NGC 3982

NGC 3982 is an intermediate spiral galaxy approximately 68 million light-years away in the constellation Ursa Major. It is also known as UGC 6918. It was discovered by William Herschel on April 14, 1789 and misclassified as planetary nebula.[3] NGC 3982 is a part of the M109 Group.

At an apparent magnitude of 12.0, NGC 3982 needs a telescope to be viewed. Using small telescopes, the galaxy appears as a very faint, diffuse patch of light with its central region appearing as a slightly brighter diffuse ball.

NGC 3982
NGC 3982 galaxy hubble
NGC 3982 as taken by the Hubble Space Telescope
Observation data (J2000 epoch)
ConstellationUrsa Major
Right ascension 11h 56m 28.1s[1]
Declination+55° 07′ 31″[1]
Redshift1109 ± 6 km/s[1]
Distance68.1 ± 2.5 Mly (20.89 ± 0.77 Mpc)[2]
Apparent magnitude (V)12.0[1]
Apparent size (V)1′.7 × 1′.5[1]
Other designations
UGC 6918,[1]PGC 37520[1]


NGC 3982 - Hubble space telescope, 2003
NGC 3982

NGC 3982 is a Seyfert 2 galaxy that spans about 30,000 light-years, about one-third of the size of our Milky Way galaxy. The galaxy is receding from us at about 1109 km/s. The galaxy is a typical spiral galaxy, similar to our Milky Way. It harbors a supermassive black hole at its core and has massive regions of star formation in the bright blue knots in the spiral arms.[4] Supernovae are likely to be found within these regions.

NGC 3982 has a high rate of star birth within its arms, which are lined by pink star-forming regions of glowing hydrogen and newborn blue star clusters. Its bright nucleus is home to older populations of stars, which grow more densely packed toward the center. The galaxy also has active star formation in the circumnuclear region estimated at 0.52 M⊙/year. The HST image of NGC 3982 shows a mini-spiral between the circumnuclear star-forming region and the galaxy's nucleus, which could be the channel through which gas is transported to the supermassive black hole from the star-forming region.

NGC 3982 is a member of the M109 Group, a group of galaxies located in the constellation Ursa Major that may contain over 50 galaxies. The group was named after the brightest galaxy in the group, the spiral galaxy M109.[5][6][7]

Astronomers are interested in studying this galaxy as it can help in measuring extragalactic distances. It is helpful because it possesses two tools used to estimate astronomical distances: a stellar explosion, or supernova; and Cepheid variable stars.

Supernova 1998aq

In 1998, the light from a supernova in NGC 3982 (later called SN 1998aq) reached earth and was discovered by British amateur astronomer Mark Armstrong. It was discovered when it had an apparent magnitude of 14.9 and it had grown considerably brighter by two days after its initial sighting (it reached a maximum magnitude of 14.0). The explosion resulted from a binary system where a white dwarf star was capturing mass from its companion star. When the white dwarf had gathered enough mass and was no longer able to support itself, the star detonated in a violent and extremely bright explosion. Since a supernova explosion roughly occurs in a typical spiral galaxy every 100 years, astronomers use high-resolution images of NGC 3982 and other galaxies to detect stars which are nearing a similar explosive descent into supernovae.


