NGC 1808

NGC 1808 is a barred spiral galaxy[5] located in the southern constellation of Columba, about two degrees to the south and east of Gamma Caeli.[2] It was discovered by Scottish astronomer James Dunlop, who described it as a "faint nebula".[10] The galaxy is a member of the NGC 1808 group, which is part of the larger Dorado Group.[10]

NGC 1808
A Hubble Space Telescope (HST) image of NGC 1808 taken using WFPC2.[1]
Credit: HST/NASA/ESA.
Observation data (J2000 epoch)
ConstellationColumba[2]
Right ascension05h 07m 42.343s[3]
Declination−37° 30′ 46.98″[3]
Redshift995[4]
Distance41.7 ± 3.9 Mly (12.8 ± 1.2 Mpc)[5]
Group or clusterDorado Group
Apparent magnitude (V)9.94[6]
Apparent magnitude (B)10.83[4]
Absolute magnitude (B)−20.17[7]
Characteristics
Type(R)SAB(s)a[7]
Apparent size (V)7′.41 × 3′.39[8]
Other designations
PGC 16779[9]

The morphological classification of this galaxy is (R)SAB(s)a,[7] which indicates a spiral galaxy with a weak-bar around the nucleus (SAB), no ring around the bar (s), an outer ring (R), and tightly-wound spiral arms (a). It is inclined by an angle of 57° to the line of sight from the Earth, with the long axis oriented at a position angle of 324°.[5] The disk of gas and stars shows a noticeable warp, and there is a pronounced asymmetry in the distribution of neutral hydrogen and H II regions.[11]

The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing star clusters and supernova remnants at a distance of ~280 pc from the center. These form a ring of peculiar "hot spots".[12] It was formerly identified as a possible Seyfert galaxy,[5] but evidence now points to starburst activity in a ~500 pc radius around the center.[13] A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes.[5] The high level of star formation in this galaxy and the nearby NGC 1792 may indicate a recent, distant tidal interaction between the two.[11]

The type Ia supernova SN 1993af was discovered in November 1993 at 220″ east and 94″ north of the galactic nucleus.[14][15]

A Hubble Space Telescope image of the center of NGC 1808. Credit: HST/NASA/ESA.

References
  1. "HubbleSite - NewsCenter - Hubble Captures the Heart of Star Birth". Retrieved 2007-04-05.
  2. Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. 1. Sky Publishing Corporation and the European Space Agency. ISBN 0-933346-84-0.
  3. Skrutskie, M. F.; et al. (February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.
  4. Tully, R. Brent; et al. (August 2016). "Cosmicflows-3". The Astronomical Journal. 152 (2): 21. arXiv:1605.01765. Bibcode:2016AJ....152...50T. doi:10.3847/0004-6256/152/2/50. 50.
  5. Busch, Gerold; et al. (February 2017). "Star formation and gas flows in the centre of the NUGA galaxy NGC 1808 observed with SINFONI". Astronomy & Astrophysics. 598: 19. arXiv:1611.07868. Bibcode:2017A&A...598A..55B. doi:10.1051/0004-6361/201629440. A55.
  6. Armando, Gil de Paz; et al. (2007). "The GALEX Ultraviolet Atlas of Nearby Galaxies". Astrophysical Journal. 173 (2): 185–255. arXiv:astro-ph/0606440. Bibcode:2007ApJS..173..185G. doi:10.1086/516636.
  7. Erwin, Peter; Debattista, Victor P. (June 2013). "Peanuts at an angle: detecting and measuring the three-dimensional structure of bars in moderately inclined galaxies". Monthly Notices of the Royal Astronomical Society. 431 (4): 3060–3086. arXiv:1301.0638. Bibcode:2013MNRAS.431.3060E. doi:10.1093/mnras/stt385.
  8. Paturel, G.; et al. (December 2003). "HYPERLEDA. I. Identification and designation of galaxies". Astronomy and Astrophysics. 412: 45–55. Bibcode:2003A&A...412...45P. doi:10.1051/0004-6361:20031411.
  9. "NASA/IPAC Extragalactic Database". Results for NGC 1808. Retrieved 2007-04-05.
  10. O'Meara, Stephen James (2013), Deep-Sky Companions: Southern Gems, Cambridge University Press, p. 116, Bibcode:2013dcsg.book.....O, ISBN 978-1107015012
  11. Dahlem, M.; et al. (July 2001). "A search for intergalactic H I gas in the NGC 1808 group of galaxies". Astronomy and Astrophysics. 373: 485–493. arXiv:astro-ph/0106050. Bibcode:2001A&A...373..485D. doi:10.1051/0004-6361:20010614.
  12. Salak, Dragan; et al. (May 2016). "Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA". The Astrophysical Journal. 823 (1): 28. arXiv:1603.05881. Bibcode:2016ApJ...823...68S. doi:10.3847/0004-637X/823/1/68. 68.
  13. Salak, Dragan; et al. (November 2017). "Evolution of Molecular Clouds in the Superwind Galaxy NGC 1808 Probed by ALMA Observations". The Astrophysical Journal. 849 (2): 20. arXiv:1710.01829. Bibcode:2017ApJ...849...90S. doi:10.3847/1538-4357/aa91cb. 90.
  14. Hamuy, M.; et al. (November 1993). Green, D. W. E. (ed.). "Supernovae 1993af, 1993ag, 1993ah". IAU Circular. 5895: 1. Bibcode:1993IAUC.5895....1H.
  15. Hamuy, M.; et al. (December 1996). "BVRI Light Curves for 29 Type IA Supernovae". Astronomical Journal. 112: 2408. arXiv:astro-ph/9609064. Bibcode:1996AJ....112.2408H. doi:10.1086/118192.
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