Presentation on the topic "Our Galaxy. Milky Way"
At the end of 1610, G. Galileo, observing the Milky Way through a telescope, established that it consists of a colossal number of very faint stars; its stellar structure is clearly visible even with ordinary binoculars. The Milky Way stretches like a silver stripe across both hemispheres, closing into a ring of stars. Observations have established that all the stars form a huge star system called the Galaxy (from the Greek word galakikos milky), the vast majority of the stars of which are concentrated in the Milky Way. The solar system is part of the Galaxy.
Gas and dust in the Galaxy are distributed very heterogeneously. In addition to thin dust clouds, dense dark clouds of dust are observed. When these dense clouds are illuminated by bright stars, they reflect their light, and then we see reflection nebulae, like those seen in the Pleiades star cluster. If there is a hot star near the gas and dust cloud, then it excites the glow of the gas, and then we see a diffuse nebula, an example of which is the Orion Nebula. Star cluster Pleiades Orion Nebula
Studies of the distribution of stars, gas and dust have shown that our Milky Way Galaxy is a flat system with a spiral structure. There are about 100 billion stars in the Galaxy. The average distance between stars in the Galaxy is about 5 light years. years. The center of the Galaxy, which is located in the constellation Sagittarius, is hidden from us by a large amount of gas and dust that absorbs the light of stars.
The galaxy is spinning. The Sun, located at a distance of about 8 kpc (light years) from the center of the Galaxy, revolves at a speed of about 220 km/s around the center of the Galaxy, completing one revolution in almost 200 million years. Matter with a mass of about 1011 M is concentrated inside the Sun’s orbit, and the total mass of the Galaxy is estimated at several hundred billion solar masses.
The distribution of stars in the “body” of the Galaxy has two distinct features: firstly, a very high concentration of stars in the galactic plane and very little outside it, and secondly, an extremely high concentration of them in the center of the Galaxy. So, if in the vicinity of the Sun, in the disk, there is one star per 16 cubic parsecs, then in the center of the Galaxy there are stars in one cubic parsec.
Observations of the movement of individual stars near the center of the Galaxy showed that there, in a small region with dimensions comparable to the size of the Solar System, invisible matter is concentrated, the mass of which exceeds the mass of the Sun by 2 million times. This indicates the existence of a massive black hole at the center of the Galaxy.
Arms of a Galaxy Spiral galaxies have arms that extend out from the center, like wheel spokes that twist in a spiral. Our Solar System is located in the central part of one of the arms, which is called the Orion Arm. The Orion Arm was once thought to be a small "offshoot" of larger arms such as the Perseus Arm or the Scutum-Centauri Arm. Not long ago, it was suggested that the Orion arm is indeed a branch of the Perseus arm and does not extend from the center of the galaxy. The problem is that we cannot see our galaxy from the outside. We can only observe those things that are around us, and judge what shape the galaxy has, being, as it were, inside it. However, scientists were able to calculate that this arm is approximately 11 thousand light years long and 3500 light years thick.
The animation demonstrates the real movement of stars around a black hole from 1997 to 2011 in the region of one cubic parsec in the center of our galaxy. When stars approach a black hole, they loop around it at incredible speeds. For example, one of these stars, S0-2, is moving at a speed of 18 million kilometers per hour: the black hole first attracts it and then sharply pushes it away.
Galactic year On Earth, a year is the time during which the Earth manages to make a full revolution around the Sun. Every 365 days we return to the same point. Our solar system revolves in the same way around a black hole located at the center of the galaxy. However, it takes 250 million years to complete a full revolution. That is, since the dinosaurs disappeared, we have only made a quarter of a full revolution. Descriptions of the solar system rarely mention that it moves through 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. To put things into perspective, 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 manages to make a full 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. 21
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The Milky Way is the galaxy that contains the Earth, the solar system, and all the individual stars visible to the naked eye. Refers to barred spiral galaxies. The Milky Way, together with the Andromeda Galaxy (M31), the Triangulum Galaxy (M33), and more than 40 small satellite galaxies of it and Andromeda form the Local Group of galaxies, which is part of the Local Supercluster (Virgo Supercluster).
