A star whose birth is accompanied by a supernova explosion. Supernova explosion

Birth of the city But let's return to those times when all this water splendor, not yet clouded by human consumerism, sparkled brightly under the rays of the sun. In that ancient time, rivers were not only natural sources of water supply, not only “suppliers”

It's quite rare for people to see this interesting phenomenon like a supernova. But this is not an ordinary birth of a star, because up to ten stars are born in our galaxy every year. A supernova is a phenomenon that can only be observed once every hundred years. The stars die so brightly and beautifully.

To understand why a supernova explosion occurs, we need to go back to the very birth of the star. Hydrogen flies in space, which gradually gathers into clouds. When the cloud is large enough, condensed hydrogen begins to accumulate in its center, and the temperature gradually rises. Under the influence of gravity, the core of the future star is assembled, where, thanks to increased temperature and increasing gravity, the thermonuclear fusion reaction begins to take place. How much hydrogen a star can attract to itself determines its future size - from a red dwarf to a blue giant. Over time, the balance of the star's work is established, the outer layers put pressure on the core, and the core expands due to the energy of thermonuclear fusion.

The star is unique and, like any reactor, someday it will run out of fuel - hydrogen. But for us to see how a supernova explodes, a little more time must pass, because in the reactor, instead of hydrogen, another fuel (helium) was formed, which the star will begin to burn, turning it into oxygen, and then into carbon. And this will continue until iron is formed in the core of the star, which during a thermonuclear reaction does not release energy, but consumes it. Under such conditions, a supernova explosion can occur.

The core becomes heavier and colder, causing the lighter upper layers to fall onto it. Fusion starts again, but this time faster than usual, as a result of which the star simply explodes, scattering its matter into the surrounding space. Depending on the known ones may also remain after it - (a substance with an incredibly high density, which is very high and can emit light). Such formations remain after very large stars that managed to produce thermonuclear fusion to very heavy elements. Smaller stars leave behind neutron or iron small stars, which emit almost no light, but also have a high density of matter.

Novas and supernovae are closely related, because the death of one of them can mean the birth of a new one. This process continues endlessly. A supernova carries millions of tons of matter into the surrounding space, which again gathers into clouds, and the formation of a new one begins celestial body. Scientists claim that all the heavy elements that are in our solar system were “stole” by the Sun during its birth from a star that once exploded. Nature is amazing, and the death of one thing always means the birth of something new. Matter disintegrates in outer space and is formed in stars, creating the great balance of the Universe.

Every morning, entering his office and turning on the computer, Paolo Mazzali hopes for news of a cosmic catastrophe. A lean Italian with a well-groomed beard is an employee of the German Max Planck Institute for Astrophysics in Garching near Munich. And a supernova hunter. He hunts down dying stars in space, trying to unravel the secrets of their blinding agony. Explosions of stars are one of the most ambitious cosmic phenomena. And the main one driving force the cycle of birth and death of worlds in the Universe. Shock waves from their explosions spread through space like circles on water. They compress interstellar gas into giant filaments and give impetus to the formation of new planets and stars. And they even influence life on Earth. “Almost all the elements that make up us and our world came from supernova explosions,” says Mazzali.

