The evolution of the Sun on the example of the star L2 Korma. The birth and evolution of stars: the giant factory of the universe

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MOSCOW STATE INSTITUTE OF COMMUNICATIONS (MIIT)

INSTITUTE OF TRANSPORT ENGINEERING AND SECURITY SYSTEMS

Department of Physics

in the discipline "The concept of modern natural science"

on the topic: “The evolution of stars. The sun"

Completed: st.gr. TUP-211

Techieva Karina

Checked by Prof. Nikitenko V.A.

Moscow 2014.

Introduction

1. The evolution of stars

2. Thermonuclear fusion in the interior of stars and the birth of stars

6. Sunspots

7. Solar cycle

Conclusion

Literature

Introduction

Modern scientific sources indicate that the Universe consists of 98% of stars, which "in turn" are the main element of the galaxy. Information sources give various definitions of this concept, here are some of them:

A star is a celestial body in which thermonuclear reactions are going, going or will go. Stars are massive luminous gaseous (plasma) balls. Formed from a gas-dust environment (hydrogen and helium) as a result of gravitational compression. The temperature of matter in the depths of stars is measured in millions of kelvins, and on their surface - in thousands of kelvins. The energy of the vast majority of stars is released as a result of thermonuclear reactions the conversion of hydrogen into helium, occurring at high temperatures in the interior. Stars are often called the main bodies of the universe, since they contain the bulk of the luminous matter in nature.

Stars are huge objects, spherical in shape, consisting of helium and hydrogen, as well as other gases. The energy of a star is contained in its core, where every second helium interacts with hydrogen.

Like everything organic in our universe, stars arise, develop, change and disappear - this process takes billions of years and is called the process of "Star Evolution".

1. The evolution of stars

The evolution of stars is the sequence of changes that a star undergoes during its life, that is, over hundreds of thousands, millions or billions of years, while it radiates light and heat.

A star begins its life as a cold rarefied cloud of interstellar gas (a rarefied gaseous medium that fills all the space between stars), shrinking under the influence of its own gravity and gradually taking the shape of a ball. When compressed, the gravitational energy (universal fundamental interaction between all material bodies) turns into heat, and the temperature of the object rises. When the temperature in the center reaches 15-20 million K, thermonuclear reactions begin and the compression stops. The object becomes a full-fledged star. The first stage of a star's life is similar to that of the sun - it is dominated by the reactions of the hydrogen cycle. In this state, he remains most of his life, being on main sequence Hertzsprung-Russell diagrams (Fig. 1) (shows the relationship between the absolute magnitude, luminosity, spectral class and surface temperature of a star, 1910), until the fuel reserves in its core run out. When all the hydrogen in the center of the star turns into helium, a helium core is formed, and the thermonuclear combustion of hydrogen continues on its periphery. During this period, the structure of the star begins to change. Its luminosity increases, the outer layers expand, and the surface temperature decreases - the star becomes a red giant, which form a branch on the Hertzsprung-Russell diagram. The star spends much less time on this branch than on the main sequence. When the accumulated mass of the helium core becomes significant, it cannot support its own weight and begins to shrink; if the star is massive enough, the rising temperature can cause further thermonuclear transformation of helium into heavier elements (helium into carbon, carbon into oxygen, oxygen into silicon, and finally silicon into iron).

2. Thermonuclear fusion in the interior of stars

By 1939, it was established that the source of stellar energy is thermonuclear fusion occurring in the interiors of stars. Most stars radiate because, in their interiors, four protons combine through a series of intermediate steps into a single alpha particle. This transformation can go in two main ways, called the proton-proton, or p-p-cycle, and carbon-nitrogen, or CN-cycle. In low-mass stars, the energy release is mainly provided by the first cycle, in heavy stars - by the second. The supply of nuclear fuel in a star is limited and is constantly spent on radiation. The process of thermonuclear fusion, which releases energy and changes the composition of the star's matter, combined with gravity, which tends to compress the star and also releases energy, as well as radiation from the surface, which carries away the released energy, are the main driving forces of stellar evolution.

The evolution of a star begins in a giant molecular cloud, also called a stellar cradle. Most of the "empty" space in the galaxy actually contains 0.1 to 1 molecule per cm?. A molecular cloud has a density of about a million molecules per cm?. The mass of such a cloud exceeds the mass of the Sun by 100,000-10,000,000 times due to its size: from 50 to 300 light-years across.

While the cloud is free to rotate around the center of the home galaxy, nothing happens. However, due to the heterogeneity gravitational field perturbations may arise in it, leading to local mass concentrations. Such perturbations cause the gravitational collapse of the cloud. One of the scenarios leading to this is the collision of two clouds. Another collapse-causing event could be the passage of a cloud through a dense arm spiral galaxy. Also a critical factor could be the explosion of a nearby supernova, the shock wave of which will collide with the molecular cloud at great speed. In addition, a collision of galaxies is possible, capable of causing a burst of star formation, as gas clouds in each of the galaxies are compressed as a result of the collision. In general, any inhomogeneities in the forces acting on the mass of the cloud can initiate the process of star formation.

Due to the inhomogeneities that have arisen, the pressure of the molecular gas can no longer prevent further compression, and the gas begins to gather around the center under the influence of gravitational attraction forces. future star. Half of the released gravitational energy is spent on heating the cloud, and half is spent on light radiation. In clouds, pressure and density increase towards the center, and the collapse of the central part occurs faster than the periphery. As the contraction progresses, the mean free path of photons decreases, and the cloud becomes less and less transparent to its own radiation. This results in a faster rise in temperature and an even faster rise in pressure. As a result, the pressure gradient balances the gravitational force, a hydrostatic core is formed, with a mass of about 1% of the mass of the cloud. This moment is invisible. The further evolution of the protostar is the accretion of the substance that continues to fall on the “surface” of the core, which, due to this, grows in size. The mass of matter freely moving in the cloud is exhausted, and the star becomes visible in the optical range. This moment is considered the end of the protostellar phase and the beginning of the young star phase.

