Each star is a huge glowing ball of gas, like our Sun. A star shines because it releases a colossal amount of energy. This energy is generated as a result of so-called thermonuclear reactions.
Each star is a huge glowing ball of gas, like our Sun. A star shines because it releases a colossal amount of energy. This energy is generated as a result of so-called thermonuclear reactions.Each star contains many chemical elements. For example, the presence of at least 60 elements has been discovered on the Sun. Among them are hydrogen, helium, iron, calcium, magnesium and others. 
Why do we see the Sun so small? Yes, because it is very far from us. Why do stars look so tiny? Remember how small our huge Sun seems to us - just the size of a football. This is because it is very far from us. And the stars are much, much further away! 
Stars like our Sun illuminate the Universe around them, warm the planets around them, and give life. Why do they glow only at night? No, no, during the day they also shine, you just can’t see them. In the daytime, our sun illuminates the blue atmosphere of the planet with its rays, which is why space is hidden, as if behind a curtain. At night, this curtain opens, and we see all the splendor of space - stars, galaxies, nebulae, comets and many other wonders of our Universe.
Karpov Dmitry
This research 1st grade student of Municipal Educational Institution Secondary School No. 25.
Purpose of the study: find out why there are stars in the sky different colors.
Methods and techniques: observations, experiment, comparison and analysis of observation results, excursion to the planetarium, work with various sources of information.
Data received: Stars are hot balls of gas. The closest star to us is the Sun. All Stars different color. The color of a star depends on the temperature on its surface. Thanks to the experiment, I was able to find out that the heated metal first begins to glow red, then yellow and, finally, white as the temperature increases. Same with the stars. Reds are the coldest, and whites (or even blues!) are the hottest. Heavy stars are hot and white, light, non-massive stars are red and relatively cool. The color of a star can also be used to determine its age. Young stars are the hottest. They shine with white and blue light. Old, cooling stars emit red light. And middle-aged stars glow with yellow light. The energy emitted by stars is so enormous that we can see them at those distant distances at which they are removed from us: tens, hundreds, thousands of light years!
Conclusions:
1. The stars are colorful. The color of a star depends on the temperature on its surface.
2. By the color of a star we can determine its age and mass.
3. We can see stars thanks to the enormous energy they emit.
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XIV city scientific and practical conference for schoolchildren
"First steps into science"
Why are stars different colors?
City of Sochi.
Head: Marina Viktorovna Mukhina, primary school teacher
Municipal educational institution secondary school No. 25
Sochi
2014
INTRODUCTION
You can admire the stars forever, they are mysterious and attractive. Since ancient times, people have attached great importance these celestial bodies. Astronomers from antiquity to the present day claim that the location of stars in the sky has a special effect on almost all aspects human life. The weather is determined by the stars, horoscopes and predictions are made, and lost ships find their way on the open sea. What are they really like, these shining luminous points?
The mystery of the starry sky is interesting to all children, without exception. Scientists and astronomers have conducted a lot of research and revealed many secrets. Many books have been written about stars, many educational films have been made, and yet many children do not know all the secrets of the starry sky.
For me, the starry sky remains a mystery. The more I looked at the stars, the more questions I had. One of which was: what color are these twinkling, mesmerizing stars.
Purpose of the study:explain why the stars in the sky are different colors.
Tasks, which I set for myself: 1. look for the answer to the question by talking with adults, reading encyclopedias, books, INTERNET materials;
2. observe the stars with the naked eye and using a telescope;
3. using an experiment, prove that the color of a star depends on its temperature;
4. tell your classmates about the diversity of the star world.
Object of study– celestial bodies (stars).
Subject of study– star parameters.
Research methods:
- Reading specialized literature and watching popular science programs;
- Study of the starry sky using a telescope and special software;
- An experiment to study the dependence of the color of an object on its temperature.
The result My job is to generate interest in this topic among my classmates.
Chapter 1. What are stars?
I often looked at the starry sky, consisting of many luminous points. The stars are especially visible at night and in cloudless weather. They always attracted my attention with their special, bewitching radiance. Astrologers believe that they can influence the fate and future of a person. But few can answer the question of what they are.
After studying the reference literature, I was able to find out that a star is a celestial body in which thermonuclear reactions occur, which is a massive luminous ball of gas.
