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81-439: A supernova ( pl. : supernovae or supernovas ) is a powerful and luminous explosion of a star . A supernova occurs during the last evolutionary stages of a massive star , or when a white dwarf is triggered into runaway nuclear fusion . The original object, called the progenitor , either collapses to a neutron star or black hole , or is completely destroyed to form a diffuse nebula . The peak optical luminosity of

162-443: A shaped charge the explosive forces are focused to produce a greater local explosion; shaped charges are often used by military to breach doors or walls. The speed of the reaction is what distinguishes an explosive reaction from an ordinary combustion reaction. Unless the reaction occurs very rapidly, the thermally expanding gases will be moderately dissipated in the medium, with no large differential in pressure and no explosion. As

243-403: A magnetic explosion . Strictly a physical process, as opposed to chemical or nuclear, e.g., the bursting of a sealed or partially sealed container under internal pressure is often referred to as an explosion. Examples include an overheated boiler or a simple tin can of beans tossed into a fire. Boiling liquid expanding vapor explosions are one type of mechanical explosion that can occur when

324-517: A ' guest star ' appeared in the middle of the Southern Gate [南門] [an asterism consisting of ε Centauri and α Centauri ], The size was half a bamboo mat. It displayed various colors, both pleasing and otherwise. It gradually lessened. In the 6th month of the succeeding year it disappeared. The gaseous shell RCW 86 is probably the supernova remnant of this event and has a relatively large angular size of roughly 45 arc minutes (larger than

405-485: A less luminous light curve than the more normal SN type Ia. Abnormally bright type Ia supernovae occur when the white dwarf already has a mass higher than the Chandrasekhar limit, possibly enhanced further by asymmetry, but the ejected material will have less than normal kinetic energy. This super-Chandrasekhar-mass scenario can occur, for example, when the extra mass is supported by differential rotation . There

486-412: A major source of elements in the interstellar medium from oxygen to rubidium . The expanding shock waves of supernovae can trigger the formation of new stars . Supernovae are a major source of cosmic rays . They might also produce gravitational waves . The word supernova has the plural form supernovae ( /- v iː / ) or supernovas and is often abbreviated as SN or SNe. It is derived from

567-679: A merger signal of about 100 ms duration, during which time is it estimated to have radiated away nine solar masses in the form of gravitational energy. The most common artificial explosives are chemical explosives, usually involving a rapid and violent oxidation reaction that produces large amounts of hot gas. Gunpowder was the first explosive to be invented and put to use. Other notable early developments in chemical explosive technology were Frederick Augustus Abel 's development of nitrocellulose in 1865 and Alfred Nobel 's invention of dynamite in 1866. Chemical explosions (both intentional and accidental) are often initiated by an electric spark or flame in

648-403: A new category of novae was performed during the 1920s. These were variously called "upper-class Novae", "Hauptnovae", or "giant novae". The name "supernovae" is thought to have been coined by Walter Baade and Zwicky in lectures at Caltech in 1931. It was used, as "super-Novae", in a journal paper published by Knut Lundmark in 1933, and in a 1934 paper by Baade and Zwicky. By 1938, the hyphen

729-449: A non-rotating star), it would no longer be able to support the bulk of its mass through electron degeneracy pressure and would begin to collapse. However, the current view is that this limit is not normally attained; increasing temperature and density inside the core ignite carbon fusion as the star approaches the limit (to within about 1%) before collapse is initiated. In contrast, for a core primarily composed of oxygen, neon and magnesium,

810-554: A one or two-letter designation. The first 26 supernovae of the year are designated with a capital letter from A to Z . Next, pairs of lower-case letters are used: aa , ab , and so on. Hence, for example, SN 2003C designates the third supernova reported in the year 2003. The last supernova of 2005, SN 2005nc, was the 367th (14 × 26 + 3 = 367). Since 2000, professional and amateur astronomers have been finding several hundred supernovae each year (572 in 2007, 261 in 2008, 390 in 2009; 231 in 2013). Historical supernovae are known simply by

891-401: A publication by Knut Lundmark , who may have coined it independently. Compared to a star's entire history, the visual appearance of a supernova is very brief, sometimes spanning several months, so that the chances of observing one with the naked eye are roughly once in a lifetime. Only a tiny fraction of the 100  billion stars in a typical galaxy have the capacity to become a supernova,

