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Galaxies are giant stellar islands outside our star system (our Galaxy). They differ in size, appearance and composition, conditions of formation and evolutionary changes.

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Democritus, the ancient Greek philosopher, believed that the Milky Way is a collection of faint stars. W. Herschel discovered many double, triple multiple stars. He presented a diagram of the structure of the Galaxy and its structure.

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I. Kant believed that our Galaxy does not include the entire stellar world and that there are other stellar systems similar to it. E. Hubble discovered Cepheids in the Andromeda and Triangle nebulae. His discoveries gave rise to a science called extragalactic astronomy.

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The distance from the center of the Galaxy to the Sun is 32,000 sv. years Diameter of the Galaxy - 100,000 St. years The thickness of the galactic disk is 10,000 sv. years Mass - 165 billion solar masses Galaxy age - 12 billion years

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The largest and smallest diameters of the bulge are, respectively, close to 20,000 and 30,000 sv. years The mass of the disk is 150 million times the mass of the Sun. The speed of rotation of the disk from the center of 200 - 240 m / s (at a distance of 2,000 light years. The rotation of the Sun around the center of the Galaxy 200 - 220 km / s (one revolution in 200 million years). Satellites of the Galaxy: Large and Small Magellanic clouds Large Magellanic Cloud Small Magellanic Cloud

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The location of the Sun in our Galaxy is rather unfortunate for the Study of this system as a whole: we are near the plane of the stellar disk and it is difficult to find out the structure of the Galaxy from the Earth. In the region where the Sun is located, there is a lot of interstellar matter that absorbs light and the stellar disk is opaque.

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There are three main parts in the Galaxy - the disk, the halo and the corona. The central thickening of the disc is called the bulge.

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The halo consists mainly of very old, dim, low-mass stars. They occur both singly and as globular clusters that can include over a million stars. The age of the population of the spherical component of the Galaxy exceeds 12 billion years. It is usually mistaken for the age of the galaxy itself.

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Disk. The population of the disk is very different from the population of the halo. Young stars and star clusters, whose age does not exceed several billion years, are concentrated near the plane of the disk. They form the so-called flat component. There are many bright and hot stars among them.

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The core of the central regions of the Galaxy is characterized by a strong concentration of stars: in each cubic parsec near the center there are many thousands of them. The distance between the stars is tens and hundreds of times less than in the vicinity of the Sun.

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I - Spherical II - Intermediate spherical III - Intermediate disc IV - Flat old V - Flat young

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Their diameter is 20-100 pc. Age 10 - 15 billion years Formed during the formation of the Galaxy itself.

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Found near the galactic plane. Consist of hundreds or thousands of stars. There are also young (blue) stars in them.

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What is the Galaxy made of? In 1609, when the great Italian Galileo Galilei was the first to direct a telescope into the sky, he immediately made a great discovery: he figured out what the Milky Way was. With the help of his primitive telescope, he was able to split the brightest clouds in the Milky Way into individual stars! But behind them I made out dimmer clouds, but I could not solve their riddle, although I made the correct conclusion that they should also consist of stars. We know today that he was right.

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The Milky Way is actually made up of 200 billion stars. And the Sun with its planets is only one of them. Moreover, our solar system is removed from the center of the Milky Way by about two-thirds of its radius. We live on the outskirts of our Galaxy. The Milky Way is circular. In its center, the stars are denser and form a huge, dense cluster. The outer edges of the circle are noticeably smoothed and thinner around the edges. When viewed from the outside, the Milky Way likely resembles the planet Saturn with its rings.

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Gas nebulae Later it was discovered that the Milky Way consists not only of stars, but of gas and dust clouds, which swirl rather slowly and randomly. However, in this case, gas clouds are located only inside the disk. Some gas nebulae glow with colorful light. One of the most famous is the nebula in the constellation Orion, which is visible even with the naked eye. Today we know that such gaseous or diffuse nebulae are the cradle of young stars.

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The Milky Way encircles the celestial sphere in a large circle. Inhabitants of the Northern Hemisphere of the Earth, in autumn evenings, manage to see that part of the Milky Way that passes through Cassiopeia, Cepheus, Cygnus, Eagle and Sagittarius, and in the morning other constellations appear. In the southern hemisphere of the Earth, the Milky Way stretches from the constellation Sagittarius to the constellations Scorpio, Compass, Centaurus, Southern Cross, Carina, Arrow.

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The Milky Way, passing through the stellar placer of the southern hemisphere, is amazingly beautiful and bright. In the constellations of Sagittarius, Scorpio, Shield, there are many brightly glowing star clouds. It is in this direction that the center of our Galaxy is located. In the same part of the Milky Way, dark clouds of cosmic dust - dark nebulae - are especially clearly distinguished. If it weren't for these dark, opaque nebulae, the Milky Way toward the center of the Galaxy would be a thousand times brighter. Looking at the Milky Way, it is not easy to imagine that it is composed of many stars indistinguishable to the naked eye. But people guessed this long ago. One of these guesses is attributed to the scientist and philosopher of ancient Greece, Democritus. He lived almost two thousand years earlier than Galileo, who was the first to prove the stellar nature of the Milky Way on the basis of observations with a telescope. In his famous “Star Messenger” in 1609, Galileo wrote: “I turned to the observation of the essence or matter of the Milky Way, and with the help of a telescope it was possible to make it so accessible to our vision that all disputes fell silent by themselves thanks to the clarity and evidence, which I am exempt from verbose dispute. In fact, the Milky Way is nothing more than an innumerable number of stars, as if arranged in heaps, no matter where the telescope is directed, now a huge number of stars becomes visible, of which very many are quite bright and quite distinguishable, the number the weaker stars do not admit any counting at all. " What relation do the stars of the Milky Way have to the only star in the solar system, to our Sun? The answer is well known today. The Sun is one of the stars of our Galaxy, the Galaxy is the Milky Way. What place does the Sun occupy in the Milky Way? Already from the fact that the Milky Way encircles our sky in a large circle, scientists have concluded that the Sun is located near the main plane of the Milky Way. To get a more accurate idea of ​​the position of the Sun in the Milky Way, and then to imagine what the shape of our Galaxy is in space, astronomers (V. Herschel, V. Ya. Struve, etc.) used the method of stellar calculations. The bottom line is that in different parts of the sky, the number of stars is counted in a sequential interval of stellar magnitudes. If we assume that the luminosities of the stars are the same, then the observed brightness can be judged on the distances to the stars, then, assuming that the stars in space are evenly spaced, consider the number of stars in spherical volumes, centered in the Sun.

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Hot stars in the southern Milky Way Hot blue stars, glowing red hydrogen gas and dark, eclipsing dust clouds are scattered across this impressive region of the Milky Way in the southern constellation of Ara. The stars on the left, 4,000 light-years from Earth, are young, massive, emitting energetic ultraviolet radiation that ionizes the surrounding star-forming hydrogen clouds, causing the line's characteristic red glow. A small cluster of born stars can be seen to the right, against the backdrop of a dark dusty nebula.

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The central region of the Milky Way. In the 1990s, the COsmic Background Explorer (COBE) satellite scanned the entire sky in infrared light. The picture you see is the result of an exploration of the central region of the Milky Way. The Milky Way is a common spiral galaxy that has a central bulge and an extended stellar disk. Gas and dust in the disk absorb radiation in the visible range, which interferes with observations of the galactic center. Since infrared light is less absorbed by gas and dust, the Diffuse InfraRed Background Experiment (DIRBE) aboard the COBE Cosmic Background Satellite detects this radiation from the stars surrounding the galactic center. The above image is a view of the galactic center from a distance of 30,000 light years (this is the distance from the Sun to the center of our galaxy). The DIBRE experiment uses liquid helium-cooled equipment specifically to detect infrared radiation, to which the human eye is insensitive.

