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)
Constellation Cetus
Right ascension 01h 04m 47.8s[2]
Declination +02° 07′ 04″[2]
Redshift -234 ± 1 km/s[2]
Distance 2.38 ± 0.07 Mly (730 ± 20 kpc)[3][4]
Apparent magnitude (V) 9.9[2]
Type IB(s)m[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]


  1. ^ "The Milky Way’s Clean and Tidy Galactic Neighbour". Retrieved 29 January 2016. 
  2. ^ a b c d e f g h i "NASA/IPAC Extragalactic Database". Results for IC 1613. Retrieved 2006-11-29. 
  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. ^ a b c d e f Cole, Andrew A.; Tolstoy, Eline; Gallagher, John S., III; Hoessel, John G.; Mould, Jeremy R.; Holtzman, Jon A.; Saha, Abhijit; Ballester, Gilda E.; Burrows, Christopher J.; Clarke, John T.; Crisp, David; Griffiths, Richard E.; Grillmair, Carl J.; Hester, Jeff J.; Krist, John E.; Meadows, Vikki; Scowen, Paul A.; Stapelfeldt, Karl R.; Trauger, John T.; Watson, Alan M.; Westphal, James R. (1999). "Stellar Populations at the Center of IC 1613". The Astronomical Journal. 118 (4): 1657–1670. Bibcode:1999AJ....118.1657C. arXiv:astro-ph/9905350Freely accessible. 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. Bibcode:2000PASP..112..529V. arXiv:astro-ph/0001040Freely accessible. doi:10.1086/316548. 
  8. ^ Tramper, F.; Straal, S. M.; Sanyal, D.; Sana, H.; De Koter, A.; Gräfener, G.; Langer, N.; Vink, J. S.; De Mink, S. E.; Kaper, L. (2015). "Massive stars on the verge of exploding: The properties of oxygen sequence Wolf-Rayet stars". Astronomy & Astrophysics. 581: A110. Bibcode:2015A&A...581A.110T. arXiv:1507.00839Freely accessible. doi:10.1051/0004-6361/201425390. 

External links[edit]

Coordinates: Sky map 01h 04m 47.8s, +02° 07′ 04″