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972-672: A rare type of very fast supernova with unusually strong calcium lines in their spectra. Models suggest they occur when material is accreted from a helium -rich companion rather than a hydrogen -rich star. Because of helium lines in their spectra, they can resemble type Ib supernovae, but are thought to have very different progenitors. The supernovae of type II can also be sub-divided based on their spectra. While most type II supernovae show very broad emission lines which indicate expansion velocities of many thousands of kilometres per second , some, such as SN 2005gl , have relatively narrow features in their spectra. These are called type IIn, where

1053-401: A result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives available, with a single weapon capable of completely destroying an entire city. Explosive force is released in a direction perpendicular to the surface of the explosive. If a grenade is in mid air during the explosion, the direction of the blast will be 360°. In contrast, in

1134-537: A small portion of the mass of the explosive material. A material in which the first three factors exist cannot be accepted as an explosive unless the reaction can be made to occur when needed. Fragmentation is the accumulation and projection of particles as the result of a high explosives detonation. Fragments could originate from: parts of a structure (such as glass , bits of structural material , or roofing material), revealed strata and/or various surface-level geologic features (such as loose rocks , soil , or sand ),

1215-702: A stellar companion to raise its core temperature enough to ignite carbon fusion , at which point it undergoes runaway nuclear fusion, completely disrupting it. There are three avenues by which this detonation is theorised to happen: stable accretion of material from a companion, the collision of two white dwarfs, or accretion that causes ignition in a shell that then ignites the core. The dominant mechanism by which type Ia supernovae are produced remains unclear. Despite this uncertainty in how type Ia supernovae are produced, type Ia supernovae have very uniform properties and are useful standard candles over intergalactic distances. Some calibrations are required to compensate for

1296-481: A supernova can be comparable to that of an entire galaxy before fading over several weeks or months. The last supernova directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye . The remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in

1377-472: A supernova's spectrum contains lines of hydrogen (known as the Balmer series in the visual portion of the spectrum) it is classified Type II ; otherwise it is Type I . In each of these two types there are subdivisions according to the presence of lines from other elements or the shape of the light curve (a graph of the supernova's apparent magnitude as a function of time). Type I supernovae are subdivided on

1458-407: A vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates. Note that the contents of the container may cause a subsequent chemical explosion, the effects of which can be dramatically more serious, such as a propane tank in the midst of a fire. In such a case, to the effects of the mechanical explosion when the tank fails are added the effects from

1539-641: A wood fire burns in a fireplace, for example, there certainly is the evolution of heat and the formation of gases, but neither is liberated rapidly enough to build up a sudden substantial pressure differential and then cause an explosion. This can be likened to the difference between the energy discharge of a battery , which is slow, and that of a flash capacitor like that in a camera flash, which releases its energy all at once. The generation of heat in large quantities accompanies most explosive chemical reactions. The exceptions are called entropic explosives and include organic peroxides such as acetone peroxide . It

1620-465: Is ASASSN-15lh , at a distance of 3.82 gigalight-years . It was first detected in June 2015 and peaked at 570 billion  L ☉ , which is twice the bolometric luminosity of any other known supernova. The nature of this supernova is debated and several alternative explanations, such as tidal disruption of a star by a black hole, have been suggested. SN 2013fs was recorded three hours after

1701-446: Is a dimensionless measure of the spectrum's frequency shift. High redshift searches for supernovae usually involve the observation of supernova light curves. These are useful for standard or calibrated candles to generate Hubble diagrams and make cosmological predictions. Supernova spectroscopy, used to study the physics and environments of supernovae, is more practical at low than at high redshift. Low redshift observations also anchor

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1782-422: Is absorbed during the formation of the compound from its elements; such a reaction is called an endothermic reaction. In explosive technology only materials that are exothermic —that have a net liberation of heat and have a negative heat of formation—are of interest. Reaction heat is measured under conditions either of constant pressure or constant volume. It is this heat of reaction that may be properly expressed as

1863-424: Is formed from its constituents, heat may either be absorbed or released. The quantity of heat absorbed or given off during transformation is called the heat of formation . Heats of formations for solids and gases found in explosive reactions have been determined for a temperature of 25 °C and atmospheric pressure, and are normally given in units of kilojoules per gram-molecule. A positive value indicates that heat

