A short message about the stars. Interesting facts about stars. How are stars born? Constellations and stars in the sky

The question of how many stars there are in the sky worried the minds of people as soon as the first star was noticed by them in the sky (and they are still solving this problem). Astronomers nevertheless made some calculations, establishing that with the naked eye you can see about 4.5 thousand celestial bodies in the sky, and our Milky Way galaxy includes about 150 billion stars. Considering that the Universe contains several trillion galaxies, the total number of stars and constellations whose light reaches the Earth's surface is equal to septillion - and this estimate is only approximate.

A star is a huge ball of gas that emits light and heat (this is its main difference from the planets, which, being completely dark bodies, can only reflect the light rays falling on them). Energy generates light and heat, resulting from thermonuclear reactions occurring inside the core: unlike planets, which contain both solid and light elements, celestial bodies contain light particles with a slight admixture of solids (for example, the Sun consists of almost 74% hydrogen and 25% helium).

The temperature of the celestial bodies is extremely hot: as a result of a large number of thermonuclear reactions, the temperature indicators of stellar surfaces range from 2 to 22 thousand degrees Celsius.

Since the weight of even the smallest star significantly exceeds the mass of the largest planets, celestial bodies have sufficient gravity to hold around them all smaller objects that begin to revolve around them, forming a planetary system (in our case, the Solar system).

Flashing luminaries

It is interesting that in astronomy there is such a thing as “new stars” - and we are not talking about the appearance of new celestial bodies: throughout their existence, hot celestial bodies of moderate luminosity periodically flare up brightly, and they begin to stand out so strongly in the sky that people in former times it was believed that new stars were being born.

In fact, data analysis showed that these celestial bodies existed before, but due to the swelling of the surface (the gaseous photosphere), they suddenly became especially bright, increasing their glow tens of thousands of times, resulting in the impression that new stars had appeared in the sky. Returning to their original level of brightness, new stars can change their brightness up to 400 thousand times (at the same time, if the outbreak itself lasts only a few days, their return to the previous state often lasts for years).

Life of heavenly bodies

Astronomers claim that stars and constellations are still being formed: according to the latest scientific data, about forty new celestial bodies appear annually in our galaxy alone.

First things first initial stage Upon its formation, a new star is a cold, rarefied cloud of interstellar gas that rotates around its galaxy. The impetus for reactions to begin to occur in the cloud, stimulating the formation of a celestial body, can be a supernova that explodes nearby (an explosion of a celestial body as a result of which it is completely destroyed after some time).

Also quite probable reasons it may be a collision with another cloud, or the process may be influenced by galaxies colliding with each other, in a word, everything that can influence the gas interstellar cloud and cause it to collapse into a ball under the influence of its own gravity.

During compression, gravitational energy is transformed into heat, causing the gas ball to become extremely hot. When the temperature inside the ball rises to 15-20 K, thermonuclear reactions begin to occur as a result of which the compression stops. The ball turns into a full-fledged celestial body, and over a long period of time, hydrogen is converted into helium inside its core.

When the hydrogen supply runs out, the reactions stop, a helium core is formed and the structure of the celestial body gradually begins to change: it becomes brighter, and its outer layers expand. After the weight of the helium core reaches its maximum, the celestial body begins to decrease and the temperature rises.

When temperatures reach 100 million K, thermonuclear processes resume inside the core, during which helium is converted into solid metals: helium - carbon - oxygen - silicon - iron (when the core becomes iron, all reactions completely stop). As a result, the bright star, having increased by a hundred times, turns into a Red Giant.

Exactly how long a particular star will live largely depends on its size: small celestial bodies burn hydrogen reserves very slowly and are quite capable of existing for billions of years. Due to their insufficient mass, reactions involving helium do not occur in them, and after cooling, they continue to emit a small amount of electromagnetic spectrum.

The life of luminaries of medium parameters, including the Sun, is about 10 billion. After this period, their surface layers usually turn into a nebula with an absolutely lifeless core inside. This core some time later transforms into a helium white dwarf, with a diameter of not much more than Earth, then darkens and becomes invisible.

If a medium-sized celestial body was quite large, it first turns into a black hole, and then a supernova breaks out in its place.

But the lifespan of supermassive luminaries (for example, the North Star) lasts only a few million years: in hot and large celestial bodies, hydrogen burns extremely quickly. After a huge celestial body ends its existence, an extremely powerful explosion occurs in its place - and a supernova appears.

Explosions in the Universe

Astronomers call a supernova an explosion of a star during which an object is almost completely destroyed. After a few years, the volume of the supernova increases so much that it becomes translucent and very rarefied - and these remnants can be seen for several thousand more years, after which it darkens and transforms into a body consisting entirely of neutrons. Interestingly, this phenomenon is not uncommon and occurs in the galaxy once every thirty years.

Classification

Most of the celestial bodies visible to us are classified as main sequence stars, that is, celestial bodies within which thermonuclear processes occur, causing the conversion of hydrogen into helium. Astronomers divide them, depending on their color and temperature indicators, into the following classes of stars:

• Blue, temperature: 22 thousand degrees Celsius (class O);
• White-blue, temperature: 14 thousand degrees Celsius (class B);
• White, temperature: 10 thousand degrees Celsius (class A);
• White-yellow, temperature: 6.7 thousand degrees Celsius (class F);
• Yellow, temperature: 5.5 thousand degrees Celsius (class G);
• Yellow-orange, temperature: 3.8 thousand degrees Celsius (class K);
• Red, temperature: 1.8 thousand degrees Celsius (class M).

In addition to the main sequence luminaries, scientists distinguish the following types of celestial bodies:

• Brown dwarfs are too small celestial bodies for the process of converting hydrogen into helium to begin inside the core, so they are not full-fledged stars. They themselves are extremely dim, and scientists only learned of their existence from the infrared radiation they emit.
• Red giants and supergiants - despite their low temperature (from 2.7 to 4.7 thousand degrees Celsius), this is an extremely bright star, the infrared radiation of which reaches its maximum.
• Wolf-Rayet type radiation is distinguished by the fact that it contains ionized helium, hydrogen, carbon, oxygen and nitrogen. This is a very hot and bright star, which is the helium remnants of huge celestial bodies, which at a certain stage of development lost their mass.
• Type T Tauri - belong to the class of variable stars, as well as to such classes as F, G, K, M, . They have a large radius and high brightness. You can see these luminaries near molecular clouds.
• Bright blue variables (also known as S doradus variables) are extremely bright, pulsating hypergiants that can be up to a million times brighter than the Sun and 150 times heavier. It is believed that a celestial body of this type is the brightest star in the Universe (it is, however, very rare).
• White dwarfs are dying celestial bodies into which medium-sized luminaries are transformed;
• Neutron stars also refer to dying celestial bodies, which after death form larger luminaries than the Sun. The nucleus in them shrinks until it is converted into neutrons.

Guiding thread for sailors

One of the most famous celestial bodies in our sky is the North Star from the constellation Ursa Minor, which almost never changes its position in the sky relative to a certain latitude. At any time of the year, it points to the north, which is why it received its second name - the North Star.

Naturally, the legend that the North Star does not move is far from the truth: like any other celestial body, it rotates. The North Star is unique in that it is closest to the North Pole - at a distance of about one degree. Therefore, due to the angle of inclination, the North Star seems motionless, and for many millennia it has served as an excellent landmark for sailors, shepherds, and travelers.

It should be noted that the North Star will move if the observer changes his location, since the North Star changes its height depending on geographical latitude. This feature made it possible for sailors to determine their location when measuring the angle of inclination between the horizon and the North Star.

In reality, the North Star consists of three objects: not far from it there are two satellite stars, which are connected to it by forces of mutual attraction. At the same time, the Polar Star itself is a giant: its radius is almost 50 times greater than the radius of the Sun, and its luminosity is 2.5 thousand times greater. This means that the North Star will have an extremely short life, and therefore, despite its relatively young age (no more than 70 million years), the North Star is considered old.

Interestingly, in the list of the brightest stars, the Northern Star is in 46th place - which is why in the city in the night sky, illuminated street lamps, The North Star is almost never visible.

Falling luminaries

Sometimes, looking at the sky, you can see a fallen star, a bright luminous point, rushing across the sky - sometimes one, sometimes several. It looks as if a star has fallen, but the legend that immediately comes to mind is that when a fallen star catches your eye, you need to make a wish - and it will certainly come true.

Few people think that in reality these are meteorites flying towards our planet from space, which, having collided with the Earth’s atmosphere, turned out to be so hot that they began to burn and resemble a bright flying star, which received the concept of a “fallen star”. Oddly enough, this phenomenon is not uncommon: if you constantly monitor the sky, you can see a star falling almost every night - over the course of a day, about a hundred million meteors and about a hundred tons of very small dust particles burn up in the atmosphere of our planet.

In some years, a fallen star appears in the sky much more often than usual, and if it is not alone, earthlings have the opportunity to observe the meteor shower - despite the fact that it seems as if the star fell on the surface of our planet, almost all celestial bodies of the shower burn up in the atmosphere.

They appear in such numbers when the comet approaches the Sun, heats up and partially collapses, releasing a certain number of stones into space. If you trace the trajectory of meteorites, you get the misleading impression that they are all flying from one point: they move along parallel trajectories and each fallen star has its own.

It is interesting that many of these meteor showers occur during the same period of the year and earthlings have the opportunity to see the fall of a star for quite a long time - from several hours to several weeks.

