Misplaced Pages

#190809

127-685: SN 1987A was a type II supernova in the Large Magellanic Cloud , a dwarf satellite galaxy of the Milky Way . It occurred approximately 51.4 kiloparsecs (168,000 light-years ) from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos from the explosion reached Earth on February 23, 1987 and was designated "SN 1987A" as the first supernova discovered that year. Its brightness peaked in May of that year, with an apparent magnitude of about 3. It

254-419: A pulsar was formed, but with either an unusually large or small magnetic field. Third, that large amounts of material fell back on the neutron star, collapsing it further into a black hole . Neutron stars and black holes often give off light as material falls onto them. If there is a compact object in the supernova remnant, but no material to fall onto it, it would be too dim for detection. A fourth hypothesis

381-408: A "track" of Cherenkov photons. The data from this track can be used to reconstruct the directionality of the muon. For high-energy interactions, the neutrino and muon directions are the same, so it's possible to tell where the neutrino came from. This is pointing direction is important in extra-solar system neutrino astronomy. Along with time, position, and possibly direction, it's possible to infer

508-558: A 2.22MeV gamma-ray as the nucleus de-excites. This process on average takes on the order of 256 microseconds. By searching for time and spatial coincidence of these gamma rays, the experimenters can be certain there was an event. Using over 3,200 days of data, Borexino used geoneutrinos to place constraints on the composition and power output of the mantle. They found that the ratio of U 238 {\displaystyle {\ce {^{238}U}}} to Th 232 {\displaystyle {\ce {^{232}Th}}}

635-426: A Chlorine isotope and can create radioactive Argon. Gallium to Germanium conversion has also been used. The IceCube Neutrino Observatory built in 2010 in the south pole is the biggest neutrino detector, consisting of thousands of optical sensors buried 500 meters underneath a cubic kilometer of deep, ultra-transparent ice, detects light emitted by charged particles that are produced when a single neutrino collides with

762-402: A Type II-P supernova has a distinctive flat stretch (called a plateau ) during the decline; representing a period where the luminosity decays at a slower rate. The net luminosity decay rate is lower, at 0.0075 magnitudes per day for Type II-P, compared to 0.012 magnitudes per day for Type II-L. The difference in the shape of the light curves is believed to be caused, in

889-453: A binary companion. Approximately two to three hours before the visible light from SN 1987A reached Earth, a burst of neutrinos was observed at three neutrino observatories . This was likely due to neutrino emission which occurs simultaneously with core collapse, but before visible light is emitted as the shock wave reaches the stellar surface. At 7:35 UT , 12 antineutrinos were detected by Kamiokande II , 8 by IMB , and 5 by Baksan in

1016-399: A brief period during which the production of elements heavier than iron occurs. Depending on initial mass of the star, the remnants of the core form a neutron star or a black hole . Because of the underlying mechanism, the resulting supernova is also described as a core-collapse supernova. There exist several categories of Type II supernova explosions, which are categorized based on

1143-459: A burst lasting less than 13 seconds. Approximately three hours earlier, the Mont Blanc liquid scintillator detected a five-neutrino burst, but this is generally not believed to be associated with SN 1987A. The Kamiokande II detection, which at 12 neutrinos had the largest sample population, showed the neutrinos arriving in two distinct pulses. The first pulse at 07:35:35 comprised 9 neutrinos over

1270-455: A depth of 2 km. The second phase as well as plans to deploy the full-size prototype tower will be pursued in the KM3NeT framework. The NESTOR Project was installed in 2004 to a depth of 4 km and operated for one month until a failure of the cable to shore forced it to be terminated. The data taken still successfully demonstrated the detector's functionality and provided a measurement of

1397-511: A depth of about 2000 m that was sufficient for track reconstruction. The AMANDA array was subsequently upgraded until January 2000 when it consisted of 19 strings with a total of 667 optical modules at a depth range between 1500 m and 2000 m. AMANDA would eventually be the predecessor to IceCube in 2005. An example of an early neutrino detector is the Artyomovsk Scintillation Detector  [ ru ] (ASD), located in

SECTION 10

#1732858317191

1524-563: A dusty ejecta on the basis of an IR excess alone. An independent Australian team advanced several argument in favour of an echo interpretation. This seemingly straightforward interpretation of the nature of the IR emission was challenged by the ESO group and definitively ruled out after presenting optical evidence for the presence of dust in the SN ejecta. To discriminate between the two interpretations, they considered

1651-426: A higher rate of reaction than would otherwise take place. This continues until nickel-56 is produced, which decays radioactively into cobalt-56 and then iron-56 over the course of a few months. As iron and nickel have the highest binding energy per nucleon of all the elements, energy cannot be produced at the core by fusion, and a nickel-iron core grows. This core is under huge gravitational pressure. As there

1778-511: A long time to diffuse outward. Therefore, neutrinos are the only way that we can obtain real-time data about the nuclear processes in the Sun. There are two main processes for stellar nuclear fusion. The first is the Proton-Proton (PP) chain, in which protons are fused together into helium, sometimes temporarily creating the heavier elements of lithium, beryllium, and boron along the way. The second

1905-494: A maximum depth of 2475 m. NEMO (NEutrino Mediterranean Observatory) was pursued by Italian groups to investigate the feasibility of a cubic-kilometer scale deep-sea detector. A suitable site at a depth of 3.5 km about 100 km off Capo Passero at the South-Eastern coast of Sicily has been identified. From 2007 to 2011 the first prototyping phase tested a "mini-tower" with 4 bars deployed for several weeks near Catania at