1944-453: Is generated, with matter reaching velocities on the order of 5,000–20,000 km/s , or roughly 3% of the speed of light. There is also a significant increase in luminosity, reaching an absolute magnitude of −19.3 (or 5 billion times brighter than the Sun), with little variation. The model for the formation of this category of supernova is a close binary star system. The larger of the two stars

2025-490: Is no formal sub-classification for non-standard type Ia supernovae. It has been proposed that a group of sub-luminous supernovae that occur when helium accretes onto a white dwarf should be classified as type Iax . This type of supernova may not always completely destroy the white dwarf progenitor and could leave behind a zombie star . One specific type of supernova originates from exploding white dwarfs, like type Ia, but contains hydrogen lines in their spectra, possibly because

2106-578: Is required. It is therefore important to discover them well before they reach their maximum. Amateur astronomers , who greatly outnumber professional astronomers, have played an important role in finding supernovae, typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier photographs. Toward the end of the 20th century, astronomers increasingly turned to computer-controlled telescopes and CCDs for hunting supernovae. While such systems are popular with amateurs, there are also professional installations such as

2187-413: Is the first to evolve off the main sequence , and it expands to form a red giant . The two stars now share a common envelope, causing their mutual orbit to shrink. The giant star then sheds most of its envelope, losing mass until it can no longer continue nuclear fusion . At this point, it becomes a white dwarf star, composed primarily of carbon and oxygen. Eventually, the secondary star also evolves off

2268-407: Is the rapid liberation of heat that causes the gaseous products of most explosive reactions to expand and generate high pressures . This rapid generation of high pressures of the released gas constitutes the explosion. The liberation of heat with insufficient rapidity will not cause an explosion. For example, although a unit mass of coal yields five times as much heat as a unit mass of nitroglycerin ,

2349-582: The Aristotelian idea that the universe beyond the Moon and planets was static and unchanging. Johannes Kepler began observing SN 1604 at its peak on 17 October 1604, and continued to make estimates of its brightness until it faded from naked eye view a year later. It was the second supernova to be observed in a generation, after Tycho Brahe observed SN 1572 in Cassiopeia . There is some evidence that

2430-515: The Chandrasekhar limit ; electron capture ; pair-instability ; or photodisintegration . The table below lists the known reasons for core collapse in massive stars, the types of stars in which they occur, their associated supernova type, and the remnant produced. The metallicity is the proportion of elements other than hydrogen or helium, as compared to the Sun. The initial mass is the mass of

2511-566: The Eta Carinae Great Outburst was noted. Supernovae in M101 (1909) and M83 (1923 and 1957) were also suggested as possible type IV or type V supernovae. These types would now all be treated as peculiar type II supernovae (IIpec), of which many more examples have been discovered, although it is still debated whether SN 1961V was a true supernova following an LBV outburst or an impostor. Supernova type codes, as summarised in

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2592-660: The Katzman Automatic Imaging Telescope . The Supernova Early Warning System (SNEWS) project uses a network of neutrino detectors to give early warning of a supernova in the Milky Way galaxy. Neutrinos are subatomic particles that are produced in great quantities by a supernova, and they are not significantly absorbed by the interstellar gas and dust of the galactic disk. Supernova searches fall into two classes: those focused on relatively nearby events and those looking farther away. Because of

2673-452: The Latin word nova , meaning ' new ' , which refers 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 Walter Baade and Fritz Zwicky , who began using it in astrophysics lectures in 1931. Its first use in a journal article came the following year in

2754-571: The Tunguska event of 1908 is believed to have resulted from a meteor air burst . Black hole mergers, likely involving binary black hole systems, are capable of radiating many solar masses of energy into the universe in a fraction of a second, in the form of a gravitational wave . This is capable of transmitting ordinary energy and destructive forces to nearby objects, but in the vastness of space, nearby objects are rare. The gravitational wave observed on 21 May 2019, known as GW190521 , produced

2835-413: The expansion of the universe , the distance to a remote object with a known emission spectrum can be estimated by measuring its Doppler shift (or redshift ); on average, more-distant objects recede with greater velocity than those nearby, and so have a higher redshift. Thus the search is split between high redshift and low redshift, with the boundary falling around a redshift range of z=0.1–0.3, where z

