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The Circinus Galaxy, a Type II Seyfert galaxy. Seyfert galaxies are one of the two largest groups of active galaxies, along with quasar host galaxies. They have quasar-like nuclei (very luminous sources of electromagnetic radiation that are outside of our own galaxy) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, [1] but unlike quasars, their ...
The characteristics of Seyfert galaxies were first observed in M77 in 1908; however, Seyferts were defined as a class in 1943. [23] First radio galaxy: Cygnus A: Cygnus: 1951 Of several items, then called radio stars, Cygnus A was identified with a distant galaxy, being the first of many radio stars to become a radio galaxy. [24] [25] First ...
The galaxy has a bar and two weak spiral arms which form a ring. [ 4 ] [ 5 ] The nucleus of NGC 7682 has been found to be active and has been categorised as a type 2 Seyfert galaxy . [ 6 ] The most accepted theory for the energy source of Seyfert galaxies is the presence of an accretion disk around a supermassive black hole .
NGC 3147 has been characterised as a Seyfert II galaxy. It is considered the best candidate to be a true type II Seyfert galaxy, [4] galaxies which feature optical/UV spectrum lacking broad emission lines due to the lack of the broad line region rather than its obscuration, since the nucleus is simultaneously seen unobscured in the X-rays.
Several dozen nearby large galaxies, including the Milky Way galaxy, that do not have an active center and do not show any activity similar to a quasar, are confirmed to contain a similar supermassive black hole in their nuclei (galactic center). Thus it is now thought that all large galaxies have a black hole of this kind, but only a small ...
Seyfert's Sextet is a group of galaxies about 190 million light-years away [2] in the constellation Serpens. The group appears to contain six members, but one of the galaxies, NGC 6027d , is a background object (700 million light years behind the group) and another "galaxy," NGC 6027e , is actually a part of the tail from galaxy NGC 6027 .
NGC 7469 is a type 1.2 Seyfert galaxy and one of the most well studied Seyfert galaxies. In 1943, this galaxy was one of six nebulae listed by American astronomer Carl K. Seyfert that showed broad emission lines in their nuclei . [ 6 ]
The galaxy was discovered by German-British astronomer William Herschel on 1 April 1790. [3] The SIMBAD database lists NGC 3079 as a Seyfert II Galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable. [4]