> Supernova
Find out, what is a supernova: description of the explosion and flare of a star, where supernovae are born, evolution and development, the role of double stars, photos and research.
Supernova- this is, in fact, a stellar explosion and the most powerful one that can be observed in outer space.
Where do supernovae appear?
Very often supernovae can be seen in other galaxies. But in our Milky Way, this is a rare phenomenon to observe because dust and gas hazes block the view. The last observed supernova was observed by Johannes Kepler in 1604. The Chandra telescope was able to find only the remains of a star that exploded more than a century ago (the consequences of a supernova explosion).
What causes a supernova?
A supernova is born when changes occur at the center of the star. There are two main types.
The first is in binary systems. Double stars are objects connected by a common center. One of them steals matter from the second and becomes too massive. But it is unable to balance internal processes and explodes in a supernova.
The second is at the moment of death. Fuel tends to run out. As a result, part of the mass begins to flow into the core, and it becomes so heavy that it cannot withstand its own gravity. An expansion process occurs and the star explodes. The Sun is a single star, but it cannot survive this, since it does not have enough mass.
Why are researchers interested in supernovae?
The process itself covers a short period of time, but can tell a lot about the Universe. For example, one of the specimens confirmed the property of the Universe to expand and that the rate is increasing.
It also turned out that these objects influence the moment of distribution of elements in space. When a star explodes, it shoots out elements and cosmic debris. Many of them even end up on our planet. Watch a video that reveals the characteristics of supernovae and their explosions.
Supernova observations
Astrophysicist Sergei Blinnikov about the discovery of the first supernova, remnants after the explosion and modern telescopes
How to find them supernovae?
To search for supernovae, researchers use various instruments. Some are needed to observe visible light after an explosion. And others track X-rays and gamma rays. Photos were taken using the Hubble and Chandra telescopes.
In June 2012, a telescope began operating, focusing light in the high-energy region of the electromagnetic spectrum. We are talking about the NuSTAR mission, which searches for collapsed stars, black holes and supernova remnants. Scientists plan to learn more about how they explode and are created.
Measuring distances to celestial bodies
Astronomer Vladimir Surdin about Cepheids, supernova explosions and the expansion rate of the Universe:
How can you help with supernova research?
You don't have to become a scientist to contribute. In 2008, a supernova was discovered by an ordinary teenager. In 2011, this was repeated by a 10-year-old Canadian girl who was looking at a photo of the night sky on her computer. Very often, amateur photographs contain many interesting objects. With a little practice, you can find the next supernova! To be more precise, you have every chance of capturing a supernova explosion.
SUPERNOVA, explosion that marked the death of a star. Sometimes a supernova explosion is brighter than the galaxy in which it occurred.
Supernovae are divided into two main types. Type I is characterized by a deficiency of hydrogen in the optical spectrum; therefore, it is believed that this is an explosion of a white dwarf - a star with a mass close to the Sun, but smaller in size and more dense. A white dwarf contains almost no hydrogen, since it is the end product of the evolution of a normal star. In the 1930s, S. Chandrasekhar showed that the mass of a white dwarf cannot be above a certain limit. If it is in a binary system with a normal star, then its matter can flow onto the surface of the white dwarf. When its mass exceeds the Chandrasekhar limit, the white dwarf collapses (shrinks), heats up and explodes. see also STARS.
A type II supernova erupted on February 23, 1987 in our neighboring galaxy, the Large Magellanic Cloud. She was given the name of Ian Shelton, who was the first to notice a supernova explosion using a telescope, and then with the naked eye. (The last such discovery belongs to Kepler, who saw a supernova explosion in our Galaxy in 1604, shortly before the invention of the telescope.) Simultaneously with the optical supernova explosion of 1987, special detectors in Japan and in the United States. Ohio (USA) recorded a flux of neutrinos - elementary particles born at very high temperatures during the collapse of the star's core and easily penetrating through its shell. Although the stream of neutrinos was emitted by a star along with an optical flare approximately 150 thousand years ago, it reached Earth almost simultaneously with photons, thereby proving that neutrinos have no mass and move at the speed of light. These observations also confirmed the assumption that about 10% of the mass of the collapsing stellar core is emitted in the form of neutrinos when the core itself collapses into a neutron star. In very massive stars, during a supernova explosion, the cores are compressed to even greater densities and probably turn into black holes, but the outer layers of the star are still shed. Cm. Also BLACK HOLE.