The process of star formation can be described in a single way, but the subsequent stages of the development of a star depend almost entirely on its mass, and only at the very end of stellar evolution can chemical composition play a role.

3. The middle of the life cycle of a star

Stars come in a wide variety of colors and sizes. They range in spectral type from hot blues to cool reds, and in mass from 0.0767 to more than 200 solar masses. The luminosity and color of a star depends on the temperature of its surface, which, in turn, is determined by its mass. All new stars "take their place" on the main sequence according to their chemical composition and mass. We are not talking about the physical movement of the star - only about its position on the indicated diagram, which depends on the parameters of the star. In fact, the movement of a star along the diagram corresponds only to a change in the parameters of the star.

Small, cool red dwarfs slowly burn off their hydrogen reserves and remain on the main sequence for hundreds of billions of years, while massive supergiants leave the main sequence within a few million years of formation.

Medium-sized stars like the Sun stay on the main sequence for an average of 10 billion years. It is believed that the Sun is still on it, as it is in the middle of its life cycle. As soon as the star depletes the supply of hydrogen in the core, it leaves the main sequence.

After a certain time - from a million to tens of billions of years, depending on the initial mass - the star depletes the hydrogen resources of the core. In large and hot stars, this happens much faster than in small and colder ones. The depletion of the supply of hydrogen leads to the cessation of thermonuclear reactions.

Without the pressure generated by these reactions to balance the star's own gravitational pull, the star begins to contract again, as it did before, during its formation. The temperature and pressure rise again, but, unlike the protostar stage, to a higher level. The collapse continues until, at a temperature of approximately 100 million K, thermonuclear reactions involving helium begin.

The thermonuclear combustion of matter resumed at a new level causes a monstrous expansion of the star. The star is "loosened", and its size increases by about 100 times. Thus, the star becomes a red giant, and the helium burning phase continues for about several million years. Almost all red giants are variable stars.

What happens next depends again on the mass of the star.

4. Later years and the death of stars

Old stars with low mass

To date, it is not known for certain what happens to light stars after the depletion of the hydrogen supply. Since the universe is 13.7 billion years old, which is not enough to deplete the supply of hydrogen fuel in such stars, current theories are based on computer simulations of the processes occurring in such stars.

Some stars can synthesize helium only in some active zones, which causes their instability and strong stellar winds. In this case, the formation of a planetary nebula does not occur, and the star only evaporates, becoming even smaller than a brown dwarf.

Stars with a mass of less than 0.5 solar are not able to convert helium even after reactions involving hydrogen cease in the core - their mass is too small to provide a new phase of gravitational compression to the extent that initiates the "ignition" of helium. Such stars include red dwarfs, such as Proxima Centauri, whose main sequence lifetimes range from tens of billions to tens of trillions of years. After the termination of thermonuclear reactions in their core, they, gradually cooling down, will continue to weakly radiate in the infrared and microwave ranges of the electromagnetic spectrum.

medium sized stars

When a star reaches an average value (from 0.4 to 3.4 solar masses) of the red giant phase, hydrogen ends in its core and reactions of carbon synthesis from helium begin. This process occurs at higher temperatures and therefore the flow of energy from the core increases, which leads to the fact that the outer layers of the star begin to expand. The beginning of carbon synthesis marks new stage in the life of a star and continues for some time. For a star similar in size to the Sun, this process can take about a billion years.

Changes in the amount of energy emitted cause the star to go through periods of instability, including changes in size, surface temperature, and energy release. The release of energy is shifted towards low-frequency radiation. All this is accompanied by an increasing mass loss due to strong stellar winds and intense pulsations. Stars in this phase are called late-type stars, OH-IR stars, or Mira-like stars, depending on their precise characteristics. The ejected gas is relatively rich in heavy elements produced in the interior of the star, such as oxygen and carbon. The gas forms an expanding shell and cools as it moves away from the star, allowing the formation of dust particles and molecules. With strong infrared radiation from the central star, ideal conditions are formed in such shells for the activation of masers.

Helium combustion reactions are very sensitive to temperature. Sometimes this leads to great instability. Strongest pulsations arise, which, in the end, give the outer layers enough acceleration to be dropped and turn into a planetary nebula. In the center of the nebula, the bare core of the star remains, in which thermonuclear reactions stop, and, as it cools, it turns into helium. white dwarf, as a rule, having a mass of up to 0.5-0.6 solar and a diameter of the order of the diameter of the Earth.

white dwarfs

Shortly after a helium flash, carbon and oxygen "light up"; each of these events causes a major rearrangement of the star and its rapid movement along the Hertzsprung-Russell diagram. The size of the star's atmosphere increases even more, and it begins to intensively lose gas in the form of expanding stellar wind streams. The fate of the central part of the star depends entirely on its initial mass: the core of the star can end its evolution as a white dwarf (low-mass stars); if its mass in the later stages of evolution exceeds the Chandrasekhar limit - like a neutron star (pulsar); if the mass exceeds the limit of Oppenheimer - Volkov - like a black hole. In the last two cases, the completion of the evolution of stars is accompanied by catastrophic events - supernova explosions.

The vast majority of stars, including the Sun, end their evolution by contracting until the pressure of degenerate electrons balances gravity. In this state, when the size of the star decreases by a factor of a hundred and the density becomes a million times higher than that of water, the star is called a white dwarf. It is deprived of sources of energy and, gradually cooling down, becomes dark and invisible.

In stars more massive than the Sun, the pressure of degenerate electrons cannot stop the further compression of the nucleus, and the electrons begin to “press” into atomic nuclei, which leads to the transformation of protons into neutrons, between which there are no electrostatic repulsion forces. Such neutronization of matter leads to the fact that the size of the star, which, in fact, now represents one huge atomic nucleus, is measured in several kilometers, and the density is 100 million times higher than the density of water. Such an object is called a neutron star.

supermassive stars

After a star with a mass greater than five solar enters the stage of a red supergiant, its core begins to shrink under the influence of gravitational forces. As the compression increases, the temperature and density increase, and a new sequence of thermonuclear reactions begins. In such reactions, increasingly heavier elements are synthesized: helium, carbon, oxygen, silicon and iron, which temporarily restrains the collapse of the nucleus.

