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NGC 547
NGC 547
	NGC 547 (center) and NGC 545 (upper left) imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Cetus
Right ascension	01h 26m 00.6s
Declination	−01° 20′ 43″
Redshift	0.018239 ± 0.000020
Heliocentric radial velocity	5,468 ± 6 km/s
Distance	216 ± 51 Mly (66.2 ± 15.5 Mpc)
Group or cluster	Abell 194
Apparent magnitude (V)	12.3
Characteristics
Type	E1
Apparent size (V)	1.9′ × 1.8′
Other designations
	UGC 1009, 3C 40B, Arp 308, CGCG 385-132, MCG +00-04-142, PGC 5324

NGC 547 is an elliptical galaxy and radio galaxy (identified as 3C 40) located in the constellation Cetus. It is located at a distance of about 220 million light years from Earth, which, given its apparent dimensions, means that NGC 547 is about 120,000 light years across. It was discovered by William Herschel on October 1, 1785.^[2] It is a member of the Abell 194 galaxy cluster and is included along with NGC 547 in the Atlas of Peculiar Galaxies.

NGC 547 is a prominent radio galaxy, with two large radio jets of Fanaroff-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 galaxy NGC 541),^[3] and the source extends for 10 arcminutes in the south–north direction.^[4] A small, smooth, dark feature has been observed running across the nucleus in images by the Hubble Space Telescope. Its projected size is 0.3 kpc and its shape suggests it is the near side of a small dust disk.^[5]

NGC 547 forms a pair with the equally bright NGC 545, which lies 0.5 arcminutes away. They share a common envelope,^[6] however, despite their close position, no tidal features like tails or bridges have been observed.^[7] A stellar bridge has been detected between the galaxy pair and NGC 541,^[8] which lies 4.5 arcminutes to the southwest (projected distance circa 100 kpc).^[9]

Observations of the galaxy by the Chandra 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.^[10]

References

^ ^a ^b ^c ^d ^e ^f ^g "NASA/IPAC Extragalactic Database". Results for NGC 547. Retrieved 2019-01-18.
^ Seligman, Courtney. "NGC 547 (= PGC 5324, and with NGC 545 = Arp 308)". Celestial Atlas. Retrieved 19 November 2018.
^ Sakelliou, Irini; Hardcastle, M. J.; Jetha, N. N. (February 2008). "3C 40 in Abell 194: can tail radio galaxies exist in a quiescent cluster?". Monthly Notices of the Royal Astronomical Society. 384 (1): 87–93. arXiv:0709.2133. Bibcode:2008MNRAS.384...87S. doi:10.1111/j.1365-2966.2007.12465.x. S2CID 16802624.
^ Condon, J. J.; Cotton, W. D.; Broderick, J. J. (August 2002). "Radio Sources and Star Formation in the Local Universe". The Astronomical Journal. 124 (2): 675–689. Bibcode:2002AJ....124..675C. doi:10.1086/341650. S2CID 122284200.
^ Martel, André R.; Baum, Stefi A.; Sparks, William B.; Wyckoff, Eric; Biretta, John A.; Golombek, Daniel; Macchetto, Ferdinando D.; de Koff, Sigrid; McCarthy, Patrick J.; Miley, George K. (May 1999). "Hubble Space Telescope Snapshot Survey of 3CR Radio Source Counterparts. III. Radio Galaxies with z<0.1". The Astrophysical Journal Supplement Series. 122 (1): 81–108. Bibcode:1999ApJS..122...81M. doi:10.1086/313205.
^ Nilson, P. (1973) Uppsala General Catalogue of Galaxies, Acta Universitatis Upsalienis, Nova Regiae Societatis Upsaliensis, Series V: A Vol. 1
^ Fasano, G.; Falomo, R.; Scarpa, R. (September 1996). "Optical surface photometry of radio galaxies — I. Observations and data analysis". Monthly Notices of the Royal Astronomical Society. 282 (1): 40–66. Bibcode:1996MNRAS.282...40F. doi:10.1093/mnras/282.1.40.
^ 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. S2CID 119331218.
^ 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. S2CID 119111765.