This presentation is intended for teachers of speech therapy groups on the topic "Acquaintance with space." The concept of the Milky Way, stars and constellations is given, how to find the North Star, what the sun is and its distinctive features from all stars, and also poems about stars and constellations are given.
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Constellations and stars Rozhkova Lidiya Nikolaevna as a teacher at GBDOU No. 58, St. Petersburg
On a cloudless, dark night you can see a light, silvery stripe in the sky - this is the Milky Way. All the stars and constellations are here. They form a system called the Galaxy. Our solar system is also located in the Milky Way. Don't forget to look into the sky to see the Milky Way. But we won’t get anywhere along this path. There are simply too many stars there, As if the road of the Firmament stretches across, The most beautiful roads of all!
Stars are burning luminous celestial bodies. Stars vary in temperature, size and brightness.
Constellations Ursa Major and Ursa Minor Among the stars in the sky Bears roam at night. The Big Dipper has a ladle in its paws; Take a closer look on a dark night - You will see your daughter nearby. What is this pair of starry bears doing over the roof?
Ursa Major is a large constellation in the sky. The seven bright stars of Ursa Major form a shape resembling a ladle. Each star of this bucket has a name.
Ursa Minor The constellation Ursa Minor is also called the Little Dipper. This dipper is much smaller than the dipper of the Big Dipper, and is less visible from Earth. The brightest star in the constellation Ursa Minor is Polaris. She is the last one in the handle of the Small Bucket.
Polaris is the brightest star in the constellation Ursa Minor. It is located near the North Pole and does not change its position. The star always points north. polar Star
How to find the North Star? To find it, you must first find the constellation Ursa Major. Then mentally draw a line upward through the two stars of the “wall” of the Bucket, opposite the “handle”. If we plot on this line the Five distances between the stars of the “wall” of the bucket, then we will find the North Star.
Cape Polar Star We won’t get lost with you - After all, it’s like a beacon for us. Traveler, sailor And cheerful tourists will find their way quickly with her. Lost - no food, quickly look for that star. In the darkest thicket, even the North will show us!
Sun A typical star that seems huge to us. but this is because it is located closer to the Earth than other large stars. The Sun is the only star that can be seen during the day. But you can't look directly at the sun. The sun gives us light and warmth, this is life. All the planets in the solar system move around the sun.
Sun Well, well, wow! Our Sun is just a star. The red-hot red ball will immediately turn into steam, If you come close, And you won’t find any traces here. But we can’t live without the Sun, it gives life, friends. It shines and warms, and can be very affectionate. He sits as if on a throne, wearing his golden crown!
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What is a star? They rose above the dinosaurs, above the great glaciation, above the Egyptian pyramids under construction. The same stars showed the way to the Phoenician sailors and Columbus's caravels, and contemplated the Hundred Years' War and the explosion of a nuclear bomb in Hiroshima from above. Some people saw in them the eyes of the gods and the gods themselves, others saw them as silver nails driven into the crystal dome of heaven, and others saw them as holes through which heavenly light streamed.
“This cosmos, the same for everyone, was not created by any of the gods, none of the people, but it always was, is and will be an eternally living fire, gradually flaring up, gradually dying out.” (Heraclitus of Ephesus) Heraclitus of Ephesus (born around BC, death unknown)
We are lucky - we live in a relatively calm region of the Universe. Perhaps it is precisely because of this that life on Earth arose and has existed for such a huge (by human standards) period of time. But from the point of view of star research, this fact causes a feeling of disappointment. For many parsecs around there are only dim and inexpressive luminaries, like our Sun. And all the rare types of stars are very far away. Apparently, this is why the diversity of the stellar world remained hidden from the human eye for so long.
The main characteristics of a star are its radiation power, mass, radius, temperature and chemical composition of the atmosphere. Knowing these parameters, you can calculate the age of the star. These parameters vary within very wide limits. Moreover, they are interconnected. The stars with the highest luminosity have the greatest mass, and vice versa.
Taking measurements from the stars. Shine The first thing a person notices when observing the night sky is the different brightness of the stars. The apparent brightness of stars is estimated in magnitude. Visible gloss is an easily measured, important, but far from exhaustive characteristic. In order to determine the radiation power of a star—the luminosity—you need to know the distance to it.