2032-626: A nearby nuclear reactor as a neutrino source. Their discovery was acknowledged with a Nobel Prize for physics in 1995. This was followed by the first atmospheric neutrino detection in 1965 by two groups almost simultaneously. One was led by Frederick Reines who operated a liquid scintillator - the Case-Witwatersrand-Irvine or CWI detector - in the East Rand gold mine in South Africa at an 8.8 km water depth equivalent. The other

2159-414: A peak brightness followed by a decline. These light curves have an average decay rate of 0.008  magnitudes per day; much lower than the decay rate for Type Ia supernovae. Type II is subdivided into two classes, depending on the shape of the light curve. The light curve for a Type II-L supernova shows a steady ( linear ) decline following the peak brightness. By contrast, the light curve of

2286-418: A period of 1.915 seconds. A second pulse of three neutrinos arrived during a 3.220-second interval from 9.219 to 12.439 seconds after the beginning of the first pulse. Although only 25 neutrinos were detected during the event, it was a significant increase from the previously observed background level. This was the first time neutrinos known to be emitted from a supernova had been observed directly, which marked

2413-510: A precursor to many of the following telescopes in the following decades. The Baikal Neutrino Telescope is installed in the southern part of Lake Baikal in Russia. The detector is located at a depth of 1.1 km and began surveys in 1980. In 1993, it was the first to deploy three strings to reconstruct the muon trajectories as well as the first to record atmospheric neutrinos underwater. AMANDA (Antarctic Muon And Neutrino Detector Array) used

2540-650: A proton or neutron inside an atom. The resulting nuclear reaction produces secondary particles traveling at high speeds that give off a blue light called Cherenkov radiation . Super-Kamiokande in Japan and ANTARES and KM3NeT in the Mediterranean are some other important neutrino detectors. Since neutrinos interact weakly, neutrino detectors must have large target masses (often thousands of tons). The detectors also must use shielding and effective software to remove background signal. Since neutrinos are very difficult to detect,

2667-619: A result of certain types of radioactive decay , nuclear reactions such as those that take place in the Sun or high energy astrophysical phenomena, in nuclear reactors , or when cosmic rays hit atoms in the atmosphere. Neutrinos rarely interact with matter (only via the weak nuclear force), travel at nearly the speed of light in straight lines, pass through large amounts of matter without any notable absorption or without being deflected by magnetic fields. Unlike photons, neutrinos rarely scatter along their trajectory. But like photons, neutrinos are some of

SECTION 20

#1732858317191

2794-441: A result, they appear to be lacking in these elements. Stars far more massive than the sun evolve in complex ways. In the core of the star, hydrogen is fused into helium , releasing thermal energy that heats the star's core and provides outward pressure that supports the star's layers against collapse – a situation known as stellar or hydrostatic equilibrium . The helium produced in the core accumulates there. Temperatures in

2921-410: A second peak in the light curve that has a spectrum which more closely resembles a Type Ib supernova . The progenitor could have been a massive star that expelled most of its outer layers, or one which lost most of its hydrogen envelope due to interactions with a companion in a binary system, leaving behind the core that consisted almost entirely of helium. As the ejecta of a Type IIb expands,

3048-415: A square centimeter on Earth. The neutrino measurements allowed upper bounds on neutrino mass and charge, as well as the number of flavors of neutrinos and other properties. For example, the data show that the rest mass of the electron neutrino is < 16 eV/c at 95% confidence, which is 30,000 times smaller than the mass of an electron . The data suggest that the total number of neutrino flavors

3175-508: A star is believed to collapse directly into a black hole without forming a supernova explosion, although uncertainties in models of supernova collapse make calculation of these limits uncertain. The Standard Model of particle physics is a theory which describes three of the four known fundamental interactions between the elementary particles that make up all matter . This theory allows predictions to be made about how particles will interact under many conditions. The energy per particle in

3302-631: A star this massive evolves, it undergoes repeated stages where fusion in the core stops, and the core collapses until the pressure and temperature are sufficient to begin the next stage of fusion, reigniting to halt collapse. The factor limiting this process is the amount of energy that is released through fusion, which is dependent on the binding energy that holds together these atomic nuclei. Each additional step produces progressively heavier nuclei, which release progressively less energy when fusing. In addition, from carbon-burning onwards, energy loss via neutrino production becomes significant, leading to

3429-619: A supernova is typically 1–150 picojoules (tens to hundreds of MeV ). The per-particle energy involved in a supernova is small enough that the predictions gained from the Standard Model of particle physics are likely to be basically correct. But the high densities may require corrections to the Standard Model. In particular, Earth-based particle accelerators can produce particle interactions which are of much higher energy than are found in supernovae, but these experiments involve individual particles interacting with individual particles, and it

3556-461: A ten-second burst. The collapse of the inner core is halted by the repulsive nuclear force and neutron degeneracy , causing the implosion to rebound and bounce outward. The energy of this expanding shock wave is sufficient to disrupt the overlying stellar material and accelerate it to escape velocity, forming a supernova explosion. The shock wave and extremely high temperature and pressure rapidly dissipate but are present for long enough to allow for

3683-567: Is 0.808 arcseconds in radius. The time light traveled to light up the inner ring gives its radius of 0.66 (ly) light years . Using this as the base of a right angle triangle and the angular size as seen from the Earth for the local angle, one can use basic trigonometry to calculate the distance to SN 1987A, which is about 168,000 light-years. The material from the explosion is catching up with the material expelled during both its red and blue supergiant phases and heating it, so we observe ring structures about

3810-530: Is a typical representative of its class then the derived mass of the warm dust formed in the debris of core collapse supernovae is not sufficient to account for all the dust observed in the early universe. However, a much larger reservoir of ~0.25 solar mass of colder dust (at ~26 K) in the ejecta of SN 1987A was found with the infrared Herschel Space Telescope in 2011 and confirmed with the Atacama Large Millimeter Array (ALMA) in 2014. Following

