NGC 4593 is abarred spiral galaxy located in the constellationVirgo. It is located at a distance of about 120 millionlight years from Earth, which, given its apparent dimensions, means that NGC 4593 is about 125,000 light years across.[1] It was discovered byWilliam Herschel on April 17, 1784.[2] It is aSeyfert galaxy.[1]
NGC 4593 is a barred spiral galaxy with a nearly completering. The galaxy has a large elliptical/boxypseudobulge with the bar emerging from its northeast and southwest corner. From its end of the bar begin two diffuse smoothspiral arms that can be traced for about half a revolution. At the south part of the ring there could emerge a third, smaller spiral arm.[3] One arm emerges from the ring at one end of the bar while a second emerges about 15 degrees before the other end.[4]
The nucleus of NGC 4593 has been found to beactive and it has been categorised as a type ISeyfert galaxy.[5] The most accepted theory for the energy source of active galactic nuclei is the presence of anaccretion disk around asupermassive black hole. The mass of the black hole in the centre of NGC 4593 is estimated to be(9.8±2.1)×106M☉ based onreverberation mapping[6] or(5.8±2.1)×106M☉ based on X-ray flux variations.[7]
The nucleus has been found to be a bright X-rays source. The source is variable both in flux and spectrum, varying at a timescale of few kiloseconds.[8] The changes in the X-ray band are followed by variations in theultraviolet and visual light band, with the lag being 1.3 ± 0.5 days in theV-band.[9] The X-rays observations byChandra X-ray Observatory indicate the presence of a warm absorber and outflows of ionised gas that are generated at different distances from the nucleus.[10] The overall X-ray spectrum indicates the presence of a hot corona, which generates the hard X-rays, and a warm medium, which is responsible for the soft X-rays excess.[7]
A circumnuclear dust ring with a radius of 5 arcseconds that is connected with the dust lanes in the bar of the galaxy is seen in visible light.[4] Similar rings in other galaxies have been found to exhibitintense star formation, but that isn't the case with NGC 4593, indicating that starburst activity is episodic.[4] Inside the ring lies a single spiral arm and no other dust features.[11]
NGC 4593 is the foremost galaxy in agalaxy group known as theNGC 4593 Group. Other members of the group the spiral galaxyNGC 4602 and the smaller galaxies MCG-01-32-37, MGC-01-32-33, SVEN 314, and SVEN 328.[12] Markarov et al. considerNGC 4604 to be a member of this group as well.[13] SVEN 314 is adwarf galaxy which lies at a projected distance of 22 kpc and is the closest galaxy to NGC 4593.[12] There are evidence that NGC 4593 is interacting with MGC-01-32-33, which lies about two disk radii away, as the spiral pattern is slightly distorted towards the direction of that galaxy, possibly as a result of tidal forces.[4]
^Seligman, Courtney."NGC 4593".Celestial Atlas. Retrieved19 November 2018.
^Eskridge, Paul B.; Frogel, Jay A.; Pogge, Richard W.; Quillen, Alice C.; Berlind, Andreas A.; Davies, Roger L.; DePoy, D. L.; Gilbert, Karoline M.; Houdashelt, Mark L.; Kuchinski, Leslie E.; Ramirez, Solange V.; Sellgren, K.; Stutz, Amelia; Terndrup, Donald M.; Tiede, Glenn P. (November 2002). "Near-Infrared and Optical Morphology of Spiral Galaxies".The Astrophysical Journal Supplement Series.143 (1):73–111.arXiv:astro-ph/0206320.Bibcode:2002ApJS..143...73E.doi:10.1086/342340.
^MacAlpine, G. M.; Williams, G. A.; Lewis, D. W. (December 1979). "Spectrophotometry of the Seyfert galaxy NGC 4593".Publications of the Astronomical Society of the Pacific.91: 746.Bibcode:1979PASP...91..746M.doi:10.1086/130580.
^Denney, Kelly D.; Bentz, Misty C.; Peterson, Bradley M.; Pogge, Richard W.; Cackett, Edward M.; Dietrich, Matthias; Fogel, Jeffrey K. J.; Ghosh, Himel; Horne, Keith D.; Kuehn, Charles; Minezaki, Takeo; Onken, Christopher A.; Pronik, Vladimir I.; Richstone, Douglas O.; Sergeev, Sergey G.; Vestergaard, Marianne; Walker, Matthew G.; Yoshii, Yuzuru (10 December 2006). "The Mass of the Black Hole in the Seyfert 1 Galaxy NGC 4593 from Reverberation Mapping".The Astrophysical Journal.653 (1):152–158.arXiv:astro-ph/0608406.Bibcode:2006ApJ...653..152D.doi:10.1086/508533.hdl:1811/48185.
