Supernova

Supernova


A supernova is a stellar explosion that is more energetic than a nova. It is pronounced / ˌ s uː p ər ˈ n <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="long 'o' in 'bode'">oʊ <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'v' in 'vie'">v <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="schwa 'a' in 'about'">ə <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; " title="Representation in the International Phonetic Alphabet (IPA)">/ with the plural supernovae <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; " title="Representation in the International Phonetic Alphabet (IPA)">/ <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="secondary stress">ˌ <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'s' in 'sigh'">s <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="long 'oo' in 'food'">uː <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'p' in 'pie'">p <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'er' in 'finger'">ər <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="primary stress">ˈ <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'n' in 'nigh'">n <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="long 'o' in 'bode'">oʊ <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="'v' in 'vie'">v <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; "><span style="border-bottom-width: 1px; border-bottom-style: dotted; border-bottom-color: initial; " title="long 'e' in 'bead'">iː <span class="IPA" style="font-family: 'Gentium Plus', Gentium, GentiumAlt, 'Charis SIL', 'Doulos SIL', 'DejaVu Sans', Code2000, 'TITUS Cyberbit Basic', 'Arial Unicode MS', 'Lucida Sans Unicode', 'Chrysanthi Unicode'; " title="Representation in the International Phonetic Alphabet (IPA)">/  orsupernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as theSun is expected to emit over its entire life span.<sup class="reference" id="cite_ref-0" style="line-height: 1em; ">[1] The explosion expels much or all of a star's material<sup class="reference" id="cite_ref-1" style="line-height: 1em; ">[2] at a velocity of up to 30,000 km/s (10% of the speed of light), driving a shock wave<sup class="reference" id="cite_ref-2" style="line-height: 1em; ">[3] into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.

<p style="margin-top: 0.4em; margin-bottom: 0.5em; line-height: 19px; color: rgb(0, 0, 0); font-family: sans-serif;">Nova (plural novae) means "new" in Latin, referring to what appears to be a very bright new star shining in the celestial sphere; the prefix "super-" distinguishes supernovae from ordinary novae, which also involve a star increasing in brightness, though to a lesser extent and through a different mechanism. The word supernovawas coined by Swiss astrophysicist and astronomer Fritz Zwicky,<sup class="reference" id="cite_ref-3" style="line-height: 1em; ">[4] <sup class="reference" id="cite_ref-Baade1934_4-0" style="line-height: 1em; ">[5] and was first used in print in 1926.<sup class="reference" id="cite_ref-5" style="line-height: 1em; ">[6] Several types of supernovae exist. Types I and II can be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an aging massive star ceases generating energy from nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers. Alternatively a white dwarf star may accumulate sufficient material from a stellar companion (either through accretion or via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it. Stellar cores whose furnaces have permanently gone out collapse when their masses exceed the Chandrasekhar limit, while accreting white dwarfs ignite as they approach this limit (roughly 1.38<sup class="reference" id="cite_ref-Mazzali2007_6-0" style="line-height: 1em; ">[7] times the solar mass). White dwarfs are also subject to a different, much smaller type of thermonuclear explosion fueled by hydrogen on their surfaces called a nova. Solitary stars with a mass below approximately 9 solar masses, such as the Sun, evolve into white dwarfs without ever becoming supernovae.

<p style="margin-top: 0.4em; margin-bottom: 0.5em; line-height: 19px; color: rgb(0, 0, 0); font-family: sans-serif;">Although no supernova has been observed in the Milky Way since 1604, supernovae remnants indicate on average the event occurs about once every 50 years in the Milky Way.<sup class="reference" id="cite_ref-supernova_rate_7-0" style="line-height: 1em; ">[8] They play a significant role in enriching the interstellar medium with higher mass elements.<sup class="reference" id="cite_ref-8" style="line-height: 1em; ">[9] Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.<sup class="reference" id="cite_ref-aaa128_9-0" style="line-height: 1em; ">[10] <sup class="reference" id="cite_ref-10" style="line-height: 1em; ">[11] <sup class="reference" id="cite_ref-11" style="line-height: 1em; ">[12]

Observation History
Hipparchus' interest in the fixed stars may have been inspired by the observation of a supernova (according to Pliny).[13] The earliest recorded supernova, SN 185, was viewed by Chinese astronomers in 185 AD. The brightest recorded supernova was the SN 1006, which was described in detail by Chinese and Islamic astronomers.[14] The widely observed supernova SN 1054 produced the Crab Nebula. Supernovae SN 1572 and SN 1604, the latest to be observed with the naked eye in the Milky Way galaxy, had notable effects on the development of astronomy in Europe because they were used to argue against the Aristotelian idea that the universe beyond the Moon and planets was immutable.[15] Johannes Kepler began observing SN 1604 on October 17, 1604.[16] It was the second supernova to be observed in a generation (after SN 1572 seen by Tycho Brahe in Cassiopeia).[13] Since the development of the telescope the field of supernova discovery has extended to other galaxies, starting with the 1885 observation of supernova S Andromedae in the Andromeda galaxy. Supernovae provide important information on cosmological distances.[17] During the twentieth century successful models for each type of supernova were developed, and scientists' comprehension of the role of supernovae in the star formation process is growing. American astronomers Rudolph Minkowski and Fritz Zwicky developed the modern supernova classification scheme beginning in 1941.[18] In the 1960s astronomers found that the maximum intensities of supernova explosions could be used as standard candles, hence indicators of astronomical distances.[19] Some of the most distant supernovae recently observed appeared dimmer than expected. This supports the view that the expansion of the universe is accelerating.[20][21] Techniques were developed for reconstructing supernova explosions that have no written records of being observed. The date of the Cassiopeia A supernova event was determined from light echoes off nebulae,[22] while the age of supernova remnant RX J0852.0-4622 was estimated from temperature measurements[23] and the gamma ray emissions from the decay of titanium-44.[24] In 2009 nitrates were discovered in Antarctic ice deposits that matched the times of past supernova events.[25][26]