NGC 6814

NGC 6814 is an intermediate spiral galaxy in constellation Aquila. It is located at a distance of about 75 million light years from Earth, which, given its apparent dimensions, means that NGC 6814 is about 85,000 light years across. NGC 6814 has an extremely bright nucleus and is a type 1.5 Seyfert galaxy. The galaxy is also a highly variable source of X-ray radiation. The ultraviolet and optical emission also varies, although more smoothly, with time lag of two days. The cause of the lag and the smoothing of light curves is considered to be the reprocessing of the X-rays in the accretion disk.[2] The cause of the active galactic nucleus is suspected to be a supermassive black hole with a mass about 18 million times that of the Sun. Many regions of ionised gas are studded along the dusty spiral arms.[3]

NGC 6814
A spiral snowflake
Observation data (J2000 epoch)
ConstellationAquila
Right ascension 19h 42m 40.6s[1]
Declination−10° 19′ 25″[1]
Redshift1563 ± 2 km/s[1]
Distance74 Mly (22.8 Mpc)[1]
Apparent magnitude (V)12.1
Characteristics
TypeSAB(rs)bc [1]
Apparent size (V)3′.0 × 2′.8[1]
Other designations
MCG -02-50-001, PGC 63545[1]

References

  1. ^ a b c d e f g "NASA/IPAC Extragalactic Database". Results for NGC 6814. Retrieved 2016-01-18.
  2. ^ Troyer, Jon; Starkey, David; Cackett, Edward M.; Bentz, Misty C.; Goad, Michael R.; Horne, Keith; Seals, James E. (14 January 2016). "Correlated X-ray/ultraviolet/optical variability in NGC 6814". Monthly Notices of the Royal Astronomical Society. 456 (4): 4040–4050. arXiv:1509.01124. Bibcode:2016MNRAS.456.4040T. doi:10.1093/mnras/stv2862.
  3. ^ "A spiral snowflake". www.spacetelescope.org. 9 May 2016. Retrieved 13 March 2017.

External links

HD 194244

HD 194244 is a variable Be star in the equatorial constellation of Aquila. With an apparent magnitude of 6.14, according to the Bortle scale it is faintly visible to the naked eye from rural skies on a dark night.

LEDA 83677

LEDA 83677 is a lenticular galaxy located about 290 million light-years away in the constellation Coma Berenices. It is a member of the Coma cluster of galaxies. LEDA 83677 is also classified as a type 1 Seyfert galaxy. The core of the galaxy is emitting high-energy X-rays and ultraviolet light, probably caused by a massive black hole lurking in the core.

NGC 3147

NGC 3147 is a spiral galaxy located in the constellation Draco. It is located at a distance of circa 130 million light years from Earth, which, given its apparent dimensions, means that NGC 3147 is about 140,000 light years across. It was discovered by William Herschel οn

April 3, 1785. It is a Type II Seyfert galaxy.

Seyfert galaxy

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.Seyfert galaxies account for about 10% of all galaxies and are some of the most intensely studied objects in astronomy, as they are thought to be powered by the same phenomena that occur in quasars, although they are closer and less luminous than quasars. These galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the observed ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material.Seen in visible light, most Seyfert galaxies look like normal spiral galaxies, but when studied under other wavelengths, it becomes clear that the luminosity of their cores is of comparable intensity to the luminosity of whole galaxies the size of the Milky Way.Seyfert galaxies are named after Carl Seyfert, who first described this class in 1943.

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