And only large-sized meteorites with sufficient mass are capable of reaching the earth’s surface, and if at that time such a star fell not far from settlement, for example, this happened several years ago in Chelyabinsk, this can cause extremely destructive consequences. Sometimes there may be more than one fallen star, which is called a meteor shower.

13.04.2014

Stars have been fascinating subjects of study throughout history. From the ancient Greeks to our modern astronomers, people are constantly looking for new stars, other planets and galaxies. AND interesting facts about stars always intrigue us. The universe is constantly expanding and also changing, so every time an astronomer looks through a telescope, he can see something that wasn't there the day before! And in this place, so full of wonder and so much unknown, there are tons of facts about the stars. We would like to present you our top 10 the most interesting facts about stars.

No. 10. Red dwarfs:

The most common stars in the universe are red dwarfs. This is largely due to their low mass, which allows them to live for a very long time before becoming white dwarfs.

No. 9. Chemical composition of stars:

Almost all the stars in the universe have the same chemical composition and the nuclear fusion reaction occurs in each star and is almost identical, determined only by the amount of fuel.

No. 8. Neutron stars:

As we know, like a white dwarf, neutron stars are one of the final processes of stellar evolution, largely arising after a supernova explosion. Previously, it was often difficult to distinguish a white dwarf from a neutron star, but now scientists are using
telescopes found differences in them. A neutron star gathers more light around itself and this is easy to see with infrared telescopes. Eighth place among interesting facts about stars.

No. 7. Black hole:

Thanks to its incredible mass, according to general theory According to Einstein's relativity, a black hole is actually a bend in space such that everything within its gravitational field is pushed towards it. The gravitational field of a black hole is so strong that not even light can escape it.

No. 6. Massive star:

As far as we know, when a star runs out of fuel, the star can grow in size by more than 1000 times, then it turns into a white dwarf, and due to the speed of the reaction, it explodes. This reaction is better known as a supernova. Scientists suggest that due to this long process and so mysterious black holes are formed.

No. 5. Confluence of stars in the sky:

Many of the stars we see in the night sky can appear as just one glimpse of light. However, this is not always the case. Most of the stars we see in the sky are actually two star systems, or binary star systems. They are simply unimaginably far away and it seems to us that we see only one speck of light.

No. 4. Lifespan of stars:

The stars that have the shortest lifespans are the most massive. They represent a high mass chemical substances and typically burn their fuel much faster.

No. 3. Twinkling stars:

Despite the fact that sometimes it seems to us that the Sun and stars are twinkling, in fact this is not the case. The flickering effect is only the light from the star, which at this time passes through the Earth's atmosphere but has not yet reached our eyes. Third place among the most interesting facts about stars.

No. 2. Huge distances to the stars:

The distances involved in estimating how far away a star is are unimaginably huge. Let's consider an example: The closest star to earth is approximately 4.2 light years away, and to get to it, even on our fastest ship, will take about 70,000 years.

No. 1. Temperature of stars:

The coolest known star is the brown dwarf CFBDSIR 1458+10B, which has a temperature of only about 100 °C.
The hottest known star, a blue supergiant in the Milky Way called Zeta Puppis, has a temperature of over 42,000 °C.

Constellations have accompanied people since ancient times: they were used to navigate the road, plan household work, and tell fortunes. Today people depend less on celestial bodies, but their study does not stop. continue to appear and amaze astronomy lovers.

1. Previously, constellations were considered figures that form stars, but today they are areas of the celestial sphere with conventional boundaries and all celestial bodies on their territory. In 1930, the number of constellations was fixed at 88, of which 47 were described before our era, but the names and titles given to star figures in ancient times are still used today.
2. The southern side of the sky began to be carefully studied with the beginning of the Great Geographical Discoveries, but the northern side was not ignored either. By the end of the 17th century, atlases of the starry sky were published with descriptions of 22 new constellations. On the map of the sky of the southern hemisphere, the Triangle, the Indian, the Bird of Paradise appeared, and the Giraffe, Shield, Sextant and other figures were highlighted above the northern side. The last figures to be formed were above South Pole earth and their names often contain the names of various devices - Clock, Pump, Telescope, Compass, Compass.

   

3. In the list of Claudius Ptolemy, an astronomer of the 2nd century BC, there are 48 names of constellations, 47 of them have survived to this day. The lost cluster was called the Ship or Argo (the ship of the Hellas hero Jason, who obtained the Golden Fleece). In the 18th century, the Ship was divided into 4 smaller figures - Stern, Keel, Sail, Compass. On ancient star maps, the place of the Compass was taken by a mast.

   

4. The static nature of stars is deceptive - without special instruments it is impossible to detect their movement relative to each other. Changes in location would become noticeable if a person had the opportunity to see the constellations after at least 26 thousand years.

   

5. There are usually 12 zodiac signs - this distinction occurred more than 4.5 thousand years ago in Ancient Egypt. Today, astronomers have calculated that in the period from November 27 to December 17, another zodiac constellation, Ophiuchus, rises on the horizon.

   

6. Hydra is considered the largest of the star figures, it occupies 3.16% of the starry sky and stretches in a long strip across a quarter of the sky, located in the northern and southern hemispheres.

   

7. The brightest stars in the northern hemisphere belong to Orion, 209 of them are visible to the naked eye. The most interesting space objects in this part of the sky are the “Orion Belt” and the Orion Nebula.

   

8. The brightest constellation in the southern sky and the smallest among all existing clusters is the Southern Cross.. Its four stars were used by sailors for orientation for several thousand years; the Romans called them the “Throne of the Emperor,” but the Cross was registered as an independent constellation only in 1589.

   

9. The closest constellation to the solar system is the Pleiades, the flight to it is only 410 light years. The Pleiades consists of 3000 stars, among which 9 are particularly bright. Scientists find their images on objects in different parts of the world, since many peoples in ancient times fervently revered the Pleiades.

   

10. The least bright constellation is Table Mountain. It is located far in the south, in the region of Antarctica, and consists of 24 stars, the brightest of which reach only the fifth magnitude.

    

11. The closest star to the Sun, Proxima, is located in the constellation Centaurus, but after 9 thousand years it will be replaced by Barnard's star from the constellation Ophiuchus. The distance from the Sun to Proxima is 4.2 light years, from Barnard's star - 6 light years.

    

12. The oldest map of constellations dates back to the 2nd century BC. Created by Hipparchus of Nicaea, it became the basis for the work of astronomers of later times.

    

13. Some astronomers tried to divide large constellations in order to get new ones, give them their own names, usually associated with the names of rulers and generals, and become famous. The clergy tried to replace pagan names with the names of saints. But these ideas did not take root, and except for the Shield, which was previously called the “Shield of Jan Sobieski”, in honor of the Polish military leader, none of the names survived.

    

14. Since ancient Rus', the characteristic dipper of the Big Dipper has been associated with a horse. In the old days it was called “A Horse at a Jump,” and Ursa Minor was not considered a separate constellation - its stars formed a “rope” with which the horse was “tied” to the Polar Star - a joke.

    

15. Star figures adorn the flags of New Zealand and Alaska. The four-star Southern Cross was adopted as part of the flag of Zealand in 1902. Alaska's flags feature the Big Dipper and the North Star.

    

There is hardly a person who has never admired the stars while looking into the twinkling night sky. You can admire them forever, they are mysterious and attractive. In this topic you will get acquainted with unusual facts about the stars and learn a lot of new things

Did you know that most of the stars you see at night are double stars? Two stars orbit each other, creating a point of gravity, or a smaller star orbits a larger one.” main star" Sometimes these major stars pull matter from smaller ones as they approach each other. There is a limit to the mass a planet can support without causing a nuclear reaction. If Jupiter had been large, it might have turned into a brown dwarf, a kind of semi-star, many moons ago

Such processes often occur in other solar systems, as evidenced by the lack of planets in them. Most of the matter that is in the gravitational field of the main star gathers in one place, eventually forming a new star and a binary system. There may be more than two stars in one system, but still binary number systems are more widespread

White Dwarfs, so-called “dead stars”. After the red giant phase, our own star, the Sun, will also become a white dwarf. White dwarfs have the radius of a planet (like Earth, not like Jupiter), but the density of a star. These specific gravities are made possible by electrons being separated from the atomic nuclei they surround. As a result, the amount of space that these atoms occupy increases and a large mass is created with a small radius

If you could hold the nucleus of an atom in your hand, the electron would circle around you at a distance of 100 meters or more. In the case of electron degeneration, this space remains free. As a result, the White Dwarf cools down and stops emitting light. These massive bodies cannot be seen, and no one knows how many of them there are in the universe.

If the star is large enough to avoid the final white dwarf phase, but too small to avoid becoming a black hole, an exotic type of star known as a neutron star will form. The process of formation of neutron stars is somewhat similar to White Dwarfs, in that they also gradually degrade - but in a different way. Neutron stars are formed from deteriorating matter called neutron when all the electrons and positively charged protons are eliminated and only the neutrons form the core of the star. The density of a neutron star is comparable to the density of atomic nuclei.

Neutron stars can have a mass similar to our Sun or slightly higher but their radius is less than 50 kilometers: usually 10-20. A teaspoon of this neutron is 900 times the mass of the Great Pyramid of Giza. If you were to observe a neutron star directly, you would see both poles because the neutron star acts like a gravitational lens, bending light around itself due to its powerful gravity. A special case of a neutron star is a pulsar. Pulsars can spin at 700 revolutions per second, emitting flashing radiation - hence their name

Eta Carinae is one of the largest stars discovered so far. It is 100 times heavier than our Sun and has approximately the same radius. Eta Carinae can shine a million times brighter than the Sun. These hypermassive stars usually only last a short time because they literally burn themselves out, which is why they are called Supernovas. Scientists believe the limit is 120 times the mass of the Sun—more than any star can weigh.