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At the Center of the Milky Way At the center of our Milky Way Galaxy is a black hole with more than two million times the mass of the Sun. Previously, this was a controversial claim, but now this startling conclusion is almost beyond question. It is based on the results of observations of stars orbiting the center of the Galaxy very close to it. Using one of the Very Large Telescopes of the Paranal Observatory and an advanced NACO infrared camera, astronomers patiently tracked the orbit of one of the stars, designated S2, which approached the center of the Milky Way at a distance of about 17 light hours (17 light hours is just three times the orbit radius Pluto). Their results convincingly show that S2 is driven by the colossal gravitational force of an invisible object, which should be extremely compact - a supermassive black hole. This deep, near-infrared image from NACO's camera shows a stellar 2 light-year region in the center of the Milky Way, with arrows pointing to the exact center. Thanks to the capabilities of the NACO camera to track stars so close to the galactic center, astronomers can observe the movement of a star in orbit around a supermassive black hole. This makes it possible to accurately determine the mass of the black hole and, probably, to carry out a previously impossible test of Einstein's theory of gravity.

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What does the Milky Way look like? What does our Milky Way Galaxy look like from a distance? No one knows for sure, since we are inside our Galaxy, in addition, opaque dust limits our view in visible light. However, this figure shows a fairly plausible assumption based on numerous observations. At the center of the Milky Way is a very bright core that surrounds a giant black hole. The bright central bulge of the Milky Way is now thought to be an asymmetric bar of relatively old red stars. The outer regions contain spiral arms, shaped by open clusters of young, bright blue stars, red emission nebulae, and dark dust. The spiral arms are located in a disk, the bulk of the mass of which is made up of relatively faint stars and a rarefied gas - mostly hydrogen. The figure does not show the huge spherical halo of invisible dark matter, which makes up most of the mass of the Milky Way and determines the movement of stars far from its center.

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MILKY WAY, a hazy glow in the night sky from billions of stars in our Galaxy. The stripe of the Milky Way encircles the sky in a wide ring. The Milky Way is especially visible far from city lights. In the Northern Hemisphere, it is convenient to observe it around midnight in July, at 10 pm in August, or at 8 pm in September, when the Northern Cross of the Cygnus constellation is near its zenith. Following our gaze to the twinkling strip of the Milky Way to the north or northeast, we pass the constellation Cassiopeia (in the shape of the letter W) and move towards the bright star Capella. Beyond the Capella, you can see how the less wide and brighter part of the Milky Way passes just east of Orion's belt and tilts towards the horizon not far from Sirius, the brightest star in the sky. The brightest part of the Milky Way is visible in the south or southwest while the Northern Cross is overhead. In this case, two branches of the Milky Way are visible, separated by a dark gap. The cloud in the Shield, which E. Barnard called "the pearl of the Milky Way", is located halfway to the zenith, and the magnificent constellations Sagittarius and Scorpio are visible below.

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WHEN THE MILKY WAY COLLIDED WITH ANOTHER GALAXY Recent studies by astronomers suggest that billions of years ago, our Milky Way galaxy collided with another smaller one, and the results of this interaction in the form of remnants of this galaxy are still present in the Universe. Observing about 1,500 sun-like stars, an international team of researchers came to the conclusion that the trajectory of their movement, as well as the relative position, may be evidence of such a collision. "The Milky Way is a large galaxy and we believe that it was the result of the merger of several smaller ones," said Rosemary Wyse of Johns Hopkins University. Vis and her colleagues from Great Britain and Australia monitored the peripheral zones of the Milky Way, believing that it was there that traces of collisions could be present. A preliminary analysis of the research results confirmed their assumption, and an extended search (scientists expect to study about 10 thousand stars) will establish this with accuracy. Collisions in the past may be repeated in the future. So, according to calculations, in billions of years, the Milky Way and the Andromeda nebula, the closest spiral galaxy to us, should collide.

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Legend ... There are many legends about the origin of the Milky Way. Two similar ancient Greek myths deserve special attention, which reveal the etymology of the word Galaxias (????????) and its connection with milk (????). One of the legends tells about the mother's milk of the goddess Hera, who was breastfeeding Hercules, spreading across the sky. When Hera found out that the baby she was breastfeeding was not her own child, but the illegitimate son of Zeus and an earthly woman, she pushed him away and the spilled milk became the Milky Way. Another legend says that the spilled milk is the milk of Rhea, the wife of Kronos, and Zeus himself was the baby. Kronos devoured his children, as it was predicted to him that he would be overthrown from the top of the Pantheon by his own son. Rhea conceived a plan to save her sixth son, newborn Zeus. She wrapped a stone in baby clothes and slipped it to Kronos. Kronos asked her to feed her son one more time before he swallowed him. Milk spilled from Rhea's breast onto a bare stone was later called the Milky Way.

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Supercomputer (part 1) One of the fastest computers in the world was designed specifically for simulating the gravitational interaction of astronomical objects. With its commissioning, scientists received a powerful tool for studying the evolution of clusters of stars and galaxies. The new supercomputer, dubbed the GravitySimulator, was designed by David Merritt of the Rochester Institute of Technology (RIT), New York. It implements a new technology - the performance gain was achieved through the use of special acceleration cards Gravity Pipelines. With a performance hit of 4 trillion. operations per second GravitySimulator entered the top 100 most powerful supercomputers in the world and became the second most powerful machine of this architecture. Its cost is $ 500 thousand. According to Universe Today, the GravitySimulator is designed to solve the classical problem of gravitational interaction of N-bodies. Productivity in 4 trillion. operations per second allows you to build a model of the simultaneous interaction of 4 million stars, which is an absolute record in the practice of astronomical calculations. Until now, standard computers have been able to simulate the gravitational interaction of no more than several thousand stars at the same time. After installing a supercomputer at RIT this spring, Merit and his collaborators were able to build for the first time a model of a close pair of black holes that form when two galaxies merge.

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Supercomputer (part 2) "It is known that there is a black hole in the center of most galaxies," Dr. Merit explains the essence of the problem. - When galaxies merge, one larger black hole is formed. The process of merging itself is accompanied by the absorption and, at the same time, the ejection outward of stars located in the immediate vicinity of the center of galaxies. Observations of nearby interacting galaxies appear to support theoretical models. However, until now, the available power of computers has not made it possible to build a numerical model to test the theory. This is the first time we have succeeded. " The next challenge that RIT astrophysicists will work on is studying the dynamics of stars in the central regions of the Milky Way to understand the nature of the formation of a black hole in the center of our own galaxy. Dr. Merit believes that, in addition to solving particular large-scale problems in the field of astronomy, installing one of the most powerful computers in the world will make Rochester Institute of Technology a leader in other areas of science. The most powerful supercomputer for the second year now remains BlueGene / L, created by IBM and installed in the Lawrence laboratory in Livermore, USA. Its current speed reaches 136.8 teraflops, but in its final configuration, which includes 65536 processors, this figure will be at least doubled.

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Milky Way System The Milky Way System is a vast star system (galaxy) to which the Sun belongs. The Milky Way system consists of many different types of stars, as well as star clusters and associations, gas and dust nebulae, and individual atoms and particles scattered in interstellar space. Most of them occupy a lenticular volume with a diameter of about 100 "000 and a thickness of about 12" 000 light years. The smaller part fills an almost spherical volume with a radius of about 50 "000 light years. All the components of the Galaxy are connected into a single dynamical system revolving around the minor axis of symmetry. The center of the System is in the direction of the constellation Sagittarius.

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The age of the Milky Way was estimated with the help of radioisotopes. The age of the Galaxy (and, generally speaking, the Universe) was tried to be determined in a manner similar to that used by archaeologists. Nicholas Daufas from the University of Chicago suggested comparing the content of various radioisotopes at the periphery of the Milky Way and in the bodies of the solar system for this. An article about this was published in the journal Nature. Thorium-232 and uranium-238 were chosen for the assessment: their half-lives are comparable to the time elapsed since the Big Bang. If you know the exact ratio of their quantities at the beginning, then by the current concentrations it is easy to estimate how much time has passed. Astronomers were able to find out how much thorium and uranium it contains from the spectrum of one old star, which is located on the edge of the Milky Way. The problem was that the star's original composition was unknown. Daufas had to turn to information about meteorites. Their age (about 4.5 billion years) is known with sufficient accuracy and is comparable to the age of the solar system, and the content of heavy elements at the time of formation was the same as that of solar matter. Considering the Sun an "average" star, Daufas transferred these characteristics to the original subject of analysis. Calculations have shown that the age of the Galaxy is 14 billion years, and the error is about one-seventh of the value itself. The previous figure - 12 billion - is quite close to this result. Astronomers got it by comparing the properties of globular clusters and individual white dwarfs. However, as Daufas notes, this approach requires additional assumptions about the evolution of stars, while his method is based on fundamental physical principles.