2916-442: The "heat of explosion." A chemical explosive is a compound or mixture which, upon the application of heat or shock, decomposes or rearranges with extreme rapidity, yielding much gas and heat. Many substances not ordinarily classed as explosives may do one, or even two, of these things. A reaction must be capable of being initiated by the application of shock, heat, or a catalyst (in the case of some explosive chemical reactions) to

2997-428: The "n" stands for "narrow". A few supernovae, such as SN 1987K and SN 1993J , appear to change types: they show lines of hydrogen at early times, but, over a period of weeks to months, become dominated by lines of helium. The term "type IIb" is used to describe the combination of features normally associated with types II and Ib. Type II supernovae with normal spectra dominated by broad hydrogen lines that remain for

3078-511: The Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through modern astronomical telescopes. The most recent naked-eye supernova was SN 1987A , which was the explosion of a blue supergiant star in the Large Magellanic Cloud , a satellite galaxy of the Milky Way. Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms:

3159-522: The Milky Way, obtaining a good sample of supernovae to study requires regular monitoring of many galaxies. Today, amateur and professional astronomers are finding several hundred every year, some when near maximum brightness, others on old astronomical photographs or plates. Supernovae in other galaxies cannot be predicted with any meaningful accuracy. Normally, when they are discovered, they are already in progress. To use supernovae as standard candles for measuring distance, observation of their peak luminosity

3240-567: The Sun, and presumably on most other stars as well. The energy source for solar flare activity comes from the tangling of magnetic field lines resulting from the rotation of the Sun's conductive plasma. Another type of large astronomical explosion occurs when a meteoroid or an asteroid impacts the surface of another object, or explodes in its atmosphere , such as a planet. This occurs because the two objects are moving at very high speed relative to each other (a minimum of 11.2 kilometres per second (7.0 mi/s) for an Earth impacting body ). For example,

3321-590: The ability being restricted to those having high mass and those in rare kinds of binary star systems with at least one white dwarf . The earliest record of a possible supernova, known as HB9, was likely viewed by an unknown prehistoric people of the Indian subcontinent and recorded on a rock carving in the Burzahama region of Kashmir , dated to 4500 ± 1000  BC . Later, SN 185 was documented by Chinese astronomers in 185 AD. The brightest recorded supernova

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3402-460: The apparent size of the full moon, which varies from 29 to 34 arc minutes). The distance to RCW 86 is estimated to be 2,800 parsecs (9,100 light-years ). Recent X-ray studies show a good match for the expected age. Infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) reveal how the supernova occurred and how its shattered remains ultimately spread out to great distances. The findings show that

3483-686: The basis of their spectra, with type Ia showing a strong ionised silicon absorption line. Type I supernovae without this strong line are classified as type Ib and Ic, with type Ib showing strong neutral helium lines and type Ic lacking them. Historically, the light curves of type I supernovae were seen as all broadly similar, too much so to make useful distinctions. While variations in light curves have been studied, classification continues to be made on spectral grounds rather than light-curve shape. A small number of type Ia supernovae exhibit unusual features, such as non-standard luminosity or broadened light curves, and these are typically categorised by referring to

3564-410: The burning substance into heat released to the surroundings, while in the latter, fast combustion ( i.e. detonation ) instead converts more internal energy into work on the surroundings ( i.e. less internal energy converted into heat); c.f. heat and work (thermodynamics) are equivalent forms of energy. See Heat of Combustion for a more thorough treatment of this topic. When a chemical compound

3645-429: The casing surrounding the explosive, and/or any other loose miscellaneous items not vaporized by the shock wave from the explosion. High velocity, low angle fragments can travel hundreds of metres with enough energy to initiate other surrounding high explosive items, injure or kill personnel, and/or damage vehicles or structures. Classical Latin explōdō means "to hiss a bad actor off the stage", "to drive an actor off

3726-414: The coal cannot be used as an explosive (except in the form of coal dust ) because the rate at which it yields this heat is quite slow. In fact, a substance that burns less rapidly ( i.e. slow combustion ) may actually evolve more total heat than an explosive that detonates rapidly ( i.e. fast combustion ). In the former, slow combustion converts more of the internal energy ( i.e. chemical potential ) of

