The sky on a clear day is, in general, a rather boring and monotonous picture: a hot ball of the Sun and a clear boundless space, sometimes adorned with clouds or occasional clouds.
Another thing is the sky on a cloudless night. It is usually all strewn with bright clusters of stars. At the same time, it should be taken into account that in the night sky with the naked eye you can see from 3 to 4.5 thousand night luminaries. And they all belong to the Milky Way, in which ours is also located. solar system.
By modern ideas stars are hot balls of gas, in the depths of which thermonuclear fusion helium nuclei from hydrogen nuclei with the release of an enormous amount of energy. It is she who provides the luminosity of stars.
The closest star to us is our Sun, which is 150 million kilometers away. But the star Proxima Centauri, next in distance, is located at a distance of 4.25 from us light year, or 270 thousand times farther than the Sun.
There are stars that are hundreds of times larger than the Sun and the same number of times inferior to it in this indicator. However, the masses of stars vary within much more modest limits - from one twelfth of the mass of the Sun to 100 of its masses. More than half visible stars are double and sometimes triple systems.
In general, the number of stars in the Universe visible to us can be denoted by the number 125,000,000,000 with eleven additional zeros.
Now, to avoid confusion with zeros, astronomers no longer keep records. individual stars, but of entire galaxies, assuming that on average there are about 100 billion stars in each of them.
American astronomer Fritz Zwicky pioneered a targeted search for supernovae.
Back in 1996, scientists estimated that 50 billion galaxies could be seen from Earth. When was it commissioned orbiting telescope name of Hubble, which is not interfered with by interference earth's atmosphere, the number of visible galaxies jumped to 125 billion.
Thanks to the all-seeing eye of this telescope, astronomers have penetrated into such depths of the universe that they have seen galaxies that appeared just one billion years after the Great Bang that gave birth to our Universe.
Several parameters are used to characterize stars: luminosity, mass, radius, and chemical composition atmosphere, as well as its temperature. And using a number of additional characteristics of a star, you can also determine its age.
Each star is a dynamic structure that is born, grows and then, having reached a certain age, quietly dies. But it also happens that it suddenly explodes. This event leads to large-scale changes in the area adjacent to the exploded star.
Thus, the perturbation that followed this explosion spreads at a gigantic speed, and for several tens of thousands of years captures huge space in interstellar medium. In this region, the temperature rises sharply, up to several million degrees, the density of cosmic rays and the strength of the magnetic field increase significantly.
Such features of the substance ejected by the exploded star allow it to form new stars and even entire planetary systems.
For this reason, both supernovae and their remnants are studied very closely by astrophysicists. After all, the information obtained in the course of studying this phenomenon can expand knowledge about the evolution of normal stars, about the processes that occur during the birth of neutron stars, and also clarify the details of those reactions that result in the formation of heavy elements, cosmic rays etc.
At one time, those stars whose brightness suddenly increased by more than 1000 times were called novae by astronomers. They appeared in the sky unexpectedly, making changes to the usual configuration of the constellations. Suddenly increasing at a maximum of several thousand times, their brightness after some time sharply decreased, and after a few years their brightness became as weak as before the explosion.
It should be noted that the frequency of outbursts, during which the star is released from one thousandth of its mass and which with great speed throws in world space, is considered one of the main signs of the birth of new stars. But, at the same time, strange as it may seem, the explosions of stars do not lead to significant changes in their structure, not even to their destruction.
How often do such events happen in our galaxy? If we take into account only those stars that did not exceed the 3rd magnitude in their brightness, then, according to historical chronicles and observations of astronomers, no more than 200 bright flashes were observed over five thousand years.
But when studies of other galaxies began to be carried out, it became obvious that the brightness of new stars that appear in these corners of space is often equal to the luminosity of the entire galaxy in which these stars appear.
Of course, the appearance of stars with such luminosity is an extraordinary event and absolutely unlike the birth ordinary stars. Therefore, back in 1934, the American astronomers Fritz Zwicky and Walter Baade proposed that those stars whose maximum brightness reaches the luminosity of ordinary galaxies should be classified as a separate class of supernovae and the most bright stars. It should be kept in mind that supernova explosions in state of the art Our Galaxy is an extremely rare phenomenon, occurring no more than once every 100 years. The most striking outbreaks that Chinese and Japanese treatises recorded occurred in 1006 and 1054.
Five hundred years later, in 1572, a flash from above new star in the constellation of Cassiopeia was observed by the outstanding astronomer Tycho Brahe. In 1604, Johannes Kepler saw the birth of a supernova in the constellation Ophiuchus. And since then, such grandiose events have not been noted in our Galaxy.