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The Heart of the Milky Way Scientists have managed to look at the heart of our galaxy. The Chandra Space Telescope has compiled a mosaic picture that spans 400 by 900 light years. On it, scientists saw a place where stars die and are reborn with amazing frequency. In addition, more than a thousand new X-ray sources have been discovered in this sector. Most X-rays do not penetrate the earth's atmosphere, so such observations can only be made using space telescopes. When the stars die, they leave clouds of gas and dust, which are squeezed out of the center and, as they cool, move to the distant regions of the galaxy. This cosmic dust contains the entire spectrum of elements, including those that are the builders of our body. So we are literally starry ash.

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The Milky Way found four more satellites Five centuries ago, in August 1519, the Portuguese admiral Fernando Magellan went on a journey around the world. During the voyage, the exact dimensions of the Earth were determined, the date line was discovered, as well as two small foggy clouds in the sky of southern latitudes, which accompanied the sailors on clear starry nights. And although the great naval commander did not know about the true origin of these ghostly condensations, later called the Large and Small Magellanic Clouds, it was then that the first satellites (dwarf galaxies) of the Milky Way were discovered. The nature of these large clusters of stars finally became clear only at the beginning of the 20th century, when astronomers learned to determine the distances to such celestial objects. It turned out that the light from the Large Magellanic Cloud goes to us for 170 thousand years, and from the Small one - 200 thousand years, and they themselves represent an extensive cluster of stars. For more than half a century, these dwarf galaxies were considered the only ones in the vicinity of our Galaxy, but in the current century their number has grown to 20, and the last 10 satellites have been discovered within two years! The next step in the search for new members of the Milky Way family was helped by observations in the Sloan Digital Sky Survey (SDSS). More recently, scientists have found four new satellites in SDSS images, located at a distance of 100 to 500 thousand light years from Earth. They are located in the firmament in the direction of the constellations Coma Veronica, Hounds of the Dogs, Hercules and Leo. Among astronomers, dwarf galaxies orbiting the center of our star system (which has a diameter of about 100,000 light years) are usually named after the constellations where they are located. As a result, the new celestial objects were named Hair of Veronica, Hounds Dogs II, Hercules and Leo IV. This means that the second such galaxy has already been discovered in the constellation of the Hounds of the Dogs, and the fourth in the constellation of Leo. The largest member of this group is Hercules, which is 1,000 light years across, and the smallest is Veronica's Hair (200 light years). It is gratifying to note that all four mini-galaxies were discovered by a group of the University of Cambridge (Great Britain), headed by Russian scientist Vasily Belokurov.

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Such relatively small star systems can be attributed more to large globular clusters than galaxies, so scientists are thinking of applying a new term to such objects - "hobbits" (hobbits, or little gnomes). The name of the new class of objects is only a matter of time. Most importantly, now astronomers have a unique opportunity to estimate the total number of dwarf star systems in the vicinity of the Milky Way. Preliminary calculations allow us to think that this figure reaches fifty. Finding the rest of the hidden "gnomes" will be more difficult, as their shine is extremely weak. Other star clusters help them hide, creating an extra background for radiation receivers. The only thing that helps out is the feature of dwarf galaxies to contain stars that are characteristic only for this type of object. Therefore, after finding the necessary stellar associations in the images, it remains only to make sure of their true location in the sky. Nevertheless, a sufficiently large number of such objects raises new questions for the supporters of the so-called "warm" dark matter, the movement of which is faster than within the framework of the theory of "cold" invisible substance. The formation of dwarf galaxies, rather, is possible with the slow motion of matter, which better ensures the merging of gravitational "lumps" and, as a consequence, the emergence of galactic clusters. Nevertheless, in any case, the presence of dark matter during the formation of mini-galaxies is mandatory, which is why such close attention is paid to these objects. In addition, according to modern cosmological views, prototypes of future giant stellar systems "grow" from dwarf galaxies in the process of merging. Thanks to the latest discoveries, we are learning more and more details about the periphery in the general sense of the word. The periphery of the solar system makes itself felt by the new objects of the Kuiper belt, the vicinity of our Galaxy, as we see, is also not empty. Finally, the outskirts of the observable universe became even more famous: at a distance of 11 billion light years, the most distant cluster of galaxies was discovered. But more on that in the next news.

When evenings turn dark in autumn, a wide flickering stripe is clearly visible in the starry sky. This is the Milky Way - a giant arch spanning the sky. The "Heavenly River" is the name of the Milky Way in Chinese legends. Ancient Greeks and Romans called it "Heavenly Road". The telescope made it possible to find out the nature of the Milky Way. This is the radiance of a myriad of stars, so far from us that they individually cannot be distinguished with the naked eye.

The diameter of the Galaxy is about 30 thousand parsecs (on the order of light years) The galaxy contains, according to the lowest estimate, about 200 billion stars (the current estimate ranges from 200 to 400 billion). As of January 2009, the mass of the Galaxy is estimated at 3 × 1012 masses of the Sun, or 6 × 1042 kg. Most of the mass of the Galaxy is contained not in stars and interstellar gas, but in a non-luminous halo of dark matter.

There is a bulge in the middle of the Galaxy called the bulge, which is about 8,000 parsecs across. In the center of the Galaxy, apparently, there is a supermassive black hole (Sagittarius A *) around which, presumably, a black hole of average mass rotates

The Galaxy belongs to the class of spiral galaxies, which means that the Galaxy has spiral arms located in the plane of the disk New data from observations of molecular gas (CO) suggests that our Galaxy has two arms, starting at a bar in the inner part of the Galaxy. In addition, there are a couple of sleeves on the inside. Then these arms transform into a four-arm structure observed in the neutral hydrogen line in the outer parts of the Galaxy

The Milky Way is observed in the sky as a dimly luminous diffuse whitish stripe, passing approximately along a large circle of the celestial sphere. In the northern hemisphere, the Milky Way crosses the constellations Eagle, Arrow, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini; in the Southern Unicorn, Poop, Sails, Southern Cross, Compass, Southern Triangle, Scorpio and Sagittarius. The galactic center is located in Sagittarius.

Most of the celestial bodies are combined into various rotating systems. So, the Moon revolves around the Earth, the satellites of the giant planets form their own systems rich in bodies. At a higher level, the Earth and the rest of the planets revolve around the Sun. A natural question arose whether the Sun is also included in an even larger system? The first systematic study of this issue was carried out in the 18th century by the English astronomer William Herschel

He counted the number of stars in different regions of the sky and found that there is a large circle in the sky (later called the galactic equator), which divides the sky into two equal parts and on which the number of stars is greatest. In addition, the more stars are, the closer the sky is to this circle. Finally, it was discovered that it is on this circle that the Milky Way is located. Thanks to this, Herschel guessed that all the stars we observe form a giant star system, which is flattened towards the galactic equator.

The history of the emergence of galaxies is not yet completely clear. Originally, the Milky Way had much more interstellar matter (mainly in the form of hydrogen and helium) than now, which has been spent and continues to be spent on the formation of stars. There is no reason to believe that this trend will change, so over the course of billions of years, further decay of natural star formation should be expected. Currently, stars are formed mainly in the arms of the Galaxy.

The structure of the Universe The structure of the Universe The Milky Way St. Years Milky Way The galaxy contains, according to the lowest estimate, about 200 billion stars. The bulk of the stars is located in the form of a flat disk. As of January 2009, the mass of the Galaxy is estimated at 3 · 10 ^ 12 solar masses, or 6 · 10 ^ 42 kg.

Nucleus In the middle of the Galaxy there is a thickening called the bulge, which is about 8 thousand parsecs across. In the center of the Galaxy, apparently, there is a supermassive black hole (Sagittarius A *) around which, presumably, a black hole of average mass revolves. Their joint gravitational action on neighboring stars makes the latter move along unusual trajectories. Balgemangle supermassive black hole Sagittarius A * The center of the Galaxy nucleus is located in the constellation Sagittarius (α = 265 °, δ = 29 °). The distance from the Sun to the center of the Galaxy is 8.5 kiloparsecs (2.62 10 ^ 17 km, or light years).