3807-398: The collapsing white dwarf will typically form a neutron star . In this case, only a fraction of the star's mass will be ejected during the collapse. Within a few seconds of the collapse process, a substantial fraction of the matter in the white dwarf undergoes nuclear fusion, releasing enough energy (1– 2 × 10  J ) to unbind the star in a supernova. An outwardly expanding shock wave

3888-453: The core against its own gravity; passing this threshold is the cause of all types of supernova except type Ia. The collapse may cause violent expulsion of the outer layers of the star resulting in a supernova. However, if the release of gravitational potential energy is insufficient, the star may instead collapse into a black hole or neutron star with little radiated energy. Core collapse can be caused by several different mechanisms: exceeding

3969-522: The distance to their host galaxies. A second model for the formation of type Ia supernovae involves the merger of two white dwarf stars, with the combined mass momentarily exceeding the Chandrasekhar limit. This is sometimes referred to as the double-degenerate model, as both stars are degenerate white dwarfs. Due to the possible combinations of mass and chemical composition of the pair there is much variation in this type of event, and, in many cases, there may be no supernova at all, in which case they will have

4050-399: The earliest example showing similar features. For example, the sub-luminous SN 2008ha is often referred to as SN 2002cx -like or class Ia-2002cx. A small proportion of type Ic supernovae show highly broadened and blended emission lines which are taken to indicate very high expansion velocities for the ejecta. These have been classified as type Ic-BL or Ic-bl. Calcium-rich supernovae are

4131-428: The explosion resulting from the released (initially liquid and then almost instantaneously gaseous) propane in the presence of an ignition source. For this reason, emergency workers often differentiate between the two events. In addition to stellar nuclear explosions , a nuclear weapon is a type of explosive weapon that derives its destructive force from nuclear fission or from a combination of fission and fusion. As

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4212-436: The gradual change in properties or different frequencies of abnormal luminosity supernovae at high redshift, and for small variations in brightness identified by light curve shape or spectrum. There are several means by which a supernova of this type can form, but they share a common underlying mechanism. If a carbon - oxygen white dwarf accreted enough matter to reach the Chandrasekhar limit of about 1.44 solar masses (for

4293-562: The increasing number of discoveries has regularly led to the additional use of three-letter designations. After zz comes aaa, then aab, aac, and so on. For example, the last supernova retained in the Asiago Supernova Catalogue ; when it was terminated on 31 December 2017 bears the designation SN 2017jzp. Astronomers classify supernovae according to their light curves and the absorption lines of different chemical elements that appear in their spectra . If

4374-431: The life of the decline are classified on the basis of their light curves. The most common type shows a distinctive "plateau" in the light curve shortly after peak brightness where the visual luminosity stays relatively constant for several months before the decline resumes. These are called type II-P referring to the plateau. Less common are type II-L supernovae that lack a distinct plateau. The "L" signifies "linear" although

4455-436: The light curve is extremely consistent across normal type Ia supernovae, having a maximum absolute magnitude of about −19.3. This is because typical type Ia supernovae arise from a consistent type of progenitor star by gradual mass acquisition, and explode when they acquire a consistent typical mass, giving rise to very similar supernova conditions and behaviour. This allows them to be used as a secondary standard candle to measure

4536-533: The light curve is not actually a straight line. Supernovae that do not fit into the normal classifications are designated peculiar, or "pec". Zwicky defined additional supernovae types based on a very few examples that did not cleanly fit the parameters for type I or type II supernovae. SN 1961i in NGC 4303 was the prototype and only member of the type III supernova class, noted for its broad light curve maximum and broad hydrogen Balmer lines that were slow to develop in

4617-460: The low-distance end of the Hubble curve , which is a plot of distance versus redshift for visible galaxies. As survey programmes rapidly increase the number of detected supernovae, collated collections of observations (light decay curves, astrometry, pre-supernova observations, spectroscopy) have been assembled. The Pantheon data set, assembled in 2018, detailed 1048 supernovae. In 2021, this data set

4698-411: The magma rises causes the gas to bubble out of solution, resulting in a rapid increase in volume, however the size of the magma chamber remains the same. This results in pressure buildup that eventually leads to an explosive eruption. Explosions can also occur outside of Earth in the universe in events such as supernovae , or, more commonly, stellar flares. Humans are also able to create explosions through