How do these space nuclear furnaces work? Which stars end their lives with an explosion? And what serves as its detonator? These fundamental questions have been of concern to scientists for a long time. Astronomical instruments are becoming more and more accurate, computer modeling programs are becoming more and more sophisticated. This is why in recent years researchers have been able to unravel many of the secrets of supernovae. And reveal amazing details about how a star lives and dies.
Such a scientific breakthrough became possible due to an increase in the number of observed objects. Previously, astronomers were only able to notice a bright flash of a dying star in space, eclipsing the light of the entire galaxy, by luck. Now automated telescopes systematically monitor the starry sky. A computer programs compare images taken at intervals of several months. And they signal the appearance of new luminous points in the sky or the intensification of the glow of already known stars.
There is also a whole army of amateur astronomers. There are especially many of them in the Northern Hemisphere. Even with the help of low-power telescopes, they are often able to capture bright flashes of dying stars. In 2010, amateurs and professionals observed a total of 339 supernovae. And in 2007, there were as many as 573 “supervised” ones. The only problem is that they are all located in other galaxies, far beyond the Milky Way. This makes them difficult to study in detail.
As soon as a new bright object with unusual characteristics is discovered in space, news of the discovery instantly spreads across the Internet. This happened in the case of supernova 2008D. The "D" in the acronym indicates that this is the fourth supernova discovered in 2008.
The news that on January 9 a group of American astronomers detected a super-powerful emission of X-rays in space found Paolo Mazzali in Tokyo, where he was giving lectures. “When we learned about this,” he says, “we immediately put everything aside and focused on studying this object for three months.”
During the day, Mazzali was in telephone contact with colleagues in Chile, coordinating observations of cosmic fireworks using one of the supertelescopes installed there. And at night he consulted with European scientists. To this day, he recalls with delight this hard work and sleepless nights. Then astronomers had a rare chance to follow the process of the explosion of a star almost from the very beginning to the end. Typically, a dying star is captured by telescopes only a few days after the start of its death throes.
A powerful impetus for development modern research supernovas became the astronomical sensation of the century. It happened in 1987. But Hans-Thomas Janka, Mazzali's colleague at the Institute of Astrophysics, remembers everything as if it were yesterday. On February 25, all employees celebrated the birthday of the head of the institute. Yanka had just defended his diploma and was selecting a topic for his doctoral dissertation. In the middle of the holiday, the news of the discovery of a supernova under the code SN 1987A struck like a bolt from the blue. “It caused quite a stir,” he says. The issue with the topic for the dissertation was instantly resolved.
What's so special about it? It was discovered in the closest galaxy to us - the Large Magellanic Cloud, at a distance of only 160 thousand light years from Earth. By cosmic standards - just a stone's throw away.
And one more interesting coincidence. The grand agony of this star began 160 thousand years ago, when a unique species of primate, Homo sapiens, appeared in the savannas of East Africa.
While the light from its flash reached the Earth, people managed to populate the planet, invent the wheel, create Agriculture and industry, study the complex laws of physics and construct powerful telescopes. Just in time to capture and analyze the light signal from the Magellanic Cloud.
Since 1987, Janka has been working on a computer model that should explain the internal dynamics of the star's death process. Now he has the opportunity to check his virtual reconstructions with real facts. All thanks to data collected during observations of the explosion of the star SN 1987A. It remains the most studied supernova in history.

Stars that are more than eight times the mass of our Sun will sooner or later “collapse” under their own weight and explode (1) By the end of its life, the star is a layered structure like an onion. Each layer consists of atoms of a specific chemical element. In the figure, the scale has been changed for clarity. In fact, the layers vary even more in thickness. For example, the hydrogen shell makes up 98 percent of the radius of the planet, and the iron core makes up only 0.002 percent. (2) When the mass of the iron core at the center of the star becomes more than 1.4 solar masses, collapse occurs: it collapses under the influence of its own gravity. And a super-dense neutron star is formed. (3) Matter falling onto a neutron star bounces off its surface and creates a blast wave, like a powerful acoustic boom, when it breaks the supersonic barrier. It spreads from the inside out. (4) Elementary neutrino particles, escaping almost at the speed of light from the depths of a neutron star, unevenly push the shock wave outward. She rushes through the layers of the star, tearing them apart

EXPLOSIVE FINALE

Supernova explosions are the driving force behind the cycle of matter. They spew out "galactic fountains" of gas from which new stars are formed.