The Pistol star is a hypergiant star similar to Eta Carinae that has no way of cooling itself. The star is so hot that it is barely held together by its gravity

As a result, the Pistol star emits what is called "solar wind" (high energy particles that, for example, create the Northern Lights). It shines 10 billion times stronger than our Sun. Due to the massive levels of radiation, it is impossible to even imagine that life could ever exist in this star system

In this topic I presented the most interesting facts about stars that I could find. I hope you found it interesting

From time immemorial, Man tried to give names to the objects and phenomena that surrounded him. This also applies to celestial bodies. First, the brightest, clearly visible stars were given names, and over time, others were given names.

Some stars are named according to the position they occupy in the constellation. For example, the star Deneb (the word translates as “tail”) located in the constellation Cygnus is actually located in this part of the body of an imaginary swan. One more example. The star Omicron, better known as Mira, which translates from Latin as “amazing,” is located in the constellation Cetus. Mira has the ability to change its brightness. For long periods it completely disappears from view, meaning observations with the naked eye. The name of the star is explained by its specificity. Basically, stars received names in the era of antiquity, so it is not surprising that most of the names have Latin, Greek, and later Arabic roots.

The discovery of stars whose apparent brightness changes over time led to special designations. They are designated by capital Latin letters, followed by the name of the constellation in the genitive case. But the first variable star discovered in a certain constellation is not designated by the letter A. It is counted from the letter R. Next Star denoted by the letter S and so on. When all the letters of the alphabet are exhausted, a new circle begins, that is, after Z, A is used again. In this case, letters can be doubled, for example “RR”. "R Leo" means it is the first variable star discovered in the constellation Leo.

HOW A STAR IS BORN.

Stars are born when a cloud of interstellar gas and dust is compressed and compacted by its own gravity. It is believed that this process leads to the formation of stars. Using optical telescopes, astronomers can see these zones; they look like dark spots against a bright background. They are called "giant molecular cloud complexes" because hydrogen is present in molecular form. These complexes, or systems, along with globular star clusters, are the largest structures in the galaxy, sometimes reaching 1,300 light-years in diameter.

Younger stars, called "stellar population I", were formed from the remnants resulting from the outbursts of older stars, they are called "stellar population II". An explosive flare causes a shock wave that reaches the nearest nebula and provokes its compression.

Bock globules .

So, part of the nebula is compressed. Simultaneously with this process, the formation of dense dark round gas and dust clouds begins. They are called "Bock globules". Bok, an American astronomer of Dutch origin (1906-1983), was the first to describe globules. The mass of the globules is approximately 200 times the mass of our Sun.

As the Bok globule continues to condense, its mass increases, attracting matter from neighboring regions due to gravity. Due to inner part The globule condenses faster than the outer one, the globule begins to heat up and rotate. After several hundred thousand years, during which compression occurs, a protostar is formed.

Evolution of a protostar.

Due to the increase in mass, more and more matter is attracted to the center of the protostar. The energy released from the gas compressed inside is transformed into heat. The pressure, density and temperature of the protostar increase. Due to the increase in temperature, the star begins to glow dark red.

The protostar has a very big sizes, and although thermal energy distributed over its entire surface, it still remains relatively cold. In the core, the temperature rises and reaches several million degrees Celsius. Rotation and round form protostars change somewhat, it becomes flatter. This process lasts millions of years.

It is difficult to see young stars, since they are still surrounded by a dark dust cloud, due to which the brightness of the star is practically invisible. But they can be viewed using special infrared telescopes. The hot core of a protostar is surrounded by a rotating disk of matter with a strong gravitational force. The core gets so hot that it begins to eject matter from the two poles, where resistance is minimal. When these emissions collide with the interstellar medium, they slow down and disperse on either side, forming a teardrop-shaped or arched structure known as a Herbic-Haro object.

Star or planet?

The temperature of a protostar reaches several thousand degrees. Further developments depend on the dimensions of this celestial body; if the mass is small and is less than 10% of the mass of the Sun, this means that there are no conditions for nuclear reactions to occur. Such a protostar will not be able to turn into a real star.

Scientists have calculated that for a contracting celestial body to transform into a star, its minimum mass must be at least 0.08 of the mass of our Sun. A gas-containing cloud of smaller sizes, condensing, will gradually cool and turn into a transitional object, something between a star and a planet, this is the so-called “brown dwarf”.

The planet Jupiter is a celestial object too small to become a star. If it were larger, perhaps nuclear reactions would begin in its depths, and it, along with the Sun, would contribute to the emergence of a system of double stars.

Nuclear reactions.

If the mass of a protostar is large, it continues to condense under the influence of its own gravity. The pressure and temperature in the core increase, the temperature gradually reaches 10 million degrees. This is enough to combine hydrogen and helium atoms.

Next, “ nuclear reactor" protostar, and it turns into an ordinary star. A strong wind is then released, which disperses the surrounding shell of dust. Light can then be seen emanating from the resulting star. This stage is called the "T-Taurus phase" and can last 30 million years. The formation of planets is possible from the remnants of gas and dust surrounding the star.

The birth of a new star can cause a shock wave. Having reached the nebula, it provokes the condensation of new matter, and the star formation process will continue through gas and dust clouds. Small stars are faint and cold, while large ones are hot and bright. For most of its existence, the star balances in the equilibrium stage.

CHARACTERISTICS OF STARS.

Observing the sky even with the naked eye, you can immediately notice such a feature of the stars as brightness. Some stars are very bright, others are fainter. Without special instruments, in ideal visibility conditions, about 6,000 stars can be seen. Thanks to binoculars or a telescope, our capabilities increase significantly; we can admire millions of stars in the Milky Way and outer galaxies.

Ptolemy and the Almagest.

The first attempt to compile a catalog of stars, based on the principle of their degree of luminosity, was made by the Hellenic astronomer Hipparchus of Nicaea in the 2nd century BC. Among his numerous works was the Star Catalog, containing a description of 850 stars classified by coordinates and luminosity. The data collected by Hipparchus, who, in addition, discovered the phenomenon of precession, was worked out and further developed thanks to Claudius Ptolemy from Alexandria in the 2nd century. AD He created the fundamental opus “Almagest” in thirteen books. Ptolemy collected all the astronomical knowledge of that time, classified it and presented it in an accessible and understandable form. The Almagest also included the Star Catalog. It was based on observations made by Hipparchus four centuries ago. But Ptolemy's Star Catalog contained about a thousand more stars.

Ptolemy's catalog was used almost everywhere for a millennium. He divided stars into six classes according to the degree of luminosity: the brightest were assigned to the first class, the less bright to the second, and so on.

The sixth class includes stars that are barely visible to the naked eye. The term “luminosity of celestial bodies” is still used today to determine the measure of brilliance of celestial bodies, not only stars, but also nebulae, galaxies and other celestial phenomena.

Magnitude in modern science.

In the middle of the 19th century. English astronomer Norman Pogson improved the method of classifying stars based on the principle of luminosity, which had existed since the times of Hipparchus and Ptolemy. Pogson took into account that the difference in luminosity between the two classes is 2.5. Pogson introduced a new scale according to which the difference between stars of the first and sixth classes is 100 AU. That is, the brightness ratio of stars of the first magnitude is 100. This ratio corresponds to an interval of 5 magnitudes.

Relative and absolute magnitude.

Magnitude, measured using special instruments mounted in a telescope, indicates how much light from a star reaches an observer on Earth. Light travels the distance from the star to us, and, accordingly, the further away the star is, the fainter it appears. That is, when determining stellar magnitude, it is necessary to take into account the distance to the star. IN in this case We are talking about relative stellar magnitude. It depends on the distance.

There are very bright and very faint stars. To compare the brightness of stars, regardless of their distance from the Earth, the concept of “absolute stellar magnitude” was introduced. It characterizes the brightness of a star at a certain distance of 10 parsecs (10 parsecs = 3.26 light years). To determine the absolute magnitude, you need to know the distance to the star.

The color of the stars.

The next important characteristic of a star is its color. Looking at the stars even with the naked eye, you can see that they are not all the same.

There are blue, yellow, orange, red stars, not just white ones. The color of stars tells a lot to astronomers, primarily depending on the temperature of the star's surface. Red stars are the coldest, their temperature is approximately 2000-3000 o C. Yellow stars, like our Sun, have an average temperature of 5000-6000 o C. The hottest are white and blue stars, their temperature is 50000-60000 o C and higher .

Mysterious lines.

If we pass starlight through a prism, we get a so-called spectrum; it will be intersected by lines. These lines are a kind of “identification card” of the star, since astronomers can use them to determine the chemical composition of the surface layers of stars. The lines belong to different chemical elements.

By comparing the lines in the stellar spectrum with lines made in the laboratory, it is possible to determine which chemical elements are included in the composition of stars. In the spectra, the main lines are hydrogen and helium; it is these elements that make up the main part of the star. But there are also elements of the metal group - iron, calcium, sodium, etc. In the bright solar spectrum, lines of almost all chemical elements are visible.

HERZSPRUNG-RUSSELL DIAGRAM.

Among the parameters characterizing a star, there are two most important ones: temperature and absolute magnitude. Temperature indicators are closely related to the color of the star, and the absolute magnitude is closely related to the spectral type. This refers to the classification of stars according to the intensity of the lines in their spectra. According to the classification currently used, stars are divided into seven main spectral classes according to their spectra. They are designated by the Latin letters O, B, A, F, G, K, M. It is in this sequence that the temperature of stars decreases from several tens of thousands of degrees of class O to 2000-3000 degrees of type M stars.