  1. ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 3982. Retrieved 2006-11-16.
  2. ^ Riess, Adam G.; Li, Weidong; Stetson, Peter B.; Filippenko, Alexei V.; et al. (2005). "Cepheid Calibrations from the Hubble Space Telescope of the Luminosity of Two Recent Type Ia Supernovae and a Redetermination of the Hubble Constant". Astrophysical Journal. 627 (2): 579–607. arXiv:astro-ph/0503159. Bibcode:2005ApJ...627..579R. doi:10.1086/430497.
  3. ^ NGC 3982. Students for the Exploration and Development of Space. Retrieved March 3, 2009
  4. ^ Zhang, Shui-Nai; Gu, Qiu-Sheng; Wang, Yi-Peng (2008). "Circumnuclear Star Forming Activity in NGC 3982". Chinese Journal of Astronomy and Astrophysics. 8 (5): 555. Bibcode:2008ChJAA...8..555Z. doi:10.1088/1009-9271/8/5/06.
  5. ^ Tully, R. B. (1988). Nearby Galaxies Catalog. Cambridge University Press. ISBN 978-0-521-35299-4.
  6. ^ Fouque, P.; Gourgoulhon, E.; Chamaraux, P.; Paturel, G. (1992). "Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members". Astronomy and Astrophysics Supplement Series. 93 (2): 211–233. Bibcode:1992A&AS...93..211F.
  7. ^ Giuricin, G.; Marinoni, C.; Ceriani, L.; Pisani, A. (2000). "Nearby Optical Galaxies: Selection of the Sample and Identification of Groups". Astrophysical Journal. 543 (1): 178–194. arXiv:astro-ph/0001140. Bibcode:2000ApJ...543..178G. doi:10.1086/317070.

External links

Herschel 400 Catalogue

The Herschel 400 catalogue is a subset of William Herschel's original Catalogue of Nebulae and Clusters of Stars, selected by Brenda F. Guzman (Branchett), Lydel Guzman, Paul Jones, James Morrison, Peggy Taylor and Sara Saey of the Ancient City Astronomy Club in St. Augustine, Florida, United States c. 1980. They decided to generate the list after reading a letter published in Sky & Telescope by James Mullaney of Pittsburgh, Pennsylvania, USA.In this letter Mr. Mullaney suggested that William Herschel's original catalogue of 2,500 objects would be an excellent basis for deep sky object selection for amateur astronomers looking for a challenge after completing the Messier Catalogue.

The Herschel 400 is a subset of John Herschel's General Catalogue of Nebulae and Clusters published in 1864 of 5,000 objects, and hence also of the New General Catalogue.

The catalogue forms the basis of the Astronomical League's Herschel 400 club. In 1997, another subset of 400 Herschel objects was selected by the Rose City Astronomers of Portland, Oregon as the Herschel II list, which forms the basis of the Astronomical League's Herschel II Program.

List of spiral galaxies

A spiral galaxy is a type of galaxy characterized by a central bulge of old Population II stars surrounded by a rotating disc of younger Population I stars. A spiral galaxy maintains its spirals arms due to density wave theory.

M109 Group

The M109 Group (also known as the NGC 3992 Group or Ursa Major cloud) is a group of galaxies about 55 million light-years away in the constellation Ursa Major. The group is named after the brightest galaxy within the group, the spiral galaxy M109.

New General Catalogue

The New General Catalogue of Nebulae and Clusters of Stars (abbreviated as NGC) is a catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. It expands upon the cataloguing work of William and Caroline Herschel, and John Herschel's General Catalogue of Nebulae and Clusters of Stars. The NGC contains 7,840 objects, known as the NGC objects. It is one of the largest comprehensive catalogues, as it includes all types of deep space objects, including galaxies, star clusters, emission nebulae and absorption nebulae. Dreyer also published two supplements to the NGC in 1895 and 1908, known as the Index Catalogues, describing a further 5,386 astronomical objects.

Objects in the sky of the southern hemisphere are catalogued somewhat less thoroughly, but many were observed by John Herschel or James Dunlop. The NGC had many errors, but an attempt to eliminate them was initiated by the NGC/IC Project in 1993, after partial attempts with the Revised New General Catalogue (RNGC) by Jack W. Sulentic and William G. Tifft in 1973, and NGC2000.0 by Roger W. Sinnott in 1988.

The Revised New General Catalogue and Index Catalogue (abbreviated as RNGC/IC) was compiled in 2009 by Wolfgang Steinicke.

SN 1998aq

SN 1998aq is a supernova located in galaxy NGC 3982. It was discovered in 1998 by amateur astronomer Mark Armstrong.

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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