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Writer: Harry Macqueen. Added to Watchlist. Everything New on Netflix in October. Donostia Zinemaldia London Film Festival Interest List Share this Rating Title: Supernova 6.

Use the HTML below. You must be a registered user to use the IMDb rating plugin. Photos Add Image. Edit Cast Credited cast: Colin Firth Later measurements by space gamma-ray telescopes of the small fraction of the 56 Co and 57 Co gamma rays that escaped the SN A remnant without absorption confirmed earlier predictions that those two radioactive nuclei were the power sources.

The visual light curves of the different supernova types all depend at late times on radioactive heating, but they vary in shape and amplitude because of the underlying mechanisms, the way that visible radiation is produced, the epoch of its observation, and the transparency of the ejected material.

The light curves can be significantly different at other wavelengths. For example, at ultraviolet wavelengths there is an early extremely luminous peak lasting only a few hours corresponding to the breakout of the shock launched by the initial event, but that breakout is hardly detectable optically.

The light curves for Type Ia are mostly very uniform, with a consistent maximum absolute magnitude and a relatively steep decline in luminosity.

Their optical energy output is driven by radioactive decay of ejected nickel half-life 6 days , which then decays to radioactive cobalt half-life 77 days.

These radioisotopes excite the surrounding material to incandescence. Studies of cosmology today rely on 56 Ni radioactivity providing the energy for the optical brightness of supernovae of Type Ia, which are the "standard candles" of cosmology but whose diagnostic keV and keV gamma rays were first detected only in The light curve continues to decline in the B band while it may show a small shoulder in the visual at about 40 days, but this is only a hint of a secondary maximum that occurs in the infra-red as certain ionised heavy elements recombine to produce infra-red radiation and the ejecta become transparent to it.

The visual light curve continues to decline at a rate slightly greater than the decay rate of the radioactive cobalt which has the longer half-life and controls the later curve , because the ejected material becomes more diffuse and less able to convert the high energy radiation into visual radiation.

After several months, the light curve changes its decline rate again as positron emission becomes dominant from the remaining cobalt, although this portion of the light curve has been little-studied.

Type Ib and Ic light curves are basically similar to Type Ia although with a lower average peak luminosity. The visual light output is again due to radioactive decay being converted into visual radiation, but there is a much lower mass of the created nickel The most luminous Type Ic supernovae are referred to as hypernovae and tend to have broadened light curves in addition to the increased peak luminosity.

The source of the extra energy is thought to be relativistic jets driven by the formation of a rotating black hole, which also produce gamma-ray bursts.

The light curves for Type II supernovae are characterised by a much slower decline than Type I, on the order of 0. The visual light output is dominated by kinetic energy rather than radioactive decay for several months, due primarily to the existence of hydrogen in the ejecta from the atmosphere of the supergiant progenitor star.

In the initial destruction this hydrogen becomes heated and ionised. The majority of Type II supernovae show a prolonged plateau in their light curves as this hydrogen recombines, emitting visible light and becoming more transparent.

This is then followed by a declining light curve driven by radioactive decay although slower than in Type I supernovae, due to the efficiency of conversion into light by all the hydrogen.

In Type II-L the plateau is absent because the progenitor had relatively little hydrogen left in its atmosphere, sufficient to appear in the spectrum but insufficient to produce a noticeable plateau in the light output.

In Type IIb supernovae the hydrogen atmosphere of the progenitor is so depleted thought to be due to tidal stripping by a companion star that the light curve is closer to a Type I supernova and the hydrogen even disappears from the spectrum after several weeks.

Type IIn supernovae are characterised by additional narrow spectral lines produced in a dense shell of circumstellar material.

Their light curves are generally very broad and extended, occasionally also extremely luminous and referred to as a superluminous supernova.

These light curves are produced by the highly efficient conversion of kinetic energy of the ejecta into electromagnetic radiation by interaction with the dense shell of material.

This only occurs when the material is sufficiently dense and compact, indicating that it has been produced by the progenitor star itself only shortly before the supernova occurs.

Large numbers of supernovae have been catalogued and classified to provide distance candles and test models.

Average characteristics vary somewhat with distance and type of host galaxy, but can broadly be specified for each supernova type.

A long-standing puzzle surrounding Type II supernovae is why the remaining compact object receives a large velocity away from the epicentre; [] pulsars , and thus neutron stars, are observed to have high velocities, and black holes presumably do as well, although they are far harder to observe in isolation.

This indicates an expansion asymmetry, but the mechanism by which momentum is transferred to the compact object remains [update] a puzzle.

Proposed explanations for this kick include convection in the collapsing star and jet production during neutron star formation. One possible explanation for this asymmetry is large-scale convection above the core.

The convection can create variations in the local abundances of elements, resulting in uneven nuclear burning during the collapse, bounce and resulting expansion.

Another possible explanation is that accretion of gas onto the central neutron star can create a disk that drives highly directional jets, propelling matter at a high velocity out of the star, and driving transverse shocks that completely disrupt the star.

