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60-462: Physically, carbon–oxygen white dwarfs with a low rate of rotation are limited to below 1.44 solar masses ( M ☉ ). Beyond this " critical mass ", they reignite and in some cases trigger a supernova explosion; this critical mass is often referred to as the Chandrasekhar mass, but is marginally different from the absolute Chandrasekhar limit , where electron degeneracy pressure

120-502: A red giant as the source. The expanding plasma from the explosion was found to contain carbon and oxygen, making it likely the progenitor was a white dwarf primarily composed of these elements. Similarly, observations of the nearby SN PTF 11kx, discovered January 16, 2011 (UT) by the Palomar Transient Factory (PTF), lead to the conclusion that this explosion arises from single-degenerate progenitor, with

180-406: A runaway reaction, releasing enough energy ( 1 × 10  J ) to unbind the star in a supernova explosion. The Type Ia category of supernova produces a fairly consistent peak luminosity because of the fixed critical mass at which a white dwarf will explode. Their consistent peak luminosity allows these explosions to be used as standard candles to measure the distance to their host galaxies:

240-497: A shock wave in which matter is typically ejected at speeds on the order of 5,000–20,000 km/s , roughly 6% of the speed of light . The energy released in the explosion also causes an extreme increase in luminosity. The typical visual absolute magnitude of Type Ia supernovae is M v  = −19.3 (about 5 billion times brighter than the Sun), with little variation. The Type Ia supernova leaves no compact remnant, but

300-437: A subgiant or (if the orbit is sufficiently close) even a main sequence star. The actual evolutionary process during this accretion stage remains uncertain, as it can depend both on the rate of accretion and the transfer of angular momentum to the white dwarf companion. It has been estimated that single degenerate progenitors account for no more than 20% of all Type Ia supernovae. A second possible mechanism for triggering

360-579: A Type Ia supernova is the merger of two white dwarfs whose combined mass exceeds the Chandrasekhar limit . The resulting merger is called a super-Chandrasekhar mass white dwarf. In such a case, the total mass would not be constrained by the Chandrasekhar limit. Collisions of solitary stars within the Milky Way occur only once every 10 to 10 years ; far less frequently than the appearance of novae. Collisions occur with greater frequency in

420-440: A characteristic light curve , their graph of luminosity as a function of time after the explosion. Near the time of maximal luminosity, the spectrum contains lines of intermediate-mass elements from oxygen to calcium ; these are the main constituents of the outer layers of the star. Months after the explosion, when the outer layers have expanded to the point of transparency, the spectrum is dominated by light emitted by material near

480-482: A collaboration of Chilean and US astronomers, the Calán/Tololo Supernova Survey . In a series of papers in the 1990s the survey showed that while Type Ia supernovae do not all reach the same peak luminosity, a single parameter measured from the light curve can be used to correct unreddened Type Ia supernovae to standard candle values. The original correction to standard candle value is known as

540-413: A composition somewhat below conventional flammability ratios. They happen most often in confined systems, but they sometimes occur in large vapor clouds. Other materials, such as acetylene , ozone , and hydrogen peroxide , are detonable in the absence of an oxidant (or reductant). In these cases the energy released results from the rearrangement of the molecular constituents of the material. Detonation

600-843: A double white dwarf merger every 100 years in the Milky Way: this rate matches the number of Type Ia supernovae detected in our neighborhood. A double degenerate scenario is one of several explanations proposed for the anomalously massive (2  M ☉ ) progenitor of SN 2003fg . It is the only possible explanation for SNR 0509-67.5 , as all possible models with only one white dwarf have been ruled out. It has also been strongly suggested for SN 1006 , given that no companion star remnant has been found there. Observations made with NASA 's Swift space telescope ruled out existing supergiant or giant companion stars of every Type Ia supernova studied. The supergiant companion's blown out outer shell should emit X-rays , but this glow

660-399: A group of sub-luminous supernovae should be classified as Type Iax . This type of supernova may not always completely destroy the white dwarf progenitor, but instead leave behind a zombie star . Known examples of type Iax supernovae include: the historical supernova SN 1181 , SN 1991T , SN 1991bg , SN 2002cx , and SN 2012Z . The supernova SN 1181 is believed to be associated with

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720-566: A pulse detonation engine took place at the Mojave Air & Space Port on January 31, 2008. Unintentional detonation when deflagration is desired is a problem in some devices. In Otto cycle , or gasoline engines it is called engine knocking or pinging, and it causes a loss of power. It can also cause excessive heating, and harsh mechanical shock that can result in eventual engine failure. In firearms, it may cause catastrophic and potentially lethal failure . Pulse detonation engines are