Arms The Galaxy belongs to the class of spiral galaxies, which means that the Galaxy has spiral arms located in the plane of the disk. The disk is immersed in a spherical halo, and a spherical crown is located around it. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy (the shift to the North Pole of the Galaxy is only 10 parsecs), on the inner edge of the arm, which is called the Orion arm. This arrangement makes it impossible to observe the shape of the sleeves visually. New data from observations of molecular gas (CO) suggest that our Galaxy has two arms starting at a bar in the inner part of the Galaxy. In addition, there are a couple of sleeves on the inside. Then these arms transform into a four-arm structure observed in the neutral hydrogen line in the outer parts of the Galaxy. The Galaxy belongs to the class of spiral galaxies, which means that the Galaxy has spiral arms located in the plane of the disk. The disk is immersed in a spherical halo, and a spherical crown is located around it. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy (the shift to the North Pole of the Galaxy is only 10 parsecs), on the inner edge of the arm, which is called the Orion arm. This arrangement makes it impossible to observe the shape of the sleeves visually. New data from observations of molecular gas (CO) suggest that our Galaxy has two arms starting at a bar in the inner part of the Galaxy. In addition, there are a couple of sleeves on the inside. These arms then transform into a four-arm structure observed in the neutral hydrogen line in the outer parts of the Galaxy.

Halo The halo of a galaxy is an invisible component of a spherical galaxy that extends beyond the visible portion of the galaxy. It is mainly composed of rarefied hot gas, stars and dark matter. The latter makes up the bulk of the galaxy spherical dark matter Galactic halo The galactic halo has a spherical shape, extending beyond the galaxy for 510 thousand light years, and a temperature of about 5 10 ^ 5 K.

The history of the discovery of the Galaxy Most of the celestial bodies are combined into various rotating systems. So, the Moon revolves around the Earth, the satellites of the giant planets form their own systems rich in bodies. At a higher level, the Earth and the rest of the planets revolve around the Sun. A natural question arose: is not the Sun also included in an even larger system? Most of the celestial bodies are combined into various rotating systems. So, the Moon revolves around the Earth, the satellites of the giant planets form their own systems rich in bodies. At a higher level, the Earth and the rest of the planets revolve around the Sun. A natural question arose: is not the Sun also included in an even larger system? The moonSatellites of giant planets of the MoonSatellites of giant planets of the planet The first systematic study of this issue was carried out in the 18th century by the English astronomer William Herschel. He counted the number of stars in different regions of the sky and found that there is a large circle in the sky (later called the galactic equator), which divides the sky into two equal parts and on which the number of stars is greatest. In addition, the more stars are, the closer the sky is to this circle. Finally, it was discovered that it is on this circle that the Milky Way is located. Thanks to this, Herschel guessed that all the stars we observe form a giant star system, which is flattened towards the galactic equator. The first systematic study of this issue was carried out in the 18th century by the English astronomer William Herschel. He counted the number of stars in different regions of the sky and found that there is a large circle in the sky (later called the galactic equator), which divides the sky into two equal parts and on which the number of stars is greatest. In addition, the more stars are, the closer the sky is to this circle. Finally, it was discovered that it is on this circle that the Milky Way is located. Thanks to this, Herschel guessed that all the stars we observe form a gigantic star system, which is flattened to the galactic equator. 18th century William Herschel Galactic equator Milky Way XVIII century William Herschel Galactic equator Milky Way At first it was assumed that all objects in the Universe are parts of our Galaxy, although some of them were still part of our Galaxy. nebulae could be galaxies like the Milky Way. Back in 1920, the question of the existence of extragalactic objects sparked debate (for example, the famous Great Dispute between Harlow Shapley and Geber Curtis; the former defended the uniqueness of our Galaxy). Kant's hypothesis was finally proved only in the 1920s, when Edwin Hubble was able to measure the distance to some spiral nebulae and show that, due to their distance, they cannot be part of the Galaxy. Initially, it was assumed that all objects in the Universe are parts of our Galaxy, although even Kant suggested that some nebulae may be galaxies similar to the Milky Way. Back in 1920, the question of the existence of extragalactic objects sparked debate (for example, the famous Great Dispute between Harlow Shapley and Geber Curtis; the former defended the uniqueness of our Galaxy). Kant's hypothesis was finally proved only in the 1920s, when Edwin Hubble was able to measure the distance to some spiral nebulae and show that by their remoteness they could not be part of the Galaxy.

Early Attempts at Classification Attempts to classify galaxies began concurrently with the discovery of the first spiral nebulae by Lord Ross in B.C. However, at that time the dominant theory was that all nebulae belong to our Galaxy. The fact that a number of nebulae are of a nongalactic nature was proved only by E. Hubble in 1924. Thus, galaxies were classified in the same way as galactic nebulae, spiral nebulae galaxies by Lord Rossom in our galaxy E. Hubble 1924 Early photographic surveys were dominated by spiral nebulae, which allowed them to be distinguished into a separate class. In 1888, A. Roberts performed a deep survey of the sky, which resulted in the discovery of a large number of elliptical structureless and very elongated spindle nebulae. In 1918, GD Curtis singled out the spirals with a bridge and a ring-like structure into a separate Φ-group into a separate group. In addition, he interpreted spindle nebulae as edge-on spirals. 1888 A. Robertselliptic structureless spindles 1918 D. Curtis

Harvard classification All galaxies in the Harvard classification were divided into 5 classes: All galaxies in the Harvard classification were divided into 5 classes: Class A galaxies brighter than 12m Class A galaxies brighter than 12mm Class B galaxies from 12m to 14m Class B galaxies from 12m to 14mm Class C galaxies from 14m to 16m Class C galaxies from 14m to 16mm Class D galaxies from 16m to 18m Class D galaxies from 16m to 18mm Class E galaxies from 18m to 20m Class E galaxies from 18m to 20mm

Elliptical galaxies Elliptical galaxies have a smooth elliptical shape (from highly flattened to almost circular) without distinctive features, with a uniform decrease in brightness from the center to the periphery. They are denoted by the letter E and a number, which is the index of the flattened galaxy. Thus, a round galaxy will be designated E0, and a galaxy with one of the semi-major axes twice as large as the other, E5. Elliptical galaxies have a smooth elliptical shape (from highly flattened to almost circular) without distinctive features, with a uniform decrease in brightness from the center to the periphery. They are denoted by the letter E and a number, which is the index of the flattened galaxy. Thus, a round galaxy will be designated E0, and a galaxy with one of the semi-major axes twice as large as the other, E5. Elliptical galaxies Elliptical galaxies M87

Spiral galaxies Spiral galaxies are composed of a flattened disk of stars and gas, at the center of which is a spherical compaction called a bulge, and an extensive spherical halo. In the plane of the disk, bright spiral arms are formed, consisting mainly of young stars, gas and dust. Hubble divided all known spiral galaxies into normal spirals (denoted by the symbol S) and spirals with a bar (SB), which in Russian literature are often called barred or crossed galaxies. In normal spirals, the spiral branches branch off tangentially from the bright central core and extend over the course of one revolution. The number of branches can be different: 1, 2, 3, ... but most often there are galaxies with only two branches. In intersected galaxies, spiral arms extend at right angles from the ends of the bar. Among them, there are also galaxies with the number of branches not equal to two, but, in the bulk, crossed galaxies have two spiral branches. Depending on whether the spiral arms are tightly twisted or clumpy, or according to the ratio of the sizes of the core and bulge, the symbols a, b or c are added. Thus, the Sa galaxies are characterized by a large bulge and a tightly twisted regular structure, while the Sc galaxies have a small bulge and a clumpy spiral structure. The Sb subclass includes galaxies that, for whatever reason, cannot be attributed to one of the extreme subclasses: Sa or Sc. Thus, the galaxy M81 has a large bulge and a clumpy spiral structure. Spiral galaxies are composed of a flattened disk of stars and gas, at the center of which is a spherical compaction called a bulge, and an extensive spherical halo. In the plane of the disk, bright spiral arms are formed, consisting mainly of young stars, gas and dust. Hubble divided all known spiral galaxies into normal spirals (denoted by the symbol S) and spirals with a bar (SB), which in Russian literature are often called barred or crossed galaxies. In normal spirals, the spiral branches branch off tangentially from the bright central core and extend over the course of one revolution. The number of branches can be different: 1, 2, 3, ... but most often there are galaxies with only two branches. In intersected galaxies, spiral arms extend at right angles from the ends of the bar. Among them, there are also galaxies with the number of branches not equal to two, but, in the bulk, crossed galaxies have two spiral branches. Depending on whether the spiral arms are tightly twisted or clumpy, or according to the ratio of the sizes of the nucleus and the bulge, the symbols a, b or c are added. Thus, the Sa galaxies are characterized by a large bulge and a tightly twisted regular structure, while the Sc galaxies have a small bulge and a clumpy spiral structure. The Sb subclass includes galaxies that, for whatever reason, cannot be attributed to one of the extreme subclasses: Sa or Sc. Thus, the galaxy M81 has a large bulge and a clumpy spiral structure. Spiral galaxies