These jets might play a crucial role in the resulting supernova. Initial asymmetries have also been confirmed in Type Ia supernovae through observation.

This result may mean that the initial luminosity of this type of supernova depends on the viewing angle.

However, the expansion becomes more symmetrical with the passage of time. Early asymmetries are detectable by measuring the polarization of the emitted light.

Although supernovae are primarily known as luminous events, the electromagnetic radiation they release is almost a minor side-effect. Particularly in the case of core collapse supernovae, the emitted electromagnetic radiation is a tiny fraction of the total energy released during the event.

There is a fundamental difference between the balance of energy production in the different types of supernova. In Type Ia white dwarf detonations, most of the energy is directed into heavy element synthesis and the kinetic energy of the ejecta.

Type Ia supernovae derive their energy from a runaway nuclear fusion of a carbon-oxygen white dwarf.

The details of the energetics are still not fully understood, but the end result is the ejection of the entire mass of the original star at high kinetic energy.

Around half a solar mass of that mass is 56 Ni generated from silicon burning. These two processes are responsible for the electromagnetic radiation from Type Ia supernovae.

In combination with the changing transparency of the ejected material, they produce the rapidly declining light curve.

Core collapse supernovae are on average visually fainter than Type Ia supernovae, but the total energy released is far higher.

In these type of supernovae, the gravitational potential energy is converted into kinetic energy that compresses and collapses the core, initially producing electron neutrinos from disintegrating nucleons, followed by all flavours of thermal neutrinos from the super-heated neutron star core.

Kinetic energies and nickel yields are somewhat lower than Type Ia supernovae, hence the lower peak visual luminosity of Type II supernovae, but energy from the de- ionisation of the many solar masses of remaining hydrogen can contribute to a much slower decline in luminosity and produce the plateau phase seen in the majority of core collapse supernovae.

In some core collapse supernovae, fallback onto a black hole drives relativistic jets which may produce a brief energetic and directional burst of gamma rays and also transfers substantial further energy into the ejected material.

This is one scenario for producing high luminosity supernovae and is thought to be the cause of Type Ic hypernovae and long duration gamma-ray bursts.

If the relativistic jets are too brief and fail to penetrate the stellar envelope then a low luminosity gamma-ray burst may be produced and the supernova may be sub-luminous.

When a supernova occurs inside a small dense cloud of circumstellar material, it will produce a shock wave that can efficiently convert a high fraction of the kinetic energy into electromagnetic radiation.

Even though the initial energy was entirely normal the resulting supernova will have high luminosity and extended duration since it does not rely on exponential radioactive decay.

This type of event may cause Type IIn hypernovae. Although pair-instability supernovae are core collapse supernovae with spectra and light curves similar to Type II-P, the nature after core collapse is more like that of a giant Type Ia with runaway fusion of carbon, oxygen, and silicon.

The total energy released by the highest mass events is comparable to other core collapse supernovae but neutrino production is thought to be very low, hence the kinetic and electromagnetic energy released is very high.

The cores of these stars are much larger than any white dwarf and the amount of radioactive nickel and other heavy elements ejected from their cores can be orders of magnitude higher, with consequently high visual luminosity.

The supernova classification type is closely tied to the type of star at the time of the collapse. The occurrence of each type of supernova depends dramatically on the metallicity, and hence the age of the host galaxy.

Type Ia supernovae are produced from white dwarf stars in binary systems and occur in all galaxy types. Core collapse supernovae are only found in galaxies undergoing current or very recent star formation, since they result from short-lived massive stars.

They are most commonly found in Type Sc spirals , but also in the arms of other spiral galaxies and in irregular galaxies , especially starburst galaxies.

The table shows the progenitor for the main types of core collapse supernova, and the approximate proportions that have been observed in the local neighbourhood.

There are a number of difficulties reconciling modelled and observed stellar evolution leading up to core collapse supernovae. Most progenitors of Type II supernovae are not detected and must be considerably fainter, and presumably less massive.

It is now proposed that higher mass red supergiants do not explode as supernovae, but instead evolve back towards hotter temperatures.

Several progenitors of Type IIb supernovae have been confirmed, and these were K and G supergiants, plus one A supergiant. Until just a few decades ago, hot supergiants were not considered likely to explode, but observations have shown otherwise.

Blue supergiants form an unexpectedly high proportion of confirmed supernova progenitors, partly due to their high luminosity and easy detection, while not a single Wolf—Rayet progenitor has yet been clearly identified.

One study has shown a possible route for low-luminosity post-red supergiant luminous blue variables to collapse, most likely as a Type IIn supernova.

Very luminous progenitors have not been securely identified, despite numerous supernovae being observed near enough that such progenitors would have been clearly imaged.

Most of these supernovae are then produced from lower-mass low-luminosity helium stars in binary systems. A small number would be from rapidly-rotating massive stars, likely corresponding to the highly-energetic Type Ic-BL events that are associated with long-duration gamma-ray bursts.

Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium, [] [] [] though the theoretical abundances of the elements produced or seen in the spectra varies significantly depending on the various supernova types.

The latter is especially true with electron capture supernovae. The r-process produces highly unstable nuclei that are rich in neutrons and that rapidly beta decay into more stable forms.

In supernovae, r-process reactions are responsible for about half of all the isotopes of elements beyond iron, [] although neutron star mergers may be the main astrophysical source for many of these elements.

In the modern universe, old asymptotic giant branch AGB stars are the dominant source of dust from s-process elements, oxides, and carbon.

Remnants of many supernovae consist of a compact object and a rapidly expanding shock wave of material. This cloud of material sweeps up surrounding interstellar medium during a free expansion phase, which can last for up to two centuries.

The wave then gradually undergoes a period of adiabatic expansion , and will slowly cool and mix with the surrounding interstellar medium over a period of about 10, years.

The Big Bang produced hydrogen , helium , and traces of lithium , while all heavier elements are synthesized in stars and supernovae.

Supernovae tend to enrich the surrounding interstellar medium with elements other than hydrogen and helium, which usually astronomers refer to as " metals ".

These injected elements ultimately enrich the molecular clouds that are the sites of star formation. Supernovae are the dominant mechanism for distributing these heavier elements, which are formed in a star during its period of nuclear fusion.

The different abundances of elements in the material that forms a star have important influences on the star's life, and may decisively influence the possibility of having planets orbiting it.

The kinetic energy of an expanding supernova remnant can trigger star formation by compressing nearby, dense molecular clouds in space. Evidence from daughter products of short-lived radioactive isotopes shows that a nearby supernova helped determine the composition of the Solar System 4.

On 1 June , astronomers reported narrowing down the source of Fast Radio Bursts FRBs , which may now plausibly include " compact-object mergers and magnetars arising from normal core collapse supernovae".

Supernova remnants are thought to accelerate a large fraction of galactic primary cosmic rays , but direct evidence for cosmic ray production has only been found in a small number of remnants.

Gamma-rays from pion -decay have been detected from the supernova remnants IC and W These are produced when accelerated protons from the SNR impact on interstellar material.

Supernovae are potentially strong galactic sources of gravitational waves , [] but none have so far been detected.

The only gravitational wave events so far detected are from mergers of black holes and neutron stars, probable remnants of supernovae.

A near-Earth supernova is a supernova close enough to the Earth to have noticeable effects on its biosphere. Depending upon the type and energy of the supernova, it could be as far as light-years away.

In it was theorized that traces of past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata.

Iron enrichment was later reported in deep-sea rock of the Pacific Ocean. Gamma rays from these supernovae could have boosted levels of nitrogen oxides, which became trapped in the ice.

Type Ia supernovae are thought to be potentially the most dangerous if they occur close enough to the Earth. Because these supernovae arise from dim, common white dwarf stars in binary systems, it is likely that a supernova that can affect the Earth will occur unpredictably and in a star system that is not well studied.

The closest known candidate is IK Pegasi see below. The next supernova in the Milky Way will likely be detectable even if it occurs on the far side of the galaxy.

It is likely to be produced by the collapse of an unremarkable red supergiant and it is very probable that it will already have been catalogued in infrared surveys such as 2MASS.

There is a smaller chance that the next core collapse supernova will be produced by a different type of massive star such as a yellow hypergiant, luminous blue variable, or Wolf—Rayet.

The chances of the next supernova being a Type Ia produced by a white dwarf are calculated to be about a third of those for a core collapse supernova.

Again it should be observable wherever it occurs, but it is less likely that the progenitor will ever have been observed.

It isn't even known exactly what a Type Ia progenitor system looks like, and it is difficult to detect them beyond a few parsecs.

The total supernova rate in our galaxy is estimated to be between 2 and 12 per century, although we haven't actually observed one for several centuries.

Statistically, the next supernova is likely to be produced from an otherwise unremarkable red supergiant, but it is difficult to identify which of those supergiants are in the final stages of heavy element fusion in their cores and which have millions of years left.

The most-massive red supergiants shed their atmospheres and evolve to Wolf—Rayet stars before their cores collapse.

All Wolf—Rayet stars end their lives from the Wolf—Rayet phase within a million years or so, but again it is difficult to identify those that are closest to core collapse.

One class that is expected to have no more than a few thousand years before exploding are the WO Wolf—Rayet stars, which are known to have exhausted their core helium.

A number of close or well known stars have been identified as possible core collapse supernova candidates: the red supergiants Antares and Betelgeuse ; [] the yellow hypergiant Rho Cassiopeiae ; [] the luminous blue variable Eta Carinae that has already produced a supernova impostor ; [] and the brightest component, a Wolf—Rayet star , in the Regor or Gamma Velorum system.

Identification of candidates for a Type Ia supernova is much more speculative. Any binary with an accreting white dwarf might produce a supernova although the exact mechanism and timescale is still debated.