Perhaps this is due to the fact that the solar system occupies such a position in our Galaxy that it can be observed in optical instruments supernova explosions from the Earth is possible only in half of its volume. In the remaining part, this is hindered by interstellar absorption of light.
And since in other galaxies these phenomena occur with approximately the same frequency as in the Milky Way, the main information about supernovae at the time of the outbreak was obtained from observations of them in other galaxies ...
For the first time in 1936, astronomers W. Baade and F. Zwicky began to engage in a targeted search for supernovae. During three years of observations in different galaxies, scientists discovered 12 supernova explosions, which were subsequently subjected to more thorough research using photometry and spectroscopy.
Moreover, the use of more advanced astronomical equipment has made it possible to expand the list of newly discovered supernovae. And the introduction of automated search has led to the fact that scientists have discovered more than a hundred supernovae per year. In total for a short time 1500 of these objects were recorded.
AT last years via powerful telescopes in one night of observations, scientists discovered more than 10 distant supernovae!
In January 1999, an event occurred that shocked even modern astronomers, accustomed to many "tricks" of the Universe: a flash was recorded in the depths of space ten times brighter than all those that were recorded by scientists before. She was noticed by two research satellites and a telescope in the mountains of New Mexico, equipped with an automatic camera. It happened unique phenomenon in the constellation Bootes. A little later, in April of the same year, scientists found that the distance to the flash was nine billion light years. This is almost three-quarters of the radius of the universe.
Calculations made by astronomers showed that in a few seconds, during which the flash lasted, energy was released many times more than the Sun produced during the five billion years of its existence. What caused such an incredible explosion? What processes gave rise to this grandiose energy release? Science cannot yet answer these questions specifically, although there is an assumption that such great amount energy could occur in the event of a merger of two neutron stars.
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Their occurrence is a rather rare cosmic phenomenon. On average, three supernovae per century flare up in the open spaces of the Universe accessible to observation. Each such flash is a gigantic cosmic catastrophe, in which an incredible amount of energy is released. At the most rough estimate, this amount of energy could be generated by the simultaneous explosion of many billions of hydrogen bombs.
A fairly rigorous theory of supernovae is not yet available, but scientists have put forward an interesting hypothesis. They suggested, based on the most complex calculations, that during the alpha fusion of elements, the core continues to shrink. The temperature in it reaches a fantastic figure - 3 billion degrees. Under such conditions, various are significantly accelerated in the nucleus; as a result, a lot of energy is released. The rapid contraction of the core entails an equally rapid contraction of the stellar envelope.
It also gets very hot, and the nuclear reactions, in turn, are greatly accelerated. Thus, literally in a matter of seconds, a huge amount of energy is released. This results in an explosion. Of course, such conditions are by no means always achieved, and therefore supernovae flare up quite rarely.
That is the hypothesis. How scientists are right in their assumptions, the future will show. But the present has led researchers to absolutely amazing guesses. Astrophysical methods have made it possible to trace how the luminosity of supernovae decreases. And here's what turned out: in the first few days after the explosion, the luminosity decreases very quickly, and then this decrease (within 600 days) slows down. Moreover, every 55 days the luminosity weakens exactly by half. From the point of view of mathematics, this decrease occurs according to the so-called exponential law. good example such a law is the law of radioactive decay. Scientists have made a bold assumption: the release of energy after a supernova explosion is due to radioactive decay an isotope of an element with a half-life of 55 days.
But what isotope and what element? This search continued for several years. "Candidates" for the role of such "generators" of energy were beryllium-7 and strontium-89. They fell apart by half in just 55 days. But they did not manage to pass the exam: calculations showed that the energy released during their beta decay is too small. And other famous radioactive isotopes did not have a similar half-life.
A new contender showed up among the elements that do not exist on Earth. He turned out to be a representative of transuranium elements synthesized artificially by scientists. The applicant's name is Californian, his serial number- ninety eight. Its isotope californium-254 has only been prepared in amounts of about 30 billionths of a gram. But even this truly weightless amount was quite enough to measure the half-life of the isotope. It turned out to be equal to 55 days.
And from this a curious hypothesis arose: it is the energy of the decay of californium-254 that provides an unusually high luminosity of a supernova for two years. The decay of californium occurs by spontaneous fission of its nuclei; with this type of decay, the nucleus, as it were, splits into two fragments - the nuclei of the elements in the middle of the periodic system.