In our Galaxy, the Crab Nebula is the remnant of a supernova explosion, which was observed by Chinese scientists in 1054. The famous astronomer T. Brahe also observed a supernova that broke out in our Galaxy in 1572. Although Shelton's supernova was the first nearby supernova discovered since Kepler, hundreds of supernovae in other, more distant galaxies have been seen by telescopes over the past 100 years.
Carbon, oxygen, iron and heavier elements can be found in the remnants of a supernova explosion. Consequently, these explosions play an important role in nucleosynthesis, the process of formation of chemical elements. It is possible that 5 billion years ago the birth of the Solar system was also preceded by a supernova explosion, as a result of which many elements that became part of the Sun and planets arose. NUCLEOSYNTHESIS.
A supernova is an explosion of dying very large stars with a huge release of energy, a trillion times the energy of the Sun. A supernova can illuminate the entire galaxy, and the light sent by the star will reach the edge of the Universe. If one of these stars explodes at a distance of 10 light years from the Earth, the Earth will completely burn up from the release of energy and radiation.
Supernova
Supernovae not only destroy, they also replenish the necessary elements into space: iron, gold, silver and others. Everything we know about the Universe was created from the remains of a supernova that once exploded. A supernova is one of the most beautiful and interesting objects in the Universe. The largest explosions in the Universe leave behind special, strangest remains in the Universe:
Neutron stars
Neutrons are very dangerous and strange bodies. When a giant star goes supernova, its core shrinks to the size of an Earth metropolis. The pressure inside the nucleus is so great that even the atoms inside begin to melt. When atoms are so compressed that there is no space left between them, colossal energy accumulates and a powerful explosion occurs. The explosion leaves behind an incredibly dense Neutron Star. A teaspoon of a Neutron star will weigh 90 million tons.
A pulsar is the remains of a supernova explosion. A body that is similar to the mass and density of a neutron star. Rotating at great speed, pulsars release bursts of radiation into space from the north and south poles. The rotation speed can reach 1000 revolutions per second.
When a star 30 times the size of our Sun explodes, it creates a star called a Magnetar. Magnetars create powerful magnetic fields that are even stranger than Neutron stars and Pulsars. Magnitar's magnetic field is several thousand times greater than the Earth's.
Black holes
After the death of hypernovae, stars even larger than a superstar, the most mysterious and dangerous place in the Universe is formed - a black hole. After the death of such a star, a black hole begins to absorb its remains. The black hole has too much material to absorb and it throws the remains of the star back into space, forming 2 beams of gamma radiation.
As for ours, the Sun, of course, does not have enough mass to become a black hole, pulsar, magnetar or even a neural star. By cosmic standards, our star is very small for such an ending to its life. Scientists say that after the fuel is depleted, our star will increase in size several tens of times, which will allow it to absorb the terrestrial planets: Mercury, Venus, Earth and, possibly, Mars.
How many impressions are associated with these words among amateurs and professionals - space explorers. The word “new” itself carries a positive meaning, and “super” has a super positive meaning, but, unfortunately, it deceives the very essence. Supernovae can rather be called super-old stars, because they are practically the last stage of the development of a Star. So to speak, a bright eccentric apotheosis of star life. The flare sometimes eclipses the entire galaxy in which the dying star is located, and ends with its complete extinction.