Ultimately, as education becomes more and more heavy elements periodic system, iron-56 is synthesized from silicon. At this stage, further thermonuclear fusion becomes impossible, since the iron-56 nucleus has a maximum mass defect and the formation of heavier nuclei with energy release is impossible. Therefore, when the iron core of a star reaches a certain size, the pressure in it is no longer able to withstand the gravity of the outer layers of the star, and an immediate collapse of the core occurs with the neutronization of its substance.

What happens next is still unclear to the end, but, in any case, the ongoing processes in a matter of seconds lead to the explosion of a supernova of incredible power.

The accompanying burst of neutrinos provokes a shock wave. Strong neutrino jets and a rotating magnetic field push out most of the material accumulated by the star - the so-called seating elements, including iron and lighter elements. The expanding matter is bombarded by neutrons escaping from the nucleus, capturing them and thereby creating a set of elements heavier than iron, including radioactive ones, up to uranium (and possibly even California). Thus, supernova explosions explain the presence of elements heavier than iron in the interstellar matter, which, however, is not the only one. possible way their formations, for example, are demonstrated by technetium stars.

The blast wave and jets of neutrinos carry matter away from dying star into interstellar space. Subsequently, as it cools and travels through space, this supernova material may collide with other space debris, and possibly participate in the formation of new stars, planets, or satellites.

The processes that take place during the formation of a supernova are still being studied, and so far this issue is not clear. Also in question is the moment what actually remains of the original star. However, two options are being considered: neutron stars and black holes.

neutron stars

It is known that in some supernovae, strong gravity in the supergiant's interior causes electrons to be absorbed by the atomic nucleus, where they merge with protons to form neutrons. This process is called neutronization. The electromagnetic forces separating nearby nuclei disappear. The core of the star is now a dense ball of atomic nuclei and individual neutrons.

Such stars, known as neutron stars, are extremely small - no more than big city, and have an unimaginably high density. Their orbital period becomes extremely short as the size of the star decreases (due to conservation of angular momentum). Some make 600 revolutions per second. For some of them, the angle between the radiation vector and the axis of rotation may be such that the Earth falls into the cone formed by this radiation; in this case, it is possible to record a radiation pulse that repeats at time intervals equal to the rotation period of the star. Such neutron stars were called "pulsars", and became the first discovered neutron stars.

Black holes

Not all supernovae become neutron stars. If the star has a large enough mass, then the collapse of the star will continue, and the neutrons themselves will begin to fall inward until its radius becomes less than the Schwarzschild radius. The star then becomes a black hole.

The existence of black holes was predicted by the general theory of relativity. According to this theory, matter and information cannot leave black hole no way. However, quantum mechanics probably makes exceptions to this rule possible.

Remains a row open questions. Chief among them: "Are there any black holes at all?". Indeed, to say for sure that a given object is a black hole, it is necessary to observe its event horizon. This is impossible purely by definition of the horizon, but with the help of very long baseline radio interferometry it is possible to determine the metric near the object, as well as to fix fast, millisecond variability. These properties, observed in a single object, should definitively prove the existence of black holes.

The sun plays an exceptional role in the life of the Earth. The entire organic world of our planet owes its existence to the Sun. The sun is not only a source of light and heat, but also the original source of many other types of energy (energy of oil, coal, water, wind).

Since ancient times, the sun has been an object of worship among different peoples. He was considered the most powerful deity. The cult of the invincible Sun was one of the most widespread (Helios - the Greek god of the Sun, Apollo - the god of the Sun among the Romans, Mitra - among the Persians, Yarilo - among the Slavs, etc.). Temples were erected in honor of the Sun, hymns were composed, and sacrifices were made. Gone is the religious worship of the daylight. Now scientists are investigating the nature of the Sun, finding out its influence on the Earth, working on the problem of using the almost inexhaustible solar energy.

The sun is our star. By studying the Sun, we learn about many phenomena and processes that occur on other stars and are inaccessible to direct observation due to the huge distances that separate us from the stars.

Solar activity is a set of non-stationary phenomena on the Sun. These phenomena include sunspots, solar flares, faculae, flocculi, prominences, coronal rays, condensations, transients, sporadic radio emission, an increase in ultraviolet, X-ray and corpuscular radiation, etc. Most of these phenomena are closely related and occur in active regions. In their course, cyclicity is clearly visible with an average period of 11.2 years, as well as with periods of 22, 80-90 years, etc.

During the development of an active region in the solar atmosphere, situations sometimes arise in which a rapid rearrangement ("reconnection") of magnetic fields is possible. This rearrangement causes outbreaks accompanied by complex movements ionized gas, its glow, particle acceleration, etc.

Solar flares are the most powerful of all manifestations of solar activity. Such flares are usually observed near sunspots.

There are usually several weak outbreaks per day.

Strong flashes - very a rare thing. A solar flare is a sudden release of energy in the upper chromosphere or lower corona, generating short-term electromagnetic radiation in a wide range of wavelengths - from hard X-rays (and even gamma rays) to kilometer radio waves. The onset of the outbreak can be very abrupt, but sometimes the "explosion" is preceded by several minutes of slow development or even a weak pre-flare. Next comes the actual explosive (hard, impulsive) phase, during which particles accelerate in 1–3 min, and a hot cloud is formed. In a number of flares (they are called thermal flares), the hard phase is absent. After reaching the maximum brightness (for example, in soft X-rays 1–15 min after the onset), the burning process of a large flare continues for several more hours. By the end of the hard phase, an outwardly directed shock wave is gradually formed: the main part of the flare energy is released in the form of the kinetic energy of matter ejections moving in the corona and interplanetary space at speeds up to 1000 km/s, the energy of hard electromagnetic radiation, and flows accelerated to gigantic energies (sometimes - tens of GeV) particles. This shock wave causes radio burst manifestations. X-rays and solar cosmic rays coming from the flare cause additional ionization of the earth's ionosphere, which affects the propagation conditions of radio waves (disturbances in radio communications, operation of navigation devices, etc.). The flow of particles ejected during the flare reaches the Earth's orbit in about a day and causes magnetic storms and auroras on Earth.