Absolute magnitude, i.e. A measure of brightness that indicates the amount of energy emitted by a star. It can be calculated theoretically, knowing the distance of the star.

Outstanding idea.

The idea to connect the two main parameters of a star came to the minds of two scientists in 1913, and they carried out work independently of each other.

We are talking about the Dutch astronomer Einar Hertzsprung and the American astrophysicist Henry Norris Russell. Scientists worked at a distance of thousands of kilometers from each other. They created a graph that linked together the two main parameters. The horizontal axis reflects the temperature, the vertical axis – the absolute magnitude. The result was a diagram that was given the names of two astronomers - the Hertzsprung-Russell diagram, or, more simply, the H-R diagram.

Star is a criterion.

Let's see how the G-R diagram is made. First of all, you need to select a criterion star. A star whose distance is known, or another with an already calculated absolute magnitude, is suitable for this.

It should be borne in mind that the luminous intensity of any source, be it a candle, a light bulb or a star, changes depending on the distance. This is expressed mathematically as follows: the luminosity intensity “I” at a certain distance “d” from the source is inversely proportional to “d2”. In practice, this means that if the distance doubles, the luminosity intensity decreases fourfold.

Then the temperature of the selected stars should be determined. To do this, you need to identify their spectral class, color and then determine the temperature. Currently, instead of the spectral type, another equivalent indicator is used - the “color index”.

These two parameters are plotted on the same plane with the temperature decreasing from left to right on the abscissa. The absolute luminosity is fixed at the ordinate, an increase is noted from bottom to top.

Main sequence.

On the diagram G-R stars located along a diagonal line running from bottom to top and from left to right. This strip is called the Main Sequence. The stars that make up it are called Main Sequence stars. The sun belongs to this group. This is a group of yellow stars with a surface temperature of approximately 5600 degrees. Main Sequence stars are in the most “quiet phase” of their existence. In the depths of their nuclei, hydrogen atoms mix and helium is formed. The Main Sequence phase accounts for 90% of a star's lifetime. Out of 100 stars, 90 are in this phase, although they are distributed in different positions depending on temperature and luminosity.

The main sequence is a “narrow region,” indicating that stars have difficulty maintaining a balance between the force of gravity, which pulls inward, and the force generated by nuclear reactions, which pulls toward the outside of the zone. A star like the Sun, equal to 5600 degrees, must have an absolute magnitude of about +4.7 to maintain balance. This follows from the G-R diagram.

Red giants and white dwarfs.

Red giants are in the upper zone on the right, located with outside Main sequence. A characteristic feature of these stars is their very low temperature (about 3000 degrees), but at the same time they are brighter than stars that have the same temperature and are located in the Main Sequence.

Naturally, the question arises: if the energy emitted by a star depends on temperature, then why do stars with the same temperature have different degrees of luminosity. The explanation should be sought in the size of the stars. Red giants are brighter because their emitting surface is much larger than that of Main Sequence stars.

It is no coincidence that this type of star is called “giant”. Indeed, their diameter can exceed the diameter of the Sun by 200 times, these stars can occupy a space of 300 million km, which is twice the distance from the Earth to the Sun! Using the statement about the influence of the size of a star, we will try to explain some aspects in the existence of other stars - white dwarfs. They are located at the bottom left of the H-R diagram.

White dwarfs are very hot, but very dim stars. At the same temperature as the large and hot blue-white stars of the Main Sequence, white dwarfs are much smaller in size. These are very dense and compact stars, they are 100 times smaller than the Sun, their diameter is approximately the same as that of Earth. A striking example of the high density of white dwarfs is that one cubic centimeter of the matter they consist of must weigh about one ton!

Globular star clusters.

When making diagrams G-R ball star clusters, and they contain mostly old stars, it is very difficult to determine the Main Sequence. Its traces are recorded mainly in the lower zone, where cooler stars are concentrated. This is due to the fact that hot and bright stars have already passed the stable phase of their existence and are moving to the right, into the red giant zone, and if they have passed it, then into the white dwarf zone. If people were able to trace all the evolutionary stages of a star over its life, they would be able to see how it changes its characteristics.

For example, when hydrogen in the core of a star stops burning, the temperature in the outer layer of the star decreases, and the layer itself expands. The star is leaving the Main Sequence phase and heading to the right side of the diagram. This applies primarily to stars that are large in mass and the brightest; it is this type that evolves faster.

Over time, stars move out of the Main Sequence. The diagram records a “turning point”, thanks to which it is possible to quite accurately calculate the age of the stars in clusters. The higher the “turning point” is on the diagram, the younger the cluster, and, accordingly, the lower it is on the diagram, the older the star cluster.

The meaning of the chart.

The Hertzsprung-Russell diagram is of great help in studying the evolution of stars throughout their existence. During this time, the stars undergo changes and transformations, and in some periods they are very profound. We already know that stars differ not in their own characteristics, but in the types of phases in which they are at one time or another.

Using this diagram you can calculate the distance to the stars. You can select any star located in the Main Sequence with an already determined temperature and see its progress on the diagram.

DISTANCE TO THE STARS.

When we look at the sky with the naked eye, stars, even the brightest ones, seem to us to be shiny points located at the same distance from us. The vault of heaven spreads out over us like a carpet. It is no coincidence that the positions of the stars are expressed in only two coordinates (right ascension and declination), and not in three, as if they are located on the surface and not in three-dimensional space. With the help of telescopes, we cannot obtain all the information about the stars; for example, from photographs of the Hubble Space Telescope, we cannot accurately determine at what distance the stars are located.

Depth of space.

People learned relatively recently that the Universe also has a third dimension – depth. Only at the beginning of the 19th century, thanks to the improvement of astronomical equipment and instruments, scientists were able to measure the distance to some stars. The first was the star 61 Cygni. Astronomer F.V. Bessel found that it was at a distance of 10 light years. Bessel was one of the first astronomers to measure the "annual parallax". Until now, the “annual parallax” method has been the basis for measuring the distance to stars. This is a purely geometric method - just measure the angle and calculate the result.

But the simplicity of the method does not always correspond to effectiveness. Due to the great distance of the stars, the angles are very small. They can be measured using telescopes. The parallax angle of the star Proxima Centauri, the closest of the triple system Alpha Centauri, is small (0.76 exact version), but from this angle you can see a hundred lire coin at a distance of ten kilometers. Of course, the further the distance, the smaller the angle becomes.

Inevitable inaccuracies.

Errors in terms of determining parallax are quite possible, and their number increases as the object moves away. Although, with the help of modern telescopes, it is possible to measure angles with an accuracy of one thousandth, there will still be errors: at a distance of 30 light years they will be approximately 7%, 150 light years. years - 35%, and 350 St. years – up to 70%. Of course, large inaccuracies render measurements useless. Using the “parallax method”, it is possible to successfully determine the distances to several thousand stars located in an area of ​​approximately 100 light years. But in our galaxy there are more than 100 billion stars, the diameter of which is 100,000 light years!

There are several variations of the annual parallax method, such as secular parallax. The method takes into account the movement of the Sun and all solar system in the direction of the constellation Hercules, at a speed of 20 km/sec. With this movement, scientists have the opportunity to collect the necessary database to carry out a successful parallax calculation. In ten years, 40 times more information has been obtained than was previously possible.

Then, using trigonometric calculations, the distance to a particular star is determined.

Distance to star clusters.

It is easier to calculate the distance to star clusters, especially open ones. The stars are located relatively close to each other, therefore, by calculating the distance to one star, you can determine the distance to the entire star cluster.

In addition, in this case, statistical methods can be used to reduce the number of inaccuracies. For example, the method of “converging points”, it is often used by astronomers. It is based on the fact that during long-term observation of stars in an open cluster, those moving towards common point, it is called a convergent point. By measuring the angles and radial velocities (that is, the speed of approaching and moving away from the Earth), you can determine the distance to the star cluster. Using this method there is a possible 15% inaccuracy at a distance of 1500 light years. It is also used at distances of 15,000 light years, which is quite suitable for celestial bodies in our Galaxy.

Main Sequence Fitting – establishment of the Main Sequence.

To determine the distance to distant star clusters, for example to the Pleiades, you can proceed as follows: construct a G-R diagram, on the vertical axis note the apparent stellar magnitude (and not the absolute magnitude, since it depends on the distance), which depends on temperature.

Then you should compare the resulting picture with the G-R Iad diagram; it has many common features in terms of Main Sequences. By combining the two diagrams as closely as possible, it is possible to determine the Main Sequence of the star cluster whose distance must be measured.

Then the equation should be used:

m-M=5log(d)-5, where

m – apparent magnitude;

M – absolute magnitude;

d – distance.

In English this method is called “Main Sequence Fitting”. It can be used for open star clusters such as NGC 2362, Alpha Persei, III Cephei, NGC 6611. Astronomers have attempted to determine the distance to the famous double open star cluster in the constellation Perseus ("h" and "chi"), where many stars are located -supergiants. But the data turned out to be contradictory. Using the “Main Sequence Fitting” method, it is possible to determine distances up to 20,000-25,000 light years, this is a fifth of our Galaxy.

Light intensity and distance.

The further away a celestial body is, the weaker its light appears. This position is consistent with the optical law, according to which the intensity of light "I" is inversely proportional to the distance squared "d".

