Presentation on the topic "milky way". Presentation on astronomy on the topic "milky way galaxy" The structure of the milky way galaxy presentation

When the evenings turn dark in autumn, a wide shimmering band can be clearly seen in the starry sky. This is the Milky Way - a giant arch thrown across the entire sky. "Heavenly River" is called the Milky Way in Chinese legends. The ancient Greeks and Romans called it the "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 cannot be distinguished individually with the naked eye.

The diameter of the Galaxy is about 30 thousand parsecs (of the order of light years) The Galaxy contains, according to the lowest estimate, about 200 billion stars (modern estimates range 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 nonluminous halo of dark matter.

In the middle part of the Galaxy there is a thickening, which is called the bulge (English bulge thickening), which is about 8 thousand parsecs in diameter. In the center of the Galaxy, apparently, there is a supermassive black hole (Sagittarius A *) around which, presumably, a medium-mass black hole 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. In addition, there are a couple of sleeves in the inner part. These arms then transition into a four-arm structure observed in the line of neutral hydrogen in the outer parts of the Galaxy.

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

Most celestial bodies are combined into various rotating systems. So, the Moon revolves around the Earth, the satellites of the giant planets form their own, rich in bodies, systems. 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 part of 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 areas of the sky and found that there is a large circle in the sky (later it was called the galactic equator), which divides the sky into two equal parts and in which the number of stars is the largest. In addition, there are more stars, the closer the area of the sky is located to this circle. Finally, it was found that the Milky Way is located on this circle. Thanks to this, Herschel guessed that all the stars we observed form a giant star system, which is flattened towards the galactic equator.

The history of the origin of galaxies is still not entirely clear. Initially, the Milky Way had much more interstellar matter (mostly in the form of hydrogen and helium) than it does now, which has been used up and continues to be used up in star formation. There is no reason to believe that this trend will change, so that as billions of years pass, further fading of natural star formation should be expected. At present, stars form mainly in the arms of the galaxy.

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Introduction The Milky Way Galaxy, also simply called the Galaxy (with a capital letter), is a giant star system that contains, among others, our Sun, all the individual stars visible to the naked eye, as well as a huge number of stars that merge together and are observed in the form of a milky way. Our Galaxy is one of many other galaxies. The Milky Way is a Hubble-classified barred SBbc spiral galaxy, and together with the Andromeda Galaxy M31 and the Triangulum Galaxy (M33), as well as several smaller satellite galaxies, forms 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 luminous diffuse whitish band that crosses the starry sky almost along a large Circle, the north pole of which is 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, strongly oblate cluster of stars in our Galaxy by an observer located 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 band of the Milky Way, about 5-30° wide, looks like a cloudy structure, due, firstly, to the existence of stellar clouds or clumps in the Galaxy and, secondly, to the uneven distribution of light-absorbing dusty dark nebulae, which form areas with an apparent shortage of stars due to for absorbing their light. In the Northern Hemisphere, the Milky Way passes through the constellations Aquila, Arrow, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini. Leaving for the Southern Hemisphere, it captures the constellations of Unicorn, Stern, Sails, Southern Cross, Compasses, Southern Triangle, Scorpio and Sagittarius. The Milky Way is especially bright in the constellation Sagittarius, which is the center of our star system, which is believed to include a supermassive black hole. The constellation Sagittarius in northern latitudes does not rise high above the horizon. 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 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 spilled across the sky of the goddess Hera, who was breastfeeding Hercules. When Hera learned 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 hatches a plan to save her sixth son, the 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. The milk spilled from Rhea's chest on a bare rock was subsequently called the Milky Way.

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Structure of the Galaxy Our Galaxy is about 30,000 parsecs across and contains about 100 billion stars. Most of the stars are 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 nonluminous halo of dark matter. The Milky Way has a convex shape - like, for example, a plate or a hat with a brim. Moreover, the galaxy not only bends, but also vibrates like an eardrum.