There is evidence of a strong influence of flare activity on the weather and the state of the Earth's biosphere.

Near the activity maximum, the particle fluxes accelerated during flares have the most effective effect on the Earth's atmosphere and magnetosphere. At the activity decline phase, by the end of the 11-year activity cycle, with a decrease in the number of flares and the development of an interplanetary current sheet, the stationary streams of the enhanced solar wind become more significant. Rotating together with the Sun, they cause repeating every 27 days. geomagnetic disturbances. This recurrent (repeating) activity is especially high for the ends of cycles with an even number, when the direction of the magnetic field of the solar "dipole" is anti-parallel to the earth's.

The manifestation of long-term biological cycles is associated with cyclic changes in solar activity. The study of the influence of changes in solar activity on the living organisms of the Earth is engaged in heliobiology - a science, the foundations of which were laid in the beginning. 1920s A.L. Chizhevsky. Chizhevsky believed that heliobiology, which shows the undoubted connection of earthly events with cosmic rhythms, is modern, scientific form ancient astrological teachings. As extensive historical studies conducted by Chizhevsky have shown, there is an undoubted connection between the cycles of solar activity and the dynamics of wars and other social upheavals, outbreaks of epidemics and epizootics, and a host of other phenomena on Earth. It is interesting that the first scientist who came up with such an idea was W. Herschel, an astronomer who discovered the first planet Uranus invisible to the naked eye. Back in 1804, he discovered a direct relationship between the level of solar activity and the price of bread. Among contemporary research On this topic, we highlight the work of the Russian historian Valery Khrapov, who discovered the "curve of giftedness". It turned out that the majority prominent people(in the most different areas politics, sports, art) is born during periods of extreme (maximum or minimum) level of solar activity. The mortality curve also correlates with the solar activity curve.

Such patterns, of course, can be considered as astrological.

As studies by Theodor Landscheidt have shown, the level of solar activity depends on the relative position of the planets and on a number of other astrological factors. Moreover, Landscheidt developed a technique that allows purely astrological methods to predict changes in solar activity.

Landscheidt's long-term predictions of solar flares and geomagnetic storms come true (according to astronomers' verification) by 90% (!).

Thus, if Solar activity depends on astrological factors, then all the phenomena on Earth associated with changes in Solar activity also depend on astrological indicators.

6. Sunspots

The fact that there are spots on the Sun, people have known for a very long time. In ancient Russian and Chinese chronicles, as well as in the chronicles of other peoples, there were often references to observations of sunspots. In Russian chronicles it was noted that the spots were visible "Aki nails". The records helped to confirm the pattern established later (in 1841) of a periodic increase in the number of sunspots. To notice such an object with a simple eye (subject, of course, to precautionary measures - through thickly smoked glass or illuminated negative film), it is necessary that its size on the Sun be at least 50 - 100 thousand kilometers, which is tens of times greater than the radius of the Earth.

The sun consists of hot gases that are constantly moving and mixing, and therefore there is nothing constant and unchanging on the solar surface. The most stable formations are sunspots.

But their appearance changes from day to day, and they, too, now appear, then disappear.

At the moment of appearance, a sunspot is usually small, it can disappear, but it can also increase greatly.

The main role in most of the phenomena observed on the Sun is played by magnetic fields. The solar magnetic field has a very complex structure and is constantly changing. The combined action of the solar plasma circulation in the convective zone and the differential rotation of the Sun constantly excites the process of amplification of weak magnetic fields and the emergence of new ones. Apparently, this circumstance is the reason for the appearance of sunspots on the Sun. Spots appear and disappear. Their number and size vary. But, approximately, every 11 years the number of spots becomes the largest. Then the Sun is said to be active. With the same period (~ 11 years) the polarity reversal of the Sun's magnetic field also occurs.

It is natural to assume that these phenomena are interconnected.

The development of the active region begins with an increase in the magnetic field in the photosphere, which leads to the appearance of brighter areas - torches (the temperature of the solar photosphere is on average 6000 K, in the region of torches it is about 300 K higher).

Further strengthening of the magnetic field leads to the appearance of spots.

At the beginning of the 11-year cycle, spots begin to appear in small numbers at relatively high latitudes (35 - 40 degrees), and then the spot formation zone gradually descends to the equator, to a latitude of plus 10 - minus 10 degrees, but at the very equator of spots, as a rule , can not be.

Galileo Galilei was one of the first to notice that spots are observed not everywhere on the Sun, but mainly at middle latitudes, within the so-called "royal zones".

First, single spots usually appear, but then a whole group arises from them, in which two large spots are distinguished - one on the western, the other on the eastern edge of the group. At the beginning of our century, it became clear that the polarities of the eastern and western spots are always opposite. They form, as it were, two poles of one magnet, and therefore such a group is called bipolar. A typical sunspot measures several tens of thousands of kilometers.

Galileo, sketching spots, marked a gray border around some of them.

Indeed, the spot consists of a central, darker part - the shadow and a lighter area - the penumbra.

Sunspots are sometimes visible on its disk even to the naked eye.

The apparent blackness of these formations is due to the fact that their temperature is about 1500 degrees lower than the temperature of the surrounding photosphere (and, accordingly, the continuous radiation from them is much less). A single developed spot consists of a dark oval - the so-called shadow of the spot, surrounded by a lighter fibrous penumbra. Undeveloped small spots without penumbra are called pores. Spots and pores often form complex groups.

A typical sunspot group initially appears as one or more pores in the region of the undisturbed photosphere. Most of these groups usually disappear after 1-2 days. But some consistently grow and develop, forming quite complex structures. Sunspots can be larger in diameter than the Earth. They often form groups. They form in a few days and usually disappear within a week. Some large spots, though, may persist for up to a month. Large groups of sunspots are more active than small groups or individual sunspots.

The Sun changes the state of the Earth's magnetosphere and atmosphere. Magnetic fields and particle streams that come from sunspots reach the Earth and affect primarily the brain, cardiovascular and circulatory system person, on her physical, nervous and psychological condition. A high level of solar activity, its rapid changes excite a person, and therefore the collective, class, society, especially when there are common interests and an understandable and perceived idea.

