NGC 7793

NGC 7793
Hubble Space Telescope image of the small bulge and spiral arms of NGC 7793
Observation data (J2000 epoch)
Constellation	Sculptor
Right ascension	23^h 57^m 49.753^s[1]
Declination	−32° 35′ 27.71″[1]
Heliocentric radial velocity	227 km/s[2]
Distance	12.2 Mly (3.7 Mpc)[3]
Group or cluster	Sculptor Group[4]
Apparent magnitude (V)	10.0[5]
Characteristics
Type	SA(s)d[6]
Mass	Stellar: 3.2×10^9 M☉
Apparent size (V)	9.3′ × 6.3′[5] (~30kly in diameter)
Other designations
NGC 7793, PGC 73049[7]

NGC 7793 is a flocculent spiral galaxy in the southern constellation of Sculptor. It was discovered in 1826 by Scottish astronomer James Dunlop.[8] The galaxy is located at a distance of 12.2[3] million light years and is receding with a heliocentric radial velocity of 227 km/s.[2] NGC 7793 is one of the five brightest galaxies within the Sculptor Group.[5][4]

The morphological class of NGC 7793 is SA(s)d,[6] 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.[5] 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′[5] and a major axis aligned along a position angle of 99.3°.[6] There are two nearby dwarf galaxy companions.[9]

On March 25, 2008, a type II-P supernova designated SN 2008bk was discovered in NGC 7793.[10][6] At apparent magnitude 12.5, it became the 2nd brightest supernova of 2008.[11] The progenitor of this supernova was a red supergiant, observed only 547 days prior to the explosion.

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.[12]

Gallery

• 
  Visual and infrared image of NGC 7793

See also

• NGC 300 - a similar spiral galaxy that is near NGC 7793
• NGC 2403 - a similar spiral galaxy

References

1. 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. 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.
3. 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.
4. 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.
5. König, Michael; Binnewies, Stefan (2017). The Cambridge Photographic Atlas of Galaxies. Cambridge University Press. p. 68. ISBN 9781108103091.
6. Crowther, Paul A. (January 2013). "On the association between core-collapse supernovae and H ii regions". Monthly Notices of the Royal Astronomical Society. 428 (3): 1927–1943. arXiv:1210.1126. Bibcode:2013MNRAS.428.1927C. doi:10.1093/mnras/sts145.
7. "NASA/IPAC Extragalactic Database". Results for NGC 7793. Retrieved 2006-11-21.
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. David Bishop. "Supernova 2008bk in NGC 7793". supernovae.net (International Supernovae Network). Archived from the original on 2011-09-27. Retrieved 2010-06-07.
11. David Bishop. "Bright Supernovae - 2008". supernovae.net (International Supernovae Network). Archived from the original on 2011-09-27. Retrieved 2010-06-07.
12. 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.

External links

• SST: NGC 7793