NGC 7421

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NGC 7421
Legacy Surveys DR10 image of NGC 7421
Observation data (J2000 epoch)
ConstellationGrus
Right ascension22h 56m 54.353s[1]
Declination−37° 20′ 50.44″[1]
Distance81.6 Mly (25.01 Mpc)[2]
Apparent magnitude (V)12.0[3]
Characteristics
TypeSB(rs)bc[4]
Mass20.9×109[5] M☉
Apparent size (V)2.2′[3]
Other designations
NGC 7421, LEDA 70083, MCG -06-50-015[6]

NGC 7421 is a barred spiral galaxy in the southern constellation of Grus. It was discovered by English astronomer John Herschel on August 30, 1834.[7] In Danish astronomer J. L. E. Dreyer's New General Catalogue of Nebulae and Clusters of Stars it was described as: considerably bright, large, very little extended, gradually pretty much brighter middle, and partially resolved.[3] NGC 7421 is located at an estimated distance of 81.6 million light-years (25.01 Mpc) from the Sun.[2] It is a member of the IC 1459 galaxy group.[5]

In the Third Reference Catalogue of Bright Galaxies, NGC 7421 was assigned a morphological classification of SB(rs)bc, which indicates a barred spiral galaxy (SB) with a transitional ring structure (rs) and moderately wound spiral arms (bc).[4] The galactic plane is inclined at an angle of 36.2° to the plane of the sky, with the major axis aligned along a position angle of 80.6°. It displays an asymmetric morphology, which shows up in a lopsided optical appearance and in the distribution of CO and neutral hydrogen atoms. New stars are forming at a rate of 0.274±0.041 M☉·yr−1. The gas fraction and star formation rate is significantly lower than normal, suggesting an interaction with the external environment.[5]

The western boundary of this galaxy resembles a bow shock that suggests an interaction with the intracluster medium. Radio mapping of neutral hydrogen by the ATCA displays an extended wake to the north and south of the galaxy, supporting this hypothesis.[8] A past tidal interaction may be needed to explain the asymmetry of this galaxy. A candidate galaxy is NGC 7418, which is located at an angular separation of ~20′. However, there are no tidal tails visible from such an encounter.[9] The total mass of the neutral hydrogen in this galaxy is 1.5×109 M☉.[8]

The type II supernova SN 2023abdg was observed in association with this galaxy. It was discovered on December 12, 2023, by ATLAS.[10]

See also

  • NGC 4654, a galaxy in Virgo with a similar appearance[9]

References

  1. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b Crook, Aidan C.; et al. (February 2007), "Groups of Galaxies in the Two Micron All Sky Redshift Survey", The Astrophysical Journal, 655 (2): 790–813, arXiv:astro-ph/0610732, Bibcode:2007ApJ...655..790C, doi:10.1086/510201, S2CID 11672751.
  3. ^ a b c Frommert, Hartmut, "NGC 7421", Students for the Exploration and Development of Space, retrieved 2024-02-05.
  4. ^ a b De Vaucouleurs, Gerard; et al. (1991), Third Reference Catalogue of Bright Galaxies, 3.9, Bibcode:1991rc3..book.....D.
  5. ^ a b c Lee, Bumhyun; et al. (September 2022), "ALMA/ACA CO Survey of the IC 1459 and NGC 4636 Groups: Environmental Effects on the Molecular Gas of Group Galaxies", The Astrophysical Journal Supplement Series, 262 (1), id. 31, arXiv:2204.06022, Bibcode:2022ApJS..262...31L, doi:10.3847/1538-4365/ac7eba.
  6. ^ "NGC 7421". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-02-01.
  7. ^ Seligman, Courtney, "NGC Objects: NGC 7400 - 7449", Celestial Atlas, retrieved 2024-02-05.
  8. ^ a b Ryder, Stuart D.; et al. (April 1997), "NGC 7421: Surfing the Intracluster Medium?", Publications of the Astronomical Society of Australia, 14 (1): 81–84, Bibcode:1997PASA...14...81R, doi:10.1071/AS97081.
  9. ^ a b Ryder, S. D.; et al. (2000), Combes, Francoise; et al. (eds.), "The Interaction of NGC 7421 with the Intracluster Medium", Dynamics of Galaxies: from the Early Universe to the Present, 15th IAP meeting held in Paris, France, July 9–13, 1999, ASP Conference Series, vol. 197, pp. 405–406, Bibcode:2000ASPC..197..405R.
  10. ^ "SN 2023abdg", Transient Name Server, retrieved 2024-02-04.
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