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]
^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.
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.