Scientists have identified 2 types of Supernovae. One is affectionately nicknamed the explosion of a white dwarf (type I) which, compared to our sun, is denser, and at the same time much smaller in radius. Small, heavy White dwarf is the penultimate normal stage of the evolution of many stars. There is practically no hydrogen in the optical spectrum anymore. And if a white dwarf exists in a symbiosis of a binary system with another star, it draws its matter until it exceeds its limit. S. Chandresekhar in the 30s of the 20th century said that each dwarf has a clear limit of density and mass, exceeding which collapse occurs. It is impossible to shrink endlessly and sooner or later an explosion must occur! The second type of supernova formation is caused by the process of thermonuclear fusion, which forms heavy metals and contracts into itself, causing the temperature in the center of the star to rise. The core of the star is compressed more and more and neutronization processes (“grating” protons and electrons, during which both turn into neutrons) begin to occur in it, which leads to a loss of energy and cooling of the center of the star. All this provokes a rarefied atmosphere, and the shell rushes towards the core. Explosion! Myriads of small pieces of a star scatter throughout space, and a bright glow from a distant galaxy, where millions of years ago (the number of zeros in years of visibility of a star depends on its distance from Earth) the star exploded, is visible today to scientists of planet Earth. News of the tragedy of the past, another life cut short, a sad beauty that we can sometimes observe for centuries.
For example, the Crab Nebula, which can be seen through the telescope eye of modern observatories, is the consequences of a supernova explosion, which was seen by Chinese astronomers in 1054. It is so interesting to realize that what you are looking at today was admired for almost 1000 years by a person who no longer existed on Earth for a long time. This is the whole mystery of the Universe, its slow, drawn-out existence, which makes our life like a flash of a spark from a fire, it amazes and leads to some awe. Scientists have identified several of the most famous supernova explosions, which are designated according to a clearly defined scheme. Latin SuperNova is abbreviated to the characters SN, followed by the year of observation, and at the end the serial number in the year is written. Thus, the following names of famous supernovae can be seen: 
The Crab Nebula - as mentioned earlier, it is the result of a supernova explosion, which is located at a distance of 6,500 light years from Earth, with a diameter today of 6,000 light years. This nebula continues to fly apart in different directions, although the explosion occurred just under 1000 years ago. And in its center there is a neutron star-pulsar, which rotates around its axis. Interestingly, at high brightness this nebula has a constant flow of energy, which allows it to be used as a reference point in the calibration of X-ray astronomy. Another find was supernova SN1572; as the name suggests, scientists observed the explosion in November 1572. By all indications, this star was a white dwarf. In 1604, for a whole year, Chinese, Korean, and then European astrologers could observe the explosion-glow of supernova SN1604, which was located in the constellation Ophiuchus. Johannes Kepler devoted his main work to its study, “On a new star in the constellation Ophiuchus,” and therefore the supernova was named after the scientist - SuperNova Kepler. The closest supernova explosion occurred in 1987 - SN1987A, located in the Large Magellanic Cloud 50 parsecs from our Sun, a dwarf galaxy - a satellite of the Milky Way. This explosion overturned some of the already established theories of stellar evolution. It was supposed that only red giants could flare up, but then, inopportunely, a blue one exploded! Blue supergiant (mass more than 17 solar masses) Sanduleak. The very beautiful remains of the planet form two unusual connecting rings, which scientists are studying today. The next supernova amazed scientists in 1993 - SN1993J, which before the explosion was a red supergiant. But the surprising thing is that the remnants, which were supposed to fade out after the explosion, on the contrary, began to gain brightness. Why?
A few years later, a satellite planet was discovered that was not damaged by the supernova explosion of its neighbor and created the conditions for the glow of the shell of the companion star that was torn off shortly before the explosion (neighbors are neighbors, but you can’t argue with gravity...), observed by scientists. This star is also predicted to become a red giant and a supernova. The explosion of the next supernova in 2006 (SN206gy) is recognized as the brightest glow in the entire history of observing these phenomena. This allowed scientists to put forward new theories of supernova explosions (such as quark stars, the collision of two massive planets, and others) and call this explosion a hypernova explosion! And the last interesting supernova is G1.9+0.3. For the first time, its signals as a radio source of the Galaxy were caught by the VLA radio telescope. And today the Chandra Observatory is studying it. The rate of expansion of the remains of the exploded star is amazing; it is 15,000 km per hour! Which is 5% of the speed of light!