3937-408: Is at most 8 but other observations and experiments give tighter estimates. Many of these results have since been confirmed or tightened by other neutrino experiments such as more careful analysis of solar neutrinos and atmospheric neutrinos as well as experiments with artificial neutrino sources. SN 1987A appears to be a core-collapse supernova, which should result in a neutron star given the size of

SN 1987A - Misplaced Pages Continue

4064-431: Is likely that the high densities within the supernova will produce novel effects. The interactions between neutrinos and the other particles in the supernova take place with the weak nuclear force , which is believed to be well understood. However, the interactions between the protons and neutrons involve the strong nuclear force , which is much less well understood. The major unsolved problem with Type II supernovae

4191-456: Is no fusion to further raise the star's temperature to support it against collapse, it is supported only by degeneracy pressure of electrons . In this state, matter is so dense that further compaction would require electrons to occupy the same energy states . However, this is forbidden for identical fermion particles, such as the electron – a phenomenon called the Pauli exclusion principle . When

4318-402: Is possible to trace back the direction of the incoming neutrino. These high-energy neutrinos are either the primary or secondary cosmic rays produced by energetic astrophysical processes. Observing neutrinos could provide insights into these processes beyond what is observable with electromagnetic radiation. In the case of the neutrino detected from a distant blazar, multi-wavelength astronomy

4445-416: Is produced by the energy from radioactive decay . Although the luminous emission consists of optical photons, it is the radioactive power absorbed that keeps the remnant hot enough to radiate light. Without the radioactive heat, it would dim quickly. The radioactive decay of Ni through its daughters Co to Fe produces gamma-ray photons that are absorbed and dominate the heating and thus the luminosity of

4572-467: Is produced. In a typical Type II supernova, the newly formed neutron core has an initial temperature of about 100 billion kelvins , 10 times the temperature of the Sun's core. Much of this thermal energy must be shed for a stable neutron star to form, otherwise the neutrons would "boil away". This is accomplished by a further release of neutrinos. These 'thermal' neutrinos form as neutrino-antineutrino pairs of all flavors , and total several times

4699-413: Is sent to professional and amateur astronomers to be on the lookout for supernova light. By using the distance between detectors and the time difference between detections, the alert can also include directionality as to the supernova's location in the sky. The Sun, like other stars, is powered by nuclear fusion in its core. The core is incredibly large, meaning that photons produced in the core will take

4826-448: Is that anti-electron neutrinos can interact with a nucleus in the detector by inverse beta decay and produce a positron and a neutron. The positron immediately will annihilate with an electron, producing two 511keV photons. The neutron will attach to another nucleus and give off a gamma with an energy of a few MeV. In general, neutrinos can interact through neutral-current and charged-current interactions. In neutral-current interactions,

4953-441: Is that it is not understood how the burst of neutrinos transfers its energy to the rest of the star producing the shock wave which causes the star to explode. From the above discussion, only one percent of the energy needs to be transferred to produce an explosion, but explaining how that one percent of transfer occurs has proven extremely difficult, even though the particle interactions involved are believed to be well understood. In

5080-414: Is that the collapsed core became a quark star . In 2019, evidence was presented for a neutron star inside one of the brightest dust clumps, close to the expected position of the supernova remnant. In 2021, further evidence was presented of hard X-ray emissions from SN 1987A originating in the pulsar wind nebula. The latter result is supported by a three-dimensional magnetohydrodynamic model, which describes

5207-484: Is the CNO cycle, in which carbon, nitrogen, and oxygen are fused with protons, and then undergo alpha decay (helium nucleus emission) to begin the cycle again. The PP chain is the primary process in the Sun, while the CNO cycle is more dominant in stars more massive than the Sun. Each step in the process has an allowed spectra of energy for the neutrino (or a discrete energy for electron capture processes). The relative rates of

SN 1987A - Misplaced Pages Continue

5334-451: Is the branch of astronomy that gathers information about astronomical objects by observing and studying neutrinos emitted by them with the help of neutrino detectors in special Earth observatories. It is an emerging field in astroparticle physics providing insights into the high-energy and non-thermal processes in the universe. Neutrinos are nearly massless and electrically neutral or chargeless elementary particles . They are created as

5461-421: Is the same as chondritic meteorites. The power output from uranium and thorium in Earth's mantle was found to be 14.2-35.7 TW with a 68% confidence interval. Neutrino tomography also provides insight into the interior of Earth. For neutrinos with energies of a few TeV, the interaction probability becomes non-negligible when passing through Earth. The interaction probability will depend on the number of nucleons

5588-568: The Homestake experiment . Davis, along with Japanese physicist Masatoshi Koshiba were jointly awarded half of the 2002 Nobel Prize in Physics "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos (the other half went to Riccardo Giacconi for corresponding pioneering contributions which have led to the discovery of cosmic X-ray sources)." The first generation of undersea neutrino telescope projects began with

5715-581: The Las Campanas Observatory in Chile on February 24, 1987, and within the same 24 hours by Albert Jones in New Zealand . Later investigations found photographs showing the supernova brightening rapidly early on February 23. On March 4–12, 1987, it was observed from space by Astron , the largest ultraviolet space telescope of that time. Four days after the event was recorded, the progenitor star

5842-723: The Soledar Salt Mine in Ukraine at a depth of more than 100 m. It was created in the Department of High Energy Leptons and Neutrino Astrophysics of the Institute of Nuclear Research of the USSR Academy of Sciences in 1969 to study antineutrino fluxes from collapsing stars in the Galaxy, as well as the spectrum and interactions of muons of cosmic rays with energies up to 10 ^ 13 eV. A feature of