Irregular or irregular galaxies Irregular or irregular galaxies A galaxy devoid of both rotational symmetry and a significant core. The Magellanic Clouds are a typical representative of irregular galaxies. There was even the term "Magellanic nebula". Irregular galaxies are distinguished by a variety of shapes, usually small in size, and an abundance of gas, dust, and young stars. Designated as I. Due to the fact that the shape of irregular galaxies is not firmly determined, how irregular galaxies are often classified as peculiar galaxies. Irregular or irregular galaxies are a galaxy devoid of both rotational symmetry and a significant core. The Magellanic Clouds are a typical representative of irregular galaxies. There was even the term "Magellanic nebula". Irregular galaxies are distinguished by a variety of shapes, usually small in size, and an abundance of gas, dust, and young stars. Designated as I. Due to the fact that the shape of irregular galaxies is not firmly determined, how irregular galaxies are often classified as peculiar galaxies. Irregular or irregular galaxies Magellanic clouds peculiar galaxies Irregular or irregular galaxies Magellanic clouds peculiar galaxies M82

Lenticular galaxies Lenticular galaxies are disk galaxies (like spiral galaxies) that have spent or lost their interstellar matter (like ellipticals). In cases where the galaxy is facing face-on towards the observer, it is often difficult to clearly distinguish lenticular and elliptical galaxies due to the inexpressiveness of the lenticular galaxy's spiral arms. Lenticular galaxies are disk galaxies (like spiral galaxies) that have spent or lost their interstellar matter (like ellipticals). In cases where the galaxy is facing face-on towards the observer, it is often difficult to clearly distinguish lenticular and elliptical galaxies due to the inexpressiveness of the lenticular galaxy's spiral arms. disk galaxies interstellar matter disk galaxies interstellar matter NGC 5866

A black hole is a region in space-time, the gravitational attraction of which is so great that even objects moving at the speed of light (including quanta of light itself) cannot leave it. A black hole is a region in space-time, the gravitational attraction of which is so great that even objects moving at the speed of light (including quanta of light itself) cannot leave it. Space-time gravitational attraction by the speed of light quanta of light in space-time gravitational attraction by the speed of light quanta of light Border of this area is called the event horizon, and its characteristic size is the gravitational radius. In the simplest case of a spherically symmetric black hole, it is equal to the Schwarzschild radius. The question of the real existence of black holes is closely related to how correct the theory of gravity, from which their existence follows. In modern physics, the standard theory of gravity, which is best confirmed experimentally, is general relativity (GR), which confidently predicts the possibility of the formation of black holes (but their existence is possible within the framework of other (not all) models, see: Alternative theories of gravity). Therefore, observational data are analyzed and interpreted, first of all, in the context of general relativity, although, strictly speaking, this theory is not experimentally confirmed for conditions corresponding to the region of space-time in the immediate vicinity of black holes of stellar masses (however, it is well confirmed under conditions corresponding to supermassive black holes). Therefore, statements about direct evidence of the existence of black holes, including in this article below, strictly speaking, should be understood in the sense of confirming the existence of astronomical objects, such dense and massive, and also possessing some other observable properties that they can be interpreted as black holes general theory of relativity. The boundary of this area is called the event horizon, and its characteristic size is the gravitational radius. In the simplest case of a spherically symmetric black hole, it is equal to the Schwarzschild radius. The question of the real existence of black holes is closely related to how correct the theory of gravity, from which their existence follows. In modern physics, the standard theory of gravity, best confirmed experimentally, is the general theory of relativity (GR), which confidently predicts the possibility of the formation of black holes (but their existence is possible within the framework of other (not all) models, see Sec. : Alternative theories of gravity). Therefore, observational data are analyzed and interpreted, first of all, in the context of general relativity, although, strictly speaking, this theory is not experimentally confirmed for conditions corresponding to the region of space-time in the immediate vicinity of black holes of stellar masses (however, it is well confirmed under conditions corresponding to supermassive black holes). Therefore, statements about direct evidence of the existence of black holes, including in this article below, strictly speaking, should be understood in the sense of confirming the existence of astronomical objects, such dense and massive, and also possessing some other observable properties that they can be interpreted as black holes general theory of relativity. event horizon gravitational radius to Schwarzschild radius theory of gravity general theory of relativity Alternative theories of gravity event horizon gravitational radius to Schwarzschild radius theory of gravity general theory of relativity Alternative theories of gravity

