NGC 7742

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NGC 7742[1]
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A Hubble Space Telescope (HST) image of NGC 7742.
Credit: NASA/ESA/STScI/AURA.
Observation data (J2000 epoch)
ConstellationPegasus
Right ascensionTemplate:RA[2]
DeclinationTemplate:DEC[2]
Redshift0.005547±0.000003[2]
Heliocentric radial velocity1663±1 km/s[2]
Galactocentric velocity1809±6 km/s[2]
Distance72.4 ± 6.2 Mly (22.20 ± 1.90 Mpc)
Apparent magnitude (V)12.35[2]
Characteristics
TypeSA(r)b,[2] LINER/HII[2]
Size~50,700 ly (15.55 kpc) (estimated)[2]Template:R/superscript
Apparent size (V)1.778 × 1.698 moa[3]
Other designations
Template:Odlist[2]

NGC 7742 (also known as the Fried Egg Galaxy) is a face-on unbarred spiral galaxy in the constellation Pegasus. Its velocity with respect to the cosmic microwave background is 1292 ± 26 km/s, which corresponds to a Hubble distance of 62.2 ± 4.5 Mly (19.06 ± 1.39 Mpc).[2]Template:R/superscript In addition, six non-redshift measurements give a farther distance of 84.09 ± 26.51 Mly (25.783 ± 8.129 Mpc).[4] It was discovered by astronomer William Herschel on 18 Oct 1784.[5]

NGC 7742 is unusual in that it contains a ring but no bar.[6] Typically, bars are needed to produce a ring structure. The bars' gravitational forces move gas to the ends of the bars, where it forms into the rings seen in many barred spiral galaxies. In this galaxy, however, no bar is present, so this mechanism cannot be used to explain the formation of the ring. O. K. Sil'chenko and A. V. Moiseev proposed the ring was formed partly as the result of a merger event in which a smaller gas-rich dwarf galaxy collided with NGC 7742. As evidence for this, they point to the unusually bright central region, the presence of highly inclined central gas disk, and the presence of gas that is counterrotating (or rotating in the opposite direction) with respect to the stars.[6] It is also classified as a Type II Seyfert Galaxy.

Supernovae

Two supernovae have been observed in NGC 7742:

See also

  • NGC 7217 – a face-on spiral galaxy with identical characteristics
  • Sombrero Galaxy – a similar galaxy with a dust ring

References

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  1. ^ Page Module:Citation/CS1/styles.css has no content.Filho, M. E.; Barthel, P. D.; Ho, L. C. (October 2002). "The Nature of Composite LINER/HII Galaxies, Part II". The Astrophysical Journal Supplement. 142 (2): 223–238. arXiv:astro-ph/0205196. Bibcode:2002ApJS..142..223F. doi:10.1086/341786. ISSN 0067-0049. S2CID 16100301.
  2. ^ a b c d e f g h i j k Page Module:Citation/CS1/styles.css has no content."NASA/IPAC Extragalactic Database". Results for object NGC 7742. Retrieved 2006-08-20.
  3. ^ Page Module:Citation/CS1/styles.css has no content."Centre de Données astronomiques de Strasbourg". Results for NGC 7742. Retrieved 2008-07-09.
  4. ^ Page Module:Citation/CS1/styles.css has no content."Distance Results for NGC 7742". NASA/IPAC EXTRAGALACTIC DATABASE. NASA. Retrieved 7 December 2024.
  5. ^ Page Module:Citation/CS1/styles.css has no content.Seligman, Courtney. "New General Catalogue Objects: NGC 7742". Celestial Atlas. Retrieved 7 December 2024.
  6. ^ a b Page Module:Citation/CS1/styles.css has no content.O. K. Sil'chenko; A. V. Moiseev (2006). "Nature of Nuclear Rings in Unbarred Galaxies: NGC 7742 and NGC 7217". Astronomical Journal. 131 (3): 1336–1346. arXiv:astro-ph/0512431. Bibcode:2006AJ....131.1336S. doi:10.1086/499945. S2CID 14589261.
  7. ^ Page Module:Citation/CS1/styles.css has no content.Treffers, R. R.; Leibundgut, B.; Filippenko, A. V.; Richmond, M. W. (1993). "Supernova 1993R in NGC 7742". International Astronomical Union Circular (5812): 1. Bibcode:1993IAUC.5812....1T.
  8. ^ Page Module:Citation/CS1/styles.css has no content."SN 1993R". Transient Name Server. IAU. Retrieved 7 December 2024.
  9. ^ Page Module:Citation/CS1/styles.css has no content.Nishimura, K. (2014). "Supernova 2014cy in NGC 7742 = PSN J23441603+1046125". Central Bureau Electronic Telegrams (3964): 1. Bibcode:2014CBET.3964....1N.
  10. ^ Page Module:Citation/CS1/styles.css has no content."SN 2014cy". Transient Name Server. IAU. Retrieved 7 December 2024.


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