5969-452: The blazar TXS 0506+056 located 3.7 billion light-years away in the direction of the constellation Orion . This is the first time that a neutrino detector has been used to locate an object in space and that a source of cosmic rays has been identified. In November 2022, the IceCube collaboration made another significant progress towards identifying the origin of cosmic rays, reporting

6096-412: The carbon produced by helium fusion does not fuse, and the star gradually cools to become a white dwarf . If they accumulate more mass from another star, or some other source, they may become Type Ia supernovae . But a much larger star is massive enough to continue fusion beyond this point. The cores of these massive stars directly create temperatures and pressures needed to cause the carbon in

6223-406: The cosmic neutrino background , origins of ultra-high-energy neutrinos, neutrino properties (such as neutrino mass hierarchy), dark matter properties, etc. It will become an integral part of multi-messenger astronomy, complementing gravitational astronomy and traditional telescopic astronomy. Neutrinos were first recorded in 1956 by Clyde Cowan and Frederick Reines in an experiment employing

6350-453: The shockwave forms and when and how it stalls and is reenergized. In fact, some theoretical models incorporate a hydrodynamical instability in the stalled shock known as the "Standing Accretion Shock Instability" (SASI). This instability comes about as a consequence of non-spherical perturbations oscillating the stalled shock thereby deforming it. The SASI is often used in tandem with neutrino theories in computer simulations for re-energizing

6477-417: The spectrum of a Type II supernova is examined, it normally displays Balmer absorption lines – reduced flux at the characteristic frequencies where hydrogen atoms absorb energy. The presence of these lines is used to distinguish this category of supernova from a Type I supernova . When the luminosity of a Type II supernova is plotted over a period of time, it shows a characteristic rise to

SECTION 50

#1732858317191

6604-410: The stellar wind of the progenitor. These rings were ionized by the ultraviolet flash from the supernova explosion, and consequently began emitting in various emission lines. These rings did not "turn on" until several months after the supernova and the process can be very accurately studied through spectroscopy. The rings are large enough that their angular size can be measured accurately: the inner ring

6731-403: The 1990s, one model for doing this involved convective overturn , which suggests that convection, either from neutrinos from below, or infalling matter from above, completes the process of destroying the progenitor star. Heavier elements than iron are formed during this explosion by neutron capture, and from the pressure of the neutrinos pressing into the boundary of the "neutrinosphere", seeding

6858-555: The 3 km thick ice layer at the South Pole and was located several hundred meters from the Amundsen-Scott station . Holes 60 cm in diameter were drilled with pressurized hot water in which strings with optical modules were deployed before the water refroze. The depth proved to be insufficient to be able to reconstruct the trajectory due to the scattering of light on air bubbles. A second group of 4 strings were added in 1995/96 to

6985-569: The Abyss ). Both KM3NeT and GVD have completed at least part of their construction and it is expected that these two along with IceCube will form a global neutrino observatory. In July 2018, the IceCube Neutrino Observatory announced that they have traced an extremely-high-energy neutrino that hit their Antarctica-based research station in September 2017 back to its point of origin in

7112-560: The Antarctic ice. The KM3NeT in the Mediterranean Sea and the GVD are in their preparatory/prototyping phase. IceCube instruments 1 km of ice. GVD is also planned to cover 1 km but at a much higher energy threshold. KM3NeT is planned to cover several km and have two components; ARCA ( Astroparticle Research with Cosmics in the Abyss ) and ORCA ( Oscillations Research with Cosmics in

7239-403: The ESO team reported an infrared excess which became apparent beginning less than one month after the explosion (March 11, 1987). Three possible interpretations for it were discussed in this work: the infrared echo hypothesis was discarded, and thermal emission from dust that could have condensed in the ejecta was favoured (in which case the estimated temperature at that epoch was ~ 1250 K, and

7366-471: The Milky Way galaxy . Neutrinos interact incredibly rarely with matter, so the vast majority of neutrinos will pass through a detector without interacting. If a neutrino does interact, it will only do so once. Therefore, to perform neutrino astronomy, large detectors must be used to obtain enough statistics. The method of neutrino detection depends on the energy and type of the neutrino. A famous example

7493-494: The SN1987A remnant without absorption confirmed earlier predictions that those two radioactive nuclei were the power source. Because the Co in SN1987A has now completely decayed, it no longer supports the luminosity of the SN 1987A ejecta. That is currently powered by the radioactive decay of Ti with a half life of about 60 years. With this change, X-rays produced by the ring interactions of

7620-437: The Sun's nuclear processes can be determined by observations in its flux at different energies. This would shed insight into the Sun's properties, such as metallicity , which is the composition of heavier elements. Borexino is one of the detectors studying solar neutrinos. In 2018, they found 5σ significance for the existence of neutrinos from the fusing of two protons with an electron (pep neutrinos). In 2020, they found for

7747-529: The Supernova Early Warning System ( SNEWS ). In a core collapse supernova, ninety-nine percent of the energy released will be in neutrinos. While photons can be trapped in the dense supernova for hours, neutrinos are able to escape on the order of seconds. Since neutrinos travel at roughly the speed of light, they can reach Earth before photons do. If two or more of SNEWS detectors observe a coincidence of an increased flux of neutrinos, an alert

SECTION 60

#1732858317191

7874-464: The Supernova Early Warning System (SNEWS), where they search for an increase of neutrino flux that could signal a supernova event. There are currently goals to detect neutrinos from other sources, such as active galactic nuclei (AGN), as well as gamma-ray bursts and starburst galaxies . Neutrino astronomy may also indirectly detect dark matter. Seven neutrino experiments (Super-K, LVD, IceCube, KamLAND, Borexino , Daya Bay, and HALO) work together as