Turning to the Sun with one or the other of its hemisphere, the Earth receives energy. This flow can be represented as a traveling wave: where the light falls - its crest, where it is dark - a dip. In other words, energy comes and goes. Mikhail Lomonosov spoke about this in his famous natural law.

The theory of the wave-like nature of the energy supply to the Earth prompted Alexander Chizhevsky, the founder of heliobiology, to pay attention to the connection between an increase in solar activity and earthly cataclysms. The first observation made by the scientist dates back to June 1915. Auroras shone in the North, observed both in Russia and in North America, and "magnetic storms continuously disrupted the movement of telegrams." Just during this period, the scientist draws attention to the fact that increased solar activity coincides with bloodshed on Earth. Indeed, immediately after the appearance of large spots on the Sun, hostilities intensified on many fronts of the First World War.

Now astronomers say that our star is getting brighter and hotter. This is due to the fact that over the past 90 years, the activity of its magnetic field has more than doubled, with the largest increase occurring over the past 30 years. In Chicago, at the annual conference of the American Astronomical Society, there was a warning from scientists about the troubles that threaten humanity. Just as computers around the planet adjust to operating conditions in the year 2000, our star will enter the most turbulent phase of its 11-year cyclical cycle. Now scientists will be able to accurately predict solar flares, which will make it possible to prepare in advance for possible failures in operation of radio and electrical networks. Now most of the solar observatories have confirmed the "storm warning" for next year, because. the peak of solar activity is observed every 11 years, and the previous storm was observed in 1989.

This can lead to the fact that power lines on Earth will fail, the orbits of satellites will change, which ensure the operation of communication systems, "direct" aircraft and ocean liners. A solar "riot" is usually characterized by powerful flares and the appearance of many of those same spots.

Alexander Chizhevsky back in the 20s. discovered that solar activity affects extreme earthly events - epidemics, wars, revolutions. The Earth not only revolves around the Sun - all life on our planet pulsates in the rhythms of solar activity, - he established.

The sun influences our whole life in a much subtler and deeper way than previously thought. In the bloody and muddy memory of the end of the century, we see a clear confirmation of his ideas. And in the special services different countries now entire departments are engaged in the analysis of solar activity... In the main, the synchronism of solar activity maxima with periods of revolutions and wars was proved, periods of increased activity of sunspots often coincided with all sorts of social turmoil.

Recently, several space satellites have detected an ejection of solar prominences characterized by an unusually high level of X-ray emission. Such phenomena pose a serious threat to the Earth and its inhabitants. A flash of this magnitude has the potential to destabilize power grids. Fortunately, the flow of energy did not affect the Earth and no expected troubles happened. But the event itself is a harbinger of the so-called "solar maximum", accompanied by the release of a much larger amount of energy that can disable communication communications and lines of force, transformers, astronauts and space satellites that are outside the Earth's magnetic field and not protected by the planet's atmosphere will be at risk. There are more NASA satellites in orbit today than ever before. There is also a threat to aircraft, expressed in the possibility of interrupting radio communications, jamming radio signals.

Solar maxima are difficult to predict, it is only known that they repeat approximately every 11 years. The next one should happen in the middle of the year 2000, and its duration will be from one to two years. So says David Hathaway, a heliophysicist at Marshall Space Flight Center, NASA.

Prominences during solar maximum can occur daily, but it is not known exactly what force they will have and whether they will affect our planet. For the past few months, bursts of solar activity and the resulting energy flows towards Earth have been too weak to cause any damage. In addition to X-rays, this phenomenon carries other dangers: the Sun is ejecting a billion tons of ionized hydrogen, a wave of which travels at a speed of a million miles per hour and can reach the Earth in a few days. An even bigger problem is the energy waves of protons and alpha particles. They move at much faster speeds and leave no time to take countermeasures, unlike waves of ionized hydrogen, which can get satellites and planes out of the way.

In some of the most extreme cases, all three waves can reach the Earth suddenly and almost simultaneously. There is no protection, scientists are not yet able to accurately predict such a release, and even more so its consequences.

7. Solar cycle

The number of sunspots is not constant value. In addition to the quite obvious variations associated with the rotation of the Sun (spots appear in the field of view and disappear beyond the edge), over time, new groups of spots form and old ones disappear. When observed over a short period of time (several weeks or months), this variation in the number of sunspots appears to be random. However, observations over many years led to the discovery of a significant feature of the Sun: the number of sunspots changes periodically, which is usually described as an 11-year cycle (in fact, the period varies and is closer to the 10.5 year cycle in our century).

In 1848, Johann Rudolf Wolf invented a technique for counting sunspots on a disk, the resulting number is called the Wolf number:

where f is the number of all individual sunspots currently observed on the solar disk, and g is the number of groups formed by them. This index very well reflects the contribution to solar activity not only from the sunspots themselves, but also from the entire active region, mainly occupied by faculae. Therefore, the W numbers are in very good agreement with the more modern and more precisely defined index, denoted by F 10.7 - the magnitude of the radio flux from the entire Sun at a wavelength of 10.7 cm. Today, Wolf numbers (averaged over many observations) are used to characterize solar activity.

During the solar cycle, the spots migrate from the pole to the equator, and the latitude distribution of the spots gives the so-called, very spectacular, butterfly diagram.

While the length of the cycle has been virtually the same this century, there have been significant variations in the past. From about 1645 to 1715 (a period known as the Maunder Minimum), there were practically no sunspots observed on the Sun, which apparently had an effect on the Earth's climate (see below).

