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==Origin==
In [[Latin]], Nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less [[luminous]]. The word supernova was coined by [https://en.wikipedia.org/wiki/Walter_Baade Walter Baade] and [https://en.wikipedia.org/wiki/Fritz_Zwicky Fritz Zwicky] in 1931.
*[http://en.wikipedia.org/wiki/20th_century 1932]
==Definition==
*1: the [[explosion]] of a [[star]] in which the star may reach a maximum intrinsic [[luminosity]] one billion times that of the [[sun]]
*2: one that explodes into [[prominence]] or [[popularity]]; also : ''superstar''
==Description==
A '''supernova''' is an astronomical event that occurs during the last stellar evolutionary [[stages]] of a massive star's life, whose dramatic and [[catastrophic]] destruction is marked by one final titanic [[explosion]]. This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months.
Supernovae are more energetic than [https://en.wikipedia.org/wiki/Nova novae]. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous.
Only three [[Milky Way]] naked-eye supernova events have been observed during the last thousand years, though many have been seen in other galaxies using [[telescopes]]. The most recent directly observed supernova in the Milky Way was [https://en.wikipedia.org/wiki/Kepler%27s_Supernova Kepler's Supernova] in 1604, but the remnants of two more recent supernovae have also been found. Statistical [[observations]] of supernovae in other galaxies suggest they occur on average about three times every century in the Milky Way, and that any galactic supernova would almost certainly be observable with modern astronomical telescopes.
Supernovae may expel much, if not all, of the [[material]] away from a star, at [[velocities]] up to 30,000 km/s or 10% of the [[speed of light]]. This drives an expanding and fast-moving shock wave into the surrounding interstellar medium, and in turn, sweeping up an expanding shell of gas and dust, which is observed as a supernova remnant. Supernovae create, fuse and eject the bulk of the [[chemical elements]] produced by [https://en.wikipedia.org/wiki/Nucleosynthesis nucleosynthesis]. Supernovae play a significant role in enriching the interstellar medium with the heavier atomic [[mass]] chemical elements. Furthermore, the expanding shock waves from supernovae can trigger the formation of new [[stars]]. Supernova remnants are expected to accelerate a large fraction of galactic primary [https://en.wikipedia.org/wiki/Cosmic_ray cosmic rays], but direct evidence for cosmic ray production was found only in a few of them so far. They are also potentially strong galactic sources of gravitational waves.
Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-[[ignition]] of nuclear [[fusion]] in a degenerate star or the sudden gravitational [[collapse]] of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through [[accretion]] or via a merger, to raise its core [[temperature]] enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical collapse mechanics have been established and accepted by most astronomers for some time.
Due to the wide range of astrophysical consequences of these [[events]], astronomers now deem supernovae [[research]], across the fields of stellar and galactic [[evolution]], as an especially important area for investigation.[https://en.wikipedia.org/wiki/Supernova#Etymology]
[[Category: Astronomy]]
[[Category: Physics]]
==Origin==
In [[Latin]], Nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less [[luminous]]. The word supernova was coined by [https://en.wikipedia.org/wiki/Walter_Baade Walter Baade] and [https://en.wikipedia.org/wiki/Fritz_Zwicky Fritz Zwicky] in 1931.
*[http://en.wikipedia.org/wiki/20th_century 1932]
==Definition==
*1: the [[explosion]] of a [[star]] in which the star may reach a maximum intrinsic [[luminosity]] one billion times that of the [[sun]]
*2: one that explodes into [[prominence]] or [[popularity]]; also : ''superstar''
==Description==
A '''supernova''' is an astronomical event that occurs during the last stellar evolutionary [[stages]] of a massive star's life, whose dramatic and [[catastrophic]] destruction is marked by one final titanic [[explosion]]. This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months.
Supernovae are more energetic than [https://en.wikipedia.org/wiki/Nova novae]. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous.
Only three [[Milky Way]] naked-eye supernova events have been observed during the last thousand years, though many have been seen in other galaxies using [[telescopes]]. The most recent directly observed supernova in the Milky Way was [https://en.wikipedia.org/wiki/Kepler%27s_Supernova Kepler's Supernova] in 1604, but the remnants of two more recent supernovae have also been found. Statistical [[observations]] of supernovae in other galaxies suggest they occur on average about three times every century in the Milky Way, and that any galactic supernova would almost certainly be observable with modern astronomical telescopes.
Supernovae may expel much, if not all, of the [[material]] away from a star, at [[velocities]] up to 30,000 km/s or 10% of the [[speed of light]]. This drives an expanding and fast-moving shock wave into the surrounding interstellar medium, and in turn, sweeping up an expanding shell of gas and dust, which is observed as a supernova remnant. Supernovae create, fuse and eject the bulk of the [[chemical elements]] produced by [https://en.wikipedia.org/wiki/Nucleosynthesis nucleosynthesis]. Supernovae play a significant role in enriching the interstellar medium with the heavier atomic [[mass]] chemical elements. Furthermore, the expanding shock waves from supernovae can trigger the formation of new [[stars]]. Supernova remnants are expected to accelerate a large fraction of galactic primary [https://en.wikipedia.org/wiki/Cosmic_ray cosmic rays], but direct evidence for cosmic ray production was found only in a few of them so far. They are also potentially strong galactic sources of gravitational waves.
Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms: the sudden re-[[ignition]] of nuclear [[fusion]] in a degenerate star or the sudden gravitational [[collapse]] of a massive star's core. In the first instance, a degenerate white dwarf may accumulate sufficient material from a binary companion, either through [[accretion]] or via a merger, to raise its core [[temperature]] enough to trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy as a supernova. While some observed supernovae are more complex than these two simplified theories, the astrophysical collapse mechanics have been established and accepted by most astronomers for some time.
Due to the wide range of astrophysical consequences of these [[events]], astronomers now deem supernovae [[research]], across the fields of stellar and galactic [[evolution]], as an especially important area for investigation.[https://en.wikipedia.org/wiki/Supernova#Etymology]
[[Category: Astronomy]]
[[Category: Physics]]
