NGC 547 is anelliptical galaxy andradio galaxy (identified as 3C 40) located in the constellationCetus. It is located at a distance of about 214 millionlight years from Earth, which, given its apparent dimensions, means that NGC 547 is about 147,000 light years across. It was discovered by German-British astronomerWilliam Herschel on October 1, 1785.[3] It is a member of theAbell 194 galaxy cluster and is included along with NGC 547 in theAtlas of Peculiar Galaxies.[2]
NGC 547 is a prominentradio galaxy, with two largeradio jets ofFanaroff-Riley class I with wide-angle tails. The galaxy is identified as 3C 40B (3C 40A is less prominent and is associated with the nearby galaxyNGC 541),[4] and the source extends for 10 arcminutes in the south–north direction.[5] A small, smooth, dark feature has been observed running across the nucleus in images by theHubble Space Telescope. Its projected size is 0.3 kpc and its shape suggests it is the near side of a smalldust disk.[6]
NGC 547 forms a pair with the equally brightNGC 545, which lies 0.5 arcminutes away. They share a common envelope,[7] however, despite their close position, no tidal features like tails or bridges have been observed.[8] A stellar bridge has been detected between the galaxy pair andNGC 541,[9] which lies 4.5 arcminutes to the southwest (projected distance circa 100 kpc).[10]
Observations of the galaxy by theChandra X-Ray Observatory revealed a large very luminous X-ray corona around the galaxy. The gas distribution appears symmetric, without evidence of tails, indicating its relatively low velocity, and thus it has been identified as the centre of the cluster, with NGC 541 and NGC 545 moving towards it.[11]
^Croft, Steve; van Breugel, Wil; de Vries, Wim; Dopita, Mike; Martin, Chris;Morganti, Raffaella; Neff, Susan; Oosterloo, Tom; Schiminovich, David; Stanford, S. A.; van Gorkom, Jacqueline (20 August 2006). "Minkowski's Object: A Starburst Triggered by a Radio Jet, Revisited".The Astrophysical Journal.647 (2):1040–1055.arXiv:astro-ph/0604557.Bibcode:2006ApJ...647.1040C.doi:10.1086/505526.S2CID119331218.
^Verdoes Kleijn, Gijs A.; Baum, Stefi A.; de Zeeuw, P. Tim; O'Dea, Chris P. (December 1999). "Hubble Space Telescope Observations of Nearby Radio-Loud Early-Type Galaxies".The Astronomical Journal.118 (6):2592–2617.arXiv:astro-ph/9909256.Bibcode:1999AJ....118.2592V.doi:10.1086/301135.
^Bogdán, Ákos; Kraft, Ralph P.; Forman, William R.; Jones, Christine; Randall, Scott W.; Sun, Ming; O'Dea, Christopher P.; Churazov, Eugene; Baum, Stefi A. (10 December 2011). "Chandra and ROSAT Observations of A194: Detection of an X-Ray Cavity and Mapping the Dynamics of the Cluster".The Astrophysical Journal.743 (1): 59.arXiv:1106.3434.Bibcode:2011ApJ...743...59B.doi:10.1088/0004-637X/743/1/59.S2CID119111765.
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