For example, if one galaxy is located at a distance of 10 million light years, then another galaxy located 20 million light years away has a brightness four times smaller than the first. That is, from a mathematical point of view, the relationship between the two quantities “I” and “d” is precise and measurable. In the language of astrophysics, the intensity of light is the absolute magnitude of the stellar magnitude M of some celestial object, the distance to which should be measured.

Using the equation m-M=5log(d)-5 (it reflects the law of change in brightness) and knowing that m can always be determined using a photometer, and M is known, the distance “d” is measured. So, knowing the absolute magnitude, using calculations it is not difficult to determine the distance.

Interstellar absorption.

One of the main problems associated with distance measuring methods is the problem of light absorption. On its way to Earth, light travels vast distances, passing through interstellar dust and gas. Accordingly, part of the light is adsorbed, and when it reaches telescopes installed on Earth, it already has a non-original strength. Scientists call this “extinction,” the weakening of light. It is very important to calculate the amount of extinction when using a number of methods, such as candela. In this case, the exact absolute magnitudes must be known.

It is not difficult to determine the extinction for our Galaxy - just take into account the dust and gas of the Milky Way. It is more difficult to determine the extinction of light from an object in another galaxy. To the extinction along the path in our Galaxy, we must also add part of the absorbed light from another.

EVOLUTION OF STARS.

The internal life of a star is regulated by the influence of two forces: the force of gravity, which counteracts the star and holds it, and the force released during nuclear reactions occurring in the core. On the contrary, it tends to “push” the star into distant space. During the formation stage, a dense and compressed star is strongly influenced by gravity. As a result, strong heating occurs, the temperature reaches 10-20 million degrees. This is enough to start nuclear reactions, as a result of which hydrogen is converted into helium.

Then, over a long period, the two forces balance each other, the star is in a stable state. When the nuclear fuel in the core gradually runs out, the star enters an instability phase, two forces opposing each other. A critical moment comes for a star; a variety of factors come into play - temperature, density, chemical composition. The mass of the star comes first; the future of this celestial body depends on it - either the star will explode like a supernova, or turn into a white dwarf, a neutron star or a black hole.

How does hydrogen run out?

Only the very largest among celestial bodies become stars, the smaller ones become planets. There are also bodies of average mass, they are too large to belong to the class of planets, and too small and cold for nuclear reactions characteristic of stars to occur in their depths.

So, a star is formed from clouds of interstellar gas. As already noted, the star remains in a balanced state for quite a long time. Then comes a period of instability. Further fate stars depends on various factors. Consider a hypothetical small star whose mass is between 0.1 and 4 solar masses. A characteristic feature of stars that have low mass, is the absence of convection in inner layers, i.e. The substances that make up the star do not mix, as happens in stars with a large mass.

This means that when the hydrogen in the core runs out, there are no new reserves of this element in the outer layers. Hydrogen burns and turns into helium. Little by little the core heats up, the surface layers destabilize their own structure, and the star, as can be seen from the H-R diagram, slowly leaves the Main Sequence. In the new phase, the density of matter inside the star increases, the composition of the core “degenerates”, and as a result a special consistency appears. It is different from normal matter.

Modification of matter.

When matter changes, pressure depends only on the density of the gases, not on temperature.

In the Hertzsprung-Russell diagram, the star moves to the right and then upward, approaching the red giant region. Its dimensions increase significantly, and because of this, the temperature of the outer layers drops. The diameter of a red giant can reach hundreds of millions of kilometers. When our sun enters this phase, it will “swallow” both Mercury and Venus, and if it cannot capture the Earth, it will heat it up to such an extent that life on our planet will cease to exist.

During the evolution of a star, the temperature of its core increases. First nuclear reactions occur, then upon reaching optimal temperature Helium begins to melt. When this happens, the sudden increase in core temperature causes a flare and the star quickly moves to the left side of the H-R diagram. This is the so-called “helium flash”. At this time, the core containing helium burns together with hydrogen, which is part of the shell surrounding the core. On the H-R diagram, this stage is recorded by moving to the right along a horizontal line.

The last phases of evolution.

When helium is transformed into a hydrocarbon, the core is modified. Its temperature rises until the carbon begins to burn. A new outbreak occurs. In any case, during the last phases of the star’s evolution, a significant loss of its mass is noted. This can happen gradually or suddenly, during an outburst, when the outer layers of the star burst like a large bubble. In the latter case, a planetary nebula is formed - a spherical shell, spreading in outer space at a speed of several tens or even hundreds of km/sec.

The final fate of a star depends on the mass remaining after everything that happens to it. If during all transformations and flares it ejected a lot of matter and its mass does not exceed 1.44 solar masses, the star turns into a white dwarf. This one is called the “Chandrasekhar limit” after the Pakistani astrophysicist Subrahmanyan Chandrasekhar. This is the maximum mass of a star at which a catastrophic end may not occur due to the pressure of electrons in the core.

After the outbreak of the outer layers, the core of the star remains, and its surface temperature is very high - about 100,000 o K. The star moves to the left edge of the H-R diagram and goes down. Its luminosity decreases as its size decreases.

The star is slowly reaching the white dwarf zone. These are stars of small diameter, but very high density, one and a half million times the density of water.

A white dwarf represents the final stage of star evolution, without outbursts. She is gradually cooling down. Scientists believe that the end of the white dwarf is very slow, at least since the beginning of the Universe, it seems that not a single white dwarf has suffered from “thermal death”.

If the star is large and its mass is greater than the Sun, it will explode like a supernova. During a flare, a star may collapse completely or partially. In the first case, what will be left behind is a cloud of gas with residual substances of the star. In the second, a celestial body of the highest density will remain - a neutron star or a black hole.

VARIABLE STARS.

According to Aristotle's concept, the celestial bodies of the Universe are eternal and permanent. But this theory underwent significant changes with the appearance in the 17th century. the first binoculars. Observations carried out over subsequent centuries demonstrated that, in fact, the apparent constancy of celestial bodies is explained by the lack of observation technology or its imperfection. Scientists have concluded that variability is general characteristic all types of stars. During evolution, a star goes through several stages, during which its main characteristics - color and luminosity - undergo profound changes. They occur during the existence of a star, which is tens or hundreds of millions of years, so a person cannot be an eyewitness to what is happening. For some classes of stars, changes occurring are recorded in short periods of time, for example, over several months, days or part of a day. The star's changes and its luminous fluxes can be measured many times over subsequent nights.

Measurements.

In fact, this problem is not as simple as it seems at first glance. When carrying out measurements, it is necessary to take into account atmospheric conditions, and they change, sometimes significantly within one night. In this regard, data on the luminous fluxes of stars vary significantly.

It is very important to be able to distinguish real changes in the light flux, and they are directly related to the brightness of the star, from apparent ones, which are explained by changes in atmospheric conditions.

To do this, it is recommended to compare the light fluxes of the observed star with other stars - landmarks visible through a telescope. If the changes are apparent, i.e. associated with changes in atmospheric conditions, they affect all observed stars.

Obtaining correct data about the state of the star at some stage is the first step. Next, a “light curve” should be drawn up to record possible changes in brightness. It will show the change in magnitude.

Variables or not.

Stars whose magnitude is not constant are called variables. For some of them, variability is only apparent. These are mainly stars belonging to the binary system. Moreover, when the orbital plane of the system more or less coincides with the observer’s line of sight, it may seem to him that one of the two stars is completely or partially eclipsed by the other and is less bright. In these cases, the changes are periodic; periods of change in the brightness of eclipsing stars are repeated at intervals that coincide with the orbital period of the binary star system. These stars are called "eclipsing variables."

The next class of variable stars is “internal variables”. The amplitudes of the brightness fluctuations of these stars depend on the physical parameters of the star, such as radius and temperature. For many years, astronomers have been observing the variability of variable stars. In our Galaxy alone, 30,000 variable stars have been recorded. They were divided into two groups. The first category includes “eruptive variable stars.” They are characterized by single or repeated outbreaks. Changes in stellar magnitudes are episodic. The class of “eruptive variables,” or explosive ones, also includes novae and supernovae. The second group includes everyone else.

Cepheids.

There are variable stars whose brightness changes strictly periodically. Changes occur at certain intervals. If you draw a light curve, it will clearly record the regularity of changes, while the shape of the curve will mark the maximum and minimum characteristics. The difference between the maximum and minimum fluctuations defines a large space between the two characteristics. Stars of this type are classified as “pulsating variables.” From the light curve we can conclude that the star's brightness increases faster than it decreases.

Variable stars are divided into classes. The prototype star is taken as a criterion; it is this star that gives the name to the class. An example is the Cepheids. This name comes from the star Cepheus. This is the simplest criterion. There is another one - stars are divided according to their spectra.

Variable stars can be divided into subgroups according to different criteria.

DOUBLE STARS.

Stars in the firmament exist in the form of clusters, an association, and not as individual bodies. Star clusters can be very densely populated with stars or not.

Closer connections can exist between stars; we are talking about binary systems, as astronomers call them. In a pair of stars, the evolution of one directly affects the second.

Opening.

The discovery of double stars, as they are now called, was one of the first discoveries made using astronomical binoculars. The first pair of this type of stars was Mizar from the constellation Ursa Major. The discovery was made by the Italian astronomer Riccioli. Considering the huge number of stars in the Universe, scientists came to the conclusion that Mizar was not the only binary system among them, and they were right; observations soon confirmed this hypothesis. In 1804, the famous astronomer William Herschel, who devoted 24 years of scientific observations, published a catalog containing descriptions of approximately 700 double stars. At first, scientists did not know for sure whether the components of the binary system were physically connected to each other.