Magnetar or magnetar is a neutron star with an extremely strong magnetic field (up to 1011 T). Theoretically, the existence of magnetars was predicted in 1992, and the first evidence of their real existence was obtained in 1998 when observing a powerful burst of gamma and X-rays from the SGR source in the constellation Eagle. The lifetime of magnetars is short, it is about years. Magnetars are a poorly understood type of neutron star due to the fact that few are close enough to Earth. Magnetars are about 20 km in diameter, but most of the masses exceed the mass of the Sun. Magnetar is so compressed that a pea of ​​its matter would weigh over 100 million tons. Most of the known magnetars rotate very rapidly, at least a few revolutions per second on an axis. The life cycle of a magnetar is rather short. Their strong magnetic fields disappear after about years, after which their activity and X-ray emission cease. According to one of the assumptions, up to 30 million magnetars could have formed in our galaxy over the entire period of its existence. Magnetars are formed from massive stars with an initial mass of about 40 M. Magnetar or magnetar is a neutron star with an extremely strong magnetic field (up to 1011 T). Theoretically, the existence of magnetars was predicted in 1992, and the first evidence of their real existence was obtained in 1998 when observing a powerful burst of gamma and X-rays from the SGR source in the constellation Eagle. The lifetime of magnetars is short, it is about years. Magnetars are a poorly understood type of neutron star due to the fact that few are close enough to Earth. Magnetars are about 20 km in diameter, but most of the masses exceed the mass of the Sun. Magnetar is so compressed that a pea of ​​its matter would weigh over 100 million tons. Most of the known magnetars rotate very rapidly, at least a few revolutions per second on an axis. The life cycle of a magnetar is rather short. Their strong magnetic fields disappear after about years, after which their activity and X-ray emission cease. According to one of the assumptions, up to 30 million magnetars could have formed in our galaxy over the entire period of its existence. Magnetars are formed from massive stars with an initial mass of about 40 M. A neutron star with a magnetic field of T 1992 1998 gamma X-rays SGR Eagle of neutron stars Earth The sun of our galaxies Neutron star with a magnetic field T 1992 1998 gamma X-rays in the Earth's magnetic field Tl 1992 1998 gamma-X-rays in the Earth SGR neutron magnetic stars also the magnetic field fluctuations that accompany them often lead to huge emissions of gamma radiation, which were recorded on Earth in 1979, 1998 and 2004. The magnetic field of a neutron star is a million million times larger than that of the Earth 1979, 1998 and 2004. The magnetic field of a neutron star is a million million times larger than the magnetic field of the Earth in years
Pulsar is a space source of radio (radio pulsar), optical (optical pulsar), X-ray (X-ray pulsar) and / or gamma (gamma-pulsar) radiation arriving at the Earth in the form of periodic bursts (pulses). According to the dominant astrophysical model, pulsars are rotating neutron stars with a magnetic field that is tilted to the axis of rotation, which modulates the radiation coming to Earth. The first pulsar was discovered in June 1967 by Jocelyn Bell, a graduate student of E. Hewish, at the meridian radio telescope of the Mallard Radio Astronomy Observatory, Cambridge University at a wavelength of 3.5 m (85.7 MHz). For this outstanding performance, Hewish received the 1974 Nobel Prize. The modern names of this pulsar PSR B or PSR J Pulsar is a cosmic source of radio (radio pulsar), optical (optical pulsar), X-ray (X-ray pulsar) and / or gamma (gamma-pulsar) radiation arriving at Earth in the form of periodic bursts (pulses ). According to the dominant astrophysical model, pulsars are rotating neutron stars with a magnetic field that is tilted to the axis of rotation, which modulates the radiation coming to Earth. The first pulsar was discovered in June 1967 by Jocelyn Bell, a graduate student of E. Hewish, at the meridian radio telescope of the Mallard Radio Astronomy Observatory, Cambridge University at a wavelength of 3.5 m (85.7 MHz). For this outstanding performance, Hewish received the 1974 Nobel Prize. The modern names of this pulsar are PSR B or PSR J Cosmic radio-radio pulsar optical pulsar X-ray X-ray pulsar gamma-gamma pulsar Earth periodic pulses of astrophysical neutron stars magnetic field and rotation modulation 1967 Jocelyn Bellaspirant. Hewish radio telescope at the Mallard Radio Astronomy Observatory, University of Cambridge at wavelength 1974 Nobel Prize PSR B space radio-radio pulsaroptical optical pulsar X-ray X-ray pulsar Hewish Radio Telescope at the Mallard Radio Astronomy Observatory, University of Cambridge, 1974 Nobel Prize PSR B The observation results were kept secret for several months, and the first discovered pulsar was named LGM-1 (short for Little Green Men). This name was associated with the assumption that these strictly periodic pulses of radio emission are of artificial origin. However, the Doppler frequency shift (characteristic of a source orbiting a star) was not detected. In addition, Hewish's group found 3 more sources of similar signals. After that, the hypothesis about signals of extraterrestrial civilization disappeared, and in February 1968 in the journal "Nature" a message appeared about the discovery of rapidly changing extraterrestrial radio sources of unknown nature with a highly stable frequency. The results of observations were kept secret for several months, and the first discovered pulsar was named LGM-1 (short for Little Green Men, little green men). This name was associated with the assumption that these strictly periodic pulses of radio emission are of artificial origin. However, the Doppler frequency shift (characteristic of a source orbiting a star) was not detected. In addition, Hewish's group found 3 more sources of similar signals. After that, the hypothesis about signals of extraterrestrial civilization disappeared, and in February 1968 in the journal "Nature" there was a message about the discovery of rapidly changing extraterrestrial radio sources of unknown nature with a highly stable frequency. Until the end of 1968, various observatories of the world discovered 58 more objects, called pulsars, the number of publications devoted to them in the very first years after their discovery amounted to several hundred. Astrophysicists soon came to the general opinion that a pulsar, or rather a radio pulsar, is a neutron star. It emits narrowly directed fluxes of radio emission, and as a result of the rotation of a neutron star, the flux enters the field of view of an external observer at regular intervals, so pulsar pulses are formed. The message caused a scientific sensation. Until the end of 1968, various observatories of the world discovered 58 more objects, called pulsars, the number of publications devoted to them in the very first years after their discovery amounted to several hundred. Astrophysicists soon came to the general opinion that a pulsar, or rather a radio pulsar, is a neutron star. It emits narrowly directed fluxes of radio emission, and as a result of the rotation of a neutron star, the flux enters the field of view of an external observer at regular intervals, this is how pulsar pulses are formed. The nearest ones are located at a distance of about 0.12 kpc (about 390 light years) from the Sun. In 2008, about 1790 radio pulsars are already known (according to the ATNF catalog). The nearest of them are located at a distance of about 0.12 kpc (about 390 light years) from the Sun. ATNFkpc light years of the Sun ATNFkpc light years of the Sun Somewhat later, sources of periodic X-ray radiation, called X-ray pulsars, were discovered. Like radio, X-ray pulsars are highly magnetized neutron stars. Unlike radio pulsars, which consume their own rotational energy for radiation, X-ray pulsars emit due to the accretion of matter from a neighboring star that has filled its Roche lobe and is gradually transformed into a white dwarf under the influence of the pulsar. As a result, the mass of the pulsar slowly grows, its moment of inertia and rotation frequency increase, while radio pulsars, on the contrary, slow down with time. An ordinary pulsar makes a revolution in a time from a few seconds to a few tenths of a second, while an X-ray pulsar makes hundreds of revolutions per second. Somewhat later, sources of periodic X-ray radiation, called X-ray pulsars, were discovered. Like radio, X-ray pulsars are highly magnetized neutron stars. Unlike radio pulsars, which consume their own rotational energy for radiation, X-ray pulsars emit due to the accretion of matter from a neighboring star that has filled its Roche lobe and is gradually transformed into a white dwarf under the influence of the pulsar. As a result, the mass of the pulsar slowly grows, its moment of inertia and rotation frequency increase, while radio pulsars, on the contrary, slow down with time. An ordinary pulsar makes a revolution in a time from a few seconds to a few tenths of a second, while an X-ray pulsar makes hundreds of revolutions per second. X-ray pulsars

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Introduction The Milky Way Galaxy, also called simply the Galaxy (with a capital letter), is a giant star system in which, among others, our Sun is located, all the individual stars visible to the naked eye, as well as a huge number of stars merging together and observed in the form of a milky paths. Our Galaxy is one of many other galaxies. The Milky Way is a Hubble-type SBbc barred spiral galaxy, and together with the Andromeda galaxy M31 and the Triangulum galaxy (M33), as well as several smaller satellite galaxies, form the Local Group, which, in turn, is part of the Virgo Supercluster.

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The Milky Way (translation of the Latin name Via Lactea, from the Greek word Galaxia (gala, galactos means "milk")) is a dimly glowing diffuse whitish strip that crosses the starry sky almost in a large Circle, the north pole of which is located in the constellation Coma Veronica; consists of a huge number of faint stars, not visible separately to the naked eye, but distinguishable separately through a telescope or in photographs taken with sufficient resolution.

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The visible picture of the Milky Way is a consequence of the perspective when observing from inside a huge, highly oblate cluster of stars in our Galaxy by an observer who is near the plane of symmetry of this cluster. The Milky Way is also the traditional name for our Galaxy. The brightness of the Milky Way is uneven in different places. The strip of the Milky Way, about 5-30 ° wide, has a seemingly cloudy structure, due, firstly, to the existence in the Galaxy of stellar clouds or condensations and, secondly, to the uneven distribution of light-absorbing dusty dark nebulae that form areas with an apparent deficit of stars due to for absorbing their light. In the Northern Hemisphere, the Milky Way passes through the constellations of Eagle, Arrow, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini. Leaving for the Southern Hemisphere, he captures the constellations of the Unicorn, Poop, Sails, Southern Cross, Compass, Southern Triangle, Scorpio and Sagittarius. The Milky Way is especially bright in the constellation Sagittarius, which houses the center of our star system, which is believed to include a supermassive black hole. The Sagittarius constellation does not rise high above the horizon in northern latitudes. Therefore, in this area, the Milky Way is not as noticeable as, say, in the constellation Cygnus, which rises very high above the horizon in the autumn in the evenings. The middle line inside the Milky Way is the galactic equator.