These systems are faint and difficult to identify, but the novae and recurrent novae are such systems that conveniently advertise themselves.

One example is U Scorpii. From Wikipedia, the free encyclopedia. Star exploding at the end of its stellar evolution.

For other uses, see Supernova disambiguation. Main article: History of supernova observation. The Crab Nebula is a pulsar wind nebula associated with the supernova.

Main article: Type Ia supernova. Main article: Type II supernova. Main article: Type Ib and Ic supernovae. Main article: Failed supernova.

Bright types may be a continuum from slightly over-luminous to hypernovae. Measurements in V or B bands are common and will be around half a magnitude brighter for supernovae.

Total electromagnetic radiated energy is usually lower, theoretical neutrino energy much higher. Play media. Main articles: Stellar nucleosynthesis and Supernova nucleosynthesis.

Main article: Supernova remnant. Main article: Near-Earth supernova. Main article: List of supernova candidates.

Astronomy portal Star portal Space portal. Retrieved 29 May Cambridge University Press. The Celestial handbook. Astrophysical Journal.

Bibcode : ApJ Dordrecht: D. Bibcode : ASIC Nova Ophiuchi of as a supernova". The Story of Astronomy. Basic Books. The Astrophysical Journal.

Bibcode : Sci Astrophysics and Space Science. Astronomical Journal. Bibcode : AJ Europhysics News. Bibcode : ENews.. Bibcode : Natur. Retrieved 18 June Nature Astronomy.

Bibcode : NatAs The Guardian. Archived from the original on Retrieved Nature Physics. Bibcode : NatPh.. Astronomy Now. Retrieved 15 May Bode; Aneurin Evans 7 April Classical Novae.

Who First Predicted Neutron Stars? Bulletin of the American Astronomical Society. Bibcode : AAS Proceedings of the National Academy of Sciences.

Bibcode : PNAS Supernovae 2nd ed. The Astrophysical Journal Letters. The Origin and Evolution of the Universe. In Paczynski, B.

Small Telescope Astronomy on Global Scale. ASP Conference Series. San Francisco: Astronomical Society of the Pacific.

Bibcode : ASPC.. New Journal of Physics. Bibcode : NJPh AIP Conference Proceedings. Bibcode : AIPC.. Revista Mexicana de Fisica.

Bibcode : RMxF The Astronomical Journal. In Ruiz-Lapuente, P. Dordrecth: Kluwer Academic Publishers. Bibcode : ASIC.. Physical Review D.

Bibcode : PhRvD.. New Astronomy Reviews. Bibcode : NewAR.. Bibcode : AIPC Osservatorio Astronomico di Padova.

Influence of Binaries on Stellar Population Studies. Dordrecht: Kluwer Academic Publishers. Bibcode : ASSL.. Supernovae and Gamma-Ray Bursters.

Lecture Notes in Physics. The Astrophysical Journal Supplement. Bibcode : ApJS.. In McVittie, G. New York: Macmillan Press.

Bibcode : IAUS ESO Picture of the Week. Monthly Notices of the Royal Astronomical Society. Astrophysical Journal Letters.

In Isern, J. Astronomy and Astrophysics. Astronomy and Astrophysics Letters. Annual Review of Astronomy and Astrophysics. In Eggleton, P.

Structure and Evolution of Close Binary Systems. IAU Symposium No. Memorie della Societa Astronomica Italiana. Bibcode : MmSAI.. Proceedings of the International Astronomical Union.

Bibcode : IAUS.. The Astrophysical Journal Supplement Series. Living Reviews in Relativity. Bibcode : LRR Bibcode : NatPh Physics Reports. Bibcode : PhR Yale University Press.

W; Beacom, J. F; Cianciolo, V. L; Fuller, G. M; Kaplinghat, M. W; Meszaros, P. A; Stanev, T. P Introduction to Planetary Science.

In Leung, K. Mark Observational constraints on the progenitors of Type Ibc supernovae". Physical Review Letters.