A particularly long period in the history of solar activity is hidden in the past abundance of carbon-14 (a radioactive isotope of ordinary carbon-12). The rate at which C-14 is produced in the Earth's atmosphere depends on a stream of high-energy particles known as galactic cosmic rays, which are produced in high-energy processes outside the solar system. The ability of these cosmic rays to penetrate the solar system depends on the magnitude and geometry of the magnetic fields carried away from the Sun by the solar wind in

periods of high activity. During photosynthesis, plants take up C-14 along with other carbon isotopes and incorporate it into their structure. Solar activity levels over the past 2000 years can be estimated by measuring the abundance of C-14 in the annual rings of old trees. The age of such rings can be easily found by counting backwards from the outer ring. Information from ancient sources about the observation of sunspots and auroras, as well as data on the abundance of C-14, were summarized by Eddy in 1976. He found that the Maunder minimum coincides with a very sharp decrease in solar activity, as evidenced by a break in the appearance of auroras and a high level of C-14. Subsequently, Eddy and other scientists showed that such periods of abnormally low solar activity last for several decades and are typical of the Sun. A similar episode, the Spurer minimum, took place between about 1450 and 1550. However, the extended period of high solar activity between about 1100 and 1250 years. coincided with relatively warm weather, which apparently made possible the migration of the Vikings to Greenland and New World. It is possible that another fading of solar activity can be expected in the next century. Why is there a solar cycle? Until the end, no one knows the final answer to this question. A detailed explanation of the nature of the solar cycle is a fundamental problem in solar physics that has yet to be solved.

Conclusion

The study of stellar evolution is impossible by observing only one star - many changes in stars proceed too slowly to be noticed even after many centuries. Therefore, scientists study many stars, each of which is at a certain stage in its life cycle.

For many centuries, astronomy has accumulated data on the stars. Based on these data, various classification systems are built. In this paper, we have considered some classification characteristics.

By being at various stages of their lives, stars are blue and red giants, white dwarfs, neutron stars or black holes.

When classifying stars according to their chemical composition, they are guided by the content of elements heavier than helium in them. These elements are usually no more than 2%, but they determine which group the star belongs to.

The classification of stars is based on their physical characteristics - brightness, luminosity, size, temperature, mass. Stars are classified by "star" and absolute magnitude, by luminosity and color, by the degree of ionization of elements. The groups of stars are most clearly reflected in the Hertzsprung-Russell diagram. By studying the physical characteristics, one can make the assumption that all stars have more or less the same mass, while all other characteristics change hundreds of thousands and many millions of times.

Of great interest is the classification and study of binary and variable stars.

Binary stars and multiple systems can be optically and physically double. Their duality is explained, respectively, by geometric effects and physical interaction.

Variable stars are eclipsing and physical. The variability of eclipsing stars is again explained by geometric effects, while the variability of physical variables is explained by internal processes.

At present, the classification of stars is continuously supplemented and improved.

star celestial sun

Literature

1. Vvedensky B.A., “Big Soviet Encyclopedia”, M.: State scientific publishing house “Great Soviet Encyclopedia”, 1952.

2. Dubintseva T.Ya., "Concepts of modern natural science", Novosibirsk: LLC Publishing house "UKEA", 1997. - 832p.

3. Shklovsky I. S. Stars: their birth, life and death - M .: Nauka, Main edition of physical and mathematical literature, 1984. - 384 p.

4. Levi D., "Stars and planets: an encyclopedia of the environment", M .: Publishing house "White City", 1998. - 288s.

5. Haber H., "Stars", M .: "Word", 1998. - 127p.

6. Kotlyakov V.M., "Anatomy of crises", M.: "Nauka", 1999. - 238p.

7. Institute of Physics. Kirensky SB RAS | The structure and evolution of the universe.

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Sun evolution

Researchers from an international team have studied the L2 star Puppis to understand what the future holds and what the evolution will be.
The team used the Alma radio telescope to study the L2 star Puppis, which is estimated to be about 208 light-years from Earth. As part of the study, experts found that the star has a lot in common with our Sun.

“We found that L2 Puppis is a fairly old object, about 10 billion years old,” said Homan Ward of KU Leuven.

About five billion Earth years ago, this star was very similar to the Sun. The Sun, as it is today, had the same mass. The third part of the star's mass was lost to it in the process of existence. The same process will affect the Sun, but it will happen in a very distant future.
Professor Sarah Dechin of the Institute of Astronomy of Kentucky said that it is likely that in a few billion years the Sun, like L2 Puppis, will become a red giant. And there will be 100 times more than now, and this is just one among other expected changes.
“The sun is also experiencing intense mass loss as a result of a very strong stellar wind,” Decin said. “Ultimately, the evolution of the Sun will turn it into a small white dwarf the size of the Earth in 7 billion years. But at the same time, it is much denser and heavier than the Earth. A teaspoon of the substance of such a white dwarf contains about 5 tons of matter.”
At a distance twice the distance from the Earth to the Sun, in the L2 orbit of Puppis, the team detected an object. He can show us what the Earth will look like after a very long time.
Probably, life on Earth at this time will no longer be possible, but the planet will not be absorbed by the Sun. Other planets terrestrial group- and Venus will most likely be destroyed by the Sun, and what will happen to the Earth is not yet fully understood.

“We already understand that the Sun will greatly increase in size and become much brighter. These circumstances will certainly destroy any manifestations of life on Earth, ”Dechin said. “But will the rocky core of the planet be able to overcome the stage of the red giant, and continue to exist in orbit around the remnants of the Sun - a white dwarf?”

Scientists are not yet sure if the Earth will survive the Sun or be absorbed by it, but studying L2 Puppis can help us understand the fate of our planet.

1 option

1. The mass of the Sun is ... from the mass of the entire solar system.

a) 99.9%; b) 39.866%; c) 32.31%; d) 27.46%.

2. The average diameter of the Sun is ... diameters of the Earth.

a) 313; b) 109; c) 198; d) 998.

3. The period of rotation of the Sun at the equator is ...

4. The amount of energy passing through a 1m 2 area perpendicular to the sun's rays in 1 s is called ...

5. The sun consists of ... hydrogen.

6. Stefan-Boltzmann law - ....

a) b) ; c) d).

7. With an increase in the number of spots on the Sun, the brilliance of a star ...

a) is increasing b) decreases; c) does not change; d) fluctuates periodically.

