IC 1613

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IC 1613
Dwarf galaxy IC 1613.jpg
IC 1613 captured with the VLT's OmegaCAM.[1]
Observation data (J2000 epoch)
Right ascension01h 04m 47.8s[2]
Declination+02° 07′ 04″[2]
Redshift-234 ± 1 km/s[2]
Distance2.38 ± 0.07 Mly (730 ± 20 kpc)[3][4]
Apparent magnitude (V)9.9[2]
Apparent size (V)16′.2 × 14′.5[2]
Notable features-
Other designations
UGC 668,[2] DDO 8,[2] PGC 3844,[2] Caldwell 51
See also: Galaxy, List of galaxies
Amateur photography of IC 1613.

IC 1613 (also known as Caldwell 51) is an irregular dwarf galaxy, visible in the constellation Cetus near the star 26 Ceti.[5] It was discovered in 1906 by Max Wolf,[5] and is approaching Earth at 234 km/s.

IC 1613 is a member of the Local Group.[5] It has played an important role in the calibration of the Cepheid variable period luminosity relation for estimating distances.[5] Other than the Magellanic Clouds, it is the only Local Group dwarf irregular galaxy where RR Lyrae-type variables have been observed; this factor, along with an unusually low abundance of interstellar dust both within IC 1613 and along the line of sight enable especially accurate distance estimates.,[5][6]

In 1999, Cole et al.[5] used the Hubble Space Telescope to find that the dominant population of this galaxy has an age of ~7 Gyr. Using its Hess diagram, they found that its evolutionary history may be similar to that of the Pegasus Dwarf Irregular Galaxy. Both galaxies are classified as Ir V in the DDO system. Also in 1999, Antonello et al. found five cepheids of Population II in IC 1613, giving self-evident support for the existence of a very old stellar population component of IC 1613. In 1999, King, Modjaz, & Li discovered the first nova ever detected in IC 1613.[7]

IC 1613 contains a WO star known as DR1, the only one so far detected further away than the Magellanic Clouds.[8] The galaxy also contains a Luminous Blue Variable candidate,[9] and a rich population of OB-type[10] stars and OB associations.[11]


  1. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  3. 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.
  4. 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.
  5. 5.0 5.1 5.2 5.3 5.4 5.5 Cole, Andrew A.; Tolstoy, Eline; Gallagher, John S., III; Hoessel, John G.; Mould, Jeremy R.; Holtzman, Jon A.; Saha, Abhijit; Ballester, Gilda E. et al. (1999). "Stellar Populations at the Center of IC 1613". The Astronomical Journal 118 (4): 1657–1670. arXiv:astro-ph/9905350. Bibcode 1999AJ....118.1657C. doi:10.1086/301042.
  6. https://www.eso.org/public/news/eso1603/
  7. van den Bergh, Sidney (April 2000). "Updated Information on the Local Group". The Publications of the Astronomical Society of the Pacific 112 (770): 529–536. arXiv:astro-ph/0001040. Bibcode 2000PASP..112..529V. doi:10.1086/316548
  8. Tramper, F.; Straal, S. M.; Sanyal, D.; Sana, H.; De Koter, A.; Gräfener, G.; Langer, N.; Vink, J. S. et al. (2015). "Massive stars on the verge of exploding: The properties of oxygen sequence Wolf-Rayet stars". Astronomy & Astrophysics 581: A110. arXiv:1507.00839. Bibcode 2015A&A...581A.110T. doi:10.1051/0004-6361/201425390.
  9. Herrero, A.; Garcia, M.; Uytterhoeven, K.; Najarro, F.; Lennon, D. J.; Vink, J. S.; Castro, N.. "The nature of V39: an LBV candidate or LBV impostor in the very low metallicity galaxy IC 1613?" (in en). Astronomy and Astrophysics 513. arXiv:1003.0875. Bibcode 2010A&A...513A..70H. doi:10.1051/0004-6361/200913562. ISSN 0004-6361. http://www.aanda.org/10.1051/0004-6361/200913562.
  10. Garcia, M.; Herrero, A.. "The young stellar population of IC 1613" (in en). Astronomy & Astrophysics 551. arXiv:1211.4582. Bibcode 2013A&A...551A..74G. doi:10.1051/0004-6361/201219977. ISSN 0004-6361. http://www.aanda.org/10.1051/0004-6361/201219977.
  11. Garcia, M.; Herrero, A.; Castro, N.; Corral, L.; Rosenberg, A.. "The young stellar population of IC 1613" (in en). Astronomy & Astrophysics 523. Bibcode 2010A&A...523A..23G. doi:10.1051/0004-6361/201015243. ISSN 0004-6361. http://www.aanda.org/10.1051/0004-6361/201015243.

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