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Mythology There are many legends about the origin of the Milky Way. Two similar ancient Greek myths deserve special attention, which reveal the etymology of the word Galaxias (Γαλαξίας) and its connection with milk (γάλα). One of the legends tells about the mother's milk of the goddess Hera, who was breastfeeding Hercules, spreading across the sky. When Hera found out that the baby she was breastfeeding was not her own child, but the illegitimate son of Zeus and an earthly woman, she pushed him away and the spilled milk became the Milky Way. Another legend says that the spilled milk is the milk of Rhea, the wife of Kronos, and Zeus himself was the baby. Kronos devoured his children, as it was predicted to him that he would be overthrown from the top of the Pantheon by his own son. Rhea conceived a plan to save her sixth son, newborn Zeus. She wrapped a stone in baby clothes and slipped it to Kronos. Kronos asked her to feed her son one more time before he swallowed him. Milk spilled from Rhea's breast onto a bare stone was later called the Milky Way.

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Structure of the Galaxy Our Galaxy is about 30 thousand parsecs across and contains about 100 billion stars. Most of the stars are located in the form of a flat disk. The mass of the Galaxy is estimated at 5.8 × 1011 solar masses, or 1.15 × 1042 kg. Most of the mass of the Galaxy is contained not in stars and interstellar gas, but in a non-luminous halo of dark matter. The Milky Way has a convex shape - like a saucer or brimmed hat. What's more, the galaxy not only bends, but vibrates like an eardrum.

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Satellites Scientists at the University of California, studying the abundance of hydrogen in distorted regions, found that these deformations are closely related to the position of the orbits of two satellite galaxies of the Milky Way - the Large and Small Magellanic clouds, which regularly pass through the surrounding dark matter. There are other galaxies even less close to the Milky Way, but their role (satellites or bodies absorbed by the Milky Way) is unclear.

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Large Magellanic Cloud Exploration history Designation LMC, BMO Observation data Type SBm Right ascension 05h 23m 34s Declination −69 ° 45 ′ 22 ″; Redshift 0.00093 Distance 168000 sv. years Apparent magnitude 0.9 Apparent dimensions 10.75 ° × 9.17 ° Constellation Doradoba Physical characteristics Radius 10,000 sv. years Properties The brightest satellite of the Milky Way

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The Large Magellanic Cloud (LMC) is an SBm-type dwarf galaxy located at a distance of about 50 kiloparsecs from our Galaxy. It occupies an area of ​​the sky of the southern hemisphere in the constellations Dorada and Table Mountain and is never visible from the territory of the Russian Federation. The LMC is about 20 times smaller in diameter than the Milky Way and contains approximately 5 billion stars (only 1/20 of the number in our Galaxy), while the Small Magellanic Cloud contains only 1.5 billion stars. In 1987, supernova SN 1987A exploded in the Large Magellanic Cloud. This is the closest supernova to us since SN 1604. The LMC is home to a well-known center of active star formation - the Tarantula Nebula.

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Small Magellanic Cloud Exploration history Discoverer Fernand Magellan Discovery date 1521 Designations NGC 292, ESO 29-21, A 0051-73, IRAS00510-7306, MMO, SMC, PGC 3085 Observational data Type SBm Right ascension 00h 52m 38.0s Declination −72 ° 48 ′ 00 ″ Distance 200,000 sv. years (61,000 parsecs) Visible stellar magnitude 2.2 Photographic stellar magnitude 2.8 Visible dimensions 5 ° × 3 ° Surface brightness 14.1 Angular position 45 ° Constellation Toucan Physical characteristics Radius 7000 sv. years Absolute magnitude −16.2 Properties Satellite of the Milky Way

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Arms The Galaxy belongs to the class of spiral galaxies, which means that the Galaxy has spiral arms that are located in the plane of the disk. The disk is immersed in a spherical halo, and a spherical crown is located around it. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy (the shift to the North Pole of the Galaxy is only 10 parsecs), on the inner edge of the arm, which is called the Orion arm. Such our arrangement does not make it possible to observe the shape of the sleeves visually.

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The disk core is immersed in a spherical halo, and a spherical crown is located around it. In the middle of the galaxy is a thickening called the bulge and is about 8 thousand parsecs across. In the center of the Galaxy there is a small region with unusual properties, where, most likely, a supermassive black hole is located. The center of the galactic nucleus is projected onto the constellation Sagittarius (α = 265 °, δ = −29 °). Distance to the center of the Galaxy 8.5 kiloparsecs (2.62 · 1022 cm, or 27,700 light years).

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The Galactic Center is a relatively small area in the center of our Galaxy, the radius of which is about 1000 parsecs and the properties of which are sharply different from those of other parts of it. Figuratively speaking, the galactic center is a space "laboratory" in which the processes of star formation are still taking place and in which the core is located, which once gave rise to the condensation of our star system. The galactic center is located at a distance of 10 kpc from the solar system, in the direction of the constellation Sagittarius. A large amount of interstellar dust is concentrated in the galactic plane, due to which the light coming from the galactic center is attenuated by 30 magnitudes, that is, 1012 times. Therefore, the center is invisible in the optical range - with the naked eye and with optical telescopes. The Galactic Center is observed in the radio range, as well as in the infrared, X-ray and gamma-ray ranges. A 400 by 900 light-year image composed of several photographs from the Chandra Telescope, with hundreds of white dwarfs, neutron stars and black holes, in clouds of gas heated to millions of degrees. Inside the bright spot in the center of the image is the supermassive black hole of the galactic center (radio source Sagittarius A *). The colors in the image correspond to the X-ray energy ranges: red (low), green (medium) and blue (high).

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Composition of the galactic center The largest feature of the galactic center is the star cluster (the stellar bulge) located there in the form of an ellipsoid of revolution, the major semiaxis of which lies in the plane of the Galaxy, and the minor one - on its axis. The semiaxis ratio is approximately 0.4. The orbital speed of stars at a distance of about a kiloparsec is about 270 km / s, and the orbital period is about 24 million years. Based on this, it turns out that the mass of the central cluster is approximately 10 billion solar masses. The concentration of cluster stars increases sharply towards the center. The stellar density varies approximately in proportion to R-1.8 (R is the distance from the center). At a distance of about a kiloparsec, it is several solar masses in a cubic parsec, in the center - more than 300 thousand solar masses in a cubic parsec (for comparison, in the vicinity of the Sun the stellar density is about 0.07 solar masses per cubic parsec). Spiral gas arms extend from the cluster, extending to a distance of 3–4.5 thousand parsecs. The arms rotate around the galactic center and at the same time move to the sides, with a radial speed of about 50 km / s. The kinetic energy of movement is 1055 erg. A gaseous disk with a radius of about 700 parsecs and a mass of about one hundred million solar masses was discovered inside the cluster. The central region of star formation is located inside the disk.

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Image composed of a dozen photographs of the Chandra telescope, covering an area 130 light years across

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Closer to the center is a rotating and expanding ring of molecular hydrogen, which has a mass of about one hundred thousand solar masses and a radius of about 150 parsecs. The rotation speed of the ring is 50 km / s, and the expansion speed is 140 km / s. The plane of rotation is tilted to the plane of the Galaxy by 10 degrees. In all likelihood, the radial movements in the galactic center are explained by an explosion that occurred there about 12 million years ago. The distribution of gas in the ring is uneven, forming huge clouds of gas and dust. The largest cloud is the Sagittarius B2 complex, located 120 pc from the center. The diameter of the complex is 30 parsecs, and the mass is about 3 million solar masses. The complex is the largest star-forming region in the Galaxy. All kinds of molecular compounds found in space are found in these clouds. Even closer to the center is the central dust cloud, with a radius of about 15 parsecs. In this cloud, bursts of radiation are periodically observed, the nature of which is unknown, but which indicate active processes taking place there. Almost in the very center there is a compact source of non-thermal radiation Sagittarius A *, the radius of which is 0.0001 parsec, and the brightness temperature is about 10 million degrees. The radio emission from this source appears to be of a synchrotron nature. At times, rapid changes in the radiation flux are observed. No other source of radiation has been found anywhere else in the Galaxy, but similar sources are found in the cores of other galaxies.

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From the point of view of the evolution models of galaxies, their nuclei are the centers of their condensation and initial star formation. The oldest stars should be there. Apparently, in the very center of the galactic core there is a supermassive black hole with a mass of about 3.7 million solar masses, which is shown by the study of the orbits of nearby stars. The radiation from the Sagittarius A * source is caused by gas accretion onto a black hole, the radius of the emitting region (accretion disk, jets) is not more than 45 AU. Galactic center of the Milky Way in the infrared range.

