NGC 3256

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NGC 3256
Hubble Interacting Galaxy NGC 3256 (2008-04-24).jpg
Observation data (J2000 epoch)
Right ascension10h 27m 51.3s[1]
Declination−43° 54′ 13″[1]
Redshift0.009354 +/- 0.000019 [1]
Helio radial velocity2,804 ± 6 km/s[1]
Distance122 Mly (37.4 Mpc)[1]
Apparent magnitude (V)11.3
TypePec [1]
Apparent size (V)3′.8 × 2′.1[1]
Notable featuresGalaxy merger, starburst galaxy
Other designations
ESO 263-IG 038, VV 65, AM 1025-433, MCG -07-22-010, PGC 030785[1]
See also: Galaxy, List of galaxies

NGC 3256 is a galaxy formed from the collision of two separate galaxies in the constellation of Vela. NGC 3256 is located about 100 million light years away and belongs to the Hydra-Centaurus supercluster complex. NGC 3256 provides a nearby template for studying the properties of young star clusters in tidal tails. The system hides a double nucleus and a tangle of dust lanes in the central region. The telltale signs of the collision are two extended luminous tails swirling out from the galaxy. The tails are studded with a particularly high density of star clusters.[2] NGC 3256 is the most luminous galaxy in the infrared spectrum located within z 0.01 from Earth.[3]



NGC 3256 has double nuclei: the northern and southern nucleus, separated by 5", which at the distance of NGC 3256 corresponds to 850 pc. The nuclei are clearly visible in radiowaves and mid infrared, but the southern nucleus is hidden by dust lanes at the optical spectrum. The two nuclei will coalesce as the merger proceeds to its final stage.[4] Lipari et al. note the presence of a third nucleus based on the presence of an obscured knot detected only at wavelengths λ ≥ 3.75 μm, which they suggest is a nuclear HII region.[5]

There is evidence of an outflow of ionised gas from the northern nucleus[5] with shocks which is attributed to a superwind powered by the starburst.[4] Based on observations by Spitzer Space Telescope, and Chandra X-ray Observatory, Ohyana et al. suggested that the southern nucleus of NGC 3256 is a heavily absorbed low luminosity active galactic nucleus, with X-ray spectrum consistent with a typical Compton-thin Seyfert 2 galaxy.[4]

HII regions[edit]

Although NGC 3256 has seven large HII regions, a number small in comparison with other interacting galaxies, they are very luminous, with a total flux 85 times that of the Tarantula Nebula and they could host super star clusters.[6] The HII regions conicide with X-ray emission regions, with possible sources being supernova remnants and X-ray binaries, which suggests the sources are in clusters with massive stars which may be initially embedded in HII regions.[6] The HI mass of these features suggests they could be progenitors of globular clusters.[7]

Tidal tails[edit]

NGC 3256 features two tidal tails. The two tails account for approximately 75% of the HI emission of the galaxy, which, however, includes a central absorption feature.[7] Michael Rubrock et al. found that the two tails have different colors, suggesting different stellar populations. The eastern tail has mean stellar population age determined to be 841+125−157 Myr and a larger percentage of mass belonging to the stellar population that was formed before the galaxy interaction. In the eastern tail were also detected several young (< 10 Myr), low mass objects with strong nebular emission, indicating a small, recent burst of star formation. The mean stellar population of the western tail was estimated to be 288+11−54 Myr and its light is dominated by stars formed after the interaction.[8] The tails feature large numbers of star clusters, especially the western tail.[9]

Nearby galaxies[edit]

NGC 3256 belongs to a small group of galaxies which includes also the tidally disrupted NGC 3263 and NGC 3256C and roughly 15 more galaxies, as well as HI fragments. Some researchers have considered that NGC 3256 and NGC 3263 form two different groups but they are difficult to distinguish from each other spatially and two different group-finding algorithms applied to the same data catalogued the same galaxies in different groups. Among the features of the NGC 3256 group is a galaxy-sized intergalactic HI cloud known as the Vela Cloud, which as seen from Earth is not clearly associated with an individual galaxy but appears to be part of the group.[10]

The NGC 3256 group belongs to the Hydra-Centaurus supercluster.