But how is californium itself synthesized? Scientists here give a logical explanation. During the compression of the nucleus, which precedes the explosion of a supernova, the nuclear reaction of the interaction of the already familiar neon-21 with alpha particles is unusually accelerated. The consequence of this is the appearance within a rather short period of time of an extremely powerful flux of neutrons. The process of neutron capture occurs again, but this time it is fast. The nuclei have time to absorb the next neutrons before they turn up to beta decay. For this process, the instability of transbismuth elements is no longer an obstacle. The chain of transformations will not break, and the end periodic table will also be filled. In this case, apparently, even such transuranium elements are formed, which in artificial conditions not received yet.
Scientists have calculated that in every supernova explosion, californium-254 alone produces a fantastic amount. From this amount, 20 balls could be made, each of which would weigh as much as our Earth. What is the further fate supernova? She dies pretty quickly. In place of its flash, only a small, very dim star remains. It's different, but it's amazing high density substances: filled with it Matchbox would weigh tens of tons. Such stars are called "". What happens to them next, we do not yet know.
Matter that is ejected into world space can condense and form new stars; they start a new one long way development. Scientists have so far made only general rough strokes of the picture of the origin of elements, pictures of the work of stars - grandiose factories of atoms. Perhaps this comparison generally conveys the essence of the matter: the artist sketches on the canvas only the first contours of the future work of art. The main idea is already clear, but many, including essential, details still have to be guessed.
The final solution of the problem of the origin of the elements will require the colossal work of scientists of various specialties. It is likely that much that now seems to us beyond doubt will in fact turn out to be grossly approximate, if not completely wrong. Probably, scientists will have to face patterns that are still unknown to us. After all, in order to understand the most complex processes, flowing in the Universe, no doubt, a new qualitative leap will be needed in the development of our ideas about it.
Astronomers have officially announced one of the most high-profile events in scientific world: in 2022 from Earth naked eye we will be able to see a unique phenomenon - one of the brightest supernova explosions. According to forecasts, it will outshine the radiance of most stars in our galaxy with its light.
We are talking about a close binary system KIC 9832227 in the constellation Cygnus, which is separated from us by 1800 light years. The stars in this system are located so close to each other that they have a common atmosphere, and the speed of their rotation is constantly increasing (now the rotation period is 11 hours).
About a possible collision, which is expected in about five years (plus or minus one year), said at the annual meeting of the American Astronomical Society Professor Larry Molnar (Larry Molnar) from Calvin College in the United States. According to him, to predict such space disasters quite difficult - the study took several years (astronomers began to study the stellar pair back in 2013).
Daniel Van Noord was the first to make such a prediction. Researcher Molnara (still a student at that time).
"He studied how the color of a star correlates with its brightness, and suggested that we are dealing with a binary object, moreover, with a close binary system - one where two stars have general atmosphere, like two peanut kernels under one shell," Molnar explains in a press release.
In 2015, Molnar, after several years of observation, told his colleagues about the forecast: astronomers are likely to experience an explosion similar to the birth of supernova V1309 in the constellation Scorpio in 2008. Not all scientists took his statement seriously, but now, after new observations, Larry Molnar again touched on this topic, presenting even more data. Spectroscopic observations and processing of more than 32 thousand images obtained from different telescopes ruled out other scenarios for the development of events.
Astronomers believe that when the stars crash into each other, both will die, but before that they will emit a lot of light and energy, forming a red supernova and increasing the brightness of the binary star ten thousand times. The supernova will be visible in the sky as part of the constellation Cygnus and the Northern Cross. This will be the first time that professionals and even amateurs will be able to follow double stars right at the time of their death.
"It will be very abrupt change in the sky and anyone can see it. You don't need a telescope to tell me in 2023 if I was right or wrong. While the absence of an explosion will disappoint me, any alternative outcome will be no less interesting," adds Molner.
According to astronomers, the forecast really cannot be taken lightly: for the first time, experts have the opportunity to observe the last few years of the life of stars before their merger.
Future research will help to learn a lot about such binary systems and their internal processes, as well as the consequences of a large-scale collision. "Explosions" of this kind, according to statistics, occur about once every ten years, but this is the first time that a collision of stars will occur on. Previously, for example, scientists observed an explosion.
A preprint of a possible future paper by Molnar (PDF document) can be read on the College website.
By the way, in 2015, ESA astronomers discovered a unique one in the Tarantula Nebula, whose orbits are at an incredibly small distance from each other. Scientists have predicted that at some point such a neighborhood will end tragically: celestial bodies will either merge into single star gigantic sizes, or a supernova explosion will occur, which will give rise to a binary system.
We also recall that earlier we talked about how supernova explosions.