Stars are the most common objects in the universe. The number of stars that exist is very difficult to imagine. It turns out that there are more than 200 billion stars in our galaxy alone, and there is a huge number of galaxies in the universe. With the naked eye, about 6,000 stars are visible in the sky, 3,000 in each hemisphere. The stars are located at enormous distances from the Earth.
The most famous star that is closest to us is, of course, the Sun. That is why it seems to us that it is very large compared to other luminaries. During the day, it eclipses all other stars with its light, so we do not see them. If the Sun is located at a distance of 150 million kilometers from the Earth, then the other star, which is closest to the others, Centaur, is already located 42,000 billion kilometers from us.
How did the Sun appear? After studying the literature, I realized that, like other stars, the Sun appeared from an accumulation of cosmic gas and dust. Such a cluster is called a nebula. Gas and dust were compressed into a dense mass, which heated to a temperature of 15,000,000 kelvins. This temperature is maintained at the center of the Sun.
Thus, I was able to find out that stars are balls of gas in the Universe. But why then do they glow in different colors?
Chapter 2. Temperature and color of stars
First I decided to find the brightest stars. I assumed that the brightest star is the Sun. Due to the lack of special instruments, I determined the luminosity of stars with the naked eye, then using my telescope. Through a telescope, stars are visible as points of varying degrees of brightness without any details. The sun can only be observed with special filters. But not all stars can be seen, even through a telescope, and then I turned to information sources.
I made the following conclusions: the brightest stars: 1. Giant star R136a12 (star forming region 30 Doradus) ; 2. Giant star VY SMA (in the constellation Canis Major) 3. Deneb (in the constellationα Swan); 4. Rigel(in the constellation β Orion); 5. Betelgeuse (in the constellation α Orion). My dad helped me determine the names of the stars using the Star Rover program for iPhone. At the same time, the first three of the stars have a bluish glow, the fourth has a white-blue glow, and the fifth has a reddish-orange glow. Scientists discovered the brightest star usingNASA's Hubble Space Telescope.
During my research, I noticed that the brightness of stars depends on their color. But why are all the stars different?
Let's look at the Sun, a star visible to the naked eye. From early childhood we portray her yellow, because this star is actually yellow. I began to study the properties of this star.The temperature on its surface is about 6000 degrees.I learned about other stars in encyclopedias and on the INTERNET. It turned out that all the stars are different colors. Some of them are white, others are blue, others are orange. There are white and red stars. It turns out that the color of a star depends on the temperature on its surface. The hottest stars appear white and blue to us. The temperature on their surface is from 10 to 100,000 degrees. An average temperature star has yellow or Orange color. The coldest stars are red. The temperature on their surface is about 3,000 degrees. And these stars are many times hotter than the flame of a fire.
My parents and I conducted the following experiment: we heated gas burner iron knitting needle At first there was a knitting needle gray. After heating, it glowed and turned red. Her temperature increased. After cooling, the spoke became gray again. I concluded that as the temperature increases, the color of the star changes.Moreover, with stars everything is not the same as with people. People usually turn red when they are hot and blue when they are cold. But with stars it’s the other way around: the hotter the star, the bluer it is, and the colder the star, the bluer it is.
As you know, a heated metal first begins to glow red, then yellow and finally white as the temperature increases. Same with the stars. Reds are the coldest, and whites (or even blues!) are the hottest.
Chapter 3. The mass of the star and its color. Star age.
When I was 6 years old, my mother and I went to the planetarium in the city of Omsk. There I learned that all stars exist different sizes. Some are large, others are small, some are heavier, others are lighter. With the help of adults, I tried to arrange the stars I was studying from lightest to heaviest. And that's what I noticed! It turned out that blue ones are heavier than white ones, white ones are heavier than yellow ones, yellow ones are heavier than orange ones, and orange ones are heavier than red ones.
The color of a star can also be used to determine its age. Young stars are the hottest. They shine with white and blue light. Old, cooling stars emit red light. And middle-aged stars glow with yellow light.
The energy emitted by stars is so enormous that we can see them at those distant distances at which they are removed from us: tens, hundreds, thousands of light years!
For us to be able to see a star, its light must pass through the air layers of the Earth's atmosphere. The vibrating layers of air somewhat refract the direct stream of light, and it seems to us that the stars are twinkling. In fact, direct, continuous light comes from the stars.