8001-482: The archetypal SN 2010jl . Most 2010jl-like supernovae were discovered with the decommissioned Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (e.g. SN 2014ab , SN 2017hcc ). A Type IIb supernova has a weak hydrogen line in its initial spectrum, which is why it is classified as a Type II. However, later on the H emission becomes undetectable, and there is also

8128-529: The atmosphere. As these hadrons decay, they produce neutrinos (called atmospheric neutrinos). At low energies, the flux of atmospheric neutrinos is many times greater than astrophysical neutrinos. At high energies, the pions and kaons have a longer lifetime (due to relativistic time dilation). The hadrons are now more likely to interact before they decay. Because of this, the astrophysical neutrino flux will dominate at high energies (~100TeV). To perform neutrino astronomy of high-energy objects, experiments rely on

8255-401: The atmosphere; only some of the highest-energy muons are able to penetrate to the depths of our detectors. Detectors must include ways of dealing with data from muons so as to not confuse them with neutrinos. Along with more complicated measures, if a muon track is first detected outside of the desired "fiducial" volume, the event is treated as a muon and not considered. Ignoring events outside

8382-655: The atmospheric muon flux. The proof of concept will be implemented in the KM3Net framework. The second generation of deep-sea neutrino telescope projects reach or even exceed the size originally conceived by the DUMAND pioneers. IceCube , located at the South Pole and incorporating its predecessor AMANDA, was completed in December 2010. It currently consists of 5160 digital optical modules installed on 86 strings at depths of 1450 to 2550 m in

8509-416: The background. While it may be unknown if an individual event is background or signal, it is possible to detect an excess about the background, signifying existence of the desired signal. When astronomical bodies, such as the Sun , are studied using light, only the surface of the object can be directly observed. Any light produced in the core of a star will interact with gas particles in the outer layers of

8636-412: The beginning of neutrino astronomy . The observations were consistent with theoretical supernova models in which 99% of the energy of the collapse is radiated away in the form of neutrinos. The observations are also consistent with the models' estimates of a total neutrino count of 10 with a total energy of 10 joules, i.e. a mean value of some dozens of MeV per neutrino. Billions of neutrinos passed through

8763-444: The blue color largely to its chemical composition rather than its evolutionary stage, particularly the low levels of heavy elements. There was some speculation that the star might have merged with a companion star before the supernova. However, it is now widely understood that blue supergiants are natural progenitors of some supernovae, although there is still speculation that the evolution of such stars could require mass loss involving

8890-462: The case of Type II-L supernovae, by the expulsion of most of the hydrogen envelope of the progenitor star. The plateau phase in Type ;II-P supernovae is due to a change in the opacity of the exterior layer. The shock wave ionizes the hydrogen in the outer envelope – stripping the electron from the hydrogen atom – resulting in a significant increase in the opacity . This prevents photons from

9017-405: The charged resultants are moving fast enough, they can create Cherenkov light . To observe neutrino interactions, detectors use photomultiplier tubes (PMTs) to detect individual photons. From the timing of the photons, it is possible to determine the time and place of the neutrino interaction. If the neutrino creates a muon during its interaction, then the muon will travel in a line, creating

9144-427: The circumstellar medium, which leads to an increased temperature of the cirumstellar dust . This warm dust can be observed as a brightening in the mid-infrared light. If the circumstellar medium extends further from the supernova, the mid-infrared brightening can cause an infrared echo , causing the brightening to last more than 1000 days. These kind of supernovae belong to the rare 2010jl-like supernovae, named after

9271-424: The clumps are destroyed by the shock wave. It is predicted the ring would fade away between 2020 and 2030. These findings are also supported by the results of a three-dimensional hydrodynamic model which describes the interaction of the blast wave with the circumstellar nebula. The model also shows that X-ray emission from ejecta heated up by the shock will be dominant very soon, after which the ring would fade away. As

9398-419: The confirmation of a large amount of cold dust in the ejecta, ALMA has continued observing SN 1987A. Synchrotron radiation due to shock interaction in the equatorial ring has been measured. Cold (20–100K) carbon monoxide (CO) and silicate molecules (SiO) were observed. The data show that CO and SiO distributions are clumpy, and that different nucleosynthesis products (C, O and Si) are located in different places of

9525-417: The core are not yet high enough to cause it to fuse. Eventually, as the hydrogen at the core is exhausted, fusion starts to slow down, and gravity causes the core to contract. This contraction raises the temperature high enough to allow a shorter phase of helium fusion, which produces carbon and oxygen , and accounts for less than 10% of the star's total lifetime. In stars of less than eight solar masses,

9652-423: The core takes place within seconds. Without the support of the now-imploded inner core, the outer core collapses inwards under gravity and reaches a velocity of up to 23% of the speed of light , and the sudden compression increases the temperature of the inner core to up to 100 billion kelvins . Neutrons and neutrinos are formed via reversed beta-decay , releasing about 10  joules (100  foe ) in

9779-443: The core to begin to fuse when the star contracts at the end of the helium-burning stage. The core gradually becomes layered like an onion, as progressively heavier atomic nuclei build up at the center, with an outermost layer of hydrogen gas, surrounding a layer of hydrogen fusing into helium, surrounding a layer of helium fusing into carbon via the triple-alpha process , surrounding layers that fuse to progressively heavier elements. As

9906-417: The core's density increases, it becomes energetically favorable for electrons and protons to merge via inverse beta decay , producing neutrons and elementary particles called neutrinos . Because neutrinos rarely interact with normal matter, they can escape from the core, carrying away energy and further accelerating the collapse, which proceeds over a timescale of milliseconds. As the core detaches from

10033-547: The core's mass exceeds the Chandrasekhar limit of about 1.4  M ☉ , degeneracy pressure can no longer support it, and catastrophic collapse ensues. The outer part of the core reaches velocities of up to 70 000  km/s (23% of the speed of light ) as it collapses toward the center of the star. The rapidly shrinking core heats up, producing high-energy gamma rays that decompose iron nuclei into helium nuclei and free neutrons via photodisintegration . As

