....118..366M. doi:10.1086/300923.

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