The Sun is not the largest star, it belongs to the stars called Yellow Dwarfs. When this star lit up, it was made of hydrogen. But under the influence of thermonuclear reactions, this substance began to turn into helium. During the existence of this star (about 5 billion years), approximately half of the hydrogen burned. Thus, the Sun has as long to “live” as it already exists. When almost all of the hydrogen is burned, this star will become larger in size and turn into a Red Giant. This will greatly affect the Earth. Our planet will become unbearably hot, the oceans will boil away, and life will become impossible.
CONCLUSION
Thus, as a result of my research, my classmates and I gained new knowledge about what stars are, as well as what the temperature and color of stars depend on.
BIBLIOGRAPHICAL LIST.
"I came into this world
To see the Sun and a blue horizon.
I came into this world
To see the Sun and the heights of the mountains.”
Our planet and earthly inhabitants cannot exist without the familiar, warm globe of the sun. A person feels sad in cloudy weather, but when the sun shimmers cheerfully in the sky, the fiery luminary instills hope and confidence that everything will be fine. Why is the sun yellow? Have you thought about this?
What is the Sun
A solar star is a hot ball of gas, the central figure of the solar system. The center of a cluster of planets, celestial bodies consisting of heavy elements. Hydrogen in the Sun is compressed under the influence of gravity. Inside the luminary it continuously flows thermonuclear reaction, creating helium from hydrogen.
The solar star arose after a series of supernova explosions five billion years ago. Thanks to its ideal location to the Sun, life began on the third planet. This is Earth.
Helium leaks and radiates through the photosphere (the thin surface layer of a star) into outer space. The star has a boundary atmosphere - the solar corona, merging with the interstellar medium. We don't see the corona because the gas is very rarefied. It becomes visible during eclipses.
The main luminary of the solar system has an 11th cycle of activity. During this period, the number of sunspots (darkened zones of the photosphere), flares (dazzling glow of the chromosphere), and prominences (hydrogen clouds condensed in the corona) increases/decreases.
The chromosphere is the boundary layer between the photosphere and the corona. The man sees him solar eclipses in the form of a bright red rim. The mass of the star is gradually decreasing. The star loses some of its weight as it converts hydrogen into helium (synthesizing energy).
The warmth that makes people happy is the lost stellar mass (sun rays). Weight is also lost due to winds on the Sun, which regularly blow electrons and protons from the star into space.
Why is the celestial body yellow?
Not every person is able to explain the reason for the pleasant, warm shade of a solar star. For scientific explanation we need knowledge about the structure of celestial bodies, the properties of the earth's atmosphere, and the abilities of the human eye. The explanation of why the Sun is yellow is given from two perspectives.
Beautiful illusion
In fact, the color of the sun star is white. But human eyes stubbornly present the shade as yellow. This is the color perception of light waves in humans. When the sun's rays pass through the earth's atmosphere, they lose part of the light spectrum, but retain their wavelength.
Nature has designed the human eye in a cunning way. We perceive only three colors: blue, red, green.
Some spectral emissions are long, others are shorter. Short spectrum waves dissipate at a faster rate, people perceive them more sensitively. The shortest color spectrum consists of blue waves. That's why the sky seems noble blue tint.
The white rays of the Sun are longer. When they penetrate the atmosphere and merge with the blue spectrum, it turns out yellow which we see. The more piercing the shade of the sky, the brighter and yellower the luminary appears. Please note that this optical effect is noticeable after rain in cloudless weather.
And in winter, when the sky is gloomy and joyless, the sun dims and is perceived by people as a whitish circle.
Astronomy speaks
What color is the Sun from the point of view of astronomers? The warm star is a “yellow dwarf”. This is the type of star that determines the size. Compared to other stars in the Galaxy, the solar star is tiny, and the range of its color radiance is yellow.
The color of a star’s radiance depends on its size, distance from Earth, and features chemical reactions happening inside.
The young star has a bright glow and long light pulses of a certain frequency. Such “newborn” stars have a sparkling white with a blue glow (young stars are white). Our middle-aged sunny lady has rays of a different frequency and is perceived by people as yellow.
For astronomers, the sun's color is important. By using special device Using a spectroscope, scientists study other stars by spectral decomposition. Determine the composition (metal or helium with hydrogen remaining in space after big bang). Understand the surface temperature of the stars.
- Cool red stars (Gliese, Arcturus, Cepheus, Betelgeuse).
- The hot ones (Rigel, Zeta Orionis, Alpha Giraffe, Tau Canis Majoris) have a pleasant bluish glow.