Distances to stars The distance to a distant object can be determined without physically reaching it. It is necessary to measure the directions to this object from the two ends of a known segment (basis), and then calculate the dimensions of the triangle formed by the ends of the segment and the distant object. This can be done because a triangle has one side (the base) and two adjacent angles. When making measurements on Earth, this method is called triangulation.
The larger the basis, the more accurate the measurement result. The distances to the stars are large, so the length of the basis must exceed the size of the globe, otherwise the measurement error will be greater than the measured value. If you make two observations of the same star with an interval of several months, it turns out that he is viewing it from different points of the earth's orbit - and this is already a decent basis.
The direction towards the star will change: it will shift slightly against the background of more distant stars and galaxies. This displacement is called parallax, and the angle by which the star has shifted on the celestial sphere is called parallax. From geometric considerations it is clear that it is exactly equal to the angle at which these two points of the earth’s orbit would be visible from the side of the star, and depends both on the distance between the points and on their orientation in space.
Luminosity When the distances to bright stars were measured, it became obvious that many of them were significantly more luminous than the Sun. If the luminosity of the Sun is taken as unity, then, for example, the radiation power of the 4 brightest stars in the sky, expressed in luminosities of the Sun, will be: Sirius 22L Canopus 4700L Arcturus 107L Vega 50L
Color and Temperature One of the easily measured characteristics of stars is color. Just as hot metal changes its color depending on the degree of heating, so the color of a star always indicates its temperature. In astronomy, an absolute temperature scale is used, the step of which is one kelvin - the same as in the Celsius scale we are used to, and the beginning of the scale is shifted by -273.
Harvard spectral classification Spectral class Effective temperature, K Color O Blue B White-blue B White F Yellow-white G Yellow K Orange M Red
The hottest stars are always blue and white, the less hot ones are yellowish, and the coolest ones are reddish. But even the coldest stars have a temperature of 2-3 thousand Kelvin - hotter than any molten metal. O - hypergiants (stars of the highest luminosity); Ia bright supergiants; Ib - weaker supergiants; II bright giants; III normal giants; IV subgiants; V dwarfs (main sequence stars).
Sizes of stars How to find out the size of a star? The Moon comes to the aid of astronomers. It moves slowly against the background of stars, one by one “blocking” the light coming from them. Although the angular size of the star is extremely small, the Moon does not obscure it immediately, but over a period of several hundredths or thousandths of a second. The angular size of the star is determined by the duration of the process of decreasing the brightness of a star when it is covered by the Moon. And knowing the distance to the star, it is easy to obtain its true size from the angular size.
The measurements showed that the smallest stars observed in optical rays - the so-called white dwarfs - have a diameter of several thousand kilometers. The sizes of the largest ones - red supergiants - are such that if it were possible to place such a star in the place of the Sun, most of the planets of the Solar system would be inside it.
Mass of a star The most important characteristic of a star is its mass. The more matter gathered into a star, the higher the pressure and temperature in its center, and this determines almost all other characteristics of the star, as well as the features of its life path. Direct estimates of mass can only be made based on the law of universal gravitation
By analyzing the most important characteristics of stars, comparing them with each other, scientists were able to establish what is inaccessible to direct observations: how stars are structured, how they form and change during their lives, what they turn into when they waste their energy reserves.
Equilibrium in a star. The gravity of the upper layers is balanced by gas pressure, which increases from the periphery to the center. The graph shows the dependence of pressure (p) on the distance to the center (R). Stars will not remain forever the same as we see them now. New stars are constantly being born in the Universe, and old ones are dying.
A star emits energy generated in its depths. The temperature in a star is distributed in such a way that in any layer at any moment in time the energy received from the underlying layer is equal to the energy given to the overlying layer. As much energy is generated in the center of the star, the same amount must be emitted from its surface, otherwise the balance will be disrupted. Thus, radiation pressure is also added to the gas pressure.