780-469: A red giant companion, thus suggesting there is no single progenitor path to SN Ia. Direct observations of the progenitor of PTF 11kx were reported in the August 24 edition of Science and support this conclusion, and also show that the progenitor star experienced periodic nova eruptions before the supernova – another surprising discovery. However, later analysis revealed that the circumstellar material

840-680: A reference frame of a stationary shock, the following flow is subsonic, so that an acoustic reaction zone follows immediately behind the lead front, the Chapman–Jouguet condition . There is also some evidence that the reaction zone is semi-metallic in some explosives. Both theories describe one-dimensional and steady wavefronts. However, in the 1960s, experiments revealed that gas-phase detonations were most often characterized by unsteady, three-dimensional structures, which can only, in an averaged sense, be predicted by one-dimensional steady theories. Indeed, such waves are quenched as their structure

900-435: A theory describes the chemistry and diffusive transport processes as occurring abruptly as the shock passes. A more complex theory was advanced during World War II independently by Zel'dovich , von Neumann , and Döring . This theory, now known as ZND theory , admits finite-rate chemical reactions and thus describes a detonation as an infinitesimally thin shock wave, followed by a zone of exothermic chemical reaction. With

960-592: A unit of measurement, the solar mass came into use before the AU and the gravitational constant were precisely measured. This is because the relative mass of another planet in the Solar System or the combined mass of two binary stars can be calculated in units of Solar mass directly from the orbital radius and orbital period of the planet or stars using Kepler's third law. The mass of the Sun cannot be measured directly, and

1020-486: Is a feature for destructive purposes while deflagration is favored for the acceleration of firearms ' projectiles. However, detonation waves may also be used for less destructive purposes, including deposition of coatings to a surface or cleaning of equipment (e.g. slag removal ) and even explosively welding together metals that would otherwise fail to fuse. Pulse detonation engines use the detonation wave for aerospace propulsion. The first flight of an aircraft powered by

1080-620: Is an explosion of fuel-air mixture. Compared to deflagration, detonation doesn't need to have an external oxidizer. Oxidizers and fuel mix when deflagration occurs. Detonation is more destructive than deflagrations. In detonation, the flame front travels through the air-fuel faster than sound; while in deflagration, the flame front travels through the air-fuel slower than sound. Detonations occur in both conventional solid and liquid explosives, as well as in reactive gases. TNT, dynamite, and C4 are examples of high power explosives that detonate. The velocity of detonation in solid and liquid explosives

1140-410: Is converted into helium through nuclear fusion , in particular the p–p chain , and this reaction converts some mass into energy in the form of gamma ray photons. Most of this energy eventually radiates away from the Sun. Second, high-energy protons and electrons in the atmosphere of the Sun are ejected directly into outer space as the solar wind and coronal mass ejections . The original mass of

1200-436: Is destroyed. The Wood-Kirkwood detonation theory can correct some of these limitations. Experimental studies have revealed some of the conditions needed for the propagation of such fronts. In confinement, the range of composition of mixes of fuel and oxidant and self-decomposing substances with inerts are slightly below the flammability limits and, for spherically expanding fronts, well below them. The influence of increasing

1260-461: Is difficult to measure and is only known with limited accuracy ( see Cavendish experiment ). The value of G times the mass of an object, called the standard gravitational parameter , is known for the Sun and several planets to a much higher accuracy than G alone. As a result, the solar mass is used as the standard mass in the astronomical system of units . The Sun is losing mass because of fusion reactions occurring within its core, leading to

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1320-508: Is generally accepted that a substantial fraction of the carbon and oxygen in the white dwarf fuses into heavier elements within a period of only a few seconds, with the accompanying release of energy increasing the internal temperature to billions of degrees. The energy released (1– 2 × 10  J ) is more than sufficient to unbind the star; that is, the individual particles making up the white dwarf gain enough kinetic energy to fly apart from each other. The star explodes violently and releases

1380-689: Is instead calculated from other measurable factors, using the equation for the orbital period of a small body orbiting a central mass. Based on the length of the year, the distance from Earth to the Sun (an astronomical unit or AU), and the gravitational constant ( G ), the mass of the Sun is given by solving Kepler's third law : M ⊙ = 4 π 2 × ( 1 A U ) 3 G × ( 1 y r ) 2 {\displaystyle M_{\odot }={\frac {4\pi ^{2}\times (1\,\mathrm {AU} )^{3}}{G\times (1\,\mathrm {yr} )^{2}}}} The value of G