In addition to these most interesting supernova explosions and their remnants, of course, there are other “everyday” events in space. But the fact remains that everything that surrounds us today is the result of supernova explosions. Indeed, in theory, at the beginning of its existence, the Universe consisted of light gases of helium and hydrogen, which, during the burning of stars, were transformed into other “building” elements for all currently existing planets. In other words, the Stars gave their lives for the birth of a new life!
One of the important achievements of the 20th century was the understanding of the fact that almost all elements heavier than hydrogen and helium are formed in the interiors of stars and enter the interstellar medium as a result of supernova explosions, one of the most powerful phenomena in the Universe.
Photo: Blazing stars and wisps of gas provide a breathtaking backdrop to the self-destruction of a massive star called Supernova 1987A. Astronomers observed its explosion in the Southern Hemisphere on February 23, 1987. This image from the Hubble Space Telescope shows supernova remnants surrounded by inner and outer rings of material in diffuse clouds of gas. This three-color image is a composite of several photographs of the supernova and its surrounding region that were taken in September 1994, February 1996, and July 1997. Numerous bright blue stars near the supernova are massive stars, each about 12 million years old and 6 times heavier than the Sun. They all belong to the same generation of stars as the one that exploded. The presence of bright gas clouds is another sign of the youth of this region, which is still fertile ground for the birth of new stars.
Initially, all stars whose brightness suddenly increased by more than 1,000 times were called new. When flaring, such stars suddenly appeared in the sky, disrupting the usual configuration of the constellation, and increased their brightness to the maximum, several thousand times, then their brightness began to fall sharply, and after a few years they became as faint as they were before the flare. The repetition of flares, during each of which the star ejects up to one thousandth of its mass at high speed, is characteristic of new stars. And yet, despite the grandeur of the phenomenon of such a flare, it is not associated either with a fundamental change in the structure of the star, or with its destruction.
Over five thousand years, information has been preserved about more than 200 bright flares of stars, if we limit ourselves to those that did not exceed the 3rd magnitude in brightness. But when the extragalactic nature of the nebulae was established, it became clear that the new stars flaring up in them were superior in their characteristics to ordinary novae, since their luminosity often turned out to be equal to the luminosity of the entire galaxy in which they flared up. The unusual nature of such phenomena led astronomers to the idea that such events were something completely different from ordinary novae, and therefore in 1934, at the suggestion of American astronomers Fritz Zwicky and Walter Baade, those stars whose flares at maximum brilliance reached the luminosities of normal galaxies were identified into a separate, brightest in luminosity and rare class of supernovae.
Unlike outbursts of ordinary novae, supernova outbursts in the current state of our Galaxy are extremely rare phenomena, occurring no more often than once every 100 years. The most striking outbreaks were in 1006 and 1054; information about them is contained in Chinese and Japanese treatises. In 1572, the outbreak of such a star in the constellation Cassiopeia was observed by the outstanding astronomer Tycho Brahe, and the last person to monitor the supernova phenomenon in the constellation Ophiuchus in 1604 was Johannes Kepler. During the four centuries of the “telescopic” era in astronomy, such flares have not been observed in our Galaxy. The position of the Solar System in it is such that we can optically observe supernova explosions in approximately half of its volume, and in the rest of its volume the brightness of the outbreaks is dimmed by interstellar absorption. IN AND. Krasovsky and I.S. Shklovsky calculated that supernova explosions in our Galaxy occur on average once every 100 years. In other galaxies, these processes occur with approximately the same frequency, so the main information about supernovae in the optical burst stage was obtained from observations of them in other galaxies.