Hertzsprung-Russell diagram At the end of the 19th - beginning of the 20th century. Astronomy included photographic methods for quantifying the apparent brightness of stars and their color characteristics. In 1913, American astronomer Henry Russell compared the luminosity of various stars with their spectral types. On the spectrum-luminosity diagram he plotted all the stars with distances known at that time.
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British Celebrities Queen of Great Britain
Elizabeth II
Queen Victoria - MOTHER OF QUEEN ELIZABETH THE SECOND
ELIZABETH THE SECOND WITH PARENTS ELIZABETH THE SECOND IN CHILDHOOD WITH MOTHER AND SISTER ELIZABETH THE SECOND WITH PARENTS AND SISTER Queen Elizabeth II was born on April 21, 1926 in London.
Queen Elizabeth ascended to the throne on February 6, 1952, following the death of her father, George the Sixth. The coronation took place on June 2, 1953 in Westminster Abbey. She was only 25 years old when she became queen
ELIZABETH THE SECOND DURING THE WEDDING CEREMONY
BUCKINGHAM PALACE – RESIDENCE OF QUEEN ELIZABETH 2
VIEW OF BUCKINGHAM PALACE FROM THE MALL STREET IN AUTUMN
The title of Her Royal Majesty in the United Kingdom is: "Elizabeth the Second, by the Grace of God Queen of the United Kingdom of Great Britain and Northern Ireland and her other Domains and Territories, Head of the Commonwealth, Defender of the Faith."
Queen Elizabeth 2 of England is a beautiful and charming woman. Now, at her advanced age, she looks great.
The Monarch's Birthday in Great Britain For many years now, her birthday has been celebrated throughout the United Kingdom twice a year: not only on April 21, but also on the 3rd Saturday in June.
On the second Saturday of June, the birthday of the English monarch is officially celebrated. In honor of this solemn event, national flags are flown on all government buildings. On this day, a ceremonial parade takes place at the residence of the British kings in Whitehall. The main content of the ceremony is the removal of the banner or, as it is also called, the ceremonial raising of the guards with the removal of the banner. The banner of the Guards Regiment, which performs guard duty at Buckingham Palace, is brought out to meet the monarch.
The regiment's banner is a dark red panel with an image of a crown and yellow ribbons sewn onto it indicating the battles and battles in which the regiment's military personnel took part.
The ceremony dates back to the 18th century, when banners were carried in front of the soldiers of the regiment. Since 1748, it has taken place on the official birthday of the monarch, and the troops passing by parade salute the Queen as she greets them.
London's most colorful ceremonial event, the Queen's Birthday Parade, is called TROOPING THE COLOR.
This is a bright and colorful sight
Specially trained units of the Royal Horse Guards, in the presence of members of the royal family, invited guests and crowds of curious people, march solemnly with banners along the Horse Guards parade ground.
Then the entire parade, led by the royal carriage, along the Mall, decorated in honor of the parade, heads to Buckingham Palace, where the Queen again receives a salute from the guards returning to their barracks on a specially erected platform.
ELIZABETH THE SECOND AT THE PARADE
From a photo album of the royal family
Stars
Slides: 19 Words: 2104 Sounds: 1 Effects: 82Stars are mysterious bodies. The starry world around us is surprisingly diverse. The life of stars is the same. Mass of the star. When the hydrogen is mostly burned out, the star shrinks even more. Neutron stars. Stars similar to our Sun are the main population. The neutron star is compressed. The number of galaxies in the Universe is estimated at 200 million. Star Altair. 3C58 - Remnants of Nova. The remnant of a nova explosion. Supergiant star. Young pulsar. A star in the Eta Carinae nebula. NGC 1850. Star cluster. Cluster M19 (NGC 6273). M50 is a dim star cluster. - Stars.pptx
starry sky
Slides: 12 Words: 302 Sounds: 0 Effects: 49Universe. Man has always been attracted to the sky; for a long time he dreamed of going into space. Stars on the sky. Late in the evening you see many stars in the sky. Constellations. The stars in the sky are grouped. Groups of stars are called constellations. Name the constellations that you know. Assignment for young astronomers. Ancient Greek legend. A legend has come down to us from the ancient Greeks. Planets. Planet Earth. The earth is the habitat of man. Earth is the third planet from the Sun in the solar system. The age of the Earth is approximately 4.5 billion years. Shells of the Earth. Moon. In 1609, Galileo first looked at the moon through a telescope. Sun. - Stars 1.ppt
