Astronomy:NGC 2442 and NGC 2443

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NGC 2442 / 2443
NGC 2442 (upper spiral structure) and NGC 2443 (lower horizontal spiral arm)[1]
Observation data (J2000 epoch)
ConstellationVolans
Right ascension 07h 36m 23.8s[2]
Declination−69° 31′ 51″[2]
Redshift1466 ± 5 km/s[2]
Apparent magnitude (V)11.2[2]
Characteristics
TypeSAB(s)bc pec[2]
Size~160,000 ly (48.94 kpc) (estimated)[2]
Apparent size (V)5′.5 × 4′.9[2]
Notable featuresSW part is NGC 2442
while NE part is NGC 2443
Other designations
PGC 21373[2]

NGC 2442 and NGC 2443 are two parts of a single intermediate spiral galaxy, commonly known as the Meathook Galaxy or the Cobra and Mouse.[3] It is about 50 million light-years away in the constellation Volans. It was discovered by Sir John Herschel on December 23, 1834 during his survey of southern skies with a 18.25 inch diameter reflecting telescope (his "20-foot telescope") from an observatory he set up in Cape Town, South Africa.[4] Associated with this galaxy is HIPASS J0731-69, a cloud of gas devoid of any stars.[5] It is likely that the cloud was torn loose from NGC 2442 by a companion.[5]

When John Louis Emil Dreyer compiled the New General Catalogue of Nebulae and Clusters of Stars he used William Herschel's earlier observations that described two objects in a "double nebula", giving the northern most the designation NGC 2443 and the southernmost most the designation NGC 2442. Herschel's later observations noted that the two objects were actually a single large nebula.[4][6]

Supernovae

Two, or perhaps three, supernovae have been observed in NGC 2442:

  • SN 1999ga (Type II, mag. 18) was discovered by the Perth Astronomical Research Group on 19 November 1999.[7][8]
  • SN 2015F (Type Ia, mag. 16.8) was discovered by Libert "Berto" Monard on 9 March 2015.[9][10] It reached magnitude 12.9, making it the brightest supernova of 2015.[11]
  • Gaia16cfr, also known as AT 2016jbu,[12][13] was a supernova imposter that occurred in NGC 2442 on 1 December 2016. It reached a Gaia apparent magnitude of 19.3 and absolute magnitude of about −12.[14] However, a paper published in August 2022 suggested that this was a genuine, but strange, supernova.[15]

References

  1. ↑ NGC/IC Project Restoration Effortngcicproject.observers.org
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 "NASA/IPAC Extragalactic Database". Results for NGC 2442 / 2443. http://ned.ipac.caltech.edu/byname?objname=NGC+2442. 
  3. ↑ Chadwick, S; Cooper, I (11 December 2012). Imaging the Southern Sky. New York: Springer. p. 263. ISBN 978-1461447498. 
  4. ↑ 4.0 4.1 Seligman, Courtney. "Celestial Atlas: NGC Objects: NGC 2400 - 2449". http://cseligman.com/text/atlas/ngc24.htm#2443. 
  5. ↑ 5.0 5.1 Ryder, S.D. (July 2001). "HIPASS Detection of an Intergalactic Gas Cloud in the NGC 2442 Group". The Astrophysical Journal 555 (1): 232–239. doi:10.1086/321453. Bibcode: 2001ApJ...555..232R. 
  6. ↑ NGC/IC Project Restoration Effortngcicproject.observers.org
  7. ↑ Woodings, S.; Martin, R.; Williams, A.; Biggs, J.; Verveer, A. (1999). "Supernova 1999ga in NGC 2442". International Astronomical Union Circular (7316): 1. Bibcode: 1999IAUC.7316....1W. http://www.cbat.eps.harvard.edu/iauc/07300/07316.html#Item1. 
  8. ↑ "SN 1999ga". IAU. https://www.wis-tns.org/object/1999ga. 
  9. ↑ Monard, L. A. G.; Fraser, M.; Smith, M.; Firth, R.; Dimitriadis, G.; Frohmaier, C.; Cartier, R.; Prajs, S. et al. (2015). "Supernova 2015F in NGC 2442 = PSN J07361576-6930230". Central Bureau Electronic Telegrams (4081): 1. Bibcode: 2015CBET.4081....1M. 
  10. ↑ "SN 2015F". IAU. https://www.wis-tns.org/object/2015F. 
  11. ↑ Bishop, David. "Bright Supernovae - 2015". https://www.rochesterastronomy.org/sn2015/index.html. 
  12. ↑ "AT 2016jbu". IAU. https://www.wis-tns.org/object/2016jbu. 
  13. ↑ Fox, Derek (4 January 2017). "PESSTO classification and characterisation of AT 2016jbu / Gaia16cfr". https://www.astronomerstelegram.org/?read=9938. 
  14. ↑ Kilpatrick, Charles D.; Foley, Ryan J.; Drout, Maria R.; Pan, Yen-Chen; Panther, Fiona H.; Coulter, David A.; Filippenko, Alexei V.; Marion, G. Howard et al. (2018). "Connecting the progenitors, pre-explosion variability and giant outbursts of luminous blue variables with Gaia16cfr". Monthly Notices of the Royal Astronomical Society 473 (4): 4805. doi:10.1093/mnras/stx2675. Bibcode: 2018MNRAS.473.4805K. 
  15. ↑ Brennan, S. J.; Elias-Rosa, N.; Fraser, M.; Van Dyk, S. D.; Lyman, J. D. (2022). "The impostor revealed: SN 2016jbu was a terminal explosion". Astronomy and Astrophysics 664: L18. doi:10.1051/0004-6361/202244262. Bibcode: 2022A&A...664L..18B. 

Coordinates: Sky map 07h 36m 23.8s, −69° 31′ 51″




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