Stars can be very different: small and large, bright and not very bright, old and young, hot and “cold”, white, blue, yellow, red, etc.
The Hertzsprung–Russell diagram allows you to understand the classification of stars.
It shows the relationship between the absolute magnitude, luminosity, spectral type and surface temperature of the star. The stars in this diagram are not located randomly, but form clearly visible areas.
Most of the stars are on the so-called main sequence. The existence of the main sequence is due to the fact that the hydrogen burning stage accounts for ~90% of the evolutionary time of most stars: the burning of hydrogen in the central regions of the star leads to the formation of an isothermal helium core, the transition to the red giant stage and the departure of the star from the main sequence. The relatively short evolution of red giants leads, depending on their mass, to the formation of white dwarfs, neutron stars or black holes.
Being at various stages of their evolutionary development, stars are divided into normal stars, dwarf stars, and giant stars.
Normal stars are main sequence stars. These include our Sun. Sometimes normal stars like the Sun are called yellow dwarfs.
Yellow dwarf
A yellow dwarf is a type of small main sequence star with a mass between 0.8 and 1.2 solar masses and a surface temperature of 5000–6000 K.
The lifespan of a yellow dwarf is on average 10 billion years.
After the entire supply of hydrogen burns, the star increases in size many times and turns into a red giant. An example of this type of star is Aldebaran.
The red giant ejects its outer layers of gas to form planetary nebulae, while the core collapses into a small, dense white dwarf.
A red giant is a large star with a reddish or orange color. The formation of such stars is possible both at the stage of star formation and at later stages of their existence.
At an early stage, the star radiates due to the gravitational energy released during compression, until the compression is stopped by the thermonuclear reaction that has begun.
In the later stages of the evolution of stars, after the burning of hydrogen in their cores, the stars leave the main sequence and move to the region of red giants and supergiants of the Hertzsprung-Russell diagram: this stage lasts approximately 10% of the time of the “active” life of stars, that is, the stages of their evolution , during which nucleosynthesis reactions occur in the stellar interior.
The giant star has a relatively low surface temperature, about 5000 degrees. A huge radius, reaching 800 solar and due to such large sizes, enormous luminosity. The maximum radiation occurs in the red and infrared regions of the spectrum, which is why they are called red giants.
The largest of the giants turn into red supergiants. A star called Betelgeuse in the constellation Orion is the most striking example of a red supergiant.
Dwarf stars are the opposite of giants and may be next.
A white dwarf is what remains of an ordinary star with a mass of less than 1.4 solar masses after it passes through the red giant stage.
Due to the lack of hydrogen, thermonuclear reactions do not occur in the core of such stars.
White dwarfs are very dense. They are no larger in size than the Earth, but their mass can be compared to the mass of the Sun.
These are incredibly hot stars, their temperatures reach 100,000 degrees or more. They shine using their remaining energy, but over time it runs out and the core cools, turning into a black dwarf.
Red dwarfs are the most common stellar-type objects in the Universe. Estimates of their number vary from 70 to 90% of the number of all stars in the galaxy. They are quite different from other stars.
The mass of red dwarfs does not exceed a third of the solar mass (the lower limit of mass is 0.08 solar, followed by brown dwarfs), the surface temperature reaches 3500 K. Red dwarfs have a spectral class of M or late K. Stars of this type emit very little light, sometimes 10,000 times smaller than the Sun.
Given their low radiation, none of the red dwarfs are visible from Earth with the naked eye. Even the closest red dwarf to the Sun, Proxima Centauri (the closest star in the triple system to the Sun), and the nearest single red dwarf, Barnard's Star, have apparent magnitudes of 11.09 and 9.53, respectively. In this case, a star with a magnitude of up to 7.72 can be observed with the naked eye.
Due to the low rate of hydrogen combustion, red dwarfs have very long lifespans, ranging from tens of billions to tens of trillions of years (a red dwarf with a mass of 0.1 solar masses will burn for 10 trillion years).
In red dwarfs, thermonuclear reactions involving helium are impossible, so they cannot turn into red giants. Over time, they gradually shrink and heat up more and more until they use up the entire supply of hydrogen fuel.