Realizing the importance of studying such powerful phenomena, astronomers W. Baade and F. Zwicky, working at the Palomar Observatory in the USA, began a systematic systematic search for supernovae in 1936. They had at their disposal a telescope of the Schmidt system, which made it possible to photograph areas of several tens of square degrees and gave very clear images of even faint stars and galaxies. Over three years, they discovered 12 supernova explosions in different galaxies, which were then studied using photometry and spectroscopy. As observational technology improved, the number of newly discovered supernovae steadily increased, and the subsequent introduction of automated searches led to an avalanche-like increase in the number of discoveries (more than 100 supernovae per year, with a total number of 1,500). In recent years, large telescopes have also begun searching for very distant and faint supernovae, since their studies can provide answers to many questions about the structure and fate of the entire Universe. In one night of observations with such telescopes, more than 10 distant supernovae can be discovered.
As a result of the explosion of a star, which is observed as a supernova phenomenon, a nebula is formed around it, expanding at enormous speed (about 10,000 km/s). A high expansion rate is the main feature by which supernova remnants are distinguished from other nebulae. In supernova remnants, everything speaks of an explosion of enormous power, which scattered the outer layers of the star and imparted enormous speeds to individual pieces of the ejected shell.
Crab Nebula
Not a single space object has given astronomers so much valuable information as the relatively small Crab Nebula, observed in the constellation Taurus and consisting of diffuse gaseous matter flying away at high speed. This nebula, a remnant of a supernova observed in 1054, became the first galactic object with which a radio source was identified. It turned out that the nature of radio emission has nothing in common with thermal emission: its intensity systematically increases with wavelength. Soon it was possible to explain the nature of this phenomenon. The supernova remnant must have a strong magnetic field that traps the cosmic rays it creates (electrons, positrons, atomic nuclei), which have speeds close to the speed of light. In a magnetic field, they emit electromagnetic energy in a narrow beam in the direction of movement. The discovery of non-thermal radio emission from the Crab Nebula prompted astronomers to search for supernova remnants using this very feature.
The nebula located in the constellation Cassiopeia turned out to be a particularly powerful source of radio emission; at meter waves, the flux of radio emission from it is 10 times higher than the flux from the Crab Nebula, although it is much further than the latter. In optical rays, this rapidly expanding nebula is very weak. The Cassiopeia nebula is believed to be the remnant of a supernova explosion that took place about 300 years ago.
A system of filament nebulae in the constellation Cygnus also showed radio emission characteristic of old supernova remnants. Radio astronomy has helped to find many other non-thermal radio sources that turned out to be supernova remnants of different ages. Thus, it was concluded that the remnants of supernova explosions that occurred even tens of thousands of years ago stand out among other nebulae for their powerful non-thermal radio emission.
As already mentioned, the Crab Nebula was the first object from which X-ray emission was discovered. In 1964, it was discovered that the source of X-ray radiation emanating from it is extensive, although its angular dimensions are 5 times smaller than the angular dimensions of the Crab Nebula itself. From which it was concluded that X-ray radiation is emitted not by a star that once erupted as a supernova, but by the nebula itself.
Supernova influence
On February 23, 1987, a supernova exploded in our neighboring galaxy, the Large Magellanic Cloud, which became extremely important for astronomers because it was the first that they, armed with modern astronomical instruments, could study in detail. And this star confirmed a whole series of predictions. Simultaneously with the optical flare, special detectors installed in Japan and Ohio (USA) detected a flux of neutrinos - elementary particles born at very high temperatures during the collapse of the star's core and easily penetrating through its shell. These observations confirmed an earlier suggestion that about 10% of the mass of a collapsing star's core is emitted as neutrinos as the core itself collapses into a neutron star. In very massive stars, during a supernova explosion, the cores are compressed to even greater densities and probably turn into black holes, but the outer layers of the star are still shed. In recent years, indications have emerged that some cosmic gamma-ray bursts are related to supernovae. It is possible that the nature of cosmic gamma-ray bursts is related to the nature of explosions.