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Scientists from the University of California, while studying the prevalence of hydrogen in areas subject to distortion, 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 History of research Designations LMC, LMC Observational data Type SBm Right ascension 05h 23m 34s Dec. −69° 45′ 22″; Redshift 0.00093 Distance 168,000 St. years Apparent magnitude 0.9 Apparent dimensions 10.75° × 9.17° Constellation Golden Fish Physical characteristics Radius 10,000 sv. years Properties The brightest satellite of the Milky Way

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The Large Magellanic Cloud (LMC, LMC) is an SBm-type dwarf galaxy located at a distance of about 50 kiloparsecs from our Galaxy. It occupies the region of the sky of the southern hemisphere in the constellations of the Dorado 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 our galaxy), while the Small Magellanic Cloud contains only 1.5 billion stars. Supernova SN 1987A erupted in the Large Magellanic Cloud in 1987. This is the closest supernova to us since SN 1604. The LMC contains a well-known hotbed of active star formation - the Tarantula Nebula.

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Small Magellanic Cloud Exploration history Discoverer Ferdinand 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 St. years (61,000 parsecs) Apparent magnitude 2.2 Photographic magnitude 2.8 Apparent dimensions 5° × 3° Surface brightness 14.1 Angular position 45° Constellation Toucan Physical characteristics Radius 7000 sv. years Absolute magnitude −16.2 Properties Satellites 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 lie 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 called the Orion arm. This position of ours makes it impossible to observe the shape of the sleeves visually.

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The Disk's core is immersed in a spherical halo, and a spherical crown is located around it. In the middle part of the Galaxy there is a thickening, which is called the bulge and is about 8 thousand parsecs in diameter. At the center of the Galaxy is a small region with unusual properties, where, apparently, there is a supermassive black hole. The center of the galactic core is projected onto the constellation Sagittarius (α = 265°, δ = −29°). The distance to the center of the Galaxy is 8.5 kiloparsecs (2.62 1022 cm, or 27,700 light years).

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The Galactic Center is a relatively small region in the center of our Galaxy, with a radius of about 1000 parsecs and whose properties differ sharply from those of its other parts. Figuratively speaking, the galactic center is a cosmic “laboratory”, in which star formation processes 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, by 1012 times. Therefore, the center is invisible in the optical range - with the naked eye and with the help of optical telescopes. The galactic center is observed in the radio range, as well as in the ranges of infrared, x-rays and gamma rays. A 400 by 900 light-year image, composed of several photographs from the Chandra telescope, of hundreds of white dwarfs, neutron stars and black holes, in clouds of million-degree hot gas. Inside the bright spot in the center of the image is a 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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The composition of the galactic center The largest feature of the galactic center is the star cluster (stellar bulge) located there in the form of an ellipsoid of revolution, the major semi-axis of which lies in the plane of the Galaxy, and the minor semi-axis lies on its axis. The ratio of the semiaxes is approximately 0.4. The orbital speed of stars at a distance of about a kiloparsec is approximately 270 km/s, and the period of revolution 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. Stellar density varies roughly with R-1.8 (R is the distance from the center). At a distance of about a kiloparsec, it is several solar masses per cubic parsec, in the center - more than 300 thousand solar masses per cubic parsec (for comparison, in the vicinity of the Sun, the stellar density is about 0.07 solar masses per cubic parsec). Spiral gas sleeves depart from the cluster, extending for a distance of up to 3 - 4.5 thousand parsecs. The arms rotate around the galactic center and simultaneously recede to the sides, with a radial velocity of about 50 km/s. The kinetic energy of motion is 1055 erg. Inside the cluster, a gas disk with a radius of about 700 parsecs and a mass of about one hundred million solar masses was found. Inside the disk is a central region of star formation.

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An image composed of a dozen photographs from 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, with a mass of about one hundred thousand solar masses and a radius of about 150 parsecs. The ring's rotation speed is 50 km/s, and the expansion speed is 140 km/s. The plane of rotation is inclined to the plane of the Galaxy by 10 degrees. In all likelihood, the radial motions 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 gas and dust clouds. The largest cloud is the Sagittarius B2 complex, located at a distance of 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 have been found in these clouds. Even closer to the center is the central dust cloud, with a radius of about 15 parsecs. In this cloud, flashes of radiation are periodically observed, the nature of which is unknown, but which indicate active processes occurring 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 is apparently of a synchrotron nature. At times, rapid changes in the radiation flux are observed. Nowhere else in the Galaxy have such sources of radiation been found, but similar sources are found in the nuclei of other galaxies.

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From the point of view of galaxy evolution models, their cores are the centers of their condensation and initial star formation. The oldest stars should be there. Apparently, in the very center of the core of the Galaxy is a supermassive black hole with a mass of about 3.7 million solar masses, as shown by the study of the orbits of nearby stars. The radiation of the Sagittarius A* source is caused by gas accretion onto a black hole, the radius of the radiating region (accretion disk, jets) is no more than 45 AU. The galactic center of the Milky Way in infrared.

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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 band, passing approximately along the great circle of the celestial sphere. In the northern hemisphere, the Milky Way crosses the constellations Aquila, Arrow, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini; in the south - Unicorn, Stern, Sails, Southern Cross, Compasses, Southern Triangle, Scorpio and Sagittarius. The galactic center is 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, rich in bodies, systems. At a higher level, the Earth and the rest of the planets revolve around the Sun. The question is, is not the Sun included in some system of 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 areas 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 in which the number of stars is the largest. In addition, there are more stars, the closer the area of the sky is located 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 observed form a giant star system, which is flattened towards the galactic equator. And yet, the existence of the Galaxy remained in question until objects beyond our star system were discovered, in particular, other galaxies.

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William Herschel (Friedrich Wilhelm Herschel, English William Herschel; November 15, 1738, Hanover - August 25, 1822, Slough near London) was an English astronomer of German origin. One of ten children of the poor musician Isaac Herschel. He entered the service in a military band (oboe player) and in 1755 was sent from Hanover to England as part of a regiment. In 1757, he left military service in order to study music. He worked as an organist and music teacher in Halifax, then moved to the resort town of Bath, where he became the manager of public concerts. Interest in musical theory led Herschel to mathematics, mathematics to optics, and finally optics to astronomy. In 1773, having no funds to buy a large telescope, he began to grind mirrors and construct telescopes himself, and later he himself made optical instruments both for his own observations and for sale. Herschel's first and most important discovery - 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 never came into use); George III, himself an amateur astronomer and patron of the Hanoverians, promoted Herschel to the rank of Royal Astronomer and provided him with 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 Saturn's satellites Mimas and Enceladus. Further, Herschel also discovered the satellites of Uranus Titania and Oberon. In his works on the satellites of the planets, Herschel first used the term "asteroid" (using it to characterize these satellites, because when observed by Herschel's telescopes, large planets looked like disks, and their satellites looked like dots, like stars). 40-foot Herschel Telescope

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Herschel's main work, however, relates to stellar astronomy. The study of the proper motion of the stars led him to the discovery of the forward 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 occurs. 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 were only randomly located in the sky in such a way that they were observed side by side). Herschel also made extensive observations of nebulae and comets, also compiling meticulous descriptions and catalogs (these were systematized and prepared for publication 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 - a solid surface of a planetary type, etc. Craters on the Moon, Mars and Mimas, as well as several newest astronomical projects.

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Evolution and the future of the Galaxy The history of the emergence of galaxies is still not quite clear. Initially, the Milky Way had much more interstellar matter (mostly in the form of hydrogen and helium) than it does now, which has been used up and continues to be used up in star formation. There is no reason to believe that this trend will change so that with the passage of billions of years a further fading 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 as the Andromeda galaxy, however, specific predictions are not yet possible 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 is not predictable.

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

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Milky Way and Andromeda Collision The Milky Way and Andromeda Collision is an estimated collision between the two largest galaxies in the local group, the Milky Way and the Andromeda Galaxy (M31), about five billion years from now. It is often used as an example of this type of phenomenon in collision simulations. 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 the galaxies and the extreme distance of the objects from each other. For example, the nearest star to the Sun (Proxima Centauri) is at a distance of almost thirty million solar diameters from the Earth (if the Sun were the size of a coin with a diameter of 1 inch, then the nearest coin/star would be at a distance of 765 kilometers). 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, then the galaxies will most likely 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 velocity of the Andromeda galaxy relative to the Milky Way can be measured by studying the Doppler shift of spectral lines from the galaxy's stars, but the lateral velocity (or "proper motion") cannot be measured directly. Thus, it is known that the Andromeda galaxy is approaching the Milky Way at a speed of about 120 km / s, but it is not yet possible to find out whether a collision will occur or whether the galaxies will simply disperse. At the moment, the best indirect measurements of the lateral 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. Planned to be launched by the European Space Agency in 2011, the Gaia space telescope will measure the positions of the stars in the Andromeda galaxy with sufficient accuracy to determine the transverse velocity. Frank Summers of the Space Telescope Science Institute created a computer rendering of the upcoming event based on research by Professor Chris Migos of Case Western Reserve University and Lars Hernquist of Harvard University. Such collisions are relatively common - Andromeda, for example, has collided with at least one dwarf galaxy in the past, just like our galaxy. It is also possible that our solar system will be ejected from the new galaxy during a collision. Such an event would 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 low. Various names have been proposed for the newly formed galaxy, such as Milkomeda.

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References http://ru.wikipedia.org Yu. N. Efremov. Milky Way. Series "Science Today". Physical encyclopedia, edited by A. M. Prokhorov, article "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

On Earth, a year is the time it takes the Earth to complete one revolution around the Sun. Every 365 days we return to the same point. Our solar system revolves around the black hole at the center of the galaxy in the same way. However, it makes a complete revolution in 250 million years. That is, since the dinosaurs disappeared, we have made only a quarter of a complete revolution. In descriptions of the solar system, it is rarely mentioned that it moves in outer space, like everything else in our world. Relative to the center of the Milky Way, the solar system moves at a speed of 792 thousand kilometers per hour. For comparison: if you were moving at the same speed, you could travel around the world in 3 minutes. The period of time during which the Sun has time to make a complete revolution around the center of the Milky Way is called the galactic year. It is estimated that the Sun has lived only 18 galactic years so far.

The work was done by a student of 7 (11) -B class of the Pervomaisky gymnasium Klimenko Daria

Our Galaxy - the star system in which the solar system is immersed, is called the Milky Way. The Milky Way is a grandiose cluster of stars visible in the sky as a bright hazy band.
In our Galaxy - the Milky Way - there are more than 200 billion stars of various luminosities and colors.
OUR GALAXY IS THE MILKY WAY

THE MILKY WAY, the hazy glow in the night sky from the billions of stars in our Galaxy. The band of the Milky Way surrounds the sky with 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 constellation Cygnus is near the zenith. As we follow the Milky Way's twinkling band to the north or northeast, we pass the constellation Cassiopeia (in the shape of a W) and move towards the bright star Capella. Beyond Capella, you can see how the less wide and bright part of the Milky Way passes just east of Orion's Belt and leans towards the horizon not far from Sirius, the brightest star in the sky. The brightest part of the Milky Way is visible to the south or southwest when 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 below the magnificent constellations Sagittarius and Scorpio are visible.

What is the galaxy made of?
In 1609, when the great Italian Galileo Galilei was the first to point a telescope into the sky, he immediately made a great discovery: he figured out what the Milky Way was. Using a primitive telescope, Galileo managed to separate the brightest clouds of the Milky Way into individual stars. But behind them, he discovered new, dimmer clouds, the riddle of which he could no longer solve with his primitive telescope. But Galileo correctly concluded that these faintly luminous clouds, visible in his telescope, must also consist of stars.
The Milky Way, which we call our Galaxy, is actually made up of about 200 billion stars. And the Sun with its planets is only one of them. At the same time, our solar system is not located in the center of the Milky Way, but is removed from it by about two-thirds of its radius. We live on the outskirts of our Galaxy.
The Horsehead Nebula is a cold cloud of gas and dust that obscures the stars and galaxies behind it.

The Milky Way encircles the celestial sphere in a large circle. The inhabitants of the Northern Hemisphere of the Earth, in the autumn evenings, manage to see that part of the Milky Way, which 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 extends from the constellation Sagittarius to the constellations Scorpio, Circulus, Centaurus, Southern Cross, Carina, Arrow.