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Etymology The name Milky Way is a tracing paper from Lat. vialactea “milk road”, which, in turn, is a translation from ancient Greek. ϰύϰλος γαλαξίας “milk circle.” According to ancient Greek legend, Zeus decided to make his son Hercules, born from a mortal woman, immortal, and for this he planted it on his sleeping wife Hera so that Hercules would drink divine milk. Hera, waking up, saw that she was not feeding her child, and pushed him away from her. The stream of milk that splashed from the goddess’s breast turned into the Milky Way. In the Soviet astronomical school, the Milky Way was simply called “our Galaxy” or “the Milky Way system”; The phrase "Milky Way" was used to refer to the visible stars that optically constitute the Milky Way to an observer.
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Structure of the Galaxy The diameter of the Galaxy is about 30 thousand parsecs (about 100,000 light years, 1 quintillion kilometers) with an estimated average thickness of about 1000 light years. The galaxy contains, according to the lowest estimate, about 200 billion stars (modern estimates range from 200 to 400 billion). The bulk of stars are located in the shape of a flat disk. As of January 2009, the mass of the Galaxy is estimated at 3·1012 solar masses, or 6·1042 kg. The new minimum estimate puts the galaxy's mass at just 5·1011 solar masses. Most of the Galaxy's mass is contained not in stars and interstellar gas, but in a non-luminous halo of dark matter.
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Disk Scientists estimate that the galactic disk, which protrudes in different directions in the region of the galactic center, has a diameter of about 100,000 light years. Compared to a halo, the disk rotates noticeably faster. The speed of its rotation is not the same at different distances from the center.
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Core In the middle part of the Galaxy there is a thickening called the bulge, which is about 8 thousand parsecs in diameter. The center of the Galaxy's core 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 (2.62·1017 km, or 27,700 light years). In the center of the Galaxy, there appears to be a supermassive black hole (Sagittarius A*) around which, presumably. The central regions of the Galaxy are characterized by a strong concentration of stars: each cubic parsec near the center contains many thousands of them. The distances between stars are tens and hundreds of times smaller than in the vicinity of the Sun. Like most other galaxies, the distribution of mass in the Milky Way is such that the orbital speed of most stars in this Galaxy does not depend significantly on their distance from the center. Further from the central bridge to the outer circle, the usual speed of rotation of stars is 210-240 km/s. Thus, such a distribution of speed, not observed in the solar system, where different orbits have significantly different speeds of rotation, is one of the prerequisites for the existence of dark matter.
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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 around it is a spherical corona. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy, on the inner edge of the arm called the Orion arm. This arrangement does not make it possible 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 more sleeves in the inner part. These arms then transform into a four-arm structure observed in the neutral hydrogen line in the outer parts of the Galaxy.
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Halo The galactic halo has a spherical shape, extending beyond the galaxy by 5-10 thousand light years, and a temperature of about 5·105 K. The center of symmetry of the Milky Way halo coincides with the center of the galactic disk. The halo consists mainly of very old, dim, low-mass stars. They occur individually and in the form of globular clusters, which can contain up to a million stars. The age of the population of the spherical component of the Galaxy exceeds 12 billion years, it is usually considered to be the age of the Galaxy itself.
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Evolution and future of the Galaxy Collisions of our Galaxy with other galaxies, including such a large one as the Andromeda Galaxy, are possible, but specific predictions are not yet possible due to ignorance of the transverse velocity of extragalactic objects.
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When the evenings become dark in autumn, a wide flickering stripe can be clearly visible in the starry sky. This is the Milky Way - a giant arch spanning the entire sky. The Milky Way is called the "Heavenly River" 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 glow 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 (modern estimates range from 200 to 400 billion) As of January 2009, the mass of the Galaxy is estimated at 3 × 1012 mass of the Sun, or 6×1042 kg. Most of the Galaxy's mass is contained not in stars and interstellar gas, but in a non-luminous halo of dark matter.