1. Supernova explosions 2. Hot gas bubble 3. Gas rises from the galactic disk 4. The gas cools down and falls back

EXPLOSIVE FINALE

The second type is supernovae with a collapsing core. In their case, the source of explosive energy is the force of gravity, which compresses the matter of a star weighing at least eight solar masses and causes it to “collapse.” Explosions of this type are recorded three times more often. And it is they who create the conditions for the formation of such heavy chemical elements as silver and cadmium.
Supernova SN 1987A belongs to the second type. This can be seen already by the size of the star - the culprit of the cosmic commotion. It was 20 times heavier than the Sun. And she went through the typical evolution for luminaries of this weight category.
A star begins its life as a cold, tenuous cloud of interstellar gas. It contracts under its own gravity and gradually takes the shape of a ball. At first, it consists primarily of hydrogen, the first chemical element to appear shortly after the Big Bang, which began our Universe. At the next stage of the star's life, hydrogen nuclei merge to form helium. During this nuclear fusion, a huge amount of energy is released, which causes the star to glow. From the “multiplied” helium, more and more complex elements are synthesized - first carbon, and then oxygen. At the same time, the temperature of the star increases, and heavier atoms are formed in its flame. Iron closes the chain of thermonuclear fusion. When iron nuclei merge with the nuclei of other elements, energy is no longer released, but, on the contrary, is expended. At this stage, the evolution of any star stops.
By that time, it already represents a layered onion-type structure. Each layer corresponds to a certain stage of its development. On the outside there is a hydrogen shell, underneath there are layers of helium, carbon, oxygen, and silicon. And in the center is a core consisting of compressed gaseous iron, heated to several billion degrees. It is compressed so tightly that a dice cube made from such material would weigh ten thousand tons.
“From now on, disaster is inevitable,” says Janka. Sooner or later, the pressure in the growing iron core can no longer contain the pressure of its own gravity. And it “collapses” in a split second. Matter exceeding the mass of the Sun is compressed into a ball with a diameter of only 20 kilometers. Under the influence of gravity inside the nucleus, negatively charged electrons are “pressed” into positively charged protons and form neutrons. A neutron star is formed from the core - a dense clot of so-called “exotic matter”.
“The neutron star can no longer contract further,” explains Janka. “Its shell turns into an impenetrable wall, from which the substance from the upper layers, attracted to the center, bounces off.” The internal explosion causes a reverse shock wave that rushes outward through all the layers. At the same time, the matter becomes monstrously hot. Near the core, its temperature reaches 50 billion degrees on the Kelvin scale. When the shock wave reaches the shell of the star, a fountain of heated gas bursts into space at a breakneck speed - over 40 thousand kilometers per second. And at the same time it emits light. The star flashes brightly. It is this flash that astronomers see through telescopes, thousands or even millions of years later, when the light reaches the Earth.

As computer models programmed taking into account all the laws of physics show, complex thermonuclear reactions occur in the hellfire around a neutron star. Light elements such as oxygen and silicon “burn out” into heavy elements such as iron and nickel, titanium and calcium.
For a long time it was believed that in this cataclysm the most severe chemical elements- gold, lead and uranium. But recent calculations by Hans-Thomas Janki and his colleagues have shaken this theory. The simulation showed that the power of the “wind of particles” emanating from the supernova is not enough to “squeeze” free neutrons into the flying nuclei of atoms to create increasingly heavier agglomerates.
But where do heavy elements come from then? They are born during the collision of neutron stars left after supernova explosions, Janka believes. This leads to a colossal ejection of hot matter into space. Moreover, the frequency distribution of heavy elements in this matter obtained during modeling coincides with the real parameters of the Solar System. So supernovae have lost their monopoly on the creation of cosmic matter. But it all starts with them.
At the moment of its explosion and then as it transforms into an expanding nebula, a supernova is a mesmerizing sight. But the paradox is that, by the standards of physics, this grandiose cosmic fireworks display, although spectacular, is just a side effect. During the gravitational collapse of a star, more energy is released in one second than all the stars in the Universe emit in the “normal mode”: about 10 46 joules. “But 99 percent of this energy is released not through a flash of light, but in the form of invisible neutrino particles,” says Janka. In ten seconds, a colossal amount of these ultra-light particles is formed in the iron core of the star - 10 octodecillion, that is, 10 to the 58th power.
On February 23, 1987, a scientific sensation thundered: three sensors in Japan, the USA and the USSR recorded two dozen neutrinos from the supernova 1987A explosion. “Before this, the idea of ​​neutron stars arising from gravitational collapse followed by the release of energy in the form of neutrinos was pure hypothesis,” says Janka. “And finally it was confirmed.” But so far this is the only recorded neutrino signal from an exploding star. It is extremely difficult to detect traces of these particles because they hardly interact with matter. Later, when analyzing this phenomenon, astrophysicists had to be content with computer modeling. And they have also come very far forward. For example, it turned out that without volatile neutrinos, cosmic fireworks could not flare up. In Yankee's first computer models, the virtual front of the blast wave of massive stars did not reach the surface, but “faded” after the first 100 kilometers, wasting all the initial energy.
The researchers realized that they had missed some important factor. After all, in reality, stars do explode. “Then we started looking for the mechanism that causes the secondary detonation of a supernova,” says Janka. To solve the “supernova problem” they spent long years. As a result, it was possible to accurately simulate the processes occurring in the first fractions of a second of the explosion. And find the solution.
Yanka shows a short animated video on her computer. First, a perfectly round red spot appears on the screen - the center of the supernova. After 40 milliseconds, this ball begins to deform more and more. The front of the shock wave bends in one direction or the other. Pulsates and sways. It seems as if the gas envelope of the star is swelling. After another 600 milliseconds it bursts. An explosion occurs.
Scientists comment on this process: funnels and bubbles form in the hot layers of the star, like on the surface of porridge during cooking. In addition, the bubbling substance moves back and forth between the shell and the core. And thanks to this, it is exposed longer to high-energy neutrinos escaping from the bowels of the star. They give matter the impulse necessary for an explosion.
Ironically, it is these “neutral” particles, which usually pass through matter without a trace, that serve as the detonator of a supernova explosion. The costs of scientists studying the mystery of dying stars are astronomical, matching the scale of the phenomenon itself. Just modeling the processes occurring in the first 0.6 seconds of stellar core collapse took three years of continuous work. "We used full power all available supercomputers in the computing centers of Garching, Stuttgart and Jülich,” says Janka.