Outside the atmosphere, the Sun appears as a white star. The color of the mesmerizing celestial beauties is surprisingly varied. From white-blue to crimson-red. The hotter the star, the longer the wavelength.
The blue tint has shorter spectral wavelengths compared to red. Therefore, hot stars emit more strongly in the blue range and appear blue, while cold stars penetrate the red spectrum more powerfully, we see them in a red tint.
Interesting fact. Why the sun is yellow was explained in 1871. English physicist John Rayleigh created the theory of molecular scattering of a light beam. The law that explains the intensity of light scattered by air was named after him - Rayleigh's law.
Explanation for children
Children's minds are inquisitive and inquisitive. The young “why” asks thousands of questions. Sometimes adults get lost when choosing an answer so that the child can understand it more clearly. How to explain obvious things to a little person (why the sun shines, why it is yellow, and why the sky is blue)? How to choose words so as not to scare away with abstruse phrases, but to encourage the little researcher to study and learn? When explaining, take into account the child's age.
We explain to the kids. It’s too early to tell little children about color spectra and light waves. Come up with a fascinating fairy tale to satisfy your little one's curiosity.
“There lived one fairy-tale wizard in the world. He loved to draw and wore magic paints all the time. Every morning he painted the sky blue and the sun yellow, so that people would have fun, warmth and joy. The magician has an older fairy sister. She watches over him, and in the evenings, when the children are tired, the fairy wraps the sky and the sun in a dark blanket and scatters stars so that the kids have wonderful dreams.
When a wizard is sad, his colors cry. Then the blue color of the sky blurs, hiding the sun. It becomes sad, but not for long. The fairy sister comes to the wizard’s aid, draws a multi-colored rainbow and colors the sun again, giving him a golden ray. After all, wizards don’t know how to grieve!”
Or this story: “Once upon a time there were magical colors. They loved to walk and went outside every day. One day they woke up in the morning, ran out into the yard - and everything there was gray and dull! It doesn’t matter, said the paints, we will return the colors! Blue colors the sky, puddles, and river - let the kids splash in the water! 
Yellow went to decorate the sun so that it would become warm and warm everyone around. Green decorated the grass, trees, black – pebbles, earth. Then they painted the flowers together - look how colorful they are! The paints did a great job, got tired, and went to bed. And everything on the street remained painted - after all, the colors are magical!”
Older children. To older children, you can explain why the Sun appears yellow in adult language, but in accessible words:
“Remember the rainbow? It consists of seven colors. But in a rainbow, the colors go separately, one after another. The light of a solar star is the same as a rainbow, but the bright star has combined, mixed colors. The sun is far away from us and sends solar rays towards our planet.
The sky has an atmosphere, it is like a sieve. sunlight, reaching the Earth, “is splashed into individual colors (like a rainbow). The rays pass through the heavenly “sieve” in different ways. They are fast, but other colors are so lazy that they don’t even reach us and get “stuck” in the strainer atmosphere. The most persistent and strongest are blue and yellow rays. That's why the sun is yellow and the sky is blue. That’s how we see them.”
Come up with your own answers, use your imagination, awaken the storytellers within you!
"Multi-colored" star
If you are one of the observant people, you know that the Sun comes in a different color. Not just yellow or whitish. Before leaving or ascending into the sky, the solar star shines with an orange, purple or reddish hue.
Why was the light red at sunset and pink at dawn? Our planet rotates around an axis, moving away and approaching the Sun. In the evening and morning, the Earth occupies the farthest distance from the hot star.
In order to reach the earth's surface in the evening or morning, the sun's rays spend more time traveling. Along the way, they dissipate faster, mixing with a large number of blue color waves. Therefore, at this time the Sun is a different color.
If a hot star is covered by a black cloud of ash or smoke (during a strong fire, volcanic eruption), the star will take on a lilac-violet, frightening hue. The more dust in the air, the more saturated the star's hue becomes. Microscopic dust particles transmit only violet and red light waves; they “take” and absorb the rest of the spectrum.
The same thing happens when air humidity rises. Water vapor only transmits red spectral waves. Therefore, during high humidity, before heavy rain, the solar star takes on a red tint.
Don’t be alarmed when the usual yellow sun appears before us in a different color guise. These are “jokes” of human visual perception, an optical effect. Any shade of the Sun is explainable and does not pose any threat to people.
Interesting observations!