10160-411: The data obtained from seismic and gravitational data. With the current data, the uncertainties on these values are still large, but future data from IceCube and KM3NeT will place tighter restrictions on this data. Neutrinos can either be primary cosmic rays (astrophysical neutrinos), or be produced from cosmic ray interactions. In the latter case, the primary cosmic ray will produce pions and kaons in

10287-598: The detector is a 100-ton scintillation tank with dimensions on the order of the length of an electromagnetic shower with an initial energy of 100 GeV. After the decline of DUMAND the participating groups split into three branches to explore deep sea options in the Mediterranean Sea. ANTARES was anchored to the sea floor in the region off Toulon at the French Mediterranean coast. It consists of 12 strings, each carrying 25 "storeys" equipped with three optical modules, an electronic container, and calibration devices down to

10414-402: The detectors from cosmic rays, which can penetrate hundreds of meters of rock. Neutrinos, on the other hand, can go through the entire planet without being absorbed, like "ghost particles". That's why neutrino detectors are placed many hundreds of meter underground, usually at the bottom of mines. There a neutrino detection liquid such as a Chlorine-rich solution is placed; the neutrinos react with

10541-528: The dust mass was approximately 6.6 × 10   M ☉ ). The possibility that the IR excess could be produced by optically thick free-free emission seemed unlikely because the luminosity in UV photons needed to keep the envelope ionized was much larger than what was available, but it was not ruled out in view of the eventuality of electron scattering, which had not been considered. However, none of these three groups had sufficiently convincing proofs to claim for

10668-423: The ejecta at intermediate times (several weeks) to late times (several months). Energy for the peak of the light curve of SN1987A was provided by the decay of Ni to Co (half life of 6 days) while energy for the later light curve in particular fit very closely with the 77.3-day half-life of Co decaying to Fe. Later measurements by space gamma-ray telescopes of the small fraction of the Co and Co gamma rays that escaped

10795-533: The ejecta began to contribute significantly to the total light curve. This was noticed by the Hubble Space Telescope as a steady increase in luminosity 10,000 days after the event in the blue and red spectral bands. X-ray lines Ti observed by the INTEGRAL space X-ray telescope showed that the total mass of radioactive Ti synthesized during the explosion was 3.1 ± 0.8 × 10 M ☉ . Observations of

10922-469: The ejecta, indicating the footprints of the stellar interior at the time of the explosion. Type II supernova Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures , causing correspondingly shorter stellar life spans. The degeneracy pressure of electrons and

11049-452: The energy generated by these fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with hydrogen and then helium , progressing up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving

11176-450: The energy of the neutrino from the interactions. The number of photons emitted is related to the neutrino energy, and neutrino energy is important for measuring the fluxes from solar and geo-neutrinos. Due to the rareness of neutrino interactions, it is important to maintain a low background signal. For this reason, most neutrino detectors are constructed under a rock or water overburden. This overburden shields against most cosmic rays in

11303-541: The evolution of SN 1987A from the SN event to the present, and reconstructs the ambient environment, predicting the absorbing power of the dense stellar material around the pulsar. In 2024, researchers using the James Webb Space Telescope (JWST) identified distinctive emission lines of ionized argon within the central region of the Supernova 1987A (SN 1987A) remnants. These emission lines, discernible only near

11430-401: The fiducial volume also decreases the signal from radiation outside the detector. Despite shielding efforts, it is inevitable that some background will make it into the detector, many times in the form of radioactive impurities within the detector itself. At this point, if it is impossible to differentiate between the background and true signal, a Monte Carlo simulation must be used to model

11557-620: The first time evidence of CNO neutrinos in the Sun. Improvements on the CNO measurement will be especially helpful in determining the Sun's metallicity. The interior of Earth contains radioactive elements such as K 40 {\displaystyle {\ce {^{40}K}}} and the decay chains of U 238 {\displaystyle {\ce {^{238}U}}} and Th 232 {\displaystyle {\ce {^{232}Th}}} . These elements decay via Beta decay , which emits an anti-neutrino. The energies of these anti-neutrinos are dependent on

11684-424: The highest energy neutrinos. To perform astronomy of distant objects, a strong angular resolution is required. Neutrinos are electrically neutral and interact weakly, so they travel mostly unperturbed in straight lines. If the neutrino interacts within a detector and produces a muon, the muon will produce an observable track. At high energies, the neutrino direction and muon direction are closely correlated, so it

11811-415: The hydrogen layer quickly becomes more transparent and reveals the deeper layers. The classic example of a Type IIb supernova is SN 1993J , while another example is Cassiopeia A . The IIb class was first introduced (as a theoretical concept) by Woosley et al. in 1987, and the class was soon applied to SN 1987K and SN 1993J . Neutrino astronomy Neutrino astronomy

11938-427: The implication of the presence of an echoing dust cloud on the optical light curve, and on the existence of diffuse optical emission around the SN. They concluded that the expected optical echo from the cloud should be resolvable, and could be very bright with an integrated visual brightness of magnitude 10.3 around day 650. However, further optical observations, as expressed in SN light curve, showed no inflection in

12065-442: The infalling matter rebounds, producing a shock wave that propagates outward. The energy from this shock dissociates heavy elements within the core. This reduces the energy of the shock, which can stall the explosion within the outer core. The core collapse phase is so dense and energetic that only neutrinos are able to escape. As the protons and electrons combine to form neutrons by means of electron capture , an electron neutrino