In the middle part of the Galaxy there is a thickening called a bulge, which is about 8 thousand parsecs in diameter. In the center of the Galaxy, there appears to be a supermassive black hole (Sagittarius A*), around which a medium-mass black hole is presumably rotating
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) suggest that our Galaxy has two arms starting at a bar in the inner part of the Galaxy. In addition, there are a couple more sleeves in the inner part. These arms then 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 the great circle of the celestial sphere. In the northern hemisphere, the Milky Way crosses the constellations Aquila, Sagittarius, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini; in the south are the Unicorn, the Poop, the Sails, the Southern Cross, the Compass, the Southern Triangle, Scorpio and Sagittarius. The galactic center is located in Sagittarius.
Most celestial bodies are combined into various rotating systems. Thus, 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 the Sun 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 discovered that there was a large circle in the sky (later it was called the galactic equator), which divides the sky into two equal parts and on which the number of stars is greatest. In addition, the closer the part of the sky is to this circle, the more stars there are. 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 observed form a giant star system, which is flattened towards the galactic equator.
The history of the formation of galaxies is not yet entirely clear. Originally, the Milky Way had much more interstellar matter (mostly in the form of hydrogen and helium) than it does now, which was, and continues to be, used up to form stars. There is no reason to believe that this trend will change, so over billions of years we should expect a further decline in natural star formation. Currently, stars are formed mainly in the arms of the Galaxy.
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Introduction The Milky Way Galaxy, also called simply the Galaxy (with a capital letter), is a giant star system that contains, among others, our Sun, all 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 ways. Our Galaxy is one of many other galaxies. The Milky Way is a Hubble SBbc barred spiral galaxy, and together with the Andromeda galaxy M31 and the Triangulum galaxy (M33), as well as several smaller satellite galaxies, it 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 stripe crossing the starry sky almost along a great Circle, the north pole of which is located in the constellation Coma Berenices; consists of a huge number of faint stars, not individually visible to the naked eye, but individually visible 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 perspective when observing from inside a huge, highly 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 strip of the Milky Way with a width of about 5-30° has an appearance of a cloudy structure, due, firstly, to the existence of stellar clouds or condensations in the Galaxy and, secondly, to the uneven distribution of light-absorbing dusty dark nebulae, forming areas with an apparent deficiency of stars from for absorbing their light. In the Northern Hemisphere, the Milky Way passes through the constellations Aquila, Sagittarius, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini. Moving into the Southern Hemisphere, it captures the constellations Monoceros, Puppis, Velae, Southern Cross, Compass, Southern Triangle, Scorpio and Sagittarius. The Milky Way is especially bright in the constellation Sagittarius, which contains the center of our star system and is believed to contain 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 the fall in the evenings. The midline within the Milky Way is the galactic equator.
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Mythology There are many legends telling 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 spilling across the sky from the goddess Hera, who was breastfeeding Hercules. 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 the baby was Zeus himself. Kronos devoured his children because it was foretold that he would be dethroned from the top of the Pantheon by his own son. Rhea hatched 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 breast onto a bare rock later became known as 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. The bulk of stars are located in the shape 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 Galaxy's mass 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 plate or a hat with a brim. Moreover, the galaxy not only bends, but also vibrates like an eardrum.
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Satellites Scientists from the University of California, studying the prevalence of hydrogen in regions 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 dark matter surrounding it. 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 the study Designations LMC, LMC Observational data Type SBm Right ascension 05h 23m 34s Declination −69° 45′ 22″; Redshift 0.00093 Distance 168,000 light. years Visible magnitude 0.9 Visible dimensions 10.75° × 9.17° Constellation Doradus Physical characteristics Radius 10,000 light years 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 in the southern hemisphere in the constellations Doradus 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, a 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 source of active star formation - the Tarantula Nebula.
