The comparative uniformity of the chemical composition of the known celestial bodies may perhaps disappoint some. However, there is no doubt that this fact is of great importance, confirming the material unity of the Cosmos. This unity gives us the right to extend to the stellar Universe the laws of nature that we have learned from experience within the modest confines of our Earth. All this is one of the clearest confirmations of the correctness of the dialectical-materialist worldview.

3. Lot in the abysses of the universe

Beyond the solar system, such a large leap in distances has to be made to the stars that it was achieved only a century ago, long after doubts about the similarity between the Sun and the stars had disappeared. The sea depth meter, - lot, in the field of astronomy, was repeatedly “thrown” in the direction of different stars and for a long time could not reach any of them, could not reach the “bottom”. This, of course, is only a figurative comparison, because, as in the case of determining the temperatures of luminaries, the possibility of direct measurements of distances is excluded here. As we will now see, they can only be found indirectly, calculated based on measurements of other quantities. This path, indicated by Copernicus, consists of measuring angles, but instruments and methods to achieve the necessary accuracy were created only in the second half of the 19th century.

As when determining the distance to any inaccessible object, the idea of ​​the method is to measure the difference in the directions in which the star is visible from the two ends of a basis of known length. The distance corresponding to this difference in direction can be calculated using trigonometry. In this case, the diameter of the Earth as a basis turned out to be too small, and for the vast majority of stars, with the modern accuracy of measuring angles, even the diameter of the Earth's orbit is insufficient. Nevertheless, it was precisely this that Copernicus recommended to take as a basis, which was carried out by scientists of later generations.

Only a century ago, the remarkable astronomer V. Ya. Struve in Russia, Bessel in Germany and Henderson in South Africa managed to make fairly accurate measurements and for the first time establish the distances to some stars. The feeling experienced by contemporaries was reminiscent of the joy of sailors who, during a long voyage, unsuccessfully threw a lot and finally reached the bottom.

The classic way to determine distances to stars is to accurately determine the direction to them (i.e., to determine their coordinates on the celestial sphere) from two ends of the diameter of the earth's orbit. To do this, they need to be determined at moments separated from each other by six months, since during this time the Earth itself carries an observer with it from one side of its orbit to the other.

The apparent displacement of the star, caused by a change in the observer's position in space, is extremely small, barely perceptible. They prefer to measure it from a photograph, taking, for example, two photographs of the chosen star and its neighbors on the same plate, one photograph six months after the other. Most stars are so far away that their displacement in the sky is completely unnoticeable, but in relation to them a fairly close star moves noticeably. This is its displacement and is measured with an accuracy of 0",01 - greater accuracy has not yet been achieved, but it is already much higher than the accuracy achieved half a century ago.

The described apparent displacement of the star is twice the angle at which the radius of the earth's orbit would be visible from it and which is called the annual parallax.

Rice. 1. Parallax and proper motion of stars. In the figure, the parallax p of two stars close to each other and their proper motions μ are the same, but their path in space is different.

The parallax of these stars is the largest and amounts to 3/4"; it is measured with an accuracy of about 1%, since the accuracy of angular measurements reaches 0",01.

At an angle of about 0",01, the diameter of a penny appears to us if it is placed on its edge on Red Square in Moscow and viewed from Tula or Ryazan! This is the accuracy of astronomical measurements! At an angle of 0",01, to be precise, a ruler is visible, which is viewed at right angles from a distance 20,626,500 times greater than the length of the ruler.

It is easy to find out the corresponding distance by parallax. We get the distance to the star in the radius of the Earth's orbit if we divide the number 206,265 by the parallax value, expressed in arcseconds. To express it in kilometers, you need to multiply the resulting number by another 150,000,000.

We already know that it is more convenient to express large distances in light years or in parsecs, and Centauri and its neighbor, nicknamed “Nearest”, since it is still a little closer to us, are 270,000 times farther from us than the Sun, i.e. 4 light years. A courier train, traveling non-stop at a speed of 100 km per hour, would reach it in 40 million years! Try to take comfort in the memory of this if you ever get tired of a long train ride...

