First image: Messier 82 on 10 December 2013. Second image: The same view on 22 January 2014. The position of the supernova is marked.
|Observation data (Epoch J2000)|
|Supernova type||Type Ia|
|Host galaxy||Messier 82|
|Right ascension||9h 55m 42.217s|
|Declination||69° 40′ 26.56″|
|Discovery date||21 January 2014
University of London Observatory
|Distance||11.5 ± 0.8 Mly (3.5 ± 0.3 Mpc)|
|Notable features||Closest Type Ia for 40 years[note 1]|
SN 2014J is a type-Ia supernova in Messier 82 (the 'Cigar Galaxy', M82) discovered in mid-January 2014. It is the closest type-Ia supernova discovered in the past 42 years.[note 1] It was discovered accidentally during an undergraduate teaching session at University of London Observatory. SN 2014J is the subject of an intense observing campaign by professional astronomers, and was bright enough to be seen by amateur astronomers. On 31 January 2014 SN2014J stopped brightening, reaching its peak brightness at magnitude 10.5.
The supernova was discovered by astronomer Steve Fossey, of University College London. Fossey was training four undergraduate students (Ben Cooke, Guy Pollack, Matthew Wilde and Thomas Wright) to use a small 0.35-metre (14 in) telescope at University of London Observatory, located in Mill Hill, north London.
The discovery was serendipitous, because Fossey was not searching for supernovae and wanted to take advantage of a short gap in the 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 the CCD camera on one of the observatory’s automated 0.35–metre telescopes."
At 19:20 GMT on 21 January 2014, Fossey and his students noticed a bright new star in their images of the galaxy Messier 82, also known as the Cigar Galaxy. 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. Their discovery was reported to the International Astronomical Union's Central Bureau for Astronomical Telegrams, who confirmed that they were the first to spot the supernova and assigned it the name SN 2014J as the tenth supernova discovered in 2014.
Follow-up adaptive optics observations with the 10-metre (390 in) Keck telescope at Mauna Kea Observatory, Hawaii were used to precisely determine the location of the new supernova. The first optical spectrum was obtained using the 3.5-metre (140 in) ARC telescope in New Mexico, which showed the supernova to be of Type Ia. Pre-discovery recovery images were found that showed the supernova as early as 15 January, six days before discovery.
Early indications were that the supernova had been discovered approximately 14 days before maximum light, so it would get brighter over the following fortnight. The supernova was expected to be bright enough to be visible with binoculars throughout the Northern Hemisphere, and to be a popular target for amateur astronomers because it is located close to The Plough asterism and visible all night for most Northern Hemisphere observers.
At a distance of 11.5 ± 0.8 million light-years (3.5 ± 0.3 megaparsecs), SN 2014J is one of the closest supernovae seen for decades. It is the closest type Ia supernova since 1972, and the closest supernova of any type since 2004.[note 1]
Observations of the diffuse interstellar bands in the spectrum of the supernova indicate that it lies behind a significant quantity of interstellar medium in M82. The supernova suffers interstellar extinction, with a reddening of at least one magnitude.
The relative closeness of the supernova—from Earth it appears brighter than most supernovae—allows astronomers to study it in much more detail than usual. Type Ia supernovae are especially important as standard candles in physical cosmology, and astronomers hope that SN 2014J will help them understand how these supernovae form and evolve. 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 the interstellar medium of M82.
Researchers used archival images from the Hubble Space Telescope to study the environment of SN 2014J prior to the supernova, in hopes of identifying the progenitor system. The progenitor star has not been identified, and may never be identified because the progenitors of type Ia supernovae are expected to be white dwarfs in binary systems, too faint to detect at the distance of M82. The companion of the white dwarf, on the other hand, would have been detectable if it had been a bright evolved giant star, rather than a white dwarf itself (the double degenerate scenario), a main-sequence star, or even on the fainter part of the giant sequence.
- Some sources initially stated that SN 2014J was the closest supernova of any type since SN 1987A, but this claim is erroneous. The last supernova that was unambiguously closer to Earth than SN 2014J was SN 2004dj, which was of type II-P and occurred in the galaxy NGC 2403. SN 1993J was a type IIb supernova at almost the same distance as SN 2014J, because it was located in Messier 81 which belongs to same group of galaxies as the Messier 82 galaxy. SN 2014J is the closest type Ia supernova since SN 1972E.
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