Supernova explosions have a strong and diverse impact on the surrounding interstellar medium. The supernova envelope, ejected at enormous speed, scoops up and compresses the gas surrounding it, which can give impetus to the formation of new stars from the clouds of gas. A team of astronomers led by Dr. John Hughes (Rutgers University), using observations from NASA's orbiting Chandra X-ray Observatory, has made an important discovery that sheds light on how silicon, iron and other elements are formed during supernova explosions. An X-ray image of supernova remnant Cassiopeia A (Cas A) reveals clumps of silicon, sulfur and iron ejected from the star's interior during the explosion.
The high quality, clarity and information content of the images of the Cas A supernova remnant obtained by the Chandra Observatory allowed astronomers not only to determine the chemical composition of many nodes of this remnant, but also to find out exactly where these nodes were formed. For example, the most compact and brightest nodes are composed primarily of silicon and sulfur with very little iron. This indicates that they formed deep inside the star, where temperatures reached three billion degrees during the collapse that ended in a supernova explosion. In other nodes, astronomers discovered a very high content of iron with admixtures of some silicon and sulfur. This substance formed even deeper in those parts where the temperature during the explosion reached higher values of four to five billion degrees. A comparison of the locations of both the silicon-rich bright and fainter iron-rich nodes in the Cas A supernova remnant revealed that the “iron” features, originating from the deepest layers of the star, are located at the outer edges of the remnant. This means that the explosion threw the “iron” nodes further than all the others. And even now they appear to be moving away from the center of the explosion at greater speed. Studying the data obtained by Chandra will allow us to settle on one of several mechanisms proposed by theorists that explain the nature of the supernova explosion, the dynamics of the process and the origin of new elements.
SN I supernovae have very similar spectra (without hydrogen lines) and light curve shapes, while SN II spectra contain bright hydrogen lines and are characterized by diversity in both spectra and light curves. In this form, the classification of supernovae existed until the mid-80s of the last century. And with the beginning of the widespread use of CCD receivers, the quantity and quality of observational material increased significantly, which made it possible to obtain spectrograms for previously inaccessible faint objects, to determine the intensity and width of lines with much greater accuracy, and also to register weaker lines in spectra. As a result, the seemingly established binary classification of supernovae began to quickly change and become more complex.
Supernovae also differ according to the types of galaxies in which they explode. In spiral galaxies, supernovae of both types explode, but in elliptical galaxies, where there is almost no interstellar medium and the star formation process has ended, only supernovae of type SN I are observed, obviously, before the explosion - these are very old stars, whose masses are close to the solar one. And since the spectra and light curves of supernovae of this type are very similar, it means that the same stars explode in spiral galaxies. The natural end of the evolutionary path of stars with masses close to the Sun is the transformation into a white dwarf with the simultaneous formation of a planetary nebula. A white dwarf contains almost no hydrogen, since it is the end product of the evolution of a normal star.
Every year, several planetary nebulae are formed in our Galaxy, therefore, most stars of this mass quietly complete their life path, and only once every hundred years does an SN type I supernova burst. What reasons determine a completely special ending, not similar to the fate of other similar stars? The famous Indian astrophysicist S. Chandrasekhar showed that if a white dwarf has a mass less than about 1.4 solar masses, it will quietly “live out” its life. But if it is in a sufficiently close binary system, its powerful gravity is capable of “pulling” matter from the companion star, which leads to a gradual increase in mass, and when it passes the permissible limit, a powerful explosion occurs, leading to the death of the star.
SN II supernovae are clearly associated with young, massive stars whose shells contain large amounts of hydrogen. Outbursts of this type of supernova are considered the final stage of the evolution of stars with an initial mass of more than 8 x 10 solar masses. In general, the evolution of such stars proceeds quite quickly - in a few million years they burn their hydrogen, then helium turns into carbon, and then the carbon atoms begin to transform into atoms with higher atomic numbers.