An accuracy of measuring parallaxes of 0.01 does not allow measuring parallaxes that are themselves less than this value, so the described method is not applicable to stars further than 300-350 light years away.

Using the described method and others using spectra, as well as using completely different indirect methods, it is possible to determine the distances to stars located much further than 300 light years. The light from the stars of some distant star systems reaches us hundreds of millions of light years away. This does not mean at all, as is often thought, that we are observing stars that may no longer exist in reality. It is not worth saying that “we see in the sky something that in reality no longer exists,” because the vast majority of stars change so slowly that millions of years ago they were the same as they are now, and even their visible places in the sky change extremely slowly, although stars move quickly in space.

This paradox arises from the fact that, in contrast to the wandering luminaries - planets, the stars of the constellations were once called motionless. Meanwhile, nothing can be stationary in the world. Two and a half centuries ago, Halley discovered the movement of Sirius across the sky. To notice a systematic change in the celestial coordinates of stars, their movement in the sky relative to each other, it is necessary to compare the exact determinations of their position in the sky made over a period of tens of years. They are invisible to the naked eye, and throughout the history of mankind not a single constellation has noticeably changed its outline.

For most stars, no movement can be detected because they are too far from us. The horseman galloping along the quarry on the horizon, as it seems to us, almost stands still, and the turtle crawling at our feet moves quite quickly. So it is in the case of stars - we more easily notice the movements of the stars closest to us. Photos of the sky, which are convenient to compare with each other, help us a lot with this. Observations of the positions of stars in the sky were made long before the invention of photography, hundreds and even thousands of years ago. Unfortunately, they were too inaccurate for the movement of the stars to be seen from comparison with modern ones.

Conclusion

At first glance, the starry sky may even seem monotonous to the naked eye. Identical sparkling dots, randomly scattered across a dark background, and that’s it! But look at the starry sky again and again. After just a few sessions of close observation, the first “sorting” begins. You discover that stars can be large - dazzlingly brilliant and small - barely noticeable dots. It was this difference in the apparent brightness of stars that made it possible to introduce their first classification back in ancient times. Legends attribute the idea to Hipparchus. As if he suggested calling the brightest points stars of the first magnitude, and the weakest ones, barely visible to the naked eye, stars of the sixth magnitude. Stellar magnitudes are conventional units that characterize the apparent brightness, or, as experts say, the apparent brightness, of stars. At first, stellar magnitudes were integers and were designated in order of decreasing brightness . But with the invention of telescopes, and then cameras and instruments that measure the smallest fractions of illumination, the scale of stellar magnitudes had to be expanded, intermediate - fractional - values ​​​​had to be introduced, and for especially bright celestial objects - zero and negative stellar magnitudes. In these relative units, they began to measure the visible brightness of not only stars, but also the Sun, Moon and all planets.

To form your own opinion about apparent stellar magnitudes, you can offer a simple experiment. On a dark, moonless night, go somewhere away from the street lights and find the Dipper, part of the constellation Ursa Major.

Take a close look at the second star from the end of the Bucket handle. This is Mizar, a star of approximately second magnitude. But it's not her that interests us. Nearby, good eyes should be able to see a small fifth magnitude star called Alcor. Even during the time of Alexander the Great, Alcor served as a standard for testing the vision of legionnaires. The recruit was taken out into the field and forced to find the faintly glowing Alcor. Found it - good vision, good! If you don't find it, go home!

Stars are large celestial bodies of hot plasma, the dimensions of which can amaze the most inquisitive reader. Are you ready to develop?

It’s worth noting right away that the rating was compiled taking into account those giants that humanity already knows about. It is possible that somewhere in outer space there are stars of even larger dimensions, but they are located at a distance of many light years, and modern equipment is simply not enough to detect and analyze them. It is also worth adding that most stars will cease to be such over time, because they belong to the class of variables. Well, don’t forget about the possible errors of astrologers. So...

