NGC 5806

Coordinates: 15^h 00^m 00.40^s, +1° 53′ 27″

NGC 5806
NGC 5806, as observed by the Hubble Space Telescope (HST). Credit: HST/NASA/ESA.
Observation data (J2000 epoch)
Constellation	Virgo[1]
Right ascension	15^h 00^m 00.40^s[2]
Declination	+1° 53′ 27″[1]
Redshift	0.004533[1]
Distance	69.76 million lightyears[1]
Type	SBb
Apparent magnitude (V)	11.7[1]

NGC 5806 is a barred spiral galaxy in the constellation Virgo.^[2][1]

Supernova Imposter

NGC 5806 contains a star that was catalogued as a supernova (SN Hunt 248), but turned out to be a supernova imposter. The progenitor was detected as a cool hypergiant with an absolute visual magnitude of −9 and 400,000 times more luminous than the sun. The eruption saw it increase in luminosity to around 80,000,000 L_☉.^[3]

Supernova

Supernova SN 2004dg in NGC 5806

NGC 5806 has also hosted a true supernova, SN 2004dg, around 100 times brighter than SN Hunt 248. This was a typical type II supernova. The progenitor has not been detected and is expected to have been a relatively low mass, low luminosity, red supergiant.^[4]

References

1. "NGC 5806". Retrieved December 8, 2011.
2. "Galaxy NGC 5806". Retrieved December 8, 2011.
3. Mauerhan, Jon C.; Van Dyk, Schuyler D.; Graham, Melissa L.; Zheng, Weikang; Clubb, Kelsey I.; Filippenko, Alexei V.; Valenti, Stefano; Brown, Peter; Smith, Nathan; Howell, D. Andrew; Arcavi, Iair (2015). "SN Hunt 248: A super-Eddington outburst from a massive cool hypergiant". Monthly Notices of the Royal Astronomical Society 447 (2): 1922. arXiv:1407.4681. Bibcode:2015MNRAS.447.1922M. doi:10.1093/mnras/stu2541.
4. Smartt, S. J.; Eldridge, J. J.; Crockett, R. M.; Maund, J. R. (2009). "The death of massive stars - I. Observational constraints on the progenitors of Type II-P supernovae". Monthly Notices of the Royal Astronomical Society 395 (3): 1409. arXiv:0809.0403. Bibcode:2009MNRAS.395.1409S. doi:10.1111/j.1365-2966.2009.14506.x.

External Links

• An LBV masquerading as a cool hypergiant
• ESA/Hubble Picture of the Week showing SN 2004dg