8. The flow of ionizing particles flowing from the solar corona into the surrounding space is called ...

9. Heavenly body, revolving around a star, having a spherical shape, under the influence of its own gravity, and removing small bodies from an orbit close to its own, is called ...

a) a planet b) an asteroid; c) a comet; d) meteorite.

10. The angle at which one could see the semi-major axis of the earth's orbit from a star is called ...

a) angular distance; b) stellar parallax;

c) annual parallax; d) perpendicular parallax.

11. The total energy radiated by a star per unit time is called ...

12. The dominant color in the spectrum of a star depends on ... the star.

a) masses; b) buildings; c) age; d) temperature.

13. In the center of the star is ...

a) convection zone; b) radiant energy transfer zone;

c) zone of thermonuclear reactions; d) atmosphere.

14. Stars in ellipses, rotating around a common center of mass, are called ...

15. Stars that change their luminosity as a result of physical processes occurring in a star are called ...

16. A star that increases its brightness thousands and millions of times in a few hours, and then dims, is called ...

a) new; b) supernova; c) Cepheid; d) pulsating.

17. The minimum cloud size in which spontaneous compression can begin is determined by ...

a) Newton b) Hubble; c) Win; d) Jeans.

18. When all the nuclear fuel inside the star burns out, the process begins ...

a) gradual expansion; b) gravitational compression;

c) the formation of a protostar; d) star pulsations.

19. If the mass of a star

20. Our Galaxy is called…

The sun. Stars. The structure and evolution of the universe

Option 2

1. The mass of the Sun is ... masses of the Earth.

a) 392109; b) 332982; c) 139209; d) 99866.

2. Average diameter of the Sun…

a) 99.866 10 9 m; b) 1.392 109 m; c) 3.131 109 m; d) 2.745 10 9 m.

3. The period of rotation of the Sun at the pole is ...

a) 52.05 days; b) 43.3 days; c) 25.05 days; d) 34.3 days.

4. Energy radiated by the Sun in 1 s. from the entire surface, is called ...

a) the solar constant; b) the luminosity of the Sun;

c) solar energy; d) thermonuclear reaction.

5. The sun consists of ... of helium.

a) 27%; b) 2%; c) 72%; d) 71%.

6. Wine's Law - ....

a) b) ; c) d).

7. The age of the Sun is (approximately):

a) 5 billion years; b) 15 billion years; c) 100 billion years; d) 25 billion years.

8. Dense condensations of relatively cold matter that rise and are held above the surface of the Sun are called ...

a) flash; b) solar wind; c) prominence; d) a torch.

9. A spatially isolated, gravitationally bound, opaque object for radiation, in which thermonuclear reactions occur, is called ...

a) a planet b) an asteroid; c) a comet; d) a star.

10. The distance to a star can be determined by the formula ...

a) b); c) d)

11. The magnitude that a star would have if it were at a distance of 10 pc from us is called ...

a) apparent stellar magnitude; b) absolute magnitude;

c) luminosity; c) stellar constant.

12. The sun belongs to the spectral class ..

a) B; b) F; c) G; d) M.

13. The transfer of energy to the surface of stars passes through ..

a) convection zone; b) radiant energy transfer zone;

c) zone of thermonuclear reactions; d) atmosphere.

14. Stars, the brightness of which changes, are called ...

a) double; b) variables; c) stationary; d) non-stationary.

15. Pulsating stars of high luminosity are called ...

a) Cepheids; b) physically variable;

c) eclipsing variables; d) spectral variables.

16. Stars that suddenly explode and reach a maximum absolute stellar magnitude from -11 m to -21 m are called ...

a) new; b) supernovae; c) Cepheids; d) pulsating.

17. Giant molecular clouds with masses greater than 105 solar masses are called ...

a) pulsars; b) nebulae; c) galaxies; d) regions of star formation.

18. In a stationary state, the star on the Hertzsprung-Russell diagram is on ...

a) the main sequence; b) into a sequence of supergiants;

c) into a sequence of subdwarfs;

d) into a sequence of white dwarfs.

19. If the mass of a star is 1.4 solar masses, when the nuclear fuel burns out, the star turns into ...

a) a white dwarf b) red giant; c) a neutron star; d) a black hole.

20. The nearest galaxy to us is called ...

a) Sombrero; b) the Andromeda nebula;

in) Milky Way; d) Horse head.

Answers to test № 2

1 option

Option 2

Stars 1 are balls of hot, mostly ionized gas. The ionization of stellar matter is a consequence of its high temperature (from several thousand to several tens of thousands of degrees).

As a result of the study chemical composition Sun and other stars have been found to contain almost all chemical elements available on Earth and presented in the table of D. I. Mendeleev. It also turned out that in most cases, 70% of the star's mass is hydrogen, 28% - helium and 2% - heavier elements.

You already know that the greater the mass of a star, the stronger the gravitational field it creates. Through action gravitational forces, compressing the stellar matter, its temperature, density, pressure increase significantly from outer layers to the center.

So, for example, the temperature of the outer layers of the Sun is approximately equal to 6 10 3 ° C, and in the center - about 14-15 million ° C, the density of matter in the center of the Sun is approximately equal to 150 g / cm 3 (19 times more than that of iron) , and the pressure from the middle layers to the center increases from 7 10 8 to 3.4 10 11 atm. At such temperatures and pressures, thermonuclear reactions can occur in the core, which are the source of energy for stars.

The radiation power of a star (also called luminosity and denoted by the letter L) is proportional to the fourth power of its mass:

Thermonuclear reactions occurring in the interiors of stars are one of the processes that significantly distinguish stars from planets, since the internal source of planetary heating is radioactive decay. This difference is due to the fact that the mass of any star is obviously greater than the mass of even the big planet. This can be illustrated by the example of Jupiter. Despite the fact that in many respects it is very similar to a star, its mass turned out to be insufficient for the conditions necessary for the occurrence of thermonuclear reactions to occur in its depths.

As a result of thermonuclear reactions, huge energy is released in the bowels of the Sun, which maintains its glow. Let's consider how this energy goes out to the surface of the Sun.