1440-428: Is much higher than that in gaseous ones, which allows the wave system to be observed with greater detail (higher resolution ). A very wide variety of fuels may occur as gases (e.g. hydrogen ), droplet fogs, or dust suspensions. In addition to dioxygen, oxidants can include halogen compounds, ozone, hydrogen peroxide, and oxides of nitrogen . Gaseous detonations are often associated with a mixture of fuel and oxidant in

1500-423: Is never initiated. Instead, the increase in pressure and density due to the increasing weight raises the temperature of the core, and as the white dwarf approaches about 99% of the limit, a period of convection ensues, lasting approximately 1,000 years. At some point in this simmering phase, a deflagration flame front is born, powered by carbon fusion . The details of the ignition are still unknown, including

1560-419: Is set for mass accretion onto the primary. During this final shared-envelope phase, the two stars spiral in closer together as angular momentum is lost. The resulting orbit can have a period as brief as a few hours. If the accretion continues long enough, the white dwarf may eventually approach the Chandrasekhar limit . The white dwarf companion could also accrete matter from other types of companions, including

1620-807: Is significant diversity within the class of Type Ia supernovae. Reflecting this, a plethora of sub-classes have been identified. Two prominent and well-studied examples include 1991T-likes, an overluminous ( M V ≲ − 19.5 ) {\displaystyle (M_{V}\lesssim -19.5)} subclass that exhibits particularly strong iron absorption lines and abnormally small silicon features, and 1991bg-likes, an exceptionally dim ( M V ≳ − 18 ) {\displaystyle (M_{V}\gtrsim -18)} subclass characterized by strong early titanium absorption features and rapid photometric and spectral evolution. Despite their abnormal luminosities , members of both peculiar groups can be standardized by use of

1680-492: Is too massive for the single-degenerate scenario, and fits better the core-degenerate scenario. In May 2015, NASA reported that the Kepler space observatory observed KSN 2011b, a Type Ia supernova in the process of exploding. Details of the pre-nova moments may help scientists better judge the quality of Type Ia supernovae as standard candles, which is an important link in the argument for dark energy . In July 2019,

1740-415: Is unable to prevent catastrophic collapse. If a white dwarf gradually accretes mass from a binary companion, or merges with a second white dwarf, the general hypothesis is that a white dwarf's core will reach the ignition temperature for carbon fusion as it approaches the Chandrasekhar mass. Within a few seconds of initiation of nuclear fusion, a substantial fraction of the matter in the white dwarf undergoes

1800-678: The Cepheid variable distance scale and direct geometric distance measurements to NGC 4258 from the dynamics of maser emission when combined with the Hubble diagram of the Type Ia supernova distances have led to an improved value of the Hubble constant . In 1998, observations of distant Type Ia supernovae indicated the unexpected result that the universe seems to undergo an accelerating expansion . Three members from two teams were subsequently awarded Nobel Prizes for this discovery. There

1860-510: The Hubble Space Telescope took three images of a Type Ia supernova through a gravitational lens . This supernova appeared at three different times in the evolution of its brightness due to the differing path length of the light in the three images; at −24, 92, and 107 days from peak luminosity. A fourth image will appear in 2037 allowing observation of the entire luminosity cycle of the supernova. Type Ia supernovae have

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1920-535: The Phillips relation , defined at blue wavelengths, to determine distance . Solar mass The solar mass ( M ☉ ) is a standard unit of mass in astronomy , equal to approximately 2 × 10   kg . It is approximately equal to the mass of the Sun . It is often used to indicate the masses of other stars , as well as stellar clusters , nebulae , galaxies and black holes . More precisely,

1980-477: The Phillips relationship and was shown by this group to be able to measure relative distances to 7% accuracy. The cause of this uniformity in peak brightness is related to the amount of nickel-56 produced in white dwarfs presumably exploding near the Chandrasekhar limit. The similarity in the absolute luminosity profiles of nearly all known Type Ia supernovae has led to their use as a secondary standard candle in extragalactic astronomy. Improved calibrations of

2040-400: The asymptotic giant branch , before peaking at a rate of 10 to 10 M ☉ /year as the Sun generates a planetary nebula . By the time the Sun becomes a degenerate white dwarf , it will have lost 46% of its starting mass. The mass of the Sun has been decreasing since the time it formed. This occurs through two processes in nearly equal amounts. First, in the Sun's core , hydrogen