Stars on the sky
Slides: 19 Words: 1963 Sounds: 1 Effects: 72History of the names of stars and constellations. Evolution of stars. Myths in astronomy. General characteristics of stars. Life cycle of a star. Temperature determines the color of a star and its spectrum. Chemical composition. Star radius. The surface of the star is 4 R 2 . The history of the constellations is very interesting. There are a lot of constellations - 88. The winter sky is the richest in bright stars. What did the ancient Greeks say about bears? There are many legends about Ursa Major and Ursa Minor. Big Dipper. "Burnout" of hydrogen. - Stars 2.ppt
Distances to stars
Slides: 14 Words: 339 Sounds: 0 Effects: 0Distances to the stars. The concept of parallax is associated with the name of one of the basic units in astronomy - parsec. 1 parsec = 3.26 light years = 206,265 astronomical units = 3.083 1015 m. The shifts in the positions of the stars must be measured too small - less than one hundredth of an arcsecond! The distance to stars can be estimated using the spectral parallax method. Using spectral lines, you can estimate the luminosity of a star and then find its distance. The supergiant in the constellation Scorpio is Antares. The Hipparchus satellite determined distances to stars with high accuracy. Hipparchus. Even in ancient times, the brightest stars were called stars of the first magnitude. - Stars 3.ppt
Stars and constellations
Slides: 14 Words: 259 Sounds: 0 Effects: 25Starry sky. On a cloudless and moonless night, far from populated areas, about 3,000 stars can be distinguished. The entire celestial sphere contains about 6,000 stars visible to the naked eye. Starry sky in the area of the constellation Auriga. The most famous group of stars in the northern hemisphere is the Ursa Major Dipper. Ancient astronomers divided the starry sky into constellations. Hipparchus. Ptolemy. Thousands of years ago, bright stars were conventionally connected into shapes called constellations. Constellations Ophiuchus and Serpens from Flamsteed's atlas. Images of constellations from the ancient atlas of Hevelius. Calf. Whale. Cassiopeia. - Stars 4.ppt
World of stars
Slides: 52 Words: 1042 Sounds: 0 Effects: 8World of stars. K. E. Tsiolkovsky. Stars. Sun. The birth of a star. Stars are supergiants. Stars are dwarfs. Temperature of stars. The brightness of the stars. Light year. Constellations. Star map of the northern hemisphere. Star map of the southern hemisphere. Star cluster. Orientation by the stars. Zodiac belt. Aries. Calf. Twins. Cancer. A lion. Virgo. Scales. Scorpion. Sagittarius. Capricorn. Aquarius. Fish. Constellation Ursa Minor. Constellation Hercules. Constellation Cepheus. Constellation Bootes. Constellation Perseus. Constellation Auriga. Constellation Cygnus. Constellation Aries. Cetus constellation. Constellation Pegasus. Orion constellation. - World of Stars.ppt
starry sky
Slides: 16 Words: 535 Sounds: 0 Effects: 0Starry sky. Celestial sphere. Ancient astronomers. Bright stars. Constellation images. A section of the celestial sphere. Johann Bayer. Bright stars. The stars were the main landmarks. Letters of the Greek alphabet. Ursa Major Bucket. Constellation Ursa Major. Stars. Winter triangle. North hemisphere. - Starry sky.ppt
Characteristics of stars
Slides: 82 Words: 1296 Sounds: 0 Effects: 0Content. What are stars? Stars are hot balls of gas. About 4.5 thousand stars can be seen in the sky with the naked eye. Starry sky. All the stars move across the sky. Movement of stars. Polar Star. Characteristics of stars. Distances to the stars. Some stars closest to Earth. Sun. Proxima Centauri. Sirius. Procyon. Parallax method. Color. Temperature. Range. Luminosity L. Types of stars. Main sequence stars. The structure of main sequence stars. Hertzsprung-Russell diagram. Giants and supergiants. Supergiant star. A star whose mass is 10 times greater than the Sun. - Characteristics of stars.ppt
Basic characteristics of stars
Slides: 24 Words: 1340 Sounds: 24 Effects: 52Basic characteristics of stars. Distances to the stars. The distance is determined by the parallax method. Distance to the star. Small angular displacements. The angle at which the radius of the Earth's orbit is visible from a star. The parallaxes of stars are very small. Distance from the Sun to the nearest star. The parallax method is currently the most accurate method. Temperature of stars. The temperature of stars is determined using Wien's law. Luminosity of stars. Like the Sun, the stars illuminate the Earth. Masses of stars. Spectral classification of stars. The color of a star depends on temperature. Lines of ionized helium. - Basic characteristics of stars.ppt