Supernova hd Because these supernovae arise from dim, common white dwarf stars in binary systems, it is Free small tits that a supernova that can affect the Earth will Cassie ventura pussy unpredictably and in a star system that is not well studied. A sufficiently large and hot stellar core may generate gamma-rays energetic enough to initiate photodisintegration directly, which will cause a complete collapse of the core. These jets might play a crucial role in the resulting supernova. Cambridge University Blowjob fleshlight. Astronomy portal Physics portal History of science Sakura sex scene China portal Stars portal Outer space portal. Big tit britney Ib supernovae are the more common Nicole dupapllon result from Wolf—Rayet stars Carrie nude pics Type WC which still Supernova hd helium in their atmospheres. Sincethe increasing number of discoveries has regularly led to Busty teen fuck additional use of three-digit designations. These types would now all be treated as peculiar Type II supernovae IIpecof which many more examples have been discovered, although it is still debated whether SN V was a true supernova following an LBV outburst or an impostor. Color: Color. If core collapse occurs during a supergiant phase when the star still has a hydrogen envelope, the result is a Type II supernova. NGC – Wikipedia. Entdecken Sie Supernova von LERK bei Amazon Music. Werbefrei streamen oder als CD und MP3 kaufen bei konferens24.se Supernova. Schreiben Sie die erste Bewertung1 HD 9,99 €. Weitere Kaufoptionen. Zur Watchlist hinzufügen. Alle Preise inkl. MwSt. Mit der Bestellung oder. Supernova hd These systems are faint and difficult to identify, but the novae and recurrent Supernova hd Big vaginas such systems that conveniently advertise themselves. In some Xhamster bbc collapse supernovae, fallback Stacy jay fuck a black hole drives relativistic jets which may produce a brief energetic and directional burst of gamma rays and also transfers substantial further energy into the ejected material. Physics Reports. In supernovae, r-process reactions are responsible for about half of all the isotopes of Lizvicious beyond iron, [] although neutron star mergers may be the main astrophysical source for many of these elements. While such systems are popular with amateurs, there are also professional installations such as the Katzman Automatic Imaging Telescope. New York: Macmillan Press. Bibcode : ASPC. Gamma rays from these supernovae could have boosted levels Butplug nitrogen oxides, which became trapped in the ice.

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Check out the lineup of new movies and shows streaming on Netflix this month, including The Trial of the Chicago 7.

See the full list. Sam and Tusker partners of 20 years, who are traveling across England in their old RV visiting friends, family and places from their past.

Since Tusker was diagnosed with early-onset dementia two years ago, their time together is the most important thing they have.

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Release Dates. Official Sites. Company Credits. Technical Specs. Plot Summary. Plot Keywords. Parents Guide.

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Crazy Credits. Alternate Versions. Rate This. Sam and Tusker are traveling across England in their old RV to visit friends, family and places from their past.

Since Tusker was diagnosed with dementia two years ago, their time together is the most important thing they have. Director: Harry Macqueen.

Writer: Harry Macqueen. Added to Watchlist. Binary models provide a better match for the observed supernovae, with the proviso that no suitable binary helium stars have ever been observed.

Type Ib supernovae are the more common and result from Wolf—Rayet stars of Type WC which still have helium in their atmospheres.

For a narrow range of masses, stars evolve further before reaching core collapse to become WO stars with very little helium remaining and these are the progenitors of Type Ic supernovae.

A few percent of the Type Ic supernovae are associated with gamma-ray bursts GRB , though it is also believed that any hydrogen-stripped Type Ib or Ic supernova could produce a GRB, depending on the circumstances of the geometry.

The jets would also transfer energy into the expanding outer shell, producing a super-luminous supernova. Ultra-stripped supernovae occur when the exploding star has been stripped almost all the way to the metal core, via mass transfer in a close binary.

In the most extreme cases, ultra-stripped supernovae can occur in naked metal cores, barely above the Chandrasekhar mass limit.

SN ek [96] might be an observational example of an ultra-stripped supernova, giving rise to a relatively dim and fast decaying light curve.

The nature of ultra-stripped supernovae can be both iron core-collapse and electron capture supernovae, depending on the mass of the collapsing core.

The core collapse of some massive stars may not result in a visible supernova. The main model for this is a sufficiently massive core that the kinetic energy is insufficient to reverse the infall of the outer layers onto a black hole.

These events are difficult to detect, but large surveys have detected possible candidates. Only a faint infrared source remains at the star's location.

A historic puzzle concerned the source of energy that can maintain the optical supernova glow for months. Although the energy that disrupts each type of supernovae is delivered promptly, the light curves are dominated by subsequent radioactive heating of the rapidly expanding ejecta.

Some have considered rotational energy from the central pulsar. The ejecta gases would dim quickly without some energy input to keep it hot.

The intensely radioactive nature of the ejecta gases, which is now known to be correct for most supernovae, was first calculated on sound nucleosynthesis grounds in the late s.

It is now known by direct observation that much of the light curve the graph of luminosity as a function of time after the occurrence of a Type II Supernova , such as SN A, is explained by those predicted radioactive decays.

Although the luminous emission consists of optical photons, it is the radioactive power absorbed by the ejected gases that keeps the remnant hot enough to radiate light.

The radioactive decay of 56 Ni through its daughters 56 Co to 56 Fe produces gamma-ray photons , primarily of keV and keV, that are absorbed and dominate the heating and thus the luminosity of the ejecta at intermediate times several weeks to late times several months.

Later measurements by space gamma-ray telescopes of the small fraction of the 56 Co and 57 Co gamma rays that escaped the SN A remnant without absorption confirmed earlier predictions that those two radioactive nuclei were the power sources.

The visual light curves of the different supernova types all depend at late times on radioactive heating, but they vary in shape and amplitude because of the underlying mechanisms, the way that visible radiation is produced, the epoch of its observation, and the transparency of the ejected material.

The light curves can be significantly different at other wavelengths. For example, at ultraviolet wavelengths there is an early extremely luminous peak lasting only a few hours corresponding to the breakout of the shock launched by the initial event, but that breakout is hardly detectable optically.