2100-445: The progenitor star for this type of supernova is a white dwarf , and empirical evidence for this was found in 2014 when a Type Ia supernova was observed in the galaxy Messier 82 . When a slowly-rotating carbon – oxygen white dwarf accretes matter from a companion, it can exceed the Chandrasekhar limit of about 1.44  M ☉ , beyond which it can no longer support its weight with electron degeneracy pressure. In

2160-526: The visual magnitude of a type Ia supernova, as observed from Earth, indicates its distance from Earth. The Type Ia supernova is a subcategory in the Minkowski–Zwicky supernova classification scheme, which was devised by German-American astronomer Rudolph Minkowski and Swiss astronomer Fritz Zwicky . There are several means by which a supernova of this type can form, but they share a common underlying mechanism. Theoretical astronomers long believed

2220-587: The IAU Division I Working Group, has the following estimates: Detonation Detonation (from Latin detonare  'to thunder down/forth') is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with speeds about 1 km/sec and differ from deflagrations which have subsonic flame speeds about 1 m/sec. Detonation

2280-477: The Sun at the time it reached the main sequence remains uncertain. The early Sun had much higher mass-loss rates than at present, and it may have lost anywhere from 1–7% of its natal mass over the course of its main-sequence lifetime. One solar mass, M ☉ , can be converted to related units: It is also frequently useful in general relativity to express mass in units of length or time. The solar mass parameter ( G · M ☉ ), as listed by

2340-408: The Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of 9″ (9  arcseconds , compared to the present value of 8.794 148 ″ ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry of Earth. The first known estimate of the solar mass was by Isaac Newton . In his work Principia (1687), he estimated that

2400-399: The absence of a countervailing process, the white dwarf would collapse to form a neutron star , in an accretion-induced non-ejective process, as normally occurs in the case of a white dwarf that is primarily composed of magnesium , neon , and oxygen. The current view among astronomers who model Type Ia supernova explosions, however, is that this limit is never actually attained and collapse

2460-572: The case of SN 2011fe , the companion star must have been smaller than the Sun , if it existed. The Chandra X-ray Observatory revealed that the X-ray radiation of five elliptical galaxies and the bulge of the Andromeda Galaxy is 30–50 times fainter than expected. X-ray radiation should be emitted by the accretion discs of Type Ia supernova progenitors. The missing radiation indicates that few white dwarfs possess accretion discs , ruling out

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2520-402: The cataclysmic explosion of the outer layers of a massive star as its core collapses, powered by release of gravitational potential energy via neutrino emission. One model for the formation of this category of supernova is a close binary star system. The progenitor binary system consists of main sequence stars, with the primary possessing more mass than the secondary. Being greater in mass,

2580-452: The common, accretion-based model of Ia supernovae. Inward spiraling white dwarf pairs are strongly-inferred candidate sources of gravitational waves , although they have not been directly observed. Double degenerate scenarios raise questions about the applicability of Type Ia supernovae as standard candles , since total mass of the two merging white dwarfs varies significantly, meaning luminosity also varies. It has been proposed that

2640-454: The concentration of diluent on expanding individual detonation cells has been elegantly demonstrated. Similarly, their size grows as the initial pressure falls. Since cell widths must be matched with minimum dimension of containment, any wave overdriven by the initiator will be quenched. Mathematical modeling has steadily advanced to predicting the complex flow fields behind shocks inducing reactions. To date, none has adequately described how

2700-406: The core of the star, heavy elements synthesized during the explosion; most prominently isotopes close to the mass of iron ( iron-peak elements). The radioactive decay of nickel-56 through cobalt-56 to iron-56 produces high-energy photons , which dominate the energy output of the ejecta at intermediate to late times. The use of Type Ia supernovae to measure precise distances was pioneered by

2760-428: The dense core regions of globular clusters ( cf. blue stragglers ). A likely scenario is a collision with a binary star system, or between two binary systems containing white dwarfs. This collision can leave behind a close binary system of two white dwarfs. Their orbit decays and they merge through their shared envelope. A study based on SDSS spectra found 15 double systems of the 4,000 white dwarfs tested, implying

2820-426: The early 1940s and Yakov B. Zel'dovich and Aleksandr Solomonovich Kompaneets in the 1960s. The simplest theory to predict the behaviour of detonations in gases is known as Chapman–Jouguet (CJ) theory, developed around the turn of the 20th century. This theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release. Such