It's worth it, scientists are sure. After all, we are not just talking about grandiose space fireworks. Supernova explosions play a leading role in the evolution of the Universe. They spew enormous amounts of dust far into interstellar space. After the explosion, a star that was initially ten times the mass of the Sun is left with a neutron star weighing only one and a half solar masses. Most of substances scatter through space. This powerful wave of matter and energy gives rise to the formation of new stars.
Sometimes supernova explosions reach such force that they eject gas from the shell of a star beyond the boundaries of the “mother” galaxy and disperse it into intergalactic space. Astrophysical computer models show that this effect is even more important for cosmic evolution. If the gas remained within the galaxies, many more new stars would form within them.
The amount of stardust and heavy element particles in the Universe can determine how often supernova explosions occur. Every second, five to ten stars explode somewhere in space.
But astronomers are especially looking forward to the appearance of supernovae in our Galaxy. Observing the explosion of a star from a “close” distance cannot be replaced even by the most advanced computer model. According to their forecasts, two old stars should detonate in our neighborhood in the next 100 years. The last supernova explosion to date within the Milky Way, visible from Earth even with the naked eye, was observed in 1604 by astronomer Johannes Kepler.
The astronomers tensed in anticipation. “It will happen again very soon,” says supernova hunter Paolo Mazzali. Scientists have already identified some of the most likely stellar candidates. Among them is the red supergiant Betelgeuse in the upper left corner of Orion, the most beautiful constellation visible in the night sky. If this star were at the center of our solar system, it would extend far beyond the orbit of Earth and Mars.
Over the millions of years of its existence, Betelgeuse has already used up most of its nuclear fuel and can explode at any moment. Before death, the giant will flare up thousands of times brighter than it shone during life. It will shine in the sky like a crescent moon, or even a full moon, astronomers say. And if you're lucky, its glow can be seen even during the day.

A supernova explosion is a phenomenon of truly cosmic proportions. In fact, this is an explosion of colossal power, as a result of which the star either ceases to exist altogether or transforms into a qualitatively new form - in the form of a neutron star or black hole. In this case, the outer layers of the star are thrown into space. Scattering at high speed, they give rise to beautiful luminous nebulae.

(Total 11 photos)

1. The Simeiz 147 nebula (aka Sh 2-240) is a huge remnant of a supernova explosion, located on the border of the constellations Taurus and Auriga. The nebula was discovered in 1952 by Soviet astronomers G. A. Shain and V. E. Gaze at the Simeiz Observatory in Crimea. The explosion occurred about 40,000 years ago, during which time the flying substance occupied an area of ​​the sky 36 times larger. full moon! The actual dimensions of the nebula are an impressive 160 light years, and the distance to it is estimated at 3000 light years. years. Distinctive feature objects - long, curved filaments of gas that give the nebula its name, Spaghetti.