12192-466: The inner parts of the explosion from escaping. When the hydrogen cools sufficiently to recombine, the outer layer becomes transparent. The "n" denotes narrow, which indicates the presence of narrow or intermediate width hydrogen emission lines in the spectra. In the intermediate width case, the ejecta from the explosion may be interacting strongly with gas around the star – the circumstellar medium. The estimated circumstellar density required to explain

12319-409: The light curve at the predicted level. Finally, the ESO team presented a convincing clumpy model for dust condensation in the ejecta. Although it had been thought more than 50 years ago that dust could form in the ejecta of a core-collapse supernova, which in particular could explain the origin of the dust seen in young galaxies, that was the first time that such a condensation was observed. If SN 1987A

12446-613: The most common particles in the universe. Because of this, neutrinos offer a unique opportunity to observe processes that are inaccessible to optical telescopes , such as reactions in the Sun's core. Neutrinos that are created in the Sun’s core are barely absorbed, so a large quantity of them escape from the Sun and reach the Earth. Neutrinos can also offer a very strong pointing direction compared to charged particle cosmic rays. Neutrinos are very hard to detect due to their non-interactive nature. In order to detect neutrinos, scientists have to shield

12573-543: The neutrino interacts with a nucleus or electron and the neutrino retains its original flavor. In charged-current interactions, the neutrino is absorbed by the nucleus and produces a lepton corresponding to the neutrino's flavor ( ν e ⟶ e − {\displaystyle {\ce {\nu_{e}-> e^-}}} , ν μ ⟶ μ − {\displaystyle {\ce {\nu_{\mu}-> \mu^{-}}}} , etc.). If

12700-446: The neutrino passed along its path, which is directly related to density. If the initial flux is known (as it is in the case of atmospheric neutrinos), then detecting the final flux provides information about the interactions that occurred. The density can then be extrapolated from knowledge of these interactions. This can provide an independent check on the information obtained from seismic data. In 2018, one year worth of IceCube data

12827-458: The nickel–iron core inert. Due to the lack of energy output creating outward thermal pressure, the core contracts due to gravity until the overlying weight of the star can be supported largely by electron degeneracy pressure. When the compacted mass of the inert core exceeds the Chandrasekhar limit of about 1.4  M ☉ , electron degeneracy is no longer sufficient to counter the gravitational compression. A cataclysmic implosion of

12954-415: The number of electron-capture neutrinos. The two neutrino production mechanisms convert the gravitational potential energy of the collapse into a ten-second neutrino burst, releasing about 10 joules (100  foe ). Through a process that is not clearly understood, about 1%, or 10  joules (1 foe), of the energy released (in the form of neutrinos ) is reabsorbed by the stalled shock, producing

13081-407: The observation of 79 neutrinos with an energy over 1 TeV originated from the nearby galaxy M77 . These findings in a well-known object are expected to help study the active nucleus of this galaxy, as well as serving as a baseline for future observations. In June 2023, astronomers reported using a new technique to detect, for the first time, the release of neutrinos from the galactic plane of

13208-672: The observational properties is much higher than that expected from the standard stellar evolution theory. It is generally assumed that the high circumstellar density is due to the high mass-loss rates of the Type IIn progenitors. The estimated mass-loss rates are typically higher than 10   M ☉ per year. There are indications that they originate as stars similar to luminous blue variables with large mass losses before exploding. SN 1998S and SN 2005gl are examples of Type IIn supernovae; SN 2006gy , an extremely energetic supernova, may be another example. Some supernovae of type IIn show interactions with

13335-411: The only bodies that have been studied in this way are the sun and the supernova SN1987A, which exploded in 1987. Scientist predicted that supernova explosions would produce bursts of neutrinos, and a similar burst was actually detected from Supernova 1987A. In the future neutrino astronomy promises to discover other aspects of the universe, including coincidental gravitational waves , gamma ray bursts ,

13462-462: The original star. The neutrino data indicate that a compact object did form at the star's core, and astronomers immediately began searching for the collapsed core. The Hubble Space Telescope took images of the supernova regularly from August 1990 without a clear detection of a neutron star. A number of possibilities for the "missing" neutron star were considered. First, that the neutron star may be obscured by surrounding dense dust clouds. Second, that

13589-410: The outer layers of the star, some of these neutrinos are absorbed by the star's outer layers, beginning the supernova explosion. For Type II supernovae, the collapse is eventually halted by short-range repulsive neutron-neutron interactions, mediated by the strong force , as well as by degeneracy pressure of neutrons, at a density comparable to that of an atomic nucleus. When the collapse stops,

13716-443: The parent nucleus. Therefore, by detecting the anti-neutrino flux as a function of energy, we can obtain the relative compositions of these elements and set a limit on the total power output of Earth's geo-reactor. Most of our current data about the core and mantle of Earth comes from seismic data, which does not provide any information as to the nuclear composition of these layers. Borexino has detected these geo-neutrinos through

13843-449: The process ν ¯ + p + ⟶ e + + n {\displaystyle {\ce {{\bar {\nu }}+p^{+}\longrightarrow e^{+}{+n}}}} . The resulting positron will immediately annihilate with an electron and produce two gamma-rays each with an energy of 511keV (the rest mass of an electron). The neutron will later be captured by another nucleus, which will lead to

13970-405: The progenitor star is below about 20  M ☉ – depending on the strength of the explosion and the amount of material that falls back – the degenerate remnant of a core collapse is a neutron star . Above this mass, the remnant collapses to form a black hole . The theoretical limiting mass for this type of core collapse scenario is about 40–50  M ☉ . Above that mass,

14097-453: The proposal by Moisey Markov in 1960 "...to install detectors deep in a lake or a sea and to determine the location of charged particles with the help of Cherenkov radiation ." The first underwater neutrino telescope began as the DUMAND project. DUMAND stands for Deep Underwater Muon and Neutrino Detector. The project began in 1976 and although it was eventually cancelled in 1995, it acted as