In nature, transformations of elements with a large release of energy end with iron, whose nuclei are the most stable, and energy release does not occur during their fusion. Thus, when the core of a star becomes iron, the release of energy in it stops, it can no longer resist gravitational forces, and therefore begins to quickly shrink, or collapse.
The processes occurring during collapse are still far from being fully understood. However, it is known that if all the matter in the core turns into neutrons, then it can resist the forces of attraction - the core of the star turns into a “neutron star”, and the collapse stops. In this case, enormous energy is released, entering the shell of the star and causing expansion, which we see as a supernova explosion.
From this one would expect a genetic connection between supernova explosions and the formation of neutron stars and black holes. If the evolution of the star had previously occurred “quietly,” then its envelope should have a radius hundreds of times greater than the radius of the Sun, and also retain a sufficient amount of hydrogen to explain the spectrum of SN II supernovae.
Supernovae and pulsars
The fact that after a supernova explosion, in addition to the expanding shell and various types of radiation, other objects remain, it became known in 1968 due to the fact that a year earlier radio astronomers had discovered pulsars - radio sources whose radiation is concentrated in individual pulses repeated after a strictly defined period of time. Scientists were amazed by the strict periodicity of the pulses and the shortness of their periods. The greatest attention was attracted by the pulsar, the coordinates of which were close to the coordinates of a nebula very interesting for astronomers, located in the southern constellation Velae, which is considered the remnant of a supernova explosion; its period was only 0.089 seconds. And after the discovery of a pulsar in the center of the Crab Nebula (its period was 1/30 of a second), it became clear that pulsars are somehow related to supernova explosions. In January 1969, a pulsar from the Crab Nebula was identified with a faint star of 16th magnitude, changing its brightness with the same period, and in 1977 it was possible to identify a pulsar in the constellation Velae with the star.
The periodicity of pulsar radiation is associated with their rapid rotation, but not a single ordinary star, not even a white dwarf, could rotate with a period characteristic of pulsars; it would be immediately torn apart by centrifugal forces, and only a neutron star, very dense and compact, could resist them. As a result of analyzing many options, scientists came to the conclusion that supernova explosions are accompanied by the formation of neutron stars - a qualitatively new type of object, the existence of which was predicted by the theory of the evolution of high-mass stars.
Supernovae and black holes
The first evidence of a direct connection between a supernova explosion and the formation of a black hole was obtained by Spanish astronomers. A study of the radiation emitted by a star orbiting a black hole in the binary system Nova Scorpii 1994 found that it contains large amounts of oxygen, magnesium, silicon and sulfur. There is an assumption that these elements were captured by it when a neighboring star, having survived a supernova explosion, turned into a black hole.
Supernovae (especially Type Ia supernovae) are among the brightest star-shaped objects in the Universe, so even the most distant of them can be studied using currently available equipment. Many Type Ia supernovae have been discovered in relatively nearby galaxies. Sufficiently accurate estimates of the distances to these galaxies made it possible to determine the luminosity of supernovae exploding in them. If we assume that distant supernovae have the same luminosity on average, then the distance to them can be estimated from the observed magnitude at maximum brightness. Comparing the distance to the supernova with the receding speed (red shift) of the galaxy in which it exploded makes it possible to determine the main quantity characterizing the expansion of the Universe - the so-called Hubble constant.
Even 10 years ago, values were obtained for it that differed by almost two times - from 55 to 100 km/s Mpc, but today the accuracy has been significantly increased, as a result of which the value 72 km/s Mpc is accepted (with an error of about 10%) . For distant supernovae, whose redshift is close to 1, the relationship between distance and redshift also allows us to determine quantities that depend on the density of matter in the Universe. According to Einstein's general theory of relativity, it is the density of matter that determines the curvature of space, and therefore the future fate of the Universe. Namely: will it expand indefinitely or will this process ever stop and be replaced by compression. Recent studies of supernovae have shown that most likely the density of matter in the Universe is insufficient to stop the expansion, and it will continue. And in order to confirm this conclusion, new observations of supernovae are needed.