Gradually, according to theoretical concepts, they turn into blue dwarfs - a hypothetical class of stars, while none of the red dwarfs have yet managed to turn into a blue dwarf, and then into white dwarfs with a helium core.
Brown dwarf - substellar objects (with masses ranging from approximately 0.01 to 0.08 solar masses, or, respectively, from 12.57 to 80.35 Jupiter masses and a diameter approximately equal to the diameter of Jupiter), in the depths of which, in contrast from main sequence stars, there is no thermonuclear fusion reaction with the conversion of hydrogen into helium.
The minimum temperature of main sequence stars is about 4000 K, the temperature of brown dwarfs lies in the range from 300 to 3000 K. Brown dwarfs constantly cool down throughout their lives, and the larger the dwarf, the slower it cools.
Subbrown dwarfs
Subbrown dwarfs, or brown subdwarfs, are cool formations that fall below the brown dwarf mass limit. Their mass is less than approximately one hundredth the mass of the Sun or, accordingly, 12.57 the mass of Jupiter, the lower limit is not defined. They are generally considered to be planets, although the scientific community has not yet come to a final conclusion about what is considered a planet and what is a sub-brown dwarf.
Black dwarf
Black dwarfs are white dwarfs that have cooled and, as a result, do not emit in the visible range. Represents the final stage of the evolution of white dwarfs. The masses of black dwarfs, like the masses of white dwarfs, are limited above 1.4 solar masses.
A binary star is two gravitationally bound stars orbiting a common center of mass.
Sometimes there are systems of three or more stars, in this general case the system is called a multiple star.
In cases where such a star system is not too far from the Earth, individual stars can be distinguished through a telescope. If the distance is significant, then astronomers can understand that a double star is visible only by indirect signs - fluctuations in brightness caused by periodic eclipses of one star by another and some others.
New star
Stars whose luminosity suddenly increases 10,000 times. The nova is a binary system consisting of a white dwarf and a companion star located on the main sequence. In such systems, gas from the star gradually flows to the white dwarf and periodically explodes there, causing a burst of luminosity.
Supernova
A supernova is a star that ends its evolution in a catastrophic explosive process. The flare in this case can be several orders of magnitude larger than in the case of a nova. Such a powerful explosion is a consequence of the processes occurring in the star at the last stage of evolution.
Neutron star
Neutron stars (NS) are stellar formations with masses of the order of 1.5 solar and sizes noticeably smaller than white dwarfs; the typical radius of a neutron star is presumably on the order of 10-20 kilometers.
They consist mainly of neutral subatomic particles - neutrons, tightly compressed by gravitational forces. The density of such stars is extremely high, it is comparable, and according to some estimates, can be several times higher than the average density of the atomic nucleus. One cubic centimeter of NS substance will weigh hundreds of millions of tons. The gravity on the surface of a neutron star is about 100 billion times higher than on Earth.
In our Galaxy, according to scientists, there may exist from 100 million to 1 billion neutron stars, that is, somewhere around one per thousand ordinary stars.
Pulsars
Pulsars are cosmic sources of electromagnetic radiation coming to Earth in the form of periodic bursts (pulses).
According to the dominant astrophysical model, pulsars are rotating neutron stars with a magnetic field that is inclined to the rotation axis. When the Earth falls into the cone formed by this radiation, it is possible to detect a pulse of radiation repeating at intervals equal to the revolution period of the star. Some neutron stars rotate up to 600 times per second.
Cepheids
Cepheids are a class of pulsating variable stars with a fairly precise period-luminosity relationship, named after the star Delta Cephei. One of the most famous Cepheids is Polaris.
The given list of the main types (types) of stars with their brief characteristics, of course, does not exhaust the entire possible variety of stars in the Universe.
We never think that perhaps there is some other life besides our planet, besides our 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 blue stars were double in the past, after which they began to undergo or are now undergoing a merger process. 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 have a larger amount of 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 white star is heated to 25 thousand Kelvin, and its radius is small. Taking this into account, scientists concluded that the satellite has a high density (at the level of 106 g/cm3, while the density of Sirius itself is approximately 0.25 g/cm3, and that of the Sun is 1.4 g/cm3). 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 usually called small main sequence stars 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 by shedding their 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, and it is also part of a complex system that 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 chemical composition and temperