NGC 5806 is an intermediate spiral galaxy in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Virgo. It was discovered on February 24, 1786, by the astronomer

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...

. It is located about 70 million

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s (or about 21 Megaparsecs) away from the Milky Way. It is a member of the NGC 5846 Group. NGC 5806 contains a star that was catalogued as a

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

(SN Hunt 248), but turned out to be a

supernova imposter Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and gia ...

. 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 . Spotting a Supernova in NGC 5806

NGC 5806 has also hosted several true supernovae. SN 2004dg ( type II, mag. 17.1) was around 100 times brighter than SN Hunt 248. The progenitor of SN 2004dg has not been detected and is expected to have been a relatively low mass, low luminosity, red supergiant. The other supernovae are SN 2012P (type IIb, mag. 15) and iPTF13bvn ( typeIb, mag. 17.2), which was discovered on 16 June 2013.

References

External links

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An LBV masquerading as a cool hypergiantESA/Hubble Picture of the Week showing SN 2004dg
{{DEFAULTSORT:NGC 5806 Intermediate spiral galaxies Virgo (constellation) 5806 Astronomical objects discovered in 1786 Discoveries by John Herschel 053578 +00-38-014 09645