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Small Magellanic Cloud History of exploration Discoverer Ferdinand Magellan Date of discovery 1521 Designations NGC 292, ESO 29-21, A 0051-73, IRAS00510-7306, IMO, 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) Visible magnitude 2.2 Photographic magnitude 2.8 Visible dimensions 5° × 3° Surface brightness 14.1 Angular position 45° Constellation Toucan Physical characteristics Radius 7000 light. 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 around it is a spherical crown. The solar system is located at a distance of 8.5 thousand parsecs from the galactic center, near the plane of the Galaxy (the offset to the North Pole of the Galaxy is only 10 parsecs), on the inner edge of the arm called the Orion arm. This 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 around it is a spherical corona. In the middle part of the Galaxy there is a thickening called a bulge and is about 8 thousand parsecs in diameter. In the center of the Galaxy there is a small region with unusual properties, where, apparently, a supermassive black hole is located. 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, the radius of which is about 1000 parsecs and the properties of which differ sharply from the properties 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 stellar 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 stellar magnitudes, that is, 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 infrared, x-ray and gamma ray ranges. An image measuring 400 by 900 light years, made up 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 at 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 located there (stellar bulge) 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 semi-axes is approximately 0.4. The orbital speed of stars at a distance of about a kiloparsec is approximately 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. 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 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 arms extend from the cluster, extending to a distance of 3 - 4.5 thousand parsecs. The arms rotate around the galactic center and simultaneously move away to the sides, with a radial speed of about 50 km/s. The kinetic energy of motion is 1055 erg. A gas disk with a radius of about 700 parsecs and a mass of about one hundred million solar masses was discovered inside the cluster. Inside the disk there is a central region of star formation.
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An image made from a dozen Chandra telescope photographs covering an area 130 light-years across.
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Closer to the center is a rotating and expanding ring of molecular hydrogen, the mass of which is about one hundred thousand solar masses, and the radius is about 150 parsecs. The ring's rotation speed is 50 km/s, and its 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 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 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. These clouds contain all kinds of molecular compounds found in space. Even closer to the center is the central dust cloud, with a radius of about 15 parsecs. Flashes of radiation are periodically observed in this cloud, 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 parsecs, 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 such radiation sources have been found anywhere else in the Galaxy, but similar sources exist in the cores of other galaxies.
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From the point of view of models of the evolution of galaxies, their nuclei are the centers of their condensation and initial star formation. The oldest stars should be there. Apparently, at the very center of the galactic core there is a supermassive black hole with a mass of about 3.7 million solar masses, as shown by studying the orbits of nearby stars. The emission of the Sagittarius A* source is caused by the accretion of gas onto a black hole, the radius of the emitting 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 stripe passing approximately along a large circle of the celestial sphere. In the northern hemisphere, the Milky Way crosses the constellations Aquila, Sagittarius, Chanterelle, Cygnus, Cepheus, Cassiopeia, Perseus, Auriga, Taurus and Gemini; in the south - Unicorn, Poop, Sails, Southern Cross, Compasses, Southern Triangle, Scorpio and Sagittarius. The galactic center is located in Sagittarius.
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History of the discovery of the Galaxy Most celestial bodies are combined into various rotating systems. Thus, 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 the Sun also part of some even larger system? 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 discovered that there was 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 closer the part of the sky is to this circle, the more stars there are. 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 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 the boundaries of our star system, in particular other galaxies, were discovered.
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William Herschel (Friedrich Wilhelm Herschel, English 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 service in a military orchestra (oboe player) and in 1755, as part of a regiment, he was sent from Hanover to England. In 1757 he left military service to study music. He worked as an organist and music teacher in Halifax, then moved to the resort town of Bath, where he became a manager of public concerts. Interest in musical theory led Herschel to mathematics, mathematics to optics, and finally optics to astronomy. In 1773, not having the funds to buy a large telescope, he began to grind mirrors and design telescopes himself, and subsequently made optical instruments himself, 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 it Georgium Sidus in his honor (the name never came into use); George III, himself a lover 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 produce the largest telescope of his time (main focal length 12 meters, mirror diameter 49½ inches (126 cm)); in the very first month of working 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 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 points, like stars). 40-foot Herschel telescope
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However, Herschel's main works relate to stellar astronomy. Studying the proper motion of 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 occurs. From observations of double stars undertaken to determine parallaxes, Herschel made an innovative conclusion about the existence of stellar systems (previously it was assumed that double stars were only randomly located in the sky in such a way that they were nearby when observed). Herschel also observed nebulae and comets extensively, also compiling careful descriptions and catalogs (their systematization and preparation for publication was carried out by Caroline Herschel). It is curious that outside of astronomy itself and the fields of physics closest to it, Herschel’s scientific views were very bizarre. He, for example, believed that all planets are inhabited, that under the hot atmosphere of the Sun there is a dense layer of clouds, and below is a solid surface of the planetary type, etc. Craters on the Moon, Mars and Mimas, as well as several new ones, are named after Herschel astronomical projects.