Top 10 biggest stars in the Universe

10

Opens the ranking of the largest stars in the Betelgeuse Galaxy, whose dimensions exceed the radius of the sun by 1190 times. It is located approximately 640 light years from Earth. Comparing with other stars, we can say that it is at a relatively short distance from our planet. The red giant may go supernova in the next few hundred years. In this case, its dimensions will increase significantly. For good reasons, the star Betelgeuse, occupying the last place in this ranking, is the most interesting!

RW

An amazing star, attracting with its extraordinary color of glow. Its size exceeds the dimensions of the sun from 1200 to 1600 solar radii. Unfortunately, we cannot say exactly how powerful and bright this star is, because it is located far from our planet. Leading astrologers from different countries have been arguing for many years regarding the history of the origin and distance of RW. Everything is due to the fact that it regularly changes in the constellation. Over time, it may disappear altogether. But it still remains in the top of the largest celestial bodies.

Next in the ranking of the largest known stars is KW Sagittarius. According to ancient Greek legend, she appeared after the death of Perseus and Andromeda. This suggests that this constellation was discovered long before our appearance. But unlike our ancestors, we know about more reliable data. It is known that the size of the star exceeds the Sun by 1470 times. Moreover, it is located relatively close to our planet. KW is a bright star that changes its temperature over time.

It is currently known for sure that the size of this large star exceeds the size of the Sun by at least 1430 times, but it is difficult to obtain an exact result because it is located 5 thousand light years from the planet. Even 13 years ago, American scientists provided completely different data. At that time, it was believed that KY Cygni had a radius that increased the size of the Sun by a factor of 2850. Now we have more reliable dimensions relative to this celestial body, which are certainly more accurate. Based on the name, you understand that the star is located in the constellation Cygnus.

A very large star included in the constellation Cepheus is V354, whose size is 1530 times larger than the Sun. Moreover, the celestial body is located relatively close to our planet, only 9 thousand light years away. It does not differ in particular brightness and temperature compared to other unique stars. However, it is a variable luminary, therefore, dimensions may vary. It is likely that Cepheus will not last long in this position in the V354 ranking. Most likely, the size will decrease over time.

Just a few years ago, it was believed that this red giant could become a competitor to VY Canis Majoris. Moreover, some experts conventionally considered WHO G64 the largest star known in our Universe. Today, in the age of rapid development of technology, astrologers have managed to obtain more reliable data. It is now known that the radius of Doradus is only 1550 times larger than the Sun. This is how huge errors are permissible in the field of astronomy. However, the incident can easily be explained by distance. The star is outside the Milky Way. Namely, in a dwarf galaxy called the Vast Magellanic Cloud.

V838

One of the most unusual stars in the Universe, located in the constellation Monoceros. It is located approximately 20 thousand light years from our planet. Even the fact that our specialists managed to detect it is surprising. V838 was even larger than Mu Cephei. It is quite difficult to make accurate calculations regarding dimensions, due to the enormous distance from the Earth. Speaking of approximate size data, they range from 1170 to 1900 solar radii.

The constellation Cepheus contains many amazing stars, and Mu Cephei is considered proof of this. One of the largest stars is 1660 times the size of the Sun. The supergiant is considered one of the brightest in the Milky Way. About 37,000 times more powerful than the illumination of the star we know best, the Sun. Unfortunately, we cannot say unambiguously at what exact distance from our planet Mu Cephei is located.

For many centuries, millions of human eyes, with the onset of night, direct their gaze upward - towards the mysterious lights in the sky - stars of our Universe. Ancient people saw various figures of animals and people in clusters of stars, and each of them created its own history. Later, such clusters began to be called constellations. Today, astronomers identify 88 constellations that divide the starry sky into certain areas by which one can navigate and determine the location of stars. In our Universe, the most numerous objects accessible to the human eye are stars. They represent a source of light and energy for the entire solar system. They also create the heavy elements necessary for the origin of life. And without the stars of the Universe there would be no life, because the Sun gives its energy to almost all living beings on Earth. It warms the surface of our planet, thereby creating a warm oasis full of life among the permafrost of space. The degree of brightness of a star in the Universe is determined by its size.

