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NGC 7793

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NGC 7793
Hubble Space Telescope image of the small bulge and spiral arms of NGC 7793
Observation data (J2000 epoch)
ConstellationSculptor
Right ascension23h 57m 49.753s[1]
Declination−32° 35′ 27.71″[1]
Redshift0.000749[2]
Heliocentric radial velocity227 km/s[3]
Distance12.2 Mly (3.7 Mpc)[4]
Group or clusterSculptor Group[5]
Apparent magnitude (V)10.0[6]
Characteristics
TypeSA(s)d[2]
MassStellar: 3.2×109 M☉
Size~50,900 ly (15.61 kpc) (estimated)[2]
Apparent size (V)9.3′ × 6.3′[6]
Other designations
ESO 349- G 012, IRAS 23552-3252, MCG -06-01-009, PGC 73049[2]

NGC 7793 is a flocculent spiral galaxy in the southern constellation of Sculptor. It was discovered on July 14, 1826, by Scottish astronomer James Dunlop.[7][8] The galaxy is located at a distance of 12.2[4] million light years and is receding with a heliocentric radial velocity of 227 km/s.[3] NGC 7793 is one of the five brightest galaxies within the Sculptor Group.[6][5]

The morphological class of NGC 7793 is SA(s)d,[2] indicating it is unbarred spiral galaxy (SA) with no inner ring structure (s) and the arms are loosely wound and disorganized (d). It is flocculent in appearance with a very small bulge and a star cluster at the nucleus.[6] The galactic disk is inclined at an angle of 53.7° to the line of sight from the Earth. The visible profile is elliptical in form with an angular size of 9.3′ × 6.3′[6] and a major axis aligned along a position angle of 99.3°.[2] There are two nearby dwarf galaxy companions.[9]

NGC 7793 hosts the ultra-luminous X-ray pulsar (ULXP) referred to as NGC 7793 P13 (previously believed to harbor a black hole), which consists of a 0.42-second pulsar in a 64-day orbit with a 18-23 solar mass B9Ia companion star.[10]

Supernova

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One supernova has been observed in NGC 7793. SN 2008bk (type II-P, mag. 12.6) was discovered by Berto Monard (bio-it) on March 25, 2008.[11][12][13] It reached apparent magnitude 12.5, making it the second-brightest supernova of 2008.[14] The progenitor of this supernova was a red supergiant, observed only 547 days prior to the explosion.[15]

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  • Visual and infrared image of NGC 7793
    Visual and infrared image of NGC 7793
  • SN 2008bk before it exploded (left) and after the explosion (right)
    SN 2008bk before it exploded (left) and after the explosion (right)

See also

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References

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  1. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c d e f "Results for object NGC 7793". NASA/IPAC Extragalactic Database. Retrieved 2006-11-21.
  3. ^ a b Tully, R. Brent; et al. (August 3, 2016). "Cosmicflows-3". The Astronomical Journal. 152 (2): 50. arXiv:1605.01765. Bibcode:2016AJ....152...50T. doi:10.3847/0004-6256/152/2/50. S2CID 250737862.
  4. ^ a b Lianou, S.; et al. (November 2019). "Dust properties and star formation of approximately a thousand local galaxies". Astronomy & Astrophysics. 631: 19. arXiv:1906.02712. Bibcode:2019A&A...631A..38L. doi:10.1051/0004-6361/201834553. S2CID 174801441. A38.
  5. ^ a b I. D. Karachentsev; E. K. Grebel; M. E. Sharina; A. E. Dolphin; et al. (2003). "Distances to nearby galaxies in Sculptor". Astronomy and Astrophysics. 404 (1): 93–111. arXiv:astro-ph/0302045. Bibcode:2003A&A...404...93K. doi:10.1051/0004-6361:20030170. S2CID 54977869.
  6. ^ a b c d e König, Michael; Binnewies, Stefan (2017). The Cambridge Photographic Atlas of Galaxies. Cambridge University Press. p. 68. ISBN 9781108103091.
  7. ^ Seligman, Courtney. "New General Catalogue Objects: NGC 7793". Celestial Atlas. Retrieved 25 April 2025.
  8. ^ James, Dunlop (1828). "A Catalogue of Nebulae and Clusters of Stars in the Southern Hemisphere observed in New South Wales". Philosophical Transactions of the Royal Society. 118: 113–151. Bibcode:1828RSPT..118..113D. doi:10.1098/rstl.1828.0010. JSTOR 107841.
  9. ^ Mondal, Chayan; et al. (March 2021). "Tracing Young Star-forming Clumps in the Nearby Flocculent Spiral Galaxy NGC 7793 with UVIT Imaging". The Astrophysical Journal. 909 (2): 13. arXiv:2101.11314. Bibcode:2021ApJ...909..203M. doi:10.3847/1538-4357/abe0b4. S2CID 231718940. 203.
  10. ^ Israel, G.L. (September 2016). "Discovery of a 0.42-s pulsar in the ultraluminous X-ray source NGC 7793 P13". Monthly Notices of the Royal Astronomical Society: Letters. 466: L48 – L52. arXiv:1609.06538. doi:10.1093/mnrasl/slw218.
  11. ^ Monard, L. A. G. (2008). "Supernova 2008bk in NGC 7793". Central Bureau Electronic Telegrams (1315): 1. Bibcode:2008CBET.1315....1M.
  12. ^ David Bishop. "Supernova 2008bk in NGC 7793". Rochester Astronomy. Retrieved 2025-04-25.
  13. ^ "SN 2008bk". Transient Name Server. IAU. Retrieved 25 April 2025.
  14. ^ David Bishop. "Bright Supernovae - 2008". Rochester Astronomy. Retrieved 2025-04-25.
  15. ^ Mattila, S.; Smartt, S. J.; Eldridge, J. J.; Maund, J. R.; Crockett, R. M.; Danziger, I. J. (2008). "VLT Detection of a Red Supergiant Progenitor of the Type II-P Supernova 2008bk". The Astrophysical Journal. 688 (2): L91 – L94. arXiv:0809.0206. Bibcode:2008ApJ...688L..91M. doi:10.1086/595587.
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