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The Milky Way as a Celestial Phenomenon The Milky Way is observed in the sky as a dimly luminous diffuse whitish stripe passing approximately along a large circle of the celestial sphere. In the northern hemisphere, the Milky Way crosses the constellations Eagle, Arrow, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini; in the south - Unicorn, Poop, Sails, Southern Cross, Compass, Southern Triangle, Scorpio and Sagittarius. The galactic center is located in Sagittarius.

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The history of the discovery of the Galaxy Most of the celestial bodies are combined into various rotating systems. So, the Moon revolves around the Earth, the satellites of the giant planets form their own systems rich in bodies. At a higher level, the Earth and the rest of the planets revolve around the Sun. The question is, is not the Sun also included in some system of an even larger size? The first systematic study of this issue was carried out in the 18th century. English astronomer William Herschel. He counted the number of stars in different regions of the sky and found that there is a large circle in the sky, which was later called the galactic equator, which divides the sky into two equal parts and on which the number of stars is greatest. In addition, the more stars are, the closer the sky is to this circle. Finally it was discovered that it was on this circle that the Milky Way was located. Thanks to this, Herschel guessed that all the stars we observe form a giant star system, which is flattened towards the galactic equator. And yet, the existence of the Galaxy remained in question until objects were discovered outside our star system, in particular, other galaxies.

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William Herschel (Friedrich Wilhelm Herschel, eng. William Herschel; November 15, 1738, Hanover - August 25, 1822, Slough near London) - English astronomer of German origin. One of ten children of the poor musician Isaac Herschel. He entered the military band (as an oboist) and in 1755 as part of the regiment was sent from Hanover to England. In 1757 he left military service to study music. He worked as organist and music teacher in Halifax, then moved to the resort town of Bath, where he became the manager of public concerts. An interest in musical theory led Herschel to mathematics, mathematician to optics, and finally optics to astronomy. In 1773, having no funds to buy a large telescope, he began polishing mirrors and constructing telescopes himself, and later he himself made optical instruments both for his own observations and for sale. The first and most important discovery of Herschel - the discovery of the planet Uranus - occurred on March 13, 1781. Herschel dedicated this discovery to King George III and named Georgium Sidus in his honor (the name was never used); George III, himself a fan of astronomy and patron of the Hanoverians, promoted Herschel to the rank of Astronomer Royal and provided him with the funds to build a separate observatory.

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Thanks to some technical improvements and an increase in the diameter of the mirrors, Herschel was able in 1789 to make the largest telescope of his time (main focal length 12 meters, mirror diameter 49½ inches (126 cm)); in the first month of work with this telescope, Herschel discovered the moons of Saturn, Mimas and Enceladus. Further, Herschel also discovered the moons of Uranus Titania and Oberon. In his works on the satellites of the planets, Herschel was the first to use the term "asteroid" (using it to characterize these satellites, because when observed with Herschel's telescopes, large planets looked like disks, and their satellites looked like points, like stars). 40-foot Herschel telescope

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However, the main works of Herschel are related to stellar astronomy. The study of the proper motion of the stars led him to the discovery of the translational motion of the solar system. He also calculated the coordinates of an imaginary point - the apex of the Sun, in the direction of which this movement takes place. From observations of binary stars undertaken to determine parallaxes, Herschel made an innovative conclusion about the existence of stellar systems (previously it was assumed that binary stars are only randomly located in the sky in such a way that they are nearby when observed). Herschel also observed a lot of nebulae and comets, also compiling detailed descriptions and catalogs (their systematization and preparation for publication was carried out by Caroline Herschel). It is curious that outside of astronomy proper and the areas of physics closest to it, Herschel's scientific views were very bizarre. For example, he believed that all planets are inhabited, that under the hot atmosphere of the Sun there is a dense layer of clouds, and below there is a solid planetary-type surface, etc. Craters on the Moon, Mars and Mimas are named after Herschel, as well as several new astronomical projects.

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Evolution and the future of the Galaxy The history of the origin of galaxies is not yet completely clear. Originally, the Milky Way had much more interstellar matter (mostly in the form of hydrogen and helium) than now, which has been spent and continues to be spent on star formation. There is no reason to believe that this trend will change so that over billions of years further decay of natural star formation should be expected. Currently, stars are formed mainly in the arms. Collisions of the Milky Way with other galaxies are also possible, incl. with such a large galaxy as Andromeda, however, specific predictions are still impossible due to ignorance of the transverse velocity of extragalactic objects. In any case, no scientific model of the evolution of the Galaxy will be able to describe all possible consequences of the development of intelligent life, and therefore the fate of the Galaxy does not seem to be predictable.

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Andromeda Galaxy The Andromeda Galaxy or the Andromeda Nebula (M31, NGC 224) is an Sb spiral galaxy. This closest to the Milky Way, another supergiant galaxy is located in the constellation Andromeda and is distant from us, according to the latest data, at a distance of 772 kiloparsecs (2.52 million light years). The plane of the galaxy is tilted to us at an angle of 15 °, its apparent size is 3.2 °, and its apparent magnitude is + 3.4m. The Andromeda Galaxy has a mass of 1.5 times the Milky Way and is the largest in the Local Group: according to currently available data, the Andromeda Galaxy (Nebula) includes about a trillion stars. It has several dwarf satellites: M32, M110, NGC 185, NGC 147, and possibly others. It spans 260,000 light years, 2.6 times the length of the Milky Way. In the night sky, the Andromeda galaxy can be seen with the naked eye. In area, for an observer from Earth, it is equal to seven full Moons.

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Milky Way Galaxy and Andromeda Galaxy Collision The Milky Way Galaxy and Andromeda Nebula collision is an alleged collision of the two largest galaxies in the local group, the Milky Way and the Andromeda galaxy (M31), in about five billion years. It is often used as an example of this type of phenomenon in collision simulation. As with all such collisions, it is unlikely that objects like the stars contained in each galaxy will actually collide due to the low concentration of matter in galaxies and the extreme distance of objects from each other. For example, the closest star to the Sun (Proxima Centauri) is nearly thirty million solar diameters from Earth (if the Sun were the size of a coin 1 inch in diameter, then the closest coin / star would be 765 kilometers away). If the theory is correct, then the stars and gas of the Andromeda galaxy will be visible to the naked eye in about three billion years. If a collision occurs, the galaxies are likely to merge into one large galaxy.

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At the moment, it is not known exactly whether a collision will occur or not. The radial speed of the Andromeda galaxy relative to the Milky Way can be measured by studying the Doppler shift of spectral lines from the stars of the galaxy, but the transverse speed (or "proper motion") cannot be directly measured. Thus, it is known that the Andromeda galaxy is approaching the Milky Way at a speed of about 120 km / s, but whether a collision will occur or the galaxies will simply disperse, it is still impossible to find out. At the moment, the best indirect measurements of the transverse velocity show that it does not exceed 100 km / s. This suggests that at least the dark matter halos of the two galaxies will collide, even if the disks themselves do not collide. The Gaia Space Telescope, scheduled to be launched by the European Space Agency in 2011, will measure the locations of the stars in the Andromeda galaxy with sufficient accuracy to establish transverse velocity. Frank Summers of the Space Telescope Science Institute has created a computer rendering of the upcoming event based on research by Professor Chris Migos of Case Western Reserve University and Lars Hernqvist of Harvard University. Such collisions are relatively common - Andromeda, for example, has collided in the past with at least one dwarf galaxy, just like our own Galaxy. It is also possible that our solar system will be ejected from a new galaxy during a collision. Such an event will not have negative consequences for our system (especially after the Sun turns into a red giant in 5-6 billion years). The likelihood of any impact on the sun or planets is small. Various names have been proposed for the newly formed galaxy, for example Milkomeda.

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Literature http://ru.wikipedia.org Yu. N. Efremov. Milky Way. Series "Science Today. Physical Encyclopedia, Ed. By A. M. Prokhorov, Art." Galactic Center. T. A. Agekyan, "Stars, Galaxies, Metagalaxy." Chandra X-ray Observatory: http: //chandra.harvard .edu / http://news.cosmoport.com/2006/11/21/3.htm