NGC 7479

NGC 7479 (also known as Caldwell 44) is a barred spiral galaxy about 105 million light-years away in the constellation Pegasus. It was discovered by William Herschel in 1784. Supernovae SN 1990U and SN2009jf occurred in NGC 7479. NGC 7479 is also recognized as a Seyfert galaxy and a Liner undergoing starburst activity not only on the nucleus and the outer arms, but also across the bar of the galaxy, where most of the stars were formed in the last 100 million years.[2] Polarization studies of this galaxy indicate that it recently underwent a minor merger and that it is unique in the radio continuum, with arms opening in a direction opposite to the optical arms.[3] This feature, along with the asymmetrical arms of the galaxy and the intense star formation activity are attributed to a merger with a smaller galaxy.[2] This galaxy is similar in both size and morphology to the barred spiral NGC 1300.

NGC 7479
NGC 7479 HST
Image taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys.
Credit: ESA/Hubble & NASA.
Observation data (J2000 epoch)
ConstellationPegasus
Right ascension 23h 04m 56.6s[1]
Declination+12° 19′ 22″[1]
Redshift2381 ± 1 km/s[1]
Distance105 Mly
Apparent magnitude (V)11.6[1]
Characteristics
TypeSB(s)c[1]
Apparent size (V)4′.1 × 3′.1[1]
Other designations
UGC 12343,[1] PGC 70419,[1] Caldwell 44
NGC7479 Goran Nilsson & The Liverpool Telescope
RGB image of the galaxy NGC 7479 from an earthbound telescope, the Liverpool Telescope
NGC 7479
An ultraviolet image of NGC 7479 taken with GALEX. Credit: GALEX/NASA.

References

  1. ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 7479. Retrieved 2006-11-25.
  2. ^ a b Zhou, Zhi-Min; Cao, Chen; Meng, Xian-Min; Wu, Hong (1 August 2011). "Star formation properties in barred galaxies (SFB). I. Ultraviolet to infrared imaging and spectroscopic studies of NGC 7479". The Astronomical Journal. 142 (2): 38. arXiv:1107.0187. Bibcode:2011AJ....142...38Z. doi:10.1088/0004-6256/142/2/38.
  3. ^ Laine, Seppo; Beck, Rainer (20 January 2008). "Radio Continuum Jet in NGC 7479". The Astrophysical Journal. 673 (1): 128–142. arXiv:0709.4476. Bibcode:2008ApJ...673..128L. doi:10.1086/523960.

External links

Caldwell catalogue

The Caldwell catalogue is an astronomical catalogue of 109 star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled by Patrick Moore as a complement to the Messier catalogue.While the Messier catalogue is used by amateur astronomers as a list of deep-sky objects for observation, Moore noted that Messier's list was not compiled for that purpose and excluded many of the sky's brightest deep-sky objects, such as the Hyades, the Double Cluster (NGC 869 and NGC 884), and the Sculptor Galaxy (NGC 253). The Messier catalogue was actually compiled as a list of known objects that might be confused with comets. Moore also observed that since Messier compiled his list from observations in Paris, it did not include bright deep-sky objects visible in the Southern Hemisphere, such as Omega Centauri, Centaurus A, the Jewel Box, and 47 Tucanae. Moore compiled a list of 109 objects to match the commonly accepted number of Messier objects (he excluded M110), and the list was published in Sky & Telescope in December 1995.Moore used his other surname – Caldwell – to name the list, since the initial of "Moore" is already used for the Messier catalogue. Entries in the catalogue are designated with a "C" and the catalogue number (1 to 109).

Unlike objects in the Messier catalogue, which are listed roughly in the order of discovery by Messier and his colleagues, the Caldwell catalogue is ordered by declination, with C1 being the most northerly and C109 being the most southerly, although two objects (NGC 4244 and the Hyades) are listed out of sequence. Other errors in the original list have since been corrected: it incorrectly identified the S Norma Cluster (NGC 6087) as NGC 6067 and incorrectly labelled the Lambda Centauri Cluster (IC 2944) as the Gamma Centauri Cluster.

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.

NGC 1300

NGC 1300 is a barred spiral galaxy located about 61 million light-years away in the constellation Eridanus. The galaxy is about 110,000 light-years across (about the same size of the Milky Way). It is a member of the Eridanus Cluster, a cluster of 200 galaxies. It was discovered by John Herschel in 1835.In the core of the larger spiral structure of NGC 1300, the nucleus shows a "grand-design" spiral structure that is about 3,300 light-years long. Only galaxies with large-scale bars appear to have these grand-design inner disks — a spiral within a spiral. Models suggest that the gas in a bar can be funneled inwards, and then spiral into the center through the grand-design disk, where it can potentially fuel a central supermassive black hole (SMBH). NGC 1300 is not known to have an active nucleus, indicating that its central black hole is not accreting matter. The SMBH has a mass of 7.3+6.9−3.5×107 M☉.

NGC 7448

NGC 7448 is a spiral galaxy located in the constellation Pegasus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 7448 is about 60,000 light years across. It was discovered by William Herschel οn October 16, 1784. It is included in the Atlas of Peculiar Galaxies in the category galaxies with detached segments.

NGC 7448 features an inner disk region of tightly wound spiral fragments with high surface brightness. At the edge of this region the surface brightness decreases abruptly. At the outer part of the disk individual arm segments and dust lanes can be discerned. The outer arms feature HII regions. One HII region complex located at the northwest portion of the disk is as bright as the bulge. Two supernovae have been observed in NGC 7448, SN 1980L (mag 13.5), and SN 1997dt (type Ia, mag 15.3).NGC 7448 belongs to a galaxy group known as the NGC 7448 group. Other members of the group are the galaxies NGC 7437, NGC 7454, NGC 7463, NGC 7464, and NGC 7465. The last three form a compact subgroup and there is evidence that NGC 7464 and NGC 7465 are in the process of merging. NGC 7479 lies a bit further to the south, and may be part of the group. There is a tail of HI gas extening from NGC 7448 and a stream of gas extending from NGC 7464/65 to NGC 7448.

NGC 7723

NGC 7723 is a barred spiral galaxy located in the constellation Aquarius. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 7723 is about 95,000 light years across. It was discovered by William Herschel οn November 27, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies one and a half degrees north-northwest from Omega1 Aquarii. It can be seen with a 4 inch telescope under dark skies.

SN 1990U

SN 1990U was a type Ic supernova event in the nucleus of the galaxy NGC 7479. It was discovered July 27, 1990 by the Berkeley Automated Supernova Search after reaching magnitude 16±0.5. Initially this was classified as a Type Ib supernova, but the weakness of the neutral helium absorption lines led to a reclassification.

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.

List
See also

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