Mass of stars
Slides: 11 Words: 531 Sounds: 0 Effects: 0Basic characteristics of stars. Spectrum-luminosity diagram. Astronomers are building giant telescopes to detect faint emissions from stars. Main sequence. The Sun is also a main sequence star. The densities of main sequence stars are comparable to the solar density. Red giants. Supergiants. Betelgeuse is a red supergiant. White dwarfs. An example is the star Sirius B, a satellite of Sirius. The mass is almost equal to the Sun, and is 2.5 times larger than the Earth. Masses of stars. Masses could only be measured for stars that are part of binary systems. - Mass of stars.ppt
Evolution of stars
Slides: 21 Words: 472 Sounds: 0 Effects: 0Evolution of stars. The Universe consists of 98% stars. Stars are the main element of the galaxy. Stars are huge balls of helium and hydrogen, as well as other gases. Astronomers are unable to trace the life of one star from beginning to end. Hertzsprung-Russell diagram. Star forming regions. Eagle Nebula. Orion Nebula. Gravitational compression. Compression is a consequence of gravitational instability, Newton's idea. Protostar. As the density of the cloud increases, it becomes opaque to radiation. A graph of the evolution of a typical star. Giants and supergiants. A white dwarf in a cloud of interstellar dust. - Compress stars.ppt
Structure of stars
Slides: 13 Words: 238 Sounds: 0 Effects: 119Physical nature of stars. Masse. Sizes. Luminosity. Temperature (color). Age. The building. Color and temperature of stars. Arcturus has a yellow-orange hue, Arcturus. Rigel. Antares. Stars come in a variety of colors. the crossbar is white and blue, Antares is bright red. For different stars, the maximum radiation occurs at different wavelengths. Harvard spectral classification of stars. One. Shaved. American. Dates. Chewed. Carrot. Class. effective temperature K. Color. Blue. White - blue. White. Yellow - white. Yellow. Orange. Red. Luminosity of stars. Radii of stars. Stars. Comparative sizes of stars. - Structure of stars.ppt
Stars and their structure
Slides: 62 Words: 730 Sounds: 0 Effects: 6The structure and evolution of stars. Stars made of degenerate matter. Degeneration. Pressure of a nonrelativistic degenerate electron gas. White dwarf mass limit. Limit number of fermions. Sirius V. Theory of relativity. Effects of general relativity on Earth. Quark state of matter. Systems of two neutron stars. Masses of BHs and NSs in binary systems. Dimensions. Hot spot. Conditions at the center of the Sun. Height of the homogeneous atmosphere NZ. Thermonuclear combustion of the atmosphere. Explosions of classic New ones on BC. Thermonuclear explosions. Oscillations during thermonuclear explosions. Spreading layer spectrum. - Stars and their structure.ppt
The structure and evolution of stars
Slides: 69 Words: 2405 Sounds: 0 Effects: 8Stars: structure and evolution. Classification of normal stars. Hertzsprung–Russell diagram. Luminosity classes. Internal structure of the Sun. Physical basis of the internal structure of stars. Hydrostatic equilibrium. Polytropic model. Special cases of polytropic models. The White Dwarf Theory. The exposed core of a star. Sirius V. Radiation transfer in stars. Opacity of matter in the interior of stars. Equations of stellar structure. Model of the Sun. Mass-luminosity relationship. Eddington luminosity limit. Nuclear energy sources of stars. Nuclear reactions in stars. Proton-proton cycle. - Structure and evolution of stars.ppt
Physical nature of stars
Slides: 20 Words: 42 Sounds: 0 Effects: 0Physical nature of stars. Our Sun is a yellow star, the temperature of the photosphere of which is about 6000 K. The same color is Capella, whose temperature is also about 6000 K. The color and spectrum of stars is related to their temperature. In hot blue stars with temperatures above 10,000–15,000 K, most of the atoms are ionized. Fully ionized atoms do not produce spectral lines, so there are few lines in the spectra of such stars. The Pleiades open cluster contains many bright, hot stars that were formed at the same time from a cloud of gas and dust. The blue haze accompanying the Pleiades is scattered dust reflecting the light of the stars. - Physical nature of stars.ppsx
Black holes