Some bright minds believed that double stars were affected by the stellar association as a whole, especially since the brightness of the components in the pair was not the same. In this regard, it seemed that they were not nearby. To determine the true position of the bodies, it was necessary to measure the parallactic displacements of the stars. This is what Herschel did. To the greatest surprise, the parallactic displacement of one star relative to another during the measurement gave an unexpected result. Herschel noticed that instead of oscillating symmetrically with a period of 6 months, each star followed a complex ellipsoidal path. In accordance with the laws of celestial mechanics, two bodies connected by gravity move in an elliptical orbit. Herschel's observations confirmed the thesis that double stars are connected physically, that is, by gravitational forces.

Classification of double stars.

There are three main classes of double stars: visual binaries, photometric binaries, and spectroscopic binaries. This classification does not fully reflect the internal differences between the classes, but gives an idea of ​​the stellar association.

The duality of visual double stars is clearly visible through a telescope as they move. Currently, about 70,000 visual binaries have been identified, but only 1% of them have had an accurately determined orbit.

This figure (1%) should not be surprising. The fact is that orbital periods can be several decades, if not entire centuries. And building a path along the orbit is a very painstaking work, requiring numerous calculations and observations from different observatories. Very often, scientists have only fragments of the orbital movement; they reconstruct the rest of the path deductively, using the available data. It should be borne in mind that the orbital plane of the system may be inclined to the line of sight. In this case, the reconstructed orbit (apparent) will differ significantly from the true one.

If the true orbit is determined, the period of revolution and the angular distance between the two stars are known, it is possible, by applying Kepler's third law, to determine the sum of the masses of the system components. The distance of the double star to us should also be known.

Double photometric stars.

The duality of this system of stars can be judged only by periodic fluctuations in brightness. When moving, such stars alternately block each other. They are also called "eclipsing double stars." These stars have orbital planes close to the direction of the line of sight. The larger the area the eclipse occupies, the more pronounced the brilliance. If you analyze the light curve of double photometric stars, you can determine the inclination of the orbital plane.

Using the light curve, you can also determine the orbital period of the system. If, for example, two eclipses are recorded, the light curve will have two decreases (minimum). The time period during which three successive decreases along the light curve are recorded corresponds to the orbital period.

The periods of photometric binary stars are much shorter compared to the periods of visual binary stars and last for several hours or several days.

Spectral dual stars.

Using spectroscopy, one can notice the splitting of spectral lines due to the Doppler effect. If one of the components is a weak star, then only a periodic oscillation of the positions of single lines is observed. This method is used when the components of a double star are very close to each other and are difficult to identify with a telescope as visual double stars. Binary stars determined using a spectroscope and the Doppler effect are called spectral binaries. Not all double stars are spectral. The two components of binary stars can move away and approach in a radial direction.

Observations indicate that double stars are found mainly in our Galaxy. It is difficult to determine the percentage of double and single stars. If we use the subtraction method and subtract the number of identified double stars from the entire stellar population, we can conclude that they constitute a minority. This conclusion may be erroneous. In astronomy there is the concept of “selection effect”. To determine the binarity of stars, it is necessary to identify their main characteristics. For this it is necessary good equipment. Binary stars can sometimes be difficult to identify. For example, visual double stars cannot always be seen at a great distance from the observer. Sometimes the angular distance between components is not recorded by the telescope. In order to detect photometric and spectroscopic binaries, their brightness must be strong enough to collect modulations of the light flux and carefully measure the wavelengths in the spectral lines.

The number of stars suitable in all respects for research is not so large. According to theoretical developments, it can be assumed that double stars make up from 30% to 70% of the stellar population.

NEW STARS.

Variable explosive stars consist of a white dwarf and a Main Sequence star, like the Sun, or a post-sequence star, like a red giant. Both stars follow a narrow orbit every few hours. They are located at a close distance from each other, and therefore they interact closely and cause spectacular phenomena.

Since the middle of the 19th century, scientists have recorded the predominance of purple at certain times, this phenomenon coincides with the presence of peaks in the light curve. Based on this principle, the stars were divided into several groups.

Classic novae.

Classical novae differ from explosive variables in that their optical outbursts do not have a repeating character. The amplitude of their light curve is more clearly expressed, and the rise to the maximum point occurs much faster. They usually reach maximum brightness in a few hours, during which time the new star acquires a magnitude of approximately 12, that is, the luminous flux increases by 60,000 units.

The slower the process of rising to maximum, the less noticeable the change in brightness. The nova does not remain at its maximum position for long; this period usually lasts from several days to several months. The shine then begins to decrease, quickly at first, then more slowly to normal levels. The duration of this phase depends on various circumstances, but its duration is at least several years.

In new classical stars, all these phenomena are accompanied by uncontrolled thermonuclear reactions occurring in the surface layers of the white dwarf, which is where the “borrowed” hydrogen from the second component of the star is located. New stars are always binary, one of the components is necessarily a white dwarf. When the mass of the star component flows to the white dwarf, the hydrogen layer begins to compress and heats up, accordingly the temperature rises, and the helium heats up. All this happens quickly, sharply, resulting in an outbreak. The emitting surface increases, the star's brightness becomes bright, and a burst is recorded in the light curve.

During the active flare phase, the nova reaches its maximum brightness. The maximum absolute magnitude is on the order of -6 to -9. in new stars this figure is reached more slowly, in variable explosive stars it is achieved faster.

New stars also exist in other galaxies. But what we observe is only their apparent magnitude; the absolute magnitude cannot be determined, since their exact distance to the Earth is unknown. Although, in principle, it is possible to find out the absolute magnitude of a nova if it is in maximum proximity to another nova, the distance to which is known. The maximum absolute value is calculated using the equation:

M=-10.9+2.3log (t).

t is the time during which the light curve of the nova drops to 3 magnitudes.

Dwarf novae and repeating novae.

The closest relatives of novae are dwarf novae, their prototype “U Gemini”. Their optical flares are almost similar to the flares of new stars, but there are differences in the light curves: their amplitudes are smaller. There are also differences in the frequency of flares - in new dwarf stars they occur more or less regularly. On average once every 120 days, but sometimes every few years. The optical flashes of the novae last from several hours to several days, after which the brightness decreases over several weeks and finally reaches normal levels.

The existing difference can be explained by different physical mechanisms that provoke the optical flash. In Gemini U, flares occur due to a sudden change in the percentage of matter on the white dwarf - an increase in it. The result is a huge release of energy. Observations of dwarf novae during the eclipse phase, that is, when the white dwarf and the disk surrounding it are obscured by a component star of the system, clearly indicate that it is the white dwarf, or rather its disk, that is the source of light.

Recurring novae are a cross between classical novae and dwarf novae. As the name suggests, their optical flares repeat regularly, which makes them similar to new dwarf stars, but this happens after several decades. The increase in brightness during a flare is more pronounced and amounts to about 8 magnitudes; this feature brings them closer to classical novae.

OPEN STAR CLUSTERS.

Open star clusters are not difficult to find. They are called galaxy clusters. We are talking about formations that include from several tens to several thousand stars, most of which are visible to the naked eye. Star clusters appear to the observer as a section of the sky densely dotted with stars. As a rule, such areas of concentration of stars are clearly visible in the sky, but it happens, quite rarely, that the cluster is practically indistinguishable. In order to determine whether any part of the sky is a star cluster or whether we are talking about stars simply located close to each other, one should study their movement and determine the distance to the Earth. The stars that make up the clusters move in the same direction. In addition, if stars that are not far from each other are located at the same distance from the solar system, they are, of course, connected to each other by gravitational forces and form an open cluster.

Classification of star clusters.

The length of these star systems varies from 6 to 30 light years, with an average extent of approximately twelve light years. Inside star clusters, stars are concentrated chaotically, unsystematically. The cluster does not have a clearly defined shape. When classifying star clusters, one must take into account angular measurements, the approximate total number of stars, their degree of concentration in the cluster, and differences in brightness.

In 1930, American astronomer Robert Trumpler proposed classifying clusters according to the following parameters. All clusters were divided into four classes based on the concentration of stars and were designated by Roman numerals from I to IV. Each of the four classes is divided into three subclasses based on the uniformity of stellar brightness. The first subclass includes clusters in which the stars have approximately the same degree of luminosity, the third - with a significant difference in this regard. Then the American astronomer introduced three more categories for classifying star clusters according to the number of stars included in the cluster. The first category “p” includes systems with less than 50 stars. The second “m” is a cluster with from 50 to 100 stars. The third - those with more than 100 stars. For example, according to this classification, a star cluster designated in the catalog as “I 3p” is a system consisting of less than 50 stars, densely concentrated in the sky and having varying degrees of brightness.

Uniformity of stars.

All stars belonging to any open star cluster have characteristic feature– homogeneity. This means that they were formed from the same gas cloud and at first they had the same chemical composition. In addition, there is an assumption that they all appeared at the same time, that is, they are the same age. The differences between them can be explained by the different course of development, and this is determined by the mass of the star from the moment of its formation. Scientists know that large stars have a shorter lifespan compared to small stars. Large ones evolve much faster. In general, open star clusters are celestial systems consisting of relatively young stars. This type of star clusters is located mainly in the spiral arms of the Milky Way. These areas were active star formation zones in the recent past. The exceptions are the clusters NGC 2244, NGC 2264 and NGC6530, their age is several tens of millions of years. This is a short time for the stars.

Age and chemical composition.

Stars in open star clusters are connected by gravity. But because this connection is not strong enough, open clusters can disintegrate. This happens over a long period of time. The dissolution process is associated with the influence of gravity from single stars located near the cluster.

