NGC 6251

NGC 6251
	Hubble image of the heart of the active galaxy NGC 6251
Observation data (J2000 epoch)
Constellation	Ursa Minor
Right ascension	16h 32m 31.9700s
Declination	+82° 32′ 16.400″
Redshift	0.02471
Distance	340 million light-years
Apparent magnitude (V)	14.3
Characteristics
Type	E
Apparent size (V)	1.82´X1.55´
Other designations
	NGC 6251, UGC 10501, LEDA 58472, 6C 1636+8239, QSO B1637+826

Short description: Seyfert galaxy in the constellation Ursa Minor

NGC 6251 is an active supergiant elliptical radio galaxy in the constellation Ursa Minor, and is more than 340 million light-years away from Earth. The galaxy has a Seyfert 2 active galactic nucleus,^[3] and is one of the most extreme examples of a Seyfert galaxy. This galaxy may be associated with gamma-ray source 3EG J1621+8203, which has high-energy gamma-ray emission.^[3] It is also noted for its one-sided radio jet—one of the brightest known—discovered in 1977.^[4] The supermassive black hole at the core has a mass of (5.9±2.0)×10⁸ M_☉.^[5]

References

↑ ^1.0 ^1.1 ^1.2 ^1.3 "NASA/IPAC Extragalactic Database". Results for NGC 6251. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC++6251&extend=no.
↑ "Distance and Length". Online-Unit-Converter.com. http://www.online-unit-converter.com/distance-and-length/.
↑ ^3.0 ^3.1 ^3.2 SIMBAD
↑ Perley, R. A.; Bridle, A. H.; Willis, A. G. (1984). "High-resolution VLA Observations of the Radio Jet in NGC 6251". Astrophysical Journal Supplement Series 54: 291–334. doi:10.1086/190931. Bibcode: 1984ApJS...54..291P.
↑ Graham, Alister W. (November 2008), "Populating the Galaxy Velocity Dispersion - Supermassive Black Hole Mass Diagram: A Catalogue of (Mbh, σ) Values", Publications of the Astronomical Society of Australia 25 (4): 167–175, doi:10.1071/AS08013, Bibcode: 2008PASA...25..167G.