Slides: 25 Words: 473 Sounds: 0 Effects: 65Black holes are the end result of the activity of stars whose mass is five or more times greater than that of the Sun. After all nuclear fuel reserves have been used up and reactions have stopped, the star dies. When a star explodes, a supernova occurs. Structure of a black hole. Far from the hole, the rays bend slightly. If the beam passes very close to the hole, it can capture it into a circular orbit or suck it into itself completely. A singularity is all the matter of a black hole collected into an infinitesimal point. The event horizon is the boundary of a black hole. Astronomer Karl Schwarzschild, in the last years of his life, calculated the gravitational field around a mass of zero volume. - Black hole.ppt
Black holes of the Universe
Slides: 18 Words: 1013 Sounds: 0 Effects: 36Black holes and dark matter. Composition of the Universe. Dark matter. Classification of dark matter. Hot dark matter. Cold dark matter. Warm dark matter. Difficulty. Black holes. Terrible experience. Region in space. The question of the real existence of black holes. Collapsed stars. History of ideas about black holes. Detection of black holes. Supermassive black holes. Primitive black holes. -
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The presentation on the topic "Stars" can be downloaded absolutely free on our website. Project subject: Astronomy. Colorful slides and illustrations will help you engage your classmates or audience. To view the content, use the player, or if you want to download the report, click on the corresponding text under the player. The presentation contains 12 slide(s).
Presentation slides
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stars. Double stars. Movement of stars.
Performed by Kirillova Anastasia
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The brightness of some stars is variable and changes over periods of time - from hours to weeks or even a year. The brightness of a variable star can be determined by comparison with surrounding stars that have constant brightness. The main reason for variable brightness is the change in the size of the star due to its instability. The most famous are pulsating stars of the Cepheid class, named after their prototype - the star delta Cephei. These are yellow supergiants that pulsate every few days or weeks, causing their brightness to change.
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The importance of such stars for astronomers is that their pulsation period is directly related to brightness: the brightest Cepheids have the longest pulsation period. Therefore, by observing the pulsation period of Cepheids, their brightness can be accurately determined. By comparing the calculated brightness with the brightness of the star visible from Earth, you can determine how far it is from us. Cepheids are relatively rare. The most numerous type of variable stars are red giants and supergiants; All of them are variable to one degree or another, but they do not have such a clear periodicity as the Cepheids. The most famous example of a variable red giant is Omicron Ceti, known as Mira. Some red variable stars, such as the supergiant Betelgeuse, show no pattern in their changes.
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A completely different type of variable stars are binary eclipsing stars. They consist of two stars with interconnected orbits; one of them periodically closes the other from us. Each time one star eclipses another, the light we see from the star system weakens. The most famous of these is the star Algol, also called beta Persei.
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The most impressive are variable stars, the brightness of which changes suddenly and often very strongly. They are called novae and supernovae. It is believed that a nova is two closely located stars, one of which is a white dwarf. Gas from the other star is pulled away by the white dwarf, explodes, and the star's light increases thousands of times for a while. When a nova explodes, the star is not destroyed. Explosions of some novae have been observed more than once, and perhaps new ones appear again after some time. New ones are often noticed first by amateur astronomers. Even more spectacular are supernovae - celestial cataclysms that mean the death of a star. When a supernova explodes, a star is torn into pieces and ends its existence, flaring up for a time millions of times more powerful than ordinary stars. Where a supernova explosion occurs, debris from the star remains scattered into space, such as in the Crab Nebula in the constellation Taurus and in the Veil Nebula in the constellation Cygnus.