There are practically no old stars in open star clusters. Although there are exceptions. This primarily applies to large clusters, in which the connection between stars is much stronger. Accordingly, the age of such systems is greater. Among them is NGC 6791. This star cluster includes approximately 10,000 stars and is about 10 billion years old. The orbits of large star clusters take them far from the galactic plane for long periods of time. Accordingly, they have less opportunity to encounter large molecular clouds, which could lead to the dissolution of the star cluster.

Stars in open star clusters are similar in chemical composition to the Sun and other stars in the galactic disk. The difference in chemical composition depends on the distance from the center of the Galaxy. The farther from the center a star cluster is located, the fewer elements from the metal group it contains. The chemical composition also depends on the age of the star cluster. This also applies to single stars.

Globular star clusters.

Globular star clusters, numbering hundreds of thousands of stars, have very unusual look: they have a spherical shape, and the stars are concentrated in them so densely that even with the help of the most powerful telescopes it is impossible to distinguish single objects. There is a strong concentration of stars towards the center.

Research on globular clusters is important in astrophysics in terms of studying the evolution of stars, the process of galaxy formation, studying the structure of our Galaxy and determining the age of the Universe.

The shape of the Milky Way.

Scientists have found that globular clusters formed at the initial stage of the formation of our Galaxy - the protogalactic gas had a spherical shape. During the gravitational interaction until the compression was completed, which led to the formation of the disk, clumps of matter, gas and dust appeared outside of it. It is from them that globular star clusters were formed. Moreover, they were formed before the appearance of the disk and remained in the same place where they were formed. They have a spherical structure, a halo, around which the plane of the galaxy was later located. This is why globular clusters are distributed symmetrically in the Milky Way.

The study of the problem of the location of globular clusters, as well as measurements of the distance from them to the Sun, made it possible to determine their extent of our Galaxy to the center - it is 30,000 light years.

Globular star clusters are very old in terms of their time of origin. Their age is 10-20 billion years. They represent essential element the Universe, and, undoubtedly, knowledge about these formations will provide considerable assistance in explaining the phenomena of the Universe. According to scientists, the age of these star clusters is identical to the age of our Galaxy, and since all galaxies were formed at approximately the same time, it means that the age of the Universe can be determined. To do this, the time from the appearance of the Universe to the beginning of the formation of galaxies should be added to the age of globular star clusters. Compared to the age of globular star clusters, this is a very short period of time.

Inside the cores of globular clusters.

The central regions of this type of cluster are characterized by a high degree of concentration of stars, approximately thousands of times more than in the zones closest to the Sun. Only over the last decade has it become possible to examine the cores of globular star clusters, or rather, those celestial objects that are located in the very center. This is of great importance in the field of studying the dynamics of stars included in the core, in terms of obtaining information about systems of celestial bodies connected by gravitational forces - star clusters belong precisely to this category - as well as in terms of studying the interaction between stars of clusters through observations or data processing on the computer.

Due to the high degree of concentration of stars, real collisions occur and new objects are formed, for example stars, which have their own characteristics. Binary systems can also appear; this happens when the collision of two stars does not lead to their destruction, but mutual capture occurs due to gravity.

Families of globular star clusters.

Globular star clusters of our Galaxy are heterogeneous formations. Four dynamic families are distinguished according to the principle of distance from the center of the Galaxy and according to their chemical composition. Some globular clusters have more metal group chemical elements, others have less. The degree of presence of metals depends on the chemical composition of the interstellar medium from which celestial objects were formed. Globular clusters with fewer metals are older and are located in the halo of the Galaxy. A higher metal composition is characteristic of younger stars, they were formed from an environment already enriched in metals due to supernova explosions - this family includes “disk clusters” found on the galactic disk.

The halo contains "halo-inner star clusters" and "halo-outer star clusters." There are also “star clusters of the peripheral part of the halo”, the distance from which to the center of the Galaxy is greatest.

Influence environment.

Star clusters are not studied and divided into families for the sake of classification as an end in themselves. Classification also plays an important role in studying the influence of the environment surrounding a star cluster on its evolution. In this case we are talking about our Galaxy.

Undoubtedly, the star cluster is greatly influenced by the gravitational field of the Galaxy's disk. Globular star clusters move around the galactic center in elliptical orbits and periodically cross the galactic disk. This happens once every 100 million years.

The gravitational field and tidal projections emanating from the galactic plane act so intensely on the star cluster that it gradually begins to disintegrate. Scientists believe that some old stars currently located in the Galaxy were once part of globular star clusters. Now they have already collapsed. It is believed that approximately 5 star clusters disintegrate every billion years. This is an example of the influence of the galactic environment on the dynamic evolution of a globular star cluster.

Under the influence of the gravitational influence of the galactic disk on the star cluster, a change in the extent of the cluster also occurs. We are talking about stars located far from the center of the cluster; they are influenced to a greater extent by the gravitational force of the galactic disk, and not by the star cluster itself. Stars “evaporate” and the size of the cluster decreases.

SUPERNOVA STARS.

Stars are also born, grow and die. Their end may be slow and gradual or abrupt and catastrophic. This is typical for very large stars that end their existence with an outburst; these are supernovae.

Discovery of supernovae.

For centuries, the nature of supernovae was unknown to scientists, but observations of them have been carried out since time immemorial. Many supernovae are so bright that they can be seen with the naked eye, sometimes even during the day. The first mentions of these stars appeared in ancient chronicles in 185 AD. Subsequently, they were observed regularly and all data was scrupulously recorded. For example, the court astronomers of the emperors Ancient China recorded many of the discovered supernovae many years later.

Notable among them is the supernova that erupted in 1054 AD. in the constellation Taurus. This supernova remnant is called the Crab Nebula because of its distinctive shape. Western astronomers began to conduct systematic observations of supernovae late. Only towards the end of the 16th century. references to them appeared in scientific documents. The first observations of supernovae by European astronomers date back to 1575 and 1604. In 1885, the first supernova was discovered in the Andromeda galaxy. This was done by Baroness Bertha de Podmanicka.

Since the 20s of the XX century. Thanks to the invention of photographic plates, supernova discoveries follow one after another. Currently, there are up to a thousand of them open. Finding supernovae requires a lot of patience and constant observation of the sky. The star must not only be very bright, its behavior must be unusual and unpredictable. There are not so many “supernova hunters”; a little more than ten astronomers can boast that they have discovered more than 20 supernovae in their lifetime. The leader in this interesting classification belongs to Fred Zwicky - since 1936, he has identified 123 stars.

What are supernovae?

Supernovae are stars that explode suddenly. This flare is a catastrophic event, the end of the evolution of large stars. During flares, the radiation power reaches 1051 erg, which is comparable to the energy emitted by the star throughout its entire life. The mechanisms that cause flares in double and single stars are different.

In the first case, the outburst occurs under the condition that the second star in the binary system is a white dwarf. White dwarfs are relatively small stars, their mass corresponds to the mass of the Sun, in the end " life path"They are the size of a planet. The white dwarf interacts with its pair in a gravitational way; it “steals” matter from its surface layers. The “borrowed” substance heats up, nuclear reactions begin, and an outbreak occurs.

In the second case, the star itself flares up; this happens when there are no longer conditions for thermonuclear reactions in its depths. At this stage, gravity dominates and the star begins to contract at a rapid rate. Due to sudden heating as a result of compression, uncontrolled nuclear reactions begin to occur in the star's core, energy is released in the form of a flash, causing the destruction of the star.

After the flash, a cloud of gas remains and spreads in space. These are “supernova remnants” - what remains from the surface layers of an exploding star. The morphology of supernova remnants is different and depends on the conditions in which the explosion of the “progenitor” star occurred, and on its characteristic internal features. The cloud spreads unequally in different directions, which is due to interaction with interstellar gas, which can significantly change the shape of the cloud over thousands of years.

Characteristics of supernovae.

Supernovae are a variation of eruptive variable stars. Like all variables, supernovae are characterized by a light curve and easily recognizable features. First of all, a supernova is characterized by a rapid increase in brightness, it lasts several days until it reaches a maximum - this period is approximately ten days. Then the shine begins to decrease - first haphazardly, then consistently. By studying the light curve, you can trace the dynamics of the flare and study its evolution. The part of the light curve from the beginning of the rise to the maximum corresponds to the flare of the star, the subsequent descent means the expansion and cooling of the gas envelope.

WHITE Dwarfs.

In the “star zoo” there are a great variety of stars, different in size, color and brilliance. Among them, “dead” stars are especially impressive; their internal structure differs significantly from the structure of ordinary stars. The category of dead stars includes large stars, white dwarfs, neutron stars and black holes. Due to the high density of these stars, they are classified as “crisis” stars.

Opening.

At first, the essence of white dwarfs was a complete mystery; all that was known was that they had a high density compared to ordinary stars.

The first white dwarf to be discovered and studied was Sirius B, a pair of Sirius, a very bright star. Using Kepler's third law, astronomers calculated the mass of Sirius B: 0.75-0.95 solar masses. On the other hand, its brightness was significantly lower than that of the sun. The brightness of a star is related to the square of its radius. After analyzing the numbers, astronomers came to the conclusion that the size of Sirius is small. In 1914, the stellar spectrum of Sirius B was compiled and the temperature was determined. Knowing the temperature and brightness, we calculated the radius - 18,800 kilometers.

First research.

The obtained result marked the discovery of a new class of stars. In 1925, Adams measured the wavelength of some emission lines in the spectrum of Sirius B and determined that they were longer than expected. The red shift fits into the framework of the theory of relativity, discovered by Einstein several years before the events taking place. Using the theory of relativity, Adams was able to calculate the radius of the star. After the discovery of two more stars similar to Sirius B, Arthur Eddington concluded that there are many such stars in the Universe.