See also[edit]

  • NGC 6240 - a nearby ultraluminous infrared galaxy
  • Arp 220 - another ultraluminous infrared galaxy and merger remnant


  1. ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 3256. Retrieved 2016-01-18.
  2. ^ "NGC 3256". 24 April 2008.
  3. ^ Sanders, D. B.; Mazzarella, J. M.; Kim, D.-C.; Surace, J. A.; Soifer, B. T. (October 2003). "The IRAS Revised Bright Galaxy Sample". The Astronomical Journal. 126 (4): 1607–1664. arXiv:astro-ph/0306263. Bibcode:2003AJ....126.1607S. doi:10.1086/376841.
  4. ^ a b c Ohyama, Youichi; Terashima, Yuichi; Sakamoto, Kazushi (29 May 2015). "INFRARED AND X-RAY EVIDENCE OF AN AGN IN THE NGC 3256 SOUTHERN NUCLEUS". The Astrophysical Journal. 805 (2): 162. arXiv:1503.08555. Bibcode:2015ApJ...805..162O. doi:10.1088/0004-637X/805/2/162.
  5. ^ a b Lípari, S.; Díaz, R.; Taniguchi, Y.; Terlevich, R.; Dottori, H.; Carranza, G. (August 2000). "Luminous Infrared Galaxies. III. Multiple Merger, Extended Massive Star Formation, Galactic Wind, and Nuclear Inflow in NGC 3256". The Astronomical Journal. 120 (2): 645–669. arXiv:astro-ph/9911019. Bibcode:2000AJ....120..645L. doi:10.1086/301480.
  6. ^ a b English, J.; Freeman, K. C. (March 2003). "Giant H [CSC]ii[/CSC] Regions in the Merging System NGC 3256: Are They the Birthplaces of Globular Clusters?". The Astronomical Journal. 125 (3): 1124–1133. arXiv:astro-ph/0302191. Bibcode:2003AJ....125.1124E. doi:10.1086/367915.
  7. ^ a b English, J.; Norris, R. P.; Freeman, K. C.; Booth, R. S. (March 2003). "NGC 3256: Kinematic Anatomy of a Merger". The Astronomical Journal. 125 (3): 1134–1149. arXiv:astro-ph/0302192. Bibcode:2003AJ....125.1134E. doi:10.1086/367914.
  8. ^ Rodruck, Michael; Konstantopoulos, Iraklis; Knierman, Karen; Fedotov, Konstantin; Mullan, Brendan; Gallagher, Sarah; Durrell, Patrick; Ciardullo, Robin; Gronwall, Caryl; Charlton, Jane (1 September 2016). "A tale of two tails: exploring stellar populations in the tidal tails of NGC 3256". Monthly Notices of the Royal Astronomical Society. 461 (1): 36–50. arXiv:1606.00008. Bibcode:2016MNRAS.461...36R. doi:10.1093/mnras/stw1294.
  9. ^ Knierman, Karen A.; Gallagher, Sarah C.; Charlton, Jane C.; Hunsberger, Sally D.; Whitmore, Bradley; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis (September 2003). "From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies". The Astronomical Journal. 126 (3): 1227–1244. arXiv:astro-ph/0307383. Bibcode:2003AJ....126.1227K. doi:10.1086/377481.
  10. ^ English, Jayanne; Koribalski, B.; Bland-Hawthorn, J.; Freeman, K. C.; McCain, Claudia F. (1 January 2010). "THE VELA CLOUD: A GIANT H I ANOMALY IN THE NGC 3256 GROUP". The Astronomical Journal. 139 (1): 102–119. arXiv:0903.2690. Bibcode:2010AJ....139..102E. doi:10.1088/0004-6256/139/1/102.
  11. ^ "Cosmic collision lights up the darkness". Retrieved 4 June 2018.
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