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There are two types of supernovae. One of them is the explosion of a white dwarf in a binary star. Another type is when a star many times larger than the Sun becomes unstable and explodes. The last supernova in our galaxy was observed in 1604, and another supernova occurred and was visible to the naked eye in the Large Magellanic Cloud in 1987.
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Double stars
The Sun is a single star. But sometimes two or more stars are located close to each other and revolve around each other. They are called double or multiple stars. There are a lot of them in the Galaxy. So, the star Mizar in the constellation Ursa Major has a satellite - Alcor. Depending on the distance between them, double stars orbit each other quickly or slowly, and the orbital period can range from a few days to many thousands of years. Some double stars are turned towards the Earth with the edge of the plane of their orbit, then one star regularly eclipses the other. At the same time, the overall brightness of the stars weakens. We perceive this as a change in the brightness of the star. For example, the “devil star” Algol in the constellation Perseus has been known since ancient times as a variable star. Every 69 hours, the orbital period of the stars in this binary system, a brighter star is eclipsed by its cooler, less luminous neighbor. From the Earth, this is perceived as a decrease in its brightness. Ten hours later, the stars disperse, and the brightness of the system again reaches its maximum.
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Binary stars are two (sometimes three or more) stars orbiting a common center of gravity. There are different double stars: there are two similar stars in a pair, and there are different ones (usually a red giant and a white dwarf). But, regardless of their type, these stars are the most amenable to study: for them, unlike ordinary stars, by analyzing their interaction it is possible to determine almost all parameters, including mass, shape of orbits, and even roughly determine the characteristics of stars located close to them. As a rule, these stars have a somewhat elongated shape due to mutual attraction. Many such stars were discovered and studied at the beginning of our century by the Russian astronomer S. N. Blazhko. About half of all the stars in our Galaxy belong to binary systems, so binary stars orbiting one another are a very common phenomenon.
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Binary stars are held together by mutual gravity. Both stars of the binary system rotate in elliptical orbits around a certain point lying between them and called the center of gravity of these stars. These can be imagined as fulcrums if you imagine the stars sitting on a children's swing: each at its own end of a board placed on a log. The farther the stars are from each other, the longer their orbital paths last. Most double stars are too close to each other to be seen individually even with the most powerful telescopes. If the distance between the partners is large enough, the orbital period can be measured in years, and sometimes as much as a century or more. Double stars that can be seen separately are called visible binaries.
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Movement of stars.
In the sky, the analogues of longitude and latitude are right ascension and declination. Right ascension begins at the point where the Sun crosses the celestial equator in a northerly direction each year. This point, called the vernal equinox, is the celestial equivalent of the Greenwich meridian on Earth. Right ascension is measured eastward from the vernal equinox in hours, from 0 to 24. Each hour of right ascension is divided into 60 minutes, and each minute is divided into 60 seconds. Declination is defined in degrees north and south of the celestial equator, from 0 at the equator to +90° at the north celestial pole and to -90° at the south celestial pole. The celestial poles are located directly above the Earth's poles, and the celestial equator passes directly overhead when viewed from the Earth's equator. Thus, the position of a star or other object can be accurately determined by its right ascension and declination, as well as by the coordinates of a point on the surface of the Earth. Coordinate grids in hours of right ascension and degrees of declination are plotted on the star maps of this book.
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However, cartographers of outer space face two problems that do not face cartographers of the earth's surface. First, each star moves slowly relative to surrounding stars (the star's proper motion). With a few exceptions, such as Barnard's Star, this motion is so slow that it can only be determined by special measurements. However, after many thousands of years, this movement will lead to a complete change in the present shape of the constellations; some stars will move to neighboring constellations. Someday, astronomers will have to reconsider the modern nomenclature of stars and constellations. The second problem is that the overall coordinate grid shifts due to the Earth's wobble in space, called precession. This causes the zero point of right ascension to complete a revolution in the sky every 26,000 years. The coordinates of all points in the sky gradually change, so usually the coordinates of celestial objects are given for a specific date.
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