2. The Crab Nebula (or M1 according to Charles Messier’s catalog) is one of the most famous cosmic objects. The point here is not its brightness or special beauty, but the role that the Crab Nebula played in the history of science. The nebula is a remnant of a supernova explosion that occurred in 1054. Mentions of the appearance of a very bright star in this place are preserved in Chinese chronicles. M1 is located in the constellation Taurus, next to the star ζ; on dark, clear nights it can be seen with binoculars.

3. The famous object Cassiopeia A, the brightest radio source in the sky. This is the remnant of a supernova that erupted around 1667 in the constellation Cassiopeia. It’s strange, but we don’t find any mention of a bright star in the annals of the second half of the 17th century. Probably, in the optical range its radiation was greatly weakened by interstellar dust. The last observed supernova in our galaxy remains a Kepler supernova.

4. The Crab Nebula became famous in 1758, when astronomers anticipated the return of Halley's Comet. Charles Messier, the famous “comet catcher” of that time, looked for the tailed guest among the horns of Taurus, where it was predicted. But instead, the astronomer discovered an elongated nebula, which confused him so much that he mistook it for a comet. In the future, in order to avoid confusion, Messier decided to compile a catalog of all the nebulous objects in the sky. The Crab Nebula was included in the catalog as number 1. This image of the Crab Nebula was taken by the Hubble Telescope. It shows many details: gas fibers, nodes, condensations. Today, the nebula is expanding at a speed of about 1,500 km/s, and the change in its size is noticeable in photographs taken at intervals of just a few years. General dimensions The Crab Nebula is over 5 light years away.

5. The Crab Nebula in optics, thermal and X-rays. At the center of the nebula is a pulsar, a super-dense neutron star that emits radio waves and generates X-rays in the surrounding material (X-rays shown in blue). Observations of the Crab Nebula at different wavelengths have given astronomers fundamental information about neutron stars, pulsars and supernovae. This image is a combination of three images taken by the Chandra, Hubble and Spitzer space telescopes.

6. The last supernova explosion observed with the naked eye occurred in 1987 in a neighboring galaxy, the Large Magellanic Cloud. The brightness of supernova 1987A reached magnitude 3, which is quite a lot considering the colossal distance to it (about 160,000 light years); The progenitor of the supernova was a blue hypergiant star. After the explosion, an expanding nebula and mysterious rings in the form of the number 8 remained in place of the star. Scientists suggest that the reason for their appearance may be the interaction of the stellar wind of the predecessor star with gas ejected during the explosion

7. Supernova Remnant Tycho. A supernova occurred in 1572 in the constellation Cassiopeia. The bright star was observed by the Dane Tycho Brahe, the best astronomer-observer of the pre-telescope era. The book written by Brahe in the wake of this event had enormous ideological significance, because at that time it was believed that the stars were unchangeable. Already in our time, astronomers have been hunting for this nebula for a long time using telescopes, and in 1952 they discovered its radio emission. The first optical image was taken only in the 1960s.

8. Supernova remnant in the constellation Velas. Most of the supernovae in our Galaxy appear in the plane of the Milky Way, since this is where they are born and spend their short life massive stars. The filamentous supernova remnants are difficult to discern in this image due to the abundance of stars and red hydrogen nebulae, but the exploding spherical shell can still be identified by its greenish glow. The supernova in Parusy erupted approximately 11-12 thousand years ago. During the flare, the star ejected a huge mass of matter into space, but did not completely collapse: in its place remained a pulsar, a neutron star emitting radio waves.

9. The Pencil Nebula (NGC 2736), part of a supernova envelope from the constellation Velae. In fact, the nebula is a shock wave propagating through space at a speed of half a million kilometers per hour (in the picture it flies from bottom to top). Several thousand years ago, this speed was even higher, but the pressure of the surrounding interstellar gas, no matter how insignificant it was, slowed down the expanding shell of the supernova

10. The Medusa Nebula, another well-known supernova remnant, is located in the constellation Gemini. The distance to this nebula is poorly known and is probably about 5 thousand light years. The date of the explosion is also known very roughly: 3 - 30 thousand years ago. The bright star on the right is an interesting Gemini variable that can be observed (and its brightness changes studied) with the naked eye.

11. NGC 6962 or Eastern Veil close-up. Another name for this object is the Network Nebula.