SN 2002bj was the explosion of a star in the galaxy

NGC 1821 NGC commonly refers to: * New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy NGC may also refer to: Companies * NGC Corporation, name of US electric company Dynegy, Inc. from 1995 to 1998 * Nati ...

, located in the constellation

Lepus Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores, and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The gen ...

. The explosion was discovered by

Jack Newton Jack Newton OAM (30 January 1950 – 14 April 2022) was an Australian professional golfer. He won the Buick-Goodwrench Open on the PGA Tour and won three times on the European Tour, including the British PGA Matchplay Championship in 1974. He ...

in scans of images produced by Tim Puckett. (It was independently discovered by the Lick/Tenagra Observatory as part of their combined supernova search program.) Initially it had an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of about 14.7 and was categorized as a Type IIn supernova. However, in 2008 Dovi Poznanski discovered that the spectrum more closely resembled a

Type Ia supernova A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...

. Further, the energy output was much lower than a typical supernova and the luminosity dropped at a dramatic pace. A team consisting of Poznanski, Joshua Bloom, Alex Filippenko and others concluded that it was a new category of exploding star. This system is believed to consist of a binary pair of

white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...

stars, with helium being transferred from one dwarf to the other. The accreted helium exploded in a thermonuclear reaction on the surface of the more massive white dwarf, resulting in the observed outburst. In this sense, it was akin to a nova explosion, although the magnitude of the explosion was a thousand times greater. In 2007

Lars Bildsten Lars Bildsten (born 1964) is an American astrophysicist, best known for his work on the physics of white dwarfs and their explosions as Type Ia supernovae. He is the sixth director of the Kavli Institute for Theoretical Physics at the Universit ...

''et al.'' had predicted this category of explosion would occur in AM Canum Venaticorum star binary systems. NGC 1821 is an

irregular galaxy An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, ...

categorized as type IB(s)m. It is

14.5 and has a redshift of 0.012029. This galaxy is located about 48 megaparsecs from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

References

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External links

Light curves and spectra
on th
Open Supernova Catalog
Supernovae Lepus (constellation)