Do you know the biggest star in the entire Universe?

The star VY Canis Majoris, located in the constellation Canis Major, is the largest representative of the stellar world. At the moment it is the largest star in the Universe. The star is located 5 thousand light years from the solar system. The diameter of the star is 2.9 billion km.

But not all stars in the Universe are so huge. There are also so-called dwarf stars.

Comparative sizes of stars

Astronomers rate the size of stars on a scale according to which the brighter the star, the lower its number. Each subsequent number corresponds to a star ten times less bright than the previous one. The brightest star in the night sky in the Universe is Sirius. Its apparent magnitude is -1.46, meaning it is 15 times brighter than a star with magnitude zero. Stars whose magnitude is 8 or more cannot be seen with the naked eye. Stars are also classified into spectral classes by color, indicating their temperature. There are the following classes of stars in the Universe: O, B, A, F, G, K, and M. Class O corresponds to the hottest stars in the Universe - blue. The coolest stars are class M and are red in color.

Contrary to popular belief, it is worth noting that the stars of the Universe do not actually twinkle. This is just an optical illusion - the result of atmospheric interference. A similar effect can be observed on a hot summer day, looking at hot asphalt or concrete. Hot air rises, and it seems as if you are looking through shaking glass. The same process causes the illusion of starry twinkling. The closer a star is to Earth, the more it will “twinkle” because its light passes through denser layers of the atmosphere.

Nuclear Hearth of the Universe Stars

A star in the Universe is a giant nuclear center. The nuclear reaction inside it converts hydrogen into helium, thanks to the process of fusion, which is how the star acquires its energy. Hydrogen nuclei with one proton combine to form helium atoms with two protons. The nucleus of an ordinary hydrogen atom has only one proton. Two isotopes of hydrogen also contain one proton, but also have neutrons. Deuterium has one neutron, while tritium has two. Deep inside the star, a deuterium atom combines with a tritium atom to form a helium atom and a free neutron. As a result of this long process, enormous amounts of energy are released.

For main sequence stars, the main source of energy is nuclear reactions involving hydrogen: the proton-proton cycle, characteristic of stars with masses around the Sun, and the CNO cycle, which occurs only in massive stars and only if they contain carbon. At later stages of a star’s life, nuclear reactions can occur with heavier elements, up to iron.

When a star's hydrogen supply is exhausted, it begins to convert helium into oxygen and carbon. If the star is massive enough, the conversion process will continue until carbon and oxygen form neon, sodium, magnesium, sulfur and silicon. Eventually, these elements are converted into calcium, iron, nickel, chromium and copper until the core is composed entirely of metal. As soon as this happens, the nuclear reaction will stop because the melting point of iron is too high. The internal gravitational pressure becomes higher than the external pressure of the nuclear reaction and, eventually, the star collapses. The further development of events depends on the initial mass of the star.

Types of stars in the Universe

The main sequence is the period of existence of stars in the Universe, during which a nuclear reaction takes place inside it, which is the longest period of a star’s life. Our Sun is currently in this period. During this time, the star undergoes slight fluctuations in brightness and temperature. The duration of this period depends on the mass of the star. In large massive stars it is shorter, and in small ones it is longer. Very large stars have internal fuel that lasts for several hundred thousand years, while small stars like the Sun will shine for billions of years. The largest stars turn into blue giants during the main sequence.