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Evolution and future of the Galaxy The history of the origin of galaxies is not yet entirely clear. Originally, the Milky Way had much more interstellar matter (mostly in the form of hydrogen and helium) than it does now, which was, and continues to be, used up to form stars. There is no reason to believe that this trend will change so that natural star formation should be expected to further decline over billions of years. Currently, stars are formed mainly in the arms. Collisions of the Milky Way with other galaxies are also possible, incl. from as 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 does not seem predictable.
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Andromeda Galaxy The Andromeda Galaxy or Andromeda Nebula (M31, NGC 224) is a Sb-type spiral galaxy. This other supergiant galaxy, closest to the Milky Way, is located in the constellation Andromeda and, according to the latest data, is distant from us 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°, its apparent magnitude is +3.4m. The Andromeda Galaxy has a mass 1.5 times greater than 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 extent 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 area, for an observer from Earth, it is equal to seven full Moons.
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Milky Way and Andromeda Galaxy Collision The Milky Way and Andromeda Galaxy Collision is a proposed collision between the two largest galaxies in the local group, the Milky Way and the Andromeda Galaxy (M31), which will occur in approximately five billion years. 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 such as 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 closest star to the Sun (Proxima Centauri) is almost thirty million solar diameters away from Earth (if the Sun were the size of a 1-inch coin, the nearest coin/star would be 765 kilometers away). If the theory is correct, 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 will most likely merge into one large galaxy.
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At the moment it is not known for sure whether a collision will occur or not. The Andromeda Galaxy's radial velocity relative to the Milky Way can be measured by studying the Doppler shift of spectral lines from the galaxy's stars, but the transverse 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 whether a collision will occur or the galaxies will simply separate cannot yet be determined. At the moment, the best indirect measurements of the transverse speed indicate that it does not exceed 100 km/s. This suggests that at least the dark matter haloes of the two galaxies will collide, even if the disks themselves do not collide. Planned for launch by the European Space Agency in 2011, the Gaia space telescope will measure the locations of stars in the Andromeda Galaxy with sufficient precision to establish transverse velocities. Frank Summers of the Space Telescope Science Institute created a computer visualization 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, collided with at least one dwarf galaxy in the past, as did our Galaxy. It is also possible that our solar system will be thrown out of the new galaxy during the 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 low. 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, 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
amazingly beautiful and bright. There are many brightly glowing star clouds in the constellations Sagittarius, Scorpio, and Scutum. It is in this direction that the center of our Galaxy is located. In this same part of the Milky Way, dark clouds of cosmic dust - dark nebulae - stand out especially clearly. If these dark, opaque nebulae were not present, 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 indistinguishable to the naked eye. But people figured this out a long time 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 first proved the stellar nature of the Milky Way based on telescope observations. In his famous “Starry Messenger” 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 turned out to be possible to make it so accessible to our vision that all disputes fell silent by themselves thanks to the clarity and evidence that I am freed from a long-winded debate. In fact, the Milky Way is nothing more than a countless number of stars, as if located in heaps, no matter what area the telescope is pointed at, a huge number of stars now become visible, many of which are quite bright and quite visible, but the number weaker stars cannot be counted at all.” What relation do the stars of the Milky Way have to the only star in the solar system, our Sun? The answer is now generally known. The Sun is one of the stars of our Galaxy, the Milky Way Galaxy. 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. 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 star counts. The point is that in different parts of the sky the number of stars in a successive interval of stellar magnitudes is counted. If we assume that the luminosities of the stars are the same, then from the observed brightness we can judge the distances to the stars, then, assuming that the stars are evenly distributed in space, we consider the number of stars that are in spherical volumes with the center in the Sun.