2880-404: The emission of electromagnetic energy , neutrinos and by the ejection of matter with the solar wind . It is expelling about (2–3) × 10   M ☉ /year. The mass loss rate will increase when the Sun enters the red giant stage, climbing to (7–9) × 10   M ☉ /year when it reaches the tip of the red-giant branch . This will rise to 10   M ☉ /year on

2940-405: The end of a star's main sequence evolutionary period, such a long-lived star system may have wandered far from the region where it originally formed. Thereafter a close binary system may spend another million years in the mass transfer stage (possibly forming persistent nova outbursts) before the conditions are ripe for a Type Ia supernova to occur. A long-standing problem in astronomy has been

3000-496: The identification of supernova progenitors. Direct observation of a progenitor would provide useful constraints on supernova models. As of 2006, the search for such a progenitor had been ongoing for longer than a century. Observation of the supernova SN 2011fe has provided useful constraints. Previous observations with the Hubble Space Telescope did not show a star at the position of the event, thereby excluding

3060-479: The location and number of points where the flame begins. Oxygen fusion is initiated shortly thereafter, but this fuel is not consumed as completely as carbon. Once fusion begins, the temperature of the white dwarf increases. A main sequence star supported by thermal pressure can expand and cool which automatically regulates the increase in thermal energy. However, degeneracy pressure is independent of temperature; white dwarfs are unable to regulate temperature in

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3120-465: The manner of normal stars, so they are vulnerable to runaway fusion reactions. The flare accelerates dramatically, in part due to the Rayleigh–Taylor instability and interactions with turbulence . It is still a matter of considerable debate whether this flare transforms into a supersonic detonation from a subsonic deflagration. Regardless of the exact details of how the supernova ignites, it

3180-415: The mass of the Sun is The solar mass is about 333 000 times the mass of Earth ( M E ), or 1047 times the mass of Jupiter ( M J ). The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance . The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of

3240-405: The primary is the first of the pair to evolve onto the asymptotic giant branch , where the star's envelope expands considerably. If the two stars share a common envelope then the system can lose significant amounts of mass, reducing the angular momentum , orbital radius and period . After the primary has degenerated into a white dwarf, the secondary star later evolves into a red giant and the stage

3300-504: The ratio of the mass of Earth to the Sun was about 1 ⁄ 28 700 . Later he determined that his value was based upon a faulty value for the solar parallax, which he had used to estimate the distance to the Sun. He corrected his estimated ratio to 1 ⁄ 169 282 in the third edition of the Principia . The current value for the solar parallax is smaller still, yielding an estimated mass ratio of 1 ⁄ 332 946 . As

3360-438: The structure is formed and sustained behind unconfined waves. When used in explosive devices, the main cause of damage from a detonation is the supersonic blast front (a powerful shock wave ) in the surrounding area. This is a significant distinction from deflagrations where the exothermic wave is subsonic and maximum pressures for non-metal specks of dust are approximately 7–10 times atmospheric pressure. Therefore, detonation

3420-504: The supernova remnant Pa 30 and its central star IRAS 00500+6713 , which is the result of a merger of a CO white dwarf and an ONe white dwarf. This makes Pa 30 and IRAS 00500+6713 the only SN Iax remnant in the Milky Way . Unlike the other types of supernovae, Type Ia supernovae generally occur in all types of galaxies, including ellipticals. They show no preference for regions of current stellar formation. As white dwarf stars form at

3480-428: The whole mass of the former white dwarf dissipates through space. The theory of this type of supernova is similar to that of novae , in which a white dwarf accretes matter more slowly and does not approach the Chandrasekhar limit. In the case of a nova, the infalling matter causes a hydrogen fusion surface explosion that does not disrupt the star. Type Ia supernovae differ from Type II supernovae , which are caused by

3540-468: Was discovered in 1881 by four French scientists Marcellin Berthelot and Paul Marie Eugène Vieille and Ernest-François Mallard and Henry Louis Le Chatelier . The mathematical predictions of propagation were carried out first by David Chapman in 1899 and by Émile Jouguet in 1905, 1906 and 1917. The next advance in understanding detonation was made by John von Neumann and Werner Döring in

3600-421: Was not detected by Swift's XRT (X-ray telescope) in the 53 closest supernova remnants. For 12 Type Ia supernovae observed within 10 days of the explosion, the satellite's UVOT (ultraviolet/optical telescope) showed no ultraviolet radiation originating from the heated companion star's surface hit by the supernova shock wave, meaning there were no red giants or larger stars orbiting those supernova progenitors. In

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