Types of stars in the Universe
Red giant is a large star of reddish or orange color. It represents the late stage of the cycle when hydrogen supplies are running low and helium begins to be converted into other elements. An increase in the internal temperature of the core leads to the collapse of the star. The outer surface of the star expands and cools, causing the star to turn red. Red giants are very large. Their size is a hundred times larger than ordinary stars. The largest of the giants turn into red supergiants. A star called Betelgeuse in the constellation Orion is the brightest example of a red supergiant.
White dwarf- this is what remains of an ordinary star after it goes through the red giant stage. When a star has no more fuel left, it can release some of its matter into space, forming a planetary nebula. What remains is a dead core. A nuclear reaction is not possible in it. It shines due to its remaining energy, but sooner or later it runs out, and then the core cools down, turning into a black dwarf. White dwarfs are very dense. They are no larger in size than the Earth, but their mass can be compared to the mass of the Sun. These are incredibly hot stars, with temperatures reaching 100,000 degrees or more.
Brown dwarf also called a substar. During their life cycle, some protostars never reach a critical mass to begin nuclear processes. If the mass of a protostar is only 1/10 the mass of the Sun, its radiance will be short-lived, after which it will quickly fade. What remains is a brown dwarf. It's a massive ball of gas, too big to be a planet and too small to be a star. It is smaller than the Sun, but several times larger than Jupiter. Brown dwarfs emit neither light nor heat. This is just a dark clot of matter existing in the vastness of the Universe.
Cepheid is a star with variable luminosity, the pulsation cycle of which ranges from a few seconds to several years, depending on the type of variable star. Cepheids typically change their luminosity at the beginning of their lives and at the end of their lives. They are internal (changing luminosity due to processes inside the star) and external, changing brightness due to external factors, such as the influence of the orbit of a nearby star. This is also called a dual system.
Many stars in the Universe are part of large star systems. Double stars is a system of two stars gravitationally bound to each other. They rotate in closed orbits around one center of mass. It has been proven that half of all the stars in our galaxy have a pair. Visually, paired stars look like two separate stars. They can be determined by the shift of spectrum lines (Doppler effect). In eclipsing binary systems, stars periodically eclipse each other because their orbits are located at a small angle to the line of sight.

Life Cycle of Stars in the Universe

A star in the Universe begins its life as a cloud of dust and gas called a nebula. The gravity of a nearby star or the blast wave from a supernova can cause the nebula to shrink. Elements of the gas cloud coalesce into a dense region called a protostar. As a result of subsequent compression, the protostar heats up. Eventually, it reaches critical mass and the nuclear process begins; Gradually the star goes through all the phases of its existence. The first (nuclear) stage of a star's life is the longest and most stable. The lifespan of a star depends on its size. Large stars use up their vital fuel faster. Their life cycle can last no more than several hundred thousand years. But small stars live for many billions of years, as they spend their energy more slowly.

But, be that as it may, sooner or later, the stellar fuel runs out, and then the small star turns into a red giant, and the large star into a red supergiant. This phase will last until the fuel is completely used up. At this critical moment, the internal pressure of the nuclear reaction will weaken and can no longer balance the force of gravity, and as a result, the star will collapse. Small stars in the universe then typically develop into a planetary nebula with a bright, shining core called a white dwarf. Over time, it cools down, turning into a dark clot of matter - a black dwarf.

For big stars, things happen a little differently. During the collapse, they release incredible amounts of energy, and a powerful explosion gives birth to a supernova. If its magnitude is 1.4 solar magnitudes, then, unfortunately, the core will not be able to maintain its existence and, after the next collapse, the supernova will become neutron. The internal matter of the star will compress to such an extent that the atoms form a dense shell consisting of neutrons. If the stellar magnitude is three times the solar magnitude, then the collapse will simply destroy it, erase it from the face of the Universe. All that will remain of it is an area of ​​​​strong gravity, nicknamed a black hole.

The nebula left behind by a star in the universe can expand over millions of years. In the end, it will be affected by the gravity of a neighboring star or the blast wave of a supernova and everything will happen again. This process will occur throughout the Universe - an endless cycle of life, death and rebirth. The result of this stellar evolution is the formation of heavy elements necessary for life. Our solar system originated from the second or third generation of the nebula, and due to this, there are heavy elements on Earth and other planets. This means that each of us contains pieces of stars. All the atoms of our body were born in an atomic source or as a result of a destructive supernova explosion
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