SUPERNOVA
SUPERNOVA, the explosion of a star, in which almost the entire STAR is destroyed. Within a week, a supernova can outshine all other stars in the galaxy. The luminosity of a supernova at 23 magnitudes(1000 million times) greater than the luminosity of the Sun, and the energy released during the explosion is equal to all the energy emitted by the star during its entire previous life. After a few years, the supernova increases in volume so much that it becomes rarefied and translucent. For hundreds or thousands of years, the remnants of the ejected matter are visible as supernova remnants. A supernova is about 1000 times brighter than a NEW STAR. Every 30 years, a galaxy like ours has about one supernova, but most of these stars are obscured by dust. Supernovae are of two main types, distinguished by their light curves and spectra.
Supernovae - unexpectedly flashing stars, sometimes acquiring a brightness of 10,000 million times greater than the brightness of the Sun. This happens in several stages. At the beginning (A), a huge star develops very quickly to the stage when various nuclear processes begin to proceed inside the star at the same time. Iron can form in the center, which means the end of production nuclear energy. The star then begins to undergo gravitational collapse (B). This, however, heats up the center of the star to such an extent that the chemical elements decay and new reactions proceed with explosive force (C). thrown out most of matter of the star into space, while the remnants of the center of the star collapse until the star becomes completely dark, possibly becoming a very dense neutron star (D). One such grain was visible in 1054. in the constellation Taurus (E). The remnant of this star is a cloud of gas called the Crab Nebula (F).
Scientific and technical encyclopedic dictionary.
See what "SUPERNOV STAR" is in other dictionaries:
"Supernova" redirects here; see also other meanings. Kepler's supernova remnant Supernovae ... Wikipedia
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Books
- The Finger of Destiny (including a full review of the unaspected planets), Hamaker-Zondag K. The book by the famous astrologer Karen Hamaker-Zondag is the fruit of twenty years of work on the study of the mysterious and often unpredictable hidden factors of the horoscope: the Finger of Destiny configurations, ...
supernovae- one of the greatest space phenomena. In short, a supernova is a real explosion of a star, when most of its mass (and sometimes all) flies apart at a speed of up to 10,000 km / s, and the rest is compressed (collapses) into a superdense neutron star or into black hole. Supernovas are playing important role in the evolution of stars. They are the final life of stars with a mass of more than 8-10 solar masses, giving birth to neutron stars and black holes and enriching the interstellar medium with heavy chemical elements. All elements heavier than iron were formed as a result of the interaction of the nuclei of lighter elements and elementary particles in explosions massive stars. Isn't here the key to the eternal attraction of mankind to the stars? Indeed, in the smallest cell of living matter there are iron atoms synthesized during the death of some massive star. And in this sense, people are akin to the snowman from Andersen's fairy tale: he experienced strange love to the hot stove, because the poker served as a frame for it ...
Scientists have noticed that in elliptical galaxies(i.e., galaxies without a spiral structure, with a very low rate of star formation, consisting mainly of low-mass red stars), only type 1 supernovae flare up. In spiral galaxies, to which our Galaxy belongs - Milky Way, both types of supernovae occur. At the same time, representatives of the 2nd type concentrate towards the spiral arms, where active process star formation and many young massive stars. These features suggest the different nature two types of supernovae.
Now it is reliably established that the explosion of any supernova releases a huge amount of energy - about 10 46 J! The main energy of the explosion is carried away not by photons, but by neutrinos - fast particles with very little or no zero mass rest. Neutrinos interact extremely weakly with matter, and for them the interior of a star is completely transparent.
A complete theory of a supernova explosion with the formation of a compact remnant and ejection of the outer shell has not yet been created due to the extreme complexity of taking into account all the physical processes. However, all evidence suggests that type 2 supernovae flare as a result of the collapse of the cores of massive stars. On the different stages the life of a star in the core took place thermonuclear reactions, in which first hydrogen was converted into helium, then helium into carbon, and so on until the formation of the "iron peak" elements - iron, cobalt and nickel. The atomic nuclei of these elements have the maximum binding energy per particle. It is clear that the addition of new particles to atomic nucleus, for example, iron will require significant energy costs, and therefore thermonuclear combustion “stops” at the elements of the iron peak.
What causes the central parts of the star to lose stability and collapse as soon as the iron core becomes massive enough (about 1.5 solar masses)? Currently, two main factors leading to loss of stability and collapse are known. Firstly, this is the "disintegration" of iron nuclei into 13 alpha particles (helium nuclei) with the absorption of photons - the so-called photodissociation of iron. Secondly, the neutronization of matter is the capture of electrons by protons with the formation of neutrons. Both processes are possible when high densities(over 1 t/cm 3 ), which are established in the center of the star at the end of evolution, and both of them effectively reduce the "elasticity" of the substance, which actually resists the compressive action of gravitational forces. As a result, the core loses its stability and shrinks. In this case, during the neutronization of the substance, a large number of neutrinos carrying away the main energy stored in the collapsing nucleus.