The light curves for Type Ia are mostly very uniform, with a consistent maximum absolute magnitude and a relatively steep decline in luminosity.

Their optical energy output is driven by radioactive decay of ejected nickel half-life 6 days , which then decays to radioactive cobalt half-life 77 days.

These radioisotopes excite the surrounding material to incandescence. Studies of cosmology today rely on 56 Ni radioactivity providing the energy for the optical brightness of supernovae of Type Ia, which are the "standard candles" of cosmology but whose diagnostic keV and keV gamma rays were first detected only in The light curve continues to decline in the B band while it may show a small shoulder in the visual at about 40 days, but this is only a hint of a secondary maximum that occurs in the infra-red as certain ionised heavy elements recombine to produce infra-red radiation and the ejecta become transparent to it.

The visual light curve continues to decline at a rate slightly greater than the decay rate of the radioactive cobalt which has the longer half-life and controls the later curve , because the ejected material becomes more diffuse and less able to convert the high energy radiation into visual radiation.

After several months, the light curve changes its decline rate again as positron emission becomes dominant from the remaining cobalt, although this portion of the light curve has been little-studied.

Type Ib and Ic light curves are basically similar to Type Ia although with a lower average peak luminosity. The visual light output is again due to radioactive decay being converted into visual radiation, but there is a much lower mass of the created nickel The most luminous Type Ic supernovae are referred to as hypernovae and tend to have broadened light curves in addition to the increased peak luminosity.

The source of the extra energy is thought to be relativistic jets driven by the formation of a rotating black hole, which also produce gamma-ray bursts.

The light curves for Type II supernovae are characterised by a much slower decline than Type I, on the order of 0. The visual light output is dominated by kinetic energy rather than radioactive decay for several months, due primarily to the existence of hydrogen in the ejecta from the atmosphere of the supergiant progenitor star.

In the initial destruction this hydrogen becomes heated and ionised. The majority of Type II supernovae show a prolonged plateau in their light curves as this hydrogen recombines, emitting visible light and becoming more transparent.

This is then followed by a declining light curve driven by radioactive decay although slower than in Type I supernovae, due to the efficiency of conversion into light by all the hydrogen.

In Type II-L the plateau is absent because the progenitor had relatively little hydrogen left in its atmosphere, sufficient to appear in the spectrum but insufficient to produce a noticeable plateau in the light output.

In Type IIb supernovae the hydrogen atmosphere of the progenitor is so depleted thought to be due to tidal stripping by a companion star that the light curve is closer to a Type I supernova and the hydrogen even disappears from the spectrum after several weeks.

Type IIn supernovae are characterised by additional narrow spectral lines produced in a dense shell of circumstellar material.

Their light curves are generally very broad and extended, occasionally also extremely luminous and referred to as a superluminous supernova.

These light curves are produced by the highly efficient conversion of kinetic energy of the ejecta into electromagnetic radiation by interaction with the dense shell of material.

This only occurs when the material is sufficiently dense and compact, indicating that it has been produced by the progenitor star itself only shortly before the supernova occurs.

Large numbers of supernovae have been catalogued and classified to provide distance candles and test models.

Average characteristics vary somewhat with distance and type of host galaxy, but can broadly be specified for each supernova type.

A long-standing puzzle surrounding Type II supernovae is why the remaining compact object receives a large velocity away from the epicentre; [] pulsars , and thus neutron stars, are observed to have high velocities, and black holes presumably do as well, although they are far harder to observe in isolation.

This indicates an expansion asymmetry, but the mechanism by which momentum is transferred to the compact object remains [update] a puzzle.

Proposed explanations for this kick include convection in the collapsing star and jet production during neutron star formation.

One possible explanation for this asymmetry is large-scale convection above the core. The convection can create variations in the local abundances of elements, resulting in uneven nuclear burning during the collapse, bounce and resulting expansion.

Another possible explanation is that accretion of gas onto the central neutron star can create a disk that drives highly directional jets, propelling matter at a high velocity out of the star, and driving transverse shocks that completely disrupt the star.

These jets might play a crucial role in the resulting supernova. Initial asymmetries have also been confirmed in Type Ia supernovae through observation.

This result may mean that the initial luminosity of this type of supernova depends on the viewing angle. However, the expansion becomes more symmetrical with the passage of time.

Early asymmetries are detectable by measuring the polarization of the emitted light. Although supernovae are primarily known as luminous events, the electromagnetic radiation they release is almost a minor side-effect.

Particularly in the case of core collapse supernovae, the emitted electromagnetic radiation is a tiny fraction of the total energy released during the event.

There is a fundamental difference between the balance of energy production in the different types of supernova.

In Type Ia white dwarf detonations, most of the energy is directed into heavy element synthesis and the kinetic energy of the ejecta.

Type Ia supernovae derive their energy from a runaway nuclear fusion of a carbon-oxygen white dwarf. The details of the energetics are still not fully understood, but the end result is the ejection of the entire mass of the original star at high kinetic energy.

