Ursa Minor Dwarf

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]

Ursa Minor Dwarf
Ursa Minor Dwarf imaged by Giuseppe Donatiello
Observation data (J2000 epoch)
ConstellationUrsa Minor
Right ascension 15h 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]
Characteristics
TypeE[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]
Amateur image, 10.7 hr. exposure with Esprit 100 APO Refractor+QHY16200CCD @-20C/ IDAS LP2 filter.

Evolutionary history

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

References
  1. "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 978-1-139-42965-8.
  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.CS1 maint: multiple names: authors list (link)
  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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