Coordinates: Sky map 22h 37m 04.0624s, +34° 24′ 56.721″

NGC 7331

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NGC 7331
NGC 7331 imaged by the Phillips 24-inch RCOS Telescope at the Mount Lemmon SkyCenter[1]
Observation data (J2000 epoch)
ConstellationPegasus
Right ascension22h 37m 04.0624s[2]
Declination+34° 24′ 56.72″[2]
Redshift0.002722±0.000003[3][2]
Heliocentric radial velocity816±1 km/s[2]
Galactocentric velocity1,030±9 km/s[2]
Distance43.79 ± 8.800 Mly (13.427 ± 2.698 Mpc)[2]
Apparent magnitude (V)10.4[2]
Characteristics
TypeSA(s)b; HII LINER[2]
Size146,250 ly
(44.84 kpc)
(diameter; 25.0 B-mag arcsec−2)[2][a]
112,920 ly × 55,316 ly
(34.62 kpc × 16.96 kpc)
(diameter; "total" magnitude)[2][a]
Apparent size (V)10.5′ × 3.7′[2]
Other designations
Caldwell 30, HOLM 795A, IRAS 22347+3409, UGC 12113, MCG +06-49-045, PGC 69327, CGCG 514-068[2]

NGC 7331, also known as Caldwell 30, is an unbarred spiral galaxy about 13.427 megaparsecs (43.79 million light-years) away in the constellation Pegasus. It was discovered by William Herschel on 6 September 1784.[4]

The galaxy appears similar almost in size and structure to the Milky Way, and is sometimes referred to as "the Milky Way's twin".[5] However, discoveries in the 2000s regarding the structure of the Milky Way may call this similarity into doubt, particularly because the latter is now believed to be a barred spiral, compared to the unbarred status of NGC 7331.[6] In spiral galaxies the central bulge typically co-rotates with the disk but the bulge in the galaxy NGC 7331 is rotating in the opposite direction to the rest of the disk.[7] In both visible light and infrared photos of the NGC 7331, the core of the galaxy appears to be slightly off-center, with one side of the disk appearing to extend further away from the core than the opposite side.

Galaxy Groups

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NGC 7331 is the brightest galaxy in the field of a visual grouping known as the NGC 7331 Group of galaxies. In fact, the other members of the group, NGC 7335, NGC 7336, NGC 7337 and NGC 7340, lie far in the background at distances of approximately 300–350 million light years.[8]

All of the members of the NGC 7331 Group, along with NGC 7325, NGC 7326, NGC 7327, NGC 7333, NGC 7338, are listed together as Holm 795 in Erik Holmberg's A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.[9]

Supernovae

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Four supernovae have been observed in NGC 7331:

  • Image of SN 2014C. The inset images are from NASA's Chandra X-ray Observatory, showing a small region of the galaxy before the supernova (left) and after it (right).
    Image of SN 2014C. The inset images are from NASA's Chandra X-ray Observatory, showing a small region of the galaxy before the supernova (left) and after it (right).
  • Amateur near-infrared image of SN 2025rbs (marked by red crosshairs)
    Amateur near-infrared image of SN 2025rbs (marked by red crosshairs)
  • SN 2025rbs imaged on 18 August 2025
    SN 2025rbs imaged on 18 August 2025


See also

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Notes

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  1. ^ a b The quick-look major axis physical diameters given by NED were based on distance estimates of 13.427 ± 2.698 Mpc (43.79×10^6 ± 8.800×10^6 ly) using a scale of 65.1 parsec/arcsec multiplied with given angular diameters.

References

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  1. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  2. ^ a b c d e f g h i j k l Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  3. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  4. ^ The NGC/IC Project Archived 2011-02-28 at the Wayback Machine : NGC Discoverers List by Bob Erdmann.
  5. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ A Counter-rotating Bulge in the Sb Galaxy NGC 7331 , F. Prada, C. Gutierrez, R.F. Peletier, C.D. McKeith, the Astrophysical Journal, 463 :L9–L12, 20/5/1996
  8. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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  14. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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  16. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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  18. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  19. ^ Cosmic Cataclysms: SN2025rbs
  20. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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  • Error creating thumbnail: File missing Media related to Lua error in Module:Commons_link at line 62: attempt to index field 'wikibase' (a nil value). at Wikimedia Commons
  • Calar Alto Observatory – NGC 7331
  • APOD (2004-07-01) – "A Galaxy So Inclined"
  • SST – "Morphology of Our Galaxy's 'Twin'"
  • NGC 7331 at the astro-photography site of Mr. T. Yoshida
  • NGC7331 at W. Kloehr Astrophotography
  • NGC 7331 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
  • SEDS – NGC 7331


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