Around half a solar mass of that mass is 56 Ni generated from silicon burning. These two processes are responsible for the electromagnetic radiation from Type Ia supernovae.

In combination with the changing transparency of the ejected material, they produce the rapidly declining light curve. Core collapse supernovae are on average visually fainter than Type Ia supernovae, but the total energy released is far higher.

In these type of supernovae, the gravitational potential energy is converted into kinetic energy that compresses and collapses the core, initially producing electron neutrinos from disintegrating nucleons, followed by all flavours of thermal neutrinos from the super-heated neutron star core.

Kinetic energies and nickel yields are somewhat lower than Type Ia supernovae, hence the lower peak visual luminosity of Type II supernovae, but energy from the de- ionisation of the many solar masses of remaining hydrogen can contribute to a much slower decline in luminosity and produce the plateau phase seen in the majority of core collapse supernovae.

In some core collapse supernovae, fallback onto a black hole drives relativistic jets which may produce a brief energetic and directional burst of gamma rays and also transfers substantial further energy into the ejected material.

This is one scenario for producing high luminosity supernovae and is thought to be the cause of Type Ic hypernovae and long duration gamma-ray bursts.

If the relativistic jets are too brief and fail to penetrate the stellar envelope then a low luminosity gamma-ray burst may be produced and the supernova may be sub-luminous.

When a supernova occurs inside a small dense cloud of circumstellar material, it will produce a shock wave that can efficiently convert a high fraction of the kinetic energy into electromagnetic radiation.

Even though the initial energy was entirely normal the resulting supernova will have high luminosity and extended duration since it does not rely on exponential radioactive decay.

This type of event may cause Type IIn hypernovae. Although pair-instability supernovae are core collapse supernovae with spectra and light curves similar to Type II-P, the nature after core collapse is more like that of a giant Type Ia with runaway fusion of carbon, oxygen, and silicon.

The total energy released by the highest mass events is comparable to other core collapse supernovae but neutrino production is thought to be very low, hence the kinetic and electromagnetic energy released is very high.

The cores of these stars are much larger than any white dwarf and the amount of radioactive nickel and other heavy elements ejected from their cores can be orders of magnitude higher, with consequently high visual luminosity.

The supernova classification type is closely tied to the type of star at the time of the collapse. The occurrence of each type of supernova depends dramatically on the metallicity, and hence the age of the host galaxy.

Type Ia supernovae are produced from white dwarf stars in binary systems and occur in all galaxy types. Core collapse supernovae are only found in galaxies undergoing current or very recent star formation, since they result from short-lived massive stars.

They are most commonly found in Type Sc spirals , but also in the arms of other spiral galaxies and in irregular galaxies , especially starburst galaxies.

The table shows the progenitor for the main types of core collapse supernova, and the approximate proportions that have been observed in the local neighbourhood.

There are a number of difficulties reconciling modelled and observed stellar evolution leading up to core collapse supernovae. Most progenitors of Type II supernovae are not detected and must be considerably fainter, and presumably less massive.

It is now proposed that higher mass red supergiants do not explode as supernovae, but instead evolve back towards hotter temperatures.

Several progenitors of Type IIb supernovae have been confirmed, and these were K and G supergiants, plus one A supergiant.

Until just a few decades ago, hot supergiants were not considered likely to explode, but observations have shown otherwise. Blue supergiants form an unexpectedly high proportion of confirmed supernova progenitors, partly due to their high luminosity and easy detection, while not a single Wolf—Rayet progenitor has yet been clearly identified.

One study has shown a possible route for low-luminosity post-red supergiant luminous blue variables to collapse, most likely as a Type IIn supernova.

Very luminous progenitors have not been securely identified, despite numerous supernovae being observed near enough that such progenitors would have been clearly imaged.

Most of these supernovae are then produced from lower-mass low-luminosity helium stars in binary systems. A small number would be from rapidly-rotating massive stars, likely corresponding to the highly-energetic Type Ic-BL events that are associated with long-duration gamma-ray bursts.

Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium, [] [] [] though the theoretical abundances of the elements produced or seen in the spectra varies significantly depending on the various supernova types.

The latter is especially true with electron capture supernovae. The r-process produces highly unstable nuclei that are rich in neutrons and that rapidly beta decay into more stable forms.

In supernovae, r-process reactions are responsible for about half of all the isotopes of elements beyond iron, [] although neutron star mergers may be the main astrophysical source for many of these elements.

In the modern universe, old asymptotic giant branch AGB stars are the dominant source of dust from s-process elements, oxides, and carbon. Remnants of many supernovae consist of a compact object and a rapidly expanding shock wave of material.

This cloud of material sweeps up surrounding interstellar medium during a free expansion phase, which can last for up to two centuries.

The wave then gradually undergoes a period of adiabatic expansion , and will slowly cool and mix with the surrounding interstellar medium over a period of about 10, years.