14224-512: The radioactive nature of the long-duration post-explosion glow of supernovae. In 2019, indirect evidence for the presence of a collapsed neutron star within the remnants of SN 1987A was discovered using the Atacama Large Millimeter Array telescope. Further evidence was subsequently uncovered in 2021 through observations conducted by the Chandra and NuSTAR X-ray telescopes. SN 1987A was discovered independently by Ian Shelton and Oscar Duhalde at

14351-475: The radioactive power from their decays in the 1987A light curve have measured accurate total masses of the Ni, Ni, and Ti created in the explosion, which agree with the masses measured by gamma-ray line space telescopes and provides nucleosynthesis constraints on the computed supernova model. The three bright rings around SN 1987A that were visible after a few months in images by the Hubble Space Telescope are material from

14478-399: The remnant's core, were analyzed using photoionization models. The models indicate that the observed line ratios and velocities can be attributed to ionizing radiation originating from a neutron star illuminating gas from the inner regions of the exploded star. Much of the light curve , or graph of luminosity as a function of time, after the explosion of a type II supernova such as SN 1987A

14605-477: The resulting light curve —a graph of luminosity versus time—following the explosion. Type II-L supernovae show a steady ( linear ) decline of the light curve following the explosion, whereas Type II-P display a period of slower decline (a plateau) in their light curve followed by a normal decay. Type Ib and Ic supernovae are a type of core-collapse supernova for a massive star that has shed its outer envelope of hydrogen and (for Type Ic) helium. As

14732-413: The shock wave passes the circumstellar ring it will trace the history of mass loss of the supernova's progenitor and provide useful information for discriminating among various models for the progenitor of SN 1987A. In 2018, radio observations from the interaction between the circumstellar ring of dust and the shockwave has confirmed the shockwave has now left the circumstellar material. It also shows that

14859-663: The speed of the shockwave, which slowed down to 2,300 km/s while interacting with the dust in the ring, has now re-accelerated to 3,600 km/s. Soon after the SN 1987A outburst, three major groups embarked in a photometric monitoring of the supernova: the South African Astronomical Observatory (SAAO), the Cerro Tololo Inter-American Observatory (CTIO), and the European Southern Observatory (ESO). In particular,

14986-413: The stalled shock. Computer models have been very successful at calculating the behavior of Type II supernovae when the shock has been formed. By ignoring the first second of the explosion, and assuming that an explosion is started, astrophysicists have been able to make detailed predictions about the elements produced by the supernova and of the expected light curve from the supernova. When

15113-402: The star, taking hundreds of thousands of years to make it to the surface, making it impossible to observe the core directly. Since neutrinos are also created in the cores of stars (as a result of stellar fusion ), the core can be observed using neutrino astronomy. Other sources of neutrinos- such as neutrinos released by supernovae- have been detected. Several neutrino experiments have formed

15240-399: The star. Around 2001, the expanding (>7,000 km/s) supernova ejecta collided with the inner ring. This caused its heating and the generation of x-rays—the x-ray flux from the ring increased by a factor of three between 2001 and 2009. A part of the x-ray radiation, which is absorbed by the dense ejecta close to the center, is responsible for a comparable increase in the optical flux from

15367-440: The supernova explosion. Neutrinos generated by a supernova were observed in the case of Supernova 1987A , leading astrophysicists to conclude that the core collapse picture is basically correct. The water-based Kamiokande II and IMB instruments detected antineutrinos of thermal origin, while the gallium -71-based Baksan instrument detected neutrinos ( lepton number = 1) of either thermal or electron-capture origin. When

15494-529: The supernova remnant in 2001–2009. This increase of the brightness of the remnant reversed the trend observed before 2001, when the optical flux was decreasing due to the decaying of Ti isotope. A study reported in June 2015, using images from the Hubble Space Telescope and the Very Large Telescope taken between 1994 and 2014, shows that the emissions from the clumps of matter making up the rings are fading as

15621-483: The surrounding space with a cloud of gas and dust which is richer in heavy elements than the material from which the star originally formed. Neutrino physics , which is modeled by the Standard Model , is crucial to the understanding of this process. The other crucial area of investigation is the hydrodynamics of the plasma that makes up the dying star; how it behaves during the core collapse determines when and how

15748-525: Was a Bombay-Osaka-Durham collaboration that operated in the Indian Kolar Gold Field mine at an equivalent water depth of 7.5 km. Although the KGF group detected neutrino candidates two months later than Reines CWI, they were given formal priority due to publishing their findings two weeks earlier. In 1968, Raymond Davis, Jr. and John N. Bahcall successfully detected the first solar neutrinos in

15875-431: Was evaluated to perform neutrino tomography. The analysis studied upward going muons, which provide both the energy and directionality of the neutrinos after passing through the Earth. A model of Earth with five layers of constant density was fit to the data, and the resulting density agreed with seismic data. The values determined for the total mass of Earth, the mass of the core, and the moment of inertia all agree with

16002-442: Was tentatively identified as Sanduleak −69 202 (Sk -69 202), a blue supergiant . After the supernova faded, that identification was definitively confirmed, as Sk −69 202 had disappeared. The possibility of a blue supergiant producing a supernova was considered surprising, and the confirmation led to further research which identified an earlier supernova with a blue supergiant progenitor. Some models of SN 1987A's progenitor attributed

16129-415: Was the first supernova that modern astronomers were able to study in great detail, and its observations have provided much insight into core-collapse supernovae . SN 1987A provided the first opportunity to confirm by direct observation the radioactive source of the energy for visible light emissions, by detecting predicted gamma-ray line radiation from two of its abundant radioactive nuclei. This proved

#190809