SN 2014J

First image: Messier 82 on 10 December 2013. Second image: The same view on 22 January 2014. The position of the supernova is marked.
Event type	Supernova
SN.Ia
Right ascension	9h 55m 42.217s[1]
Declination	69° 40′ 26.56″[1]
Epoch	J2000
Distance	11,500,000 ly (3,500,000 pc)
Host	Messier 82
Progenitor	unknown
Notable features	Closest Type Ia for 40 years
Peakapparent magnitude	10.1[2]
Other designations	SN 2014J
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SN 2014J was aType-Iasupernova inMessier 82 (the 'Cigar Galaxy', M82) discovered in mid-January 2014.^[3] It was the closest Type-Ia supernova discovered for 42 years, and no subsequent supernova has been closer as of 2023^[update]. The supernova was discovered by chance during an undergraduate teaching session at theUniversity of London Observatory. It peaked on 31 January 2014, reaching anapparent magnitude of 10.5.^[4] SN 2014J was the subject of an intense observing campaign by professional astronomers and was bright enough to be seen byamateur astronomers.

The supernova was discovered by astronomerSteve Fossey, ofUniversity College London and four of his undergraduate students: Ben Cooke, Guy Pollack, Matthew Wilde and Thomas Wright. Fossey was training the students on how to use a small 0.35-metre (14 in) telescope atUniversity of London Observatory, located inMill Hill, a suburb of northLondon.^[5][6][7]

The discovery was serendipitous, because Fossey was not searching for supernovae, had not planned to look at M82, and only wanted to take advantage of a short gap in the London cloud cover. He later said that "The weather was closing in, with increasing cloud, so instead of the planned practical astronomy class, I gave the students an introductory demonstration of how to use theCCD camera on one of the observatory’s automated 0.35–metre telescopes."^[6]

At 19:20GMT on 21 January 2014, Fossey and his students noticed a bright new star in their images of the galaxyMessier 82, also known as the Cigar Galaxy.^[6] After comparing their image to archival ones of the same galaxy, they used observations with a second telescope to eliminate the possibility of an instrumental artefact.^[7] Their discovery was reported to theInternational Astronomical Union'sCentral Bureau for Astronomical Telegrams, who confirmed that they were the first to spot the supernova andassigned it the name SN 2014J as the tenth supernova discovered in 2014.^[6] Fossey and the four students were credited as joint discoverers.^[8]

Follow-upadaptive optics observations with the 10-metre (390 in)Keck telescope atMauna Kea Observatory,Hawaii were used to precisely determine the location of the new supernova.^[1] The firstoptical spectrum was obtained using the 3.5-metre (140 in)ARC telescope inNew Mexico, which showed the supernova to be ofType Ia.^[10]Pre-discovery recovery images were found that showed the supernova as early as 15 January, six days before discovery.^[11]

Early indications were that the supernova had been discovered approximately 14 days before maximum light, so it would get brighter over the following fortnight.^[10] It was predicted to be bright enough to be visible with binoculars throughout the Northern Hemisphere.^[5] The supernova continued to get brighter until 31 January, when it peaked at anapparent magnitude of 10.5.^[4]

SN 2014J was a popular target foramateur astronomers because it was located close toThe Ploughasterism (the 'Big Dipper') and visible all night for most Northern Hemisphere observers.^[12][13]

Its unusual brightness and relative closeness led to SN 2014J becoming the subject of intense follow-up observations by astronomers worldwide,^[7] including with theHubble Space Telescope.^[14] Over 435scientific papers have discussed the supernova.^[15][16]

Type Ia supernovae are especially important asstandard candles inphysical cosmology, and the relative closeness of SN2014J allowed astronomers to study the explosion in much more detail than is possible for most objects of this type.^[7]

SN2014J was observed by theINTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) which detected thegamma-rayspectral lines characteristic of theradioactive decay chain⁵⁶Ni→⁵⁶Co→⁵⁶Fe.^[18] This was the first time these lines were detected in a Type Ia supernova,^{[citation needed]} providing support for the standard model that this class of supernova produces large quantities of⁵⁶Ni throughnucleosynthesis.^[19]

Observations of thediffuse interstellar bands in the spectrum of the supernova indicated that it lay behind a significant quantity ofinterstellar medium in M82. The supernova therefore suffered frominterstellar extinction, with areddening of at least onemagnitude.^[20] The degree of light extinction from M82 dust blocking SN 2014J reduces its value as an observational prototype for Type Ia supernovae, but makes it a powerful probe of theinterstellar medium of M82.^[21]

Researchers used archival images from the Hubble Space Telescope to study the environment of SN 2014J prior to the supernova, hoping to identify the progenitor system,^[22] but found no identifiableprogenitor star.^[23] This is not unexpected, because the progenitors of Type Ia supernovae are thought to bewhite dwarfs inbinary systems,^[24] and observation of SN 2014J provided empirical confirmation for this.^[25] The white dwarf is much too faint to detect at the distance of M82, but its companion would have been detectable if it had been a bright evolvedgiant star. It will however remain too faint if it is a second white dwarf (thedouble degenerate Type Ia supernova path), alower main-sequence star, or even a giant star on the fainter part of the giant sequence.

At a distance of 11.5 ± 0.8 millionlight-years (3.5 ± 0.3megaparsecs),^[26] SN 2014J was one of the closest supernovae seen for decades. It was the closestType Ia supernova sinceSN 1972E,^[12] and the closest supernova of any type since 2004. Some sources initially stated that SN 2014J was the closest supernova of any type sinceSN 1987A,^[5] but this claim is erroneous.^[12] The last supernova that was unambiguously closer to Earth than SN 2014J wasSN 2004dj, aType II-P supernova in the galaxyNGC 2403, 8 million light-years from Earth.SN 1993J was aType IIb supernova at almost the same distance as SN 2014J, because it was located inMessier 81, which together with Messier 82 andNGC 3077 forms the core of the M81group of galaxies.^[6]

• History of supernova observation
• List of supernovae

• Light curves and spectraArchived 22 October 2017 at theWayback Machine on theOpen Supernova CatalogArchived 3 March 2016 at theWayback Machine.

• Astronomical objects discovered in 2014
• M81 Group
• Ursa Major
• Supernovae

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