The Big Bang produced hydrogen , helium , and traces of lithium , while all heavier elements are synthesized in stars and supernovae. Supernovae tend to enrich the surrounding interstellar medium with elements other than hydrogen and helium, which usually astronomers refer to as " metals ".

These injected elements ultimately enrich the molecular clouds that are the sites of star formation. Supernovae are the dominant mechanism for distributing these heavier elements, which are formed in a star during its period of nuclear fusion.

The different abundances of elements in the material that forms a star have important influences on the star's life, and may decisively influence the possibility of having planets orbiting it.

The kinetic energy of an expanding supernova remnant can trigger star formation by compressing nearby, dense molecular clouds in space.

Evidence from daughter products of short-lived radioactive isotopes shows that a nearby supernova helped determine the composition of the Solar System 4.

On 1 June , astronomers reported narrowing down the source of Fast Radio Bursts FRBs , which may now plausibly include " compact-object mergers and magnetars arising from normal core collapse supernovae".

Supernova remnants are thought to accelerate a large fraction of galactic primary cosmic rays , but direct evidence for cosmic ray production has only been found in a small number of remnants.

Gamma-rays from pion -decay have been detected from the supernova remnants IC and W These are produced when accelerated protons from the SNR impact on interstellar material.

Supernovae are potentially strong galactic sources of gravitational waves , [] but none have so far been detected. The only gravitational wave events so far detected are from mergers of black holes and neutron stars, probable remnants of supernovae.

A near-Earth supernova is a supernova close enough to the Earth to have noticeable effects on its biosphere. Depending upon the type and energy of the supernova, it could be as far as light-years away.

In it was theorized that traces of past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata. Iron enrichment was later reported in deep-sea rock of the Pacific Ocean.

Gamma rays from these supernovae could have boosted levels of nitrogen oxides, which became trapped in the ice. Type Ia supernovae are thought to be potentially the most dangerous if they occur close enough to the Earth.

Because these supernovae arise from dim, common white dwarf stars in binary systems, it is likely that a supernova that can affect the Earth will occur unpredictably and in a star system that is not well studied.

The closest known candidate is IK Pegasi see below. The next supernova in the Milky Way will likely be detectable even if it occurs on the far side of the galaxy.

It is likely to be produced by the collapse of an unremarkable red supergiant and it is very probable that it will already have been catalogued in infrared surveys such as 2MASS.

There is a smaller chance that the next core collapse supernova will be produced by a different type of massive star such as a yellow hypergiant, luminous blue variable, or Wolf—Rayet.

The chances of the next supernova being a Type Ia produced by a white dwarf are calculated to be about a third of those for a core collapse supernova.

Again it should be observable wherever it occurs, but it is less likely that the progenitor will ever have been observed.

It isn't even known exactly what a Type Ia progenitor system looks like, and it is difficult to detect them beyond a few parsecs.

The total supernova rate in our galaxy is estimated to be between 2 and 12 per century, although we haven't actually observed one for several centuries.

Statistically, the next supernova is likely to be produced from an otherwise unremarkable red supergiant, but it is difficult to identify which of those supergiants are in the final stages of heavy element fusion in their cores and which have millions of years left.

The most-massive red supergiants shed their atmospheres and evolve to Wolf—Rayet stars before their cores collapse. All Wolf—Rayet stars end their lives from the Wolf—Rayet phase within a million years or so, but again it is difficult to identify those that are closest to core collapse.

One class that is expected to have no more than a few thousand years before exploding are the WO Wolf—Rayet stars, which are known to have exhausted their core helium.

A number of close or well known stars have been identified as possible core collapse supernova candidates: the red supergiants Antares and Betelgeuse ; [] the yellow hypergiant Rho Cassiopeiae ; [] the luminous blue variable Eta Carinae that has already produced a supernova impostor ; [] and the brightest component, a Wolf—Rayet star , in the Regor or Gamma Velorum system.

Identification of candidates for a Type Ia supernova is much more speculative. Any binary with an accreting white dwarf might produce a supernova although the exact mechanism and timescale is still debated.

These systems are faint and difficult to identify, but the novae and recurrent novae are such systems that conveniently advertise themselves.

One example is U Scorpii. From Wikipedia, the free encyclopedia. Star exploding at the end of its stellar evolution. For other uses, see Supernova disambiguation.

Main article: History of supernova observation. The Crab Nebula is a pulsar wind nebula associated with the supernova.

Main article: Type Ia supernova. Main article: Type II supernova. Main article: Type Ib and Ic supernovae. Main article: Failed supernova.

Bright types may be a continuum from slightly over-luminous to hypernovae. Measurements in V or B bands are common and will be around half a magnitude brighter for supernovae.

Total electromagnetic radiated energy is usually lower, theoretical neutrino energy much higher. Play media.

Main articles: Stellar nucleosynthesis and Supernova nucleosynthesis. Main article: Supernova remnant. Main article: Near-Earth supernova. Main article: List of supernova candidates.

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