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 spilled across the sky of the goddess Hera, who was breastfeeding Hercules. When Hera learned 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 hatches a plan to save her sixth son, the 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. The milk spilled from Rhea's chest on a bare rock was subsequently called the Milky Way.
Legend…

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 stars of various types, 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 about 100,000 across and about 12,000 light-years thick. A smaller part fills an almost spherical volume with a radius of about 50,000 light years. All components of the Galaxy are connected into a single dynamic system rotating around a minor axis of symmetry. The center of the System is in the direction of the constellation Sagittarius.

Heart of the Milky Way
Scientists have managed to look at the heart of our galaxy. Using the Chandra Space Telescope, a mosaic image was compiled that covers a distance of 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. As stars die, they leave clouds of gas and dust that are squeezed out of the center and, cooling, move to the outer regions of the galaxy. This cosmic dust contains the whole range of elements, including those that are the builders of our body. So we are literally made of stellar ash.

There are many space objects that we can see - these are stars, nebulae, planets. But most of the universe is invisible. For example, black holes. A black hole is the core of a massive star, the density and attraction of which after a supernova explosion have increased so much that even light does not escape from its surface. Therefore, no one has yet been able to see black holes. These objects are still being studied by theoretical astronomy. However, many scientists are convinced that black holes exist. They believe that there are more than 100 million of them in our Galaxy alone, and each of them is the remnant of a giant star that exploded in the distant past. The mass of a black hole must be colossal, many times greater than the mass of the Sun, since it absorbs everything that is nearby: both interstellar gas and any other cosmic matter. According to astronomers, most of the mass of the universe is hidden in black holes. Until now, their existence is evidenced only by X-ray radiation observed in some places in space, where nothing can be seen either in an optical or in a radio telescope.
What is a black hole?

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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. At the same time, 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 in the shape of a circle. In the center of it, the stars are denser and form a huge dense cluster. The outer borders of the circle are visibly smoothed and become thinner at the edges. When viewed from the side, the Milky Way probably resembles the planet Saturn with its rings.

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Gaseous nebulae It was later discovered that the Milky Way is composed not only of stars, but of gas and dust clouds, which swirl rather slowly and erratically. However, in this case, gas clouds are located only inside the disk. Some gaseous nebulae glow with multicolored light. One of the most famous is the nebula in the constellation Orion, which is visible even to the naked eye. Today we know that such gaseous or diffuse nebulae serve as a cradle for young stars.

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The Milky Way, passing through the starry scattering of the southern hemisphere, is surprisingly beautiful and bright. In the constellations of Sagittarius, Scorpio, Scutum, 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 were not for these dark, opaque nebulae, then the Milky Way towards the center of the Galaxy would be a thousand times brighter. Looking at the Milky Way, it is not easy to imagine that it consists of many stars that are indistinguishable to the naked eye. But people have known this for a long time. 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 first proved the stellar nature of the Milky Way based on telescope observations. In his famous "Starry Herald" in 1609, Galileo wrote: "I turned to the observation of the essence or substance 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 were silent by themselves due to the visibility and evidence, which and I am relieved of a verbose dispute. In fact, the Milky Way is nothing but an innumerable multitude of stars, as if arranged in heaps, no matter where the telescope is directed, a huge number of stars immediately become visible, of which very many are quite bright and quite distinguishable, the number of weaker stars does not allow any calculation at all. What is the relation of the stars of the Milky Way to the only star in the solar system, to our Sun? The answer is now public knowledge. The Sun is one of the stars in our Galaxy, the Galaxy is the Milky Way. What is the position of the Sun 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. In order 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 counts. 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 used to judge the distances to the stars, then, assuming that the stars are evenly spaced in space, they consider the number of stars that are in spherical volumes centered on the Sun.

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Hot Stars in the Southern Milky Way Hot blue stars, brightly glowing red hydrogen, and dark, eclipsing dust clouds are scattered across this spectacular 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 hydrogen clouds where star formation is taking place, causing the line's characteristic red glow. A small cluster of nascent stars can be seen to the right, against 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 a study of the central region of the Milky Way. The Milky Way is an ordinary 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 center of the galaxy. Since infrared light is less absorbed by gas and dust, the Diffuse InfraRed Background Experiment (DIRBE) aboard the COBE Cosmic Background Survey satellite detects this radiation from 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 lies a black hole with a mass more than two million times that of the Sun. This was previously a controversial statement, but now this startling conclusion is almost beyond doubt. It is based on the results of observations of stars orbiting the center of the Galaxy very close to it. Using one of the Paranal Observatory's Very Large Telescopes and NACO's advanced infrared camera, astronomers patiently tracked the orbit of one of the stars, designated S2, as it approached the center of the Milky Way at a distance of about 17 light hours (17 light hours is only three times the radius of the orbit). Pluto). Their results conclusively show that S2 is moving under the colossal gravitational pull of an invisible object that should be exceptionally compact - a supermassive black hole. This deep near-infrared image from NACO shows a 2-light-year star-filled region at the center of the Milky Way, the exact position of the center marked with arrows. Thanks to the NACO camera's ability to track stars so close to the center of the galaxy, astronomers can observe the star's orbit around the supermassive black hole. This allows us to accurately determine the mass of a 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 nucleus surrounding a giant black hole. The Milky Way's bright central bulge is currently thought to be an asymmetric bar of relatively old red stars. In the outer regions are spiral arms, their appearance due to open clusters of young, bright blue stars, red emission nebulae and dark dust. Spiral arms are located in a disk, the bulk of the mass of which is made up of relatively faint stars and rarefied gas - mostly hydrogen. The figure does not show a huge spherical halo of invisible dark matter, which makes up most of the mass of the Milky Way and determines the movement of stars away from its center.

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THE MILKY WAY WERE COLLISION WITH ANOTHER GALAXY Recent studies by astronomers suggest that billions of years ago our Milky Way galaxy collided with another, smaller galaxy, 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 concluded that their trajectory, as well as their relative positions, may be evidence of such a collision. "The Milky Way is a large galaxy and we believe it was formed from the merger of several smaller ones," said Rosemary Wyse of Johns Hopkins University. Whis and her colleagues in the UK and Australia have been observing the outer regions of the Milky Way, believing that this is where collision traces may be present. Preliminary analysis of the research results confirmed their assumption, and an advanced search (scientists expect to study about 10 thousand stars) will make it possible to establish this with accuracy. Collisions that have taken place 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 nearest 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 spilled across the sky of the goddess Hera, who was breastfeeding Hercules. When Hera learned 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 hatches a plan to save her sixth son, the 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. The milk spilled from Rhea's chest on a bare rock was subsequently called the Milky Way.

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Supercomputer (part 1) One of the fastest computers in the world was designed specifically to simulate 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 GravitySimulator (simulator of gravitational interaction), designed by David Merit (David Merritt) of the Rochester Institute of Technology (RIT), New York. It implements a new technology - performance gains were achieved through the use of special Gravity Pipelines acceleration boards. With the achievement of productivity 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 $500,000. According to Universe Today, GravitySimulator is designed to solve the classical problem of N-body gravitational interaction. Productivity in 4 trillion. operations per second makes it possible 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, with the help of standard computers, it was possible to simulate the gravitational interaction of no more than a few thousand stars at the same time. With the installation of a supercomputer at RIT this spring, Merit and his collaborators have for the first time been able to model the close pair of black holes that form when two galaxies merge.