So, the existence of dwarfs was established, but their nature still remained a mystery. In particular, scientists could not understand how a mass similar to the sun could fit in such a small body. Eddington concludes that “at such a high density the gas loses its properties. Most likely, white dwarfs consist of degenerate gas."

The essence of white dwarfs.

In August 1926, Enrico Fermi and Paul Dirac developed a theory describing the state of gas under conditions of very high density. Using it, Fowler in the same year found an explanation for the stable structure of white dwarfs. In his opinion, due to its high density, the gas in the interior of the white dwarf is in a degenerate state, and the gas pressure is practically independent of temperature. The stability of a white dwarf is maintained by the fact that the force of gravity is opposed by the gas pressure in the bowels of the dwarf. The study of white dwarfs was continued by the Indian physicist Chandrasekhar.

In one of his works, published in 1931, he makes an important discovery - the mass of white dwarfs cannot exceed a certain limit, this is due to their chemical composition. This limit is 1.4 solar masses and is called the “Chandrasekhar limit” in honor of the scientist.

Almost a ton per cm3!

As their name suggests, white dwarfs are small stars. Even if their mass is equal to the mass of the Sun, they are still similar in size to a planet like Earth. Their radius is approximately 6000 km - 1/100 of the radius of the Sun. Considering the mass of white dwarfs and their size, only one conclusion can be drawn - their density is very high. A cubic centimeter of white dwarf matter weighs almost a ton by Earth standards.

Such a high density leads to the fact that the gravitational field of the star is very strong - about 100 times higher than the solar one, and with the same mass.

Main characteristics.

Although the core of white dwarfs no longer undergoes nuclear reactions, its temperature is very high. Heat rushes to the surface of the star and then spreads out into space. The stars themselves slowly cool down until they become invisible. The surface temperature of “young” white dwarfs is about 20,000-30,000 degrees. White dwarfs are not only white, there are also yellow ones. Despite the high surface temperature, due to small sizes The luminosity is low, the absolute magnitude can be 12-16. White dwarfs cool very slowly, which is why we see them in such large numbers. Scientists have the opportunity to study their main characteristics. White dwarfs are included in the H-R diagram and occupy a small space below the Main Sequence.

NEUTRON STARS AND PULSARS.

The name "pulsar" comes from the English combination "pulsating star" - "pulsating star". Characteristic feature Pulsars, unlike other stars, do not emit constant radiation, but regular pulsed radio emission. The pulses are very fast, the duration of one pulse lasts from thousandths of a second to, at most, several seconds. The pulse shape and periods are different for different pulsars. Due to the strict periodicity of radio emission, pulsars can be considered as cosmic chronometers. Over time, the periods decrease to 10-14 s/s. Every second the period changes by 10-14 seconds, that is, the decrease occurs over about 3 million years.

Regular signals.

The history of the discovery of pulsars is quite interesting. The first pulsar, PSR 1919+21, was detected in 1967 by Bell and Anthony Husch of the University of Cambridge. Bell, a young physicist, conducted research in the field of radio astronomy to confirm the theses he put forward. Suddenly he discovered a radio signal of moderate intensity in an area close to the galactic plane. The strange thing was that the signal was intermittent - it disappeared and reappeared at regular intervals of 1.377 seconds. They say that Bell ran to his professor to notify him of the discovery, but the latter did not pay due attention to this, believing that it was a radio signal from the Earth.

Nevertheless, the signal continued to appear regardless of terrestrial radioactivity. This indicated that the source of its appearance had not yet been established. As soon as the data about the discovery were published, numerous speculations arose that the signals were coming from a ghostly extraterrestrial civilization. But scientists were able to understand the essence of pulsars without the help of alien worlds.

The essence of pulsars.

After the first one, many more pulsars were discovered. Astronomers have concluded that these celestial bodies are sources of pulsed radiation. The most numerous objects in the Universe are stars, so scientists decided that these celestial bodies most likely belong to the class of stars.

The rapid movement of the star around its axis is most likely the cause of the pulsations. Scientists measured the periods and tried to determine the essence of these celestial bodies. If a body rotates at a speed exceeding a certain maximum speed, it disintegrates under the influence of centrifugal forces. This means that there must be a minimum value of the rotation period.

From the calculations performed, it followed that for a star to rotate with a period measured in thousandths of a second, its density should be on the order of 1014 g/cm3, like that of atomic nuclei. For clarity, we can give the following example: imagine a mass equal to Everest in the volume of a piece of sugar.

Neutron stars.

Since the thirties, scientists have assumed that something similar exists in the sky. Neutron stars are very small, super-dense celestial bodies. Their mass is approximately equal to 1.5 solar masses, concentrated in a radius of approximately 10 km.

Neutron stars are made primarily of neutrons, particles without electric charge, which together with protons make up the nucleus of an atom. Because of high temperature in the interior of a star, matter is ionized, electrons exist separately from the nuclei. At such a high density, all nuclei decay into their constituent neutrons and protons. Neutron stars are the end result of the evolution of a large mass star. After exhausting the sources of thermonuclear energy in its depths, it explodes sharply, like a supernova. The outer layers of the star are thrown into space, gravitational collapse occurs in the core, and a hot neutron star is formed. The collapse process takes a fraction of a second. As a result of the collapse, it begins to rotate very quickly, with periods of thousandths of a second, which is typical for a pulsar.

Radiation of pulsations.

There are no sources of thermonuclear reactions in a neutron star, i.e. they are inactive. The emission of pulsations does not come from the interior of the star, but from the outside, from zones surrounding the surface of the star.

The magnetic field of neutron stars is very strong, millions of times greater than the magnetic field of the Sun, it cuts through space, creating a magnetosphere.

A neutron star emits streams of electrons and positrons into the magnetosphere; they rotate at speeds close to the speed of light. The magnetic field influences the movement of these elementary particles, they move along the lines of force, following a spiral trajectory. Thus, they release kinetic energy in the form electromagnetic radiation.

The rotation period increases due to the decrease in rotational energy. Older pulsars have a longer pulsation period. By the way, the pulsation period is not always strictly periodic. Sometimes it slows down sharply, this is associated with phenomena called “glitches” - this is the result of “microstarquakes”.

BLACK HOLES.

The image of the firmament amazes with the variety of shapes and colors of celestial bodies. What is there in the Universe: stars of all colors and sizes, spiral galaxies, nebulae of unusual shapes and color ranges. But in this “cosmic zoo” there are “specimens” that arouse special interest. These are even more mysterious celestial bodies, as they are difficult to observe. In addition, their nature is not fully understood. Among them, a special place belongs to “black holes”.

Movement speed.

In everyday speech, the expression “black hole” means something bottomless, where a thing falls, and no one will ever know what happened to it in the future. What are black holes really? To understand this, let's go back in history two centuries ago. In the 18th century, the French mathematician Pierre Simon de Laplace first introduced this term while studying the theory of gravitation. As you know, any body that has a certain mass - the Earth, for example - also has a gravitational field; it attracts surrounding bodies.

This is why an object thrown up falls to the Earth. If the same object is thrown forward with force, it will overcome the gravity of the Earth for some time and fly some distance. The minimum required speed is called “movement speed”; for the Earth it is 11 km/s. The speed of movement depends on the density of the celestial body, which creates a gravitational field. The higher the density, the higher the speed should be. Accordingly, one can make the assumption, as Laplace did two centuries ago, that there are bodies in the Universe with such high density yu that the speed of their movement exceeds the speed of light, that is, 300,000 km/s.

In this case, even light could succumb to the gravitational force of such a body. Such a body could not emit light, and therefore it would remain invisible. We can imagine it as a huge hole, black in the picture. Undoubtedly, the theory formulated by Laplace does not bear the imprint of time and seems too simplified. However, at the time of Laplace, quantum theory had not yet been formulated, and from a conceptual point of view, considering light as a material body seemed nonsense. At the very beginning of the 20th century, with the advent and development of quantum mechanics, it became known that light under certain conditions also acts as material radiation.

This position was developed in Albert Einstein's theory of relativity, published in 1915, and in the work of German physicist Karl Schwarzschild in 1916, he provided a mathematical basis for the theory of black holes. Light can also be subject to gravity. Two centuries ago, Laplace raised a very important problem in terms of the development of physics as a science.

How do black holes appear?

The phenomena we are talking about received the name “black holes” in 1967 thanks to the American astrophysicist John Wheeler. They are the end result of the evolution of large stars whose mass is greater than five solar masses. When all nuclear fuel reserves are exhausted and reactions no longer occur, the death of the star occurs. Further, its fate depends on its mass.

If the mass of a star is less than the mass of the sun, it continues to contract until it goes out. If the mass is significant, the star explodes, then we are talking about a supernova. The star leaves behind traces - when gravitational collapse occurs in the core, all the mass is collected into a ball of compact size with a very high density - 10,000 times more than that of the nucleus of an atom.

Relative effects.

For scientists, black holes are an excellent natural laboratory that allows them to conduct experiments on various hypotheses in terms of theoretical physics. According to Einstein's theory of relativity, the laws of physics are influenced by a local gravitational field. In principle, time flows differently near gravitational fields of different intensities.

In addition, a black hole affects not only time, but also the surrounding space, affecting its structure. According to the theory of relativity, the presence of a strong gravitational field arising from such a powerful celestial body as a black hole distorts the structure of the surrounding space, and its geometric data changes. This means that about black hole a short distance connecting two points will not be a straight line, but a curve.