In the radiant energy transfer zone (Fig. 188), the heat released in the core spreads from the center to the surface of the Sun by radiation, that is, through the absorption and emission of portions of light - quanta - by matter. Since quanta are emitted by atoms in any direction, their path to the surface takes thousands of years.

Rice. 188. Structure of the Sun

In the convection zone, energy is transferred to the surface by rising hot gas flows. Having reached the surface, the gas, radiating energy, cools, condenses and sinks to the base of the zone. In the convective zone, the gas is opaque. Therefore, you can see only those layers that are above it: the photosphere, chromosphere and corona (not indicated in the figure). These three layers belong to the solar atmosphere.

The photosphere ("sphere of light") in the photographs looks like a collection of bright spots - granules (Fig. 189), separated by thin dark lines. The bright spots are streams of hot gas that float to the surface of the convective zone.

Rice. 189. Granules and a spot in the solar photosphere

The chromosphere ("sphere of color") is so named for its reddish-violet color. One of the most interesting phenomena that can be observed in the chromosphere are prominences 2 . The length of the chromosphere reaches 10-15 thousand km.

The outermost part of the Sun's atmosphere is the corona. It extends for millions of kilometers (that is, for a distance of the order of several solar radii), despite the fact that the force of gravity on the Sun is very strong. The large length of the corona is explained by the fact that the movements of atoms and electrons in the corona, heated to a temperature of 1-2 million ° C, occur at great speeds. The solar corona is clearly visible during solar eclipse(Fig. 190). The shape and brightness of the corona change in accordance with the cycle of solar activity, i.e., with a frequency of 11 years.

Rice. 190. Solar corona (during the total solar eclipse of 1999)

The magnetic field induction on the Sun is only 2 times greater than on the Earth's surface. But from time to time, concentrated magnetic fields arise in a small region of the solar atmosphere, several thousand times stronger than on Earth. They prevent the rise of hot plasma, as a result of which, instead of light granules, a dark area is formed - a sunspot (see Fig. 189). When large groups of spots appear, the power of visible, ultraviolet and X-ray radiation increases sharply, which can adversely affect people's well-being.

The movement of spots across the solar disk is a consequence of its rotation, which occurs with a period equal to 25.4 days relative to the stars.

The final stage of the process of stellar evolution includes several stages. When all the hydrogen in the center of the star turns into helium, the structure of the star begins to noticeably change. Its luminosity increases, the surface temperature decreases, the outer layers expand and the inner layers contract. The star becomes a red giant, i.e., a huge star with high luminosity and very low density. A dense and hot helium core forms in the center. When the temperature in it reaches 100 million ° C, the reaction of converting helium into carbon begins, accompanied by the release of a large amount of energy.

At the next stage, stars like the Sun shed some of their matter, shrink to the size of planets, turning into small, very dense stars - white dwarfs, and slowly cool down.

Questions

At a temperature in the core of the order of 14-15 million ° C and pressures from 7 10 8 to 3.4 10 11 atm, the star would have to turn into an expanding gas cloud. But that doesn't happen. What forces do you think oppose the star's expansion?
What is the source of energy emitted by a star?
What physical process is the source of the internal heating of the planet?
What causes sunspots to form?
What are the layers of the solar atmosphere?
Tell us about the main stages of the evolution of the Sun.

2 Prominences are huge, up to hundreds of thousands of kilometers long, plasma formations in the solar corona, which have a higher density and lower temperature than the coronal plasma surrounding them.

Introduction

sun star eclipse

Since ancient times, the sun has been an object of worship among different peoples. He was considered the most powerful deity. The cult of the invincible Sun was one of the most widespread (Helios - the Greek god of the Sun, Apollo - the god of the Sun among the Romans, Mitra - among the Persians, Yarilo - among the Slavs, etc.). Temples were erected in honor of the Sun, hymns were composed, and sacrifices were made. Gone is the religious worship of the daylight. Now scientists are investigating the nature of the Sun, finding out its influence on the Earth, and working on the problem of using the almost inexhaustible solar energy.

Evolution of the Sun and Solar System

The age of the Sun is approximately 4.5 billion years. Since its birth, it has used up half of the hydrogen contained in the core. It will continue to radiate "peacefully" for the next 5 billion years or so (although its luminosity will roughly double over that time). But in the end, it will run out of hydrogen fuel, which will lead to drastic changes, which is common for stars, but alas, will lead to the complete destruction of the Earth (and the creation of a planetary nebula).

Sun evolution:

A. On the Sun, nuclear reactions begin to take place in the core. This is called the birth of a star, before the start of nuclear reactions, the object is called a protostar, and there is still too much low temperature in order to start nuclear combustion.

B. By this time, about half of the hydrogen in the core will have been converted to helium. This is the situation in which the Sun is now (approximately 4.5 billion years have passed since the birth of the Sun).

C. The hydrogen in the core is almost completely recycled, and the combustion of hydrogen begins in a layered source around the core. This causes the Sun to swell. Its radius becomes about 40% larger, and its luminosity doubles.

D. In one and a half billion years, the surface of the Sun will be 3.3 times larger than it is now, and the temperature will drop to 4300 degrees Kelvin. When viewed from the Earth, the Sun will look like a large orange ball. However, the main problem is that the temperature of the Earth will rise by 100 degrees and all the seas will evaporate, so that there will be no observers of this grandiose picture. In the next 250 million years, the radius of the Sun will increase by a factor of 100, and its luminosity will increase by more than 500 times. It will take up almost half the sky on a planet that was once Earth.

E. The temperature of the core will rise so high that the reaction of converting helium into carbon will begin to proceed. Perhaps this process will be explosive and one third of the solar shell will be dispersed in space.

What happens after that is currently unknown. The sun will become brighter, and all the outer layers will be blown into space by a very strong solar wind. This phenomenon is called the formation of a planetary nebula; examples of such objects are often observed in space (there is always a star inside a planetary nebula that gave birth to it).

After that, almost only the core will remain. former sun, the so-called white dwarf, having a mass half that of the modern Sun, but with an abnormally high density of matter: 2 tons per cubic centimeter. This white dwarf will slowly cool down, turn into a black dwarf, and this will be the end of the Sun.