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Supercomputer (part 2) “It is known that in the center of most galaxies there is a black hole,” Dr. Merit explains the essence of the problem. - When galaxies merge, one larger black hole is formed. The merging process itself is accompanied by the absorption and simultaneous ejection of stars located in the immediate vicinity of the center of galaxies. Observations of nearby interacting galaxies seem to confirm the theoretical models. However, until now, the available power of computers has not made it possible to build a numerical model to test the theory. We succeeded for the first time." The next task 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 at the center of our own galaxy. Dr. Merit believes that, in addition to solving particular large-scale problems in the field of astronomy, the installation of one of the most powerful computers in the world will make the Rochester Institute of Technology a leader in other areas of science. The most powerful supercomputer for the second year has been BlueGene / L, created by IBM and installed in the Lawrence Laboratory in Livermore, USA. Currently, it 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 stars of various types, 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 about 100,000 across and about 12,000 light-years thick. A smaller part fills an almost spherical volume with a radius of about 50,000 light years. All components of the Galaxy are connected into a single dynamic system rotating around a 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 using radioisotopes The age of the Galaxy (and, generally speaking, the Universe) was tried to be determined in a way similar to that used by archaeologists. Nicholas Daufas from the University of Chicago suggested comparing the content of various radioisotopes on 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 evaluation: their half-lives are comparable to the time that has passed since the Big Bang. If you know the exact ratio of their quantities at the beginning, then it is easy to estimate how much time has passed by the current concentrations. From the spectrum of one old star, which is located on the border of the Milky Way, astronomers were able to find out how much thorium and uranium is contained in it. The problem was that the star's original composition is unknown. Daufas had to turn to information about meteorites. Their age (about 4.5 billion years) is known with sufficient accuracy and is comparable with the age of the solar system, and the content of heavy elements at the time of formation was the same as that of the solar matter. Considering the Sun an "averaged" 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 approximately 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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Heart of the Milky Way Scientists have managed to look at the heart of our galaxy. Using the Chandra Space Telescope, a mosaic image was compiled that covers a distance of 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. As stars die, they leave clouds of gas and dust that are squeezed out of the center and, cooling, move to the outer regions of the galaxy. This cosmic dust contains the whole range of elements, including those that are the builders of our body. So we are literally made of stellar ash.

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The Milky Way found four more satellites Five centuries ago, in August 1519, the Portuguese admiral Fernando Magellan set off 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 had no idea about the true origin of these ghostly concentrations, 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 comes to us for 170 thousand years, and from the Small one - 200 thousand years, and they themselves are a vast 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, with the last 10 satellites discovered within two years! The next step in the search for new members of the Milky Way family was made possible by observations from the Sloan Digital Sky Survey (SDSS). More recently, scientists have found four new satellites on SDSS images, distant from Earth at distances from 100 to 500 thousand light years. They are located in the sky in the direction of the constellations Coma Berenices, Hounds of the Dogs, Hercules and Leo. Among astronomers, dwarf galaxies revolving around the center of our star system (having 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 Veronica's Hair, Hounds II, Hercules, and Leo IV. This means that the second such galaxy has already been discovered in the constellation Canis Hounds, and the fourth in the constellation Leo. The largest representative of this group is Hercules, which is 1000 light years across, and the smallest is Veronica's Coma (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 a Russian scientist Vasily Belokurov.

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Such relatively small star systems can be attributed more to large star globular clusters than to galaxies, so scientists are thinking of applying a new term to such objects - "hobbits" (hobbits, or little gnomes). The name of a 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, since their brilliance is extremely weak. Other clusters of stars help them hide, creating an extra background for radiation receivers. Only the peculiarity of dwarf galaxies to contain in their composition stars that are characteristic only for this type of objects helps out. Therefore, after finding the necessary stellar associations in the images, it remains only to make sure of their true location in the sky. Still, a sufficiently large number of such objects raises new questions for supporters of the so-called "warm" dark matter, the movement of which is faster than in the framework of the theory of "cold" invisible substance. The formation of dwarf galaxies, rather, is possible with a slow motion of matter, which better ensures the merging of gravitational "lumps" and, as a result, 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 these objects receive such close attention. In addition, according to modern cosmological views, prototypes of future giant star systems “grow” from dwarf galaxies in the process of merging. Thanks to recent discoveries, we are learning more and more about the periphery in the general sense of the word. The periphery of the solar system makes itself felt with new objects of the Kuiper belt, the neighborhood of our Galaxy, as we see, is also not empty. Finally, the outskirts of the observable universe have become even more famous: at a distance of 11 billion light years, the most distant cluster of galaxies has been discovered. But more on that in the next post.

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