Unlike the catastrophic collapse of the core, which has been theoretically developed in sufficient detail, the ejection of the stellar shell (the explosion itself) is not so easy to explain. More likely, essential role neutrinos play in this processAccording to computer calculations, the density near the core is so high that even neutrinos that interact weakly with matter are for some time "locked" by the outer layers of the star. But gravitational forces pull the shell towards the core, and a situation arises similar to that which occurs when trying to pour a denser liquid, such as water, over a less dense liquid, such as kerosene or oil. (From experience it is well known that a light liquid tends to "float" from under a heavy one - here the so-called Rayleigh-Taylor instability manifests itself.) This mechanism causes giant convective motions, and when in the end the momentum of the neutrino is transferred outer shell, it is discharged into the surrounding space.
Perhaps it is the neutrino convective motions that lead to the violation spherical symmetry supernova explosion. In other words, a direction appears along which the substance is predominantly ejected, and then the resulting residue receives a recoil momentum and begins to move in space by inertia at a speed of up to 1000 km/s. Such high spatial velocities were noted in young neutron stars- radio pulsars.
The described schematic picture of a type 2 supernova explosion makes it possible to understand the main observational features of this phenomenon. And the theoretical predictions based on this model (especially concerning the total energy and spectrum of a neutrino burst) turned out to be in full agreement with a neutrino pulse registered on February 23, 1987, which came from a supernova in the Large Magellanic Cloud.
Now a few words about type 1 supernovae. The absence of hydrogen emission in their spectra indicates that the explosion occurs in stars devoid of a hydrogen shell. As it is now believed, this may be the explosion of a white dwarf or the result of the collapse of a star. Wolf-Rayet type(in fact, these are the cores of massive stars rich in helium, carbon and oxygen).
How can it explode white dwarf? Indeed, in this very dense star, nuclear reactions do not take place, and the forces of gravity are counteracted by the pressure of a dense gas consisting of electrons and ions (the so-called degenerate electron gas). The reason here is the same as in the collapse of the cores of massive stars - a decrease in the elasticity of the matter of the star with an increase in its density. This is again due to the “pressing” of electrons into protons with the formation of neutrons, as well as some relativistic effects.
Why does the density of a white dwarf increase? This is not possible if it is single. But if a white dwarf is part of a fairly close binary system, then under the action of gravitational forces gas from a neighboring star is able to flow to a white dwarf (as in the case of a new star). At the same time, its mass and density will gradually increase, which will eventually lead to collapse and explosion.
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Another possible variant more exotic, but no less real, is the collision of two white dwarfs. How can this be, because the probability of two white dwarfs colliding in space is negligible, since the number of stars per unit volume is negligible - at most a few stars in 100 pc3. And here (for the umpteenth time!) "guilty" double stars, but now consisting of two white dwarfs.
As follows from general theory Einstein's relativity, any two masses orbiting each other must sooner or later collide due to the constant, albeit very insignificant, entrainment of energy from such a system by gravity waves - gravitational waves. For example, the Earth and the Sun, if the latter lived infinitely long, would have collided as a result of this effect, though after a colossal time, many orders of magnitude greater than the age of the Universe. It has been calculated that in the case of close binary systems with stellar masses near the solar mass (2 10 30 kg), their merger should occur within a time less than the age of the Universe, approximately 10 billion years. Estimates show that in a typical galaxy such events occur once every several hundred years. The gigantic energy released during this catastrophic process is quite enough to explain the supernova phenomenon.
By the way, the approximate equality of the masses of white dwarfs makes their mergers “similar” to each other, which means that type 1 supernovae should look the same in their characteristics, regardless of when and in which galaxy the outbreak occurred. Therefore, the apparent brightness of supernovae reflects the distances to the galaxies in which they are observed. This property of type 1 supernovae is currently used by scientists to obtain independent evaluation the most important cosmological parameter - the Hubble constant, which serves as a quantitative measure of the expansion rate of the Universe. We have only talked about the most powerful explosions stars originating in the Universe and observed in the optical range. Since in the case of supernovae the main energy of the explosion is carried away by neutrinos, and not by light, the study of the sky by the methods of neutrino astronomy has very interesting prospects. It will allow in the future to "look" into the very "inferno" of a supernova, hidden by huge thicknesses of matter opaque to light. Even more amazing discoveries promises gravitational-wave astronomy, which in the near future will tell us about the grandiose phenomena of the merger of double white dwarfs, neutron stars and black holes.