In ancient times, people thought that the stars were the souls of people, living ones, or nails that held up the sky. They came up with many explanations for why the stars glow at night and the Sun for a long time considered an object completely different from stars.
The problem of thermal reactions occurring in stars in general and on the Sun, the closest star to us, in particular, has long worried scientists in many areas of science. Physicists, chemists, and astronomers tried to figure out what leads to the release of thermal energy, accompanied by powerful radiation.
Chemists believed that exothermic chemical reactions occur in stars, resulting in the release of large amounts of heat. Physicists did not agree that reactions between substances occur in these cosmic objects, since no reactions could produce so much light for billions of years.
When Mendeleev wrote his famous table, a new era in the study of chemical reactions began - radioactive elements were found and soon it was the radioactive decay reactions main reason radiation from stars.
The debate stopped for a while, as almost all scientists recognized this theory as the most suitable.
Modern theory about stellar radiation
In 1903, the already established idea of why stars shine and emit heat was overturned by the Swedish scientist Svante Arrhenius, who electrolytic dissociation. According to his theory, the source of energy in stars is hydrogen atoms, which combine with each other and form heavier helium nuclei. These processes are caused by strong gas pressure, high density and temperature (about fifteen million degrees Celsius) and occur in the inner regions of the star. This hypothesis began to be studied by other scientists, who came to the conclusion that such a fusion reaction is enough to release the colossal amount of energy that stars produce. It is also likely that hydrogen fusion would allow stars to shine for several billion years.
In some stars, helium synthesis has ended, but they continue to shine as long as they have enough energy.
The energy released in the interior of stars is transferred to the outer regions of the gas, to the surface of the star, from where it begins to be emitted in the form of light. Scientists believe that light rays travel from the cores of stars to the surface for many tens or even hundreds of thousands of years. After this, the radiation reaches the Earth, which also takes a lot of time. Thus, the radiation of the Sun reaches our planet in eight minutes, the light of the second closest star, Proxima Centrauri, reaches us in more than four years, and the light of many stars that can be seen with the naked eye has traveled several thousand or even millions of years.
We never think that perhaps there is some kind of life other than our planet, other than ours. solar system. Perhaps there is life on one of the planets orbiting a blue or white or red, or maybe a yellow star. Perhaps there is another planet like this, on which the same people live, but we still don’t know anything about it. Our satellites and telescopes have discovered a number of planets that may have life, but these planets are tens of thousands and even millions of light years away.
Blue stragglers are stars that are blue in color.
Stars located in globular star clusters, whose temperature is higher than that of ordinary stars, and whose spectrum is characterized by a significant shift to the blue region than that of cluster stars with a similar luminosity, are called blue stragglers. This feature allows them to stand out relative to other stars in this cluster on the Hertzsprung-Russell diagram. The existence of such stars refutes all theories of stellar evolution, the essence of which is that stars that arose in the same period of time are expected to be located in a well-defined region of the Hertzsprung-Russell diagram. In this case, the only factor that affects the exact location of the star is its initial mass. The frequent appearance of blue stragglers outside the above curve may confirm the existence of such a thing as anomalous stellar evolution. 
Experts trying to explain the nature of their occurrence have put forward several theories. The most likely of them indicates that these stars blue color in the past they were double, after which they began to undergo or are now undergoing a process of merging. The result of the merger of two stars is the emergence of a new star, which has a much greater mass, brightness and temperature than stars of the same age.
If this theory could somehow be proven correct, the theory of stellar evolution would be free of the problem of blue stragglers. The resulting star would contain large quantity hydrogen, which would behave similarly to a young star. There are facts that support this theory. Observations have shown that stragglers are most often found in the central regions of globular clusters. As a result of the predominant number of unit-volume stars there, close passages or collisions become more likely.
To test this hypothesis, it is necessary to study the pulsation of blue stragglers, because There may be some differences between the asteroseismological properties of merged stars and normally pulsating variables. It is worth noting that measuring pulsations is quite difficult. This process is also negatively affected by the overcrowding of the starry sky, small fluctuations in the pulsations of blue stragglers, as well as the rarity of their variables.
One example of a merger could be observed in August 2008, when such an incident affected object V1309, the brightness of which, after discovery, increased several tens of thousands of times, and after several months returned to its original value. As a result of 6 years of observations, scientists came to the conclusion that this object is two stars whose orbital period around each other is 1.4 days. These facts led scientists to believe that in August 2008, the process of merging these two stars took place.
Blue stragglers are characterized by high torque. For example, the rotation speed of the star, which is located in the middle of the 47 Tucanae cluster, is 75 times higher than the rotation speed of the Sun. According to the hypothesis, their mass is 2-3 times greater than the mass of other stars that are located in the cluster. Also, through research, it was found that if blue stars are located close to any other stars, then the latter will have a lower percentage of oxygen and carbon than their neighbors. Presumably, stars pull these substances from other stars moving in their orbit, as a result of which their brightness and temperature increase. In “robbed” stars, places are discovered where the process of transformation of the original carbon into other elements took place.
Names of blue stars - examples
Rigel, Gamma Paralis, Alpha Giraffe, Zeta Orionis, Tau Canis Majoris, Zeta Puppis
White stars are white stars
Friedrich Bessel, who headed the Königsberg Observatory, made an interesting discovery in 1844. The scientist noticed the slightest deviation of the brightest star in the sky, Sirius, from its trajectory across the sky. The astronomer suggested that Sirius had a satellite, and also calculated the approximate period of rotation of stars around their center of mass, which was about fifty years. Bessel did not find adequate support from other scientists, because No one was able to detect the satellite, although its mass should have been comparable to Sirius.
And only 18 years later, Alvan Graham Clark, who was testing the best telescope of those times, discovered a dim white star near Sirius, which turned out to be its satellite, called Sirius B.
The surface of this star white heated up to 25 thousand Kelvin, and its radius is small. Taking this into account, scientists concluded that high density satellite (at the level of 106 g/cm 3 , while the density of Sirius itself is approximately 0.25 g/cm 3 , and that of the Sun is 1.4 g/cm 3 ). 55 years later (in 1917), another white dwarf was discovered, named after the scientist who discovered it - van Maanen's star, which is located in the constellation Pisces.
Names of white stars - examples
Vega in the constellation Lyra, Altair in the constellation Aquila (visible in summer and autumn), Sirius, Castor.
Yellow stars - yellow stars
Yellow dwarfs are commonly called small stars main sequence, whose mass is within the mass of the Sun (0.8-1.4). Judging by the name, such stars have a yellow glow, which is released during the thermonuclear process of fusion from hydrogen to helium.
The surface of such stars heats up to a temperature of 5-6 thousand Kelvin, and their spectral classes range between G0V and G9V. A yellow dwarf lives for about 10 billion years. The combustion of hydrogen in a star causes it to multiply in size and become a red giant. One example of a red giant is Aldebaran. Such stars can form planetary nebulae, getting rid of the outer layers of gas. In this case, the core transforms into a white dwarf, which has a high density.
If we take into account the Hertzsprung-Russell diagram, then on it the yellow stars are located in the central part of the main sequence. Since the Sun can be called a typical yellow dwarf, its model is quite suitable for considering the general model of yellow dwarfs. But there are other characteristic yellow stars in the sky, whose names are Alhita, Dabikh, Toliman, Khara, etc. These stars are not very bright. For example, the same Toliman, which, if you do not take into account Proxima Centauri, is closest to the Sun, has a 0th magnitude, but at the same time its brightness is the highest among all yellow dwarfs. This star is located in the constellation Centaurus, it is also a link complex system, which includes 6 stars. The spectral class of Toliman is G. But Dabih, located 350 light years from us, belongs to the spectral class F. But its high brightness is due to the presence of a nearby star belonging to the spectral class - A0.
In addition to Toliman, spectral class G has HD82943, which is located on the main sequence. This star, due to its similarity with the Sun chemical composition and temperature, also has two planets large sizes. However, the shape of the orbits of these planets is far from circular, so their approaches to HD82943 occur relatively often. Currently, astronomers have been able to prove that previously this star had much larger number planets, but over time it absorbed them all.
Names of yellow stars - examples
Toliman, star HD 82943, Hara, Dabih, Alhita
Red stars are red stars
If at least once in your life you have seen through the lens of your telescope red stars in the sky that were burning against a black background, then remembering this moment will help you more clearly imagine what will be written about in this article. If you have never seen such stars before, be sure to try to find them next time. 
If you set out to compile a list of the brightest red stars in the sky, which can be easily found even with an amateur telescope, you will find that they are all carbon stars. The first red stars were discovered back in 1868. The temperature of such red giants is low, in addition, their outer layers are filled with huge amounts of carbon. If previously similar stars made up two spectral classes - R and N, now scientists have defined them into one general class - C. Each spectral class has subclasses - from 9 to 0. Moreover, class C0 means that the star has high temperature, but less red than C9 class stars. It is also important that all carbon-dominated stars are inherently variable: long-period, semi-regular or irregular.
In addition, two stars called red semi-regular variables were included in this list, the most famous of which is m Cephei. William Herschel became interested in its unusual red color and dubbed it “pomegranate.” Such stars are characterized by irregular changes in luminosity, which can last from a couple of tens to several hundred days. Such variable stars belong to class M (cool stars with surface temperatures from 2400 to 3800 K).
Considering the fact that all the stars in the rating are variables, it is necessary to bring some clarity to the notation. It is generally accepted that red stars have a name that consists of two components– letters of the Latin alphabet and the name of the variable constellation (for example, T Hare). The first variable discovered in a given constellation is assigned the letter R, and so on, up to the letter Z. If there are many such variables, a double combination is provided for them Latin letters– from RR to ZZ. This method allows you to “name” 334 objects. In addition, stars can be designated using the letter V in combination with a serial number (V228 Cygnus). The first column of the rating is reserved for the designation of variables.
The next two columns in the table indicate the location of the stars in the period 2000.0. As a result of the increased popularity of the Uranometria 2000.0 atlas among astronomy enthusiasts, the last column of the rating displays the search chart number for each star that is in the rating. In this case, the first digit is a display of the volume number, and the second is the serial number of the card.
The rating also displays the maximum and minimum brightness values of stellar magnitudes. It is worth remembering that greater saturation of red color is observed in stars whose brightness is minimal. For stars whose period of variability is known, it is displayed as the number of days, but objects that do not have the correct period are displayed as Irr.
Finding a carbon star does not require much skill; it is enough that the capabilities of your telescope are enough to see it. Even if its size is small, its bright red color should attract your attention. Therefore, you should not be upset if you cannot detect them immediately. It is enough to use the atlas to find a nearby bright star, and then move from it to the red one.
Different observers see carbon stars differently. To some, they resemble rubies or an ember burning in the distance. Others see crimson or blood-red shades in such stars. To begin with, the rating has a list of the six brightest red stars, which, once found, you can fully enjoy their beauty.
Names of red stars - examples
Star color differences
There is a huge variety of stars with indescribable color shades. As a result, even one constellation received the name “Jewel Box”, the basis of which is made up of blue and sapphire stars, and in its very center is a brightly shining orange star. If we consider the Sun, it has a pale yellow color.
A direct factor influencing the difference in color between stars is their surface temperature. This is explained simply. Light by its nature is radiation in the form of waves. The wavelength is the distance between its crests and is very small. To imagine it, you need to divide 1 cm into 100 thousand identical parts. Several of these particles will make up the wavelength of light.
Considering that this number turns out to be quite small, every, even the most insignificant, change in it will be the reason why the picture we observe will change. After all, our vision perceives different wavelengths of light as different colors. For example, blue has waves whose length is 1.5 times shorter than that of red.
Also, almost every one of us knows that temperature can have a very direct effect on the color of bodies. For example, you can take any metal object and put it on the fire. It will turn red while heating. If the temperature of the fire increased significantly, the color of the object would change - from red to orange, from orange to yellow, from yellow to white, and finally from white to blue-white.
Since the Sun has a surface temperature of around 5.5 thousand 0 C, it is a typical example of yellow stars. But the hottest blue stars can heat up to 33 thousand degrees.
Color and temperature were linked by scientists using physical laws. How the temperature of a body is directly proportional to its radiation and inversely proportional to the wavelength. Waves of blue color have shorter wavelengths compared to red. Hot gases emit photons, the energy of which is directly proportional to temperature and inversely proportional to wavelength. That is why the hottest stars are characterized by a blue-blue emission range.
Since nuclear fuel on stars is not unlimited, it tends to be consumed, which leads to the cooling of stars. Therefore, middle-aged stars are yellow, and we see old stars as red.
As a result of the fact that the Sun is very close to our planet, its color can be accurately described. But for stars that are a million light years away, the task becomes more complicated. This is what a device called a spectrograph is used for. Scientists pass through it the light emitted by stars, as a result of which it is possible to spectrally analyze almost any star.
In addition, using the color of a star, you can determine its age, because mathematical formulas allow the use of spectral analysis to determine the temperature of a star, from which it is easy to calculate its age.
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