IC 1101

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IC 1101
IC 1101 in Abell 2029 (hst 06228 03 wfpc2 f702w pc).jpg
June 1995 image of IC 1101 taken by the Hubble Space Telescope
Observation data (J2000 epoch)
Right ascension 15h 10m 56.1s[1]
Declination+05° 44′ 41″[1]
Helio radial velocity23,368 ± 26 km/s (14,520 ± 16 mi/s)[1]
Galactocentric velocity23,395 ± 26 km/s (14,537 ± 16 mi/s)[1]
Distance1.045 ± 0.073 billion ly (320.4 ± 22.4 Mpc)h−1
Group or clusterAbell 2029
Apparent magnitude (V)14.73[1]
Number of stars100 trillion (1014)
Size210 ± 39 thousand ly (64 ± 12 kpc) effective radius[4]
Apparent size (V)1'.2 × 0'.6[1]
Other designations
UGC 9752,[1] PGC 54167,[1] A2029-BCG[1]

IC 1101 is a supergiant elliptical galaxy at the center of the Abell 2029 galaxy cluster and is one of the largest known galaxies. Its halo extends about 600 kiloparsecs (2 million light-years) from its core, and it has a mass of about 100 trillion stars.[citation needed] The galaxy is located 320 megaparsecs (1.04 billion light-years) from Earth.


The galaxy is classified as a supergiant elliptical (E) to lenticular (S0)[3] and is the brightest galaxy in A2029 (hence its other designation A2029-BCG; BCG meaning brightest cluster galaxy).[5][6] The galaxy's morphological type is debated due to it possibly being shaped like a flat disc but only visible from Earth at its broadest dimensions. However, most lenticulars have sizes ranging from 15 to 37 kpc (50 to 120 thousand ly).[7][specify]

IC 1101 is among the largest known galaxies, but there is debate in the astronomical literature about how to define the size of such a galaxy. Photographic plates of blue light from the galaxy (sampling stars excluding the diffuse halo) yield an effective radius (the radius within which half the light is emitted) of 65 ± 12 kpc (212 ± 39 thousand ly).[4] The galaxy has a very large halo of much lower intensity "diffuse light" extending to a radius of 600 kpc (2 million ly).[8] The authors of the study identifying the halo conclude that IC 1101 is "possibly one of the largest and most luminous galaxies in the universe".[8]

Like most large galaxies, IC 1101 is populated by a number of metal-rich stars, some of which are seven billion years older than the Sun, making it appear golden yellow in color. It has a bright radio source at the center, which is likely associated with an ultramassive black hole in the mass range of 40–100 billion M, one of the largest known black holes in the universe.[9][10]


The galaxy was discovered on 19 June 1790, by the British astronomer Frederick William Herschel I.[11] It was catalogued in 1895 by John Louis Emil Dreyer as the 1,101st object of the Index Catalogue of Nebulae and Star Clusters (IC). At its discovery, it was identified as a nebulous feature. Following Edwin Hubble's 1932 discovery that some of the "nebulous features" were actually independent galaxies, subsequent analysis of objects in the sky were conducted and IC 1101 was therefore found to be one of the independent galaxies.[citation needed]

See also[edit]


  1. ^ a b c d e f g h i j "NED results for object IC 1101". NASA/IPAC Extragalactic Database. Retrieved 11 November 2006.
  2. ^ Hoessel, J.; Gunn, J.; Thuan, T. (October 1980). "The photometric properties of brightest cluster galaxies. I - Absolute magnitudes in 116 nearby Abell clusters". The Astrophysical Journal. 241: 486–492. Bibcode:1980ApJ...241..486H. doi:10.1086/158363.
  3. ^ a b "IC 1101". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 21 December 2014.
  4. ^ a b Fisher, David; Illingworth, Garth; Franx, Marijn (January 1995). "Kinematics of 13 brightest cluster galaxies". The Astrophysical Journal. 438 (2): 539–562. Bibcode:1995ApJ...438..539F. doi:10.1086/175100.
  5. ^ Lewis, Aaron D.; Buote, David A.; Stocke, John T. (March 2003). "Chandra Observations of A2029: The Dark Matter Profile Down to below 0.01rvir in an Unusually Relaxed Cluster". The Astrophysical Journal. 586 (1): 135–142. arXiv:astro-ph/0209205. Bibcode:2003ApJ...586..135L. doi:10.1086/367556.
  6. ^ Uson, Juan M.; Boughn, Stephen P.; Kuhn, Jeffrey R. (October 1990). "The central galaxy in Abell 2029 - an old supergiant". Science. 250 (4980): 539–540. Bibcode:1990Sci...250..539U. doi:10.1126/science.250.4980.539. PMID 17751483.
  7. ^ Seligman, Courtney. "NGC Objects: NGC 50 - 99". Cseligman.com. Celestial Atlas. Retrieved 14 April 2015.
  8. ^ a b Uson, Juan M.; Boughn, Stephen P.; Kuhn, Jeffrey R. (March 1991). "Diffuse light in dense clusters of galaxies. I. R-band observations of Abell 2029". The Astrophysical Journal. 369: 46–53. Bibcode:1991ApJ...369...46U. doi:10.1086/169737.
  9. ^ Dullo, Bililign T.; Graham, Alister W.; Knapen, Johan H. (October 2017). "A remarkably large depleted core in the Abell 2029 BCG IC 1101". Monthly Notices of the Royal Astronomical Society. 471 (2): 2321–2333. arXiv:1707.02277. Bibcode:2017MNRAS.471.2321D. doi:10.1093/mnras/stx1635.
  10. ^ Brockamp, M.; Baumgardt, H.; Britzen, S.; Zensus, A. (January 2016). "Unveiling Gargantua: A new search strategy for the most massive central cluster black holes". Astronomy & Astrophysics. 585. A153. arXiv:1509.04782. Bibcode:2016A&A...585A.153B. doi:10.1051/0004-6361/201526873.
  11. ^ "William Herschel's astronomical discoveries". MacTutor. University of St Andrews, Scotland. Retrieved 4 April 2020.

External links[edit]

Coordinates: Sky map 15h 10m 56.1s, +05° 44′ 41″