4779-490: The main sequence to form a red giant. Matter from the giant is accreted by the white dwarf, causing the latter to increase in mass. The exact details of initiation and of the heavy elements produced in the catastrophic event remain unclear. Type Ia supernovae produce a characteristic light curve—the graph of luminosity as a function of time—after the event. This luminosity is generated by the radioactive decay of nickel -56 through cobalt -56 to iron -56. The peak luminosity of

4860-410: The most distant spectroscopically confirmed supernova at a redshift of 3.6, indicating its explosion occurred when the universe was merely 1.8 billion years old. These findings offer crucial insights into the early universe's stellar evolution and the frequency of supernovae during its formative years. Because supernovae are relatively rare events within a galaxy, occurring about three times a century in

4941-440: The newly ejected material. Explosion For an explosion to occur, there must be a rapid, forceful expansion of matter. There are numerous ways this can happen, both naturally and artificially, such as volcanic eruptions , or two objects striking each other at very high speeds, as in an impact event . Explosive volcanic eruptions occur when magma rises from below, it has dissolved gas in it. The reduction of pressure as

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5022-419: The presence of oxygen. Accidental explosions may occur in fuel tanks, rocket engines, etc. A high current electrical fault can create an "electrical explosion" by forming a high-energy electrical arc which rapidly vaporizes metal and insulation material. This arc flash hazard is a danger to people working on energized switchgear . Excessive magnetic pressure within an ultra-strong electromagnet can cause

5103-450: The spectrum. SN 1961f in NGC 3003 was the prototype and only member of the type IV class, with a light curve similar to a type II-P supernova, with hydrogen absorption lines but weak hydrogen emission lines . The type V class was coined for SN 1961V in NGC 1058 , an unusual faint supernova or supernova impostor with a slow rise to brightness, a maximum lasting many months, and an unusual emission spectrum. The similarity of SN 1961V to

5184-521: The stage by making noise", from ex- ("out") + plaudō ("to clap; to applaud"). The modern meaning developed later: In English: SN 185 SN 185 was a transient astronomical event observed in the year AD 185 , likely a supernova . The transient occurred in the direction of Alpha Centauri , between the constellations Circinus and Centaurus , centered at RA 14 43 Dec −62° 30′, in Circinus. This " guest star "

5265-513: The star prior to the supernova event, given in multiples of the Sun's mass, although the mass at the time of the supernova may be much lower. Type IIn supernovae are not listed in the table. They can be produced by various types of core collapse in different progenitor stars, possibly even by type Ia white dwarf ignitions, although it seems that most will be from iron core collapse in luminous supergiants or hypergiants (including LBVs). The narrow spectral lines for which they are named occur because

5346-597: The stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise. Differing modern interpretations of the Chinese records of the guest star have led to quite different suggestions for the astronomical mechanism behind the event, from a core-collapse supernova to a distant, slow-moving comet – with correspondingly wide-ranging estimates of its apparent visual magnitude (−8 to +4). The recent Chandra results suggest that it

5427-419: The sudden re-ignition of nuclear fusion in a white dwarf , or the sudden gravitational collapse of a massive star's core . Supernovae can expel several solar masses of material at speeds up to several percent of the speed of light . This drives an expanding shock wave into the surrounding interstellar medium , sweeping up an expanding shell of gas and dust observed as a supernova remnant. Supernovae are

5508-508: The supernova event on 6 October 2013, by the Intermediate Palomar Transient Factory . This is among the earliest supernovae caught after detonation, and it is the earliest for which spectra have been obtained, beginning six hours after the actual explosion. The star is located in a spiral galaxy named NGC 7610 , 160 million light-years away in the constellation of Pegasus. The supernova SN 2016gkg

5589-468: The supernova is expanding into a small dense cloud of circumstellar material. It appears that a significant proportion of supposed type IIn supernovae are supernova impostors, massive eruptions of LBV-like stars similar to the Great Eruption of Eta Carinae . In these events, material previously ejected from the star creates the narrow absorption lines and causes a shock wave through interaction with

5670-409: The table above, are taxonomic : the type number is based on the light observed from the supernova, not necessarily its cause. For example, type Ia supernovae are produced by runaway fusion ignited on degenerate white dwarf progenitors, while the spectrally similar type Ib/c are produced from massive stripped progenitor stars by core collapse. A white dwarf star may accumulate sufficient material from

5751-430: The use of explosives , or through nuclear fission or fusion , as in a nuclear weapon . Explosions frequently occur during bushfires in eucalyptus forests where the volatile oils in the tree tops suddenly combust. Among the largest known explosions in the universe are supernovae , which occur after the end of life of some types of stars . Solar flares are an example of common, much less energetic, explosions on

5832-541: The view that the expansion of the universe is accelerating . Techniques were developed for reconstructing supernovae events that have no written records of being observed. The date of the Cassiopeia A supernova event was determined from light echoes off nebulae , while the age of supernova remnant RX J0852.0-4622 was estimated from temperature measurements and the gamma ray emissions from the radioactive decay of titanium-44 . The most luminous supernova ever recorded

5913-481: The white dwarf is surrounded by an envelope of hydrogen-rich circumstellar material . These supernovae have been dubbed type Ia/IIn , type Ian , type IIa and type IIan . The quadruple star HD 74438 , belonging to the open cluster IC 2391 the Vela constellation , has been predicted to become a non-standard type Ia supernova. Very massive stars can undergo core collapse when nuclear fusion becomes unable to sustain

5994-459: The year they occurred: SN 185, SN 1006, SN 1054, SN 1572 (called Tycho's Nova ) and SN 1604 ( Kepler's Star ). Since 1885 the additional letter notation has been used, even if there was only one supernova discovered that year (for example, SN 1885A, SN 1907A, etc.); this last happened with SN 1947A. SN , for SuperNova, is a standard prefix. Until 1987, two-letter designations were rarely needed; since 1988, they have been needed every year. Since 2016,

6075-446: The youngest known supernova in our galaxy, G1.9+0.3 , occurred in the late 19th century, considerably more recently than Cassiopeia A from around 1680. Neither was noted at the time. In the case of G1.9+0.3, high extinction from dust along the plane of the galactic disk could have dimmed the event sufficiently for it to go unnoticed. The situation for Cassiopeia A is less clear; infrared light echoes have been detected showing that it

6156-648: Was SN 1006 , which was observed in AD 1006 in the constellation of Lupus . This event was described by observers in China, Japan, Iraq, Egypt and Europe. The widely observed supernova SN 1054 produced the Crab Nebula . Supernovae SN 1572 and SN 1604 , the latest Milky Way supernovae to be observed with the naked eye, had a notable influence on the development of astronomy in Europe because they were used to argue against

6237-767: Was detected by amateur astronomer Victor Buso from Rosario , Argentina, on 20 September 2016. It was the first time that the initial "shock breakout" from an optical supernova had been observed. The progenitor star has been identified in Hubble Space Telescope images from before its collapse. Astronomer Alex Filippenko noted: "Observations of stars in the first moments they begin exploding provide information that cannot be directly obtained in any other way." The James Webb Space Telescope (JWST) has significantly advanced our understanding of supernovae by identifying around 80 new instances through its JWST Advanced Deep Extragalactic Survey (JADES) program. This includes

6318-493: Was expanded to 1701 light curves for 1550 supernovae taken from 18 different surveys, a 50% increase in under 3 years. Supernova discoveries are reported to the International Astronomical Union 's Central Bureau for Astronomical Telegrams , which sends out a circular with the name it assigns to that supernova. The name is formed from the prefix SN , followed by the year of discovery, suffixed with

6399-442: Was no longer used and the modern name was in use. American astronomers Rudolph Minkowski and Fritz Zwicky developed the modern supernova classification scheme beginning in 1941. During the 1960s, astronomers found that the maximum intensities of supernovae could be used as standard candles , hence indicators of astronomical distances. Some of the most distant supernovae observed in 2003 appeared dimmer than expected. This supports

6480-481: Was not in a region of especially high extinction. SN's identification With the development of the astronomical telescope , observation and discovery of fainter and more distant supernovae became possible. The first such observation was of SN 1885A in the Andromeda Galaxy . A second supernova, SN 1895B , was discovered in NGC 5253 a decade later. Early work on what was originally believed to be simply

6561-519: Was observed by Chinese astronomers in the Book of Later Han (后汉书), and might have been recorded in Roman literature. It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist. The Book of Later Han gives the following description: In the 2nd year of the epoch Zhongping [中平], the 10th month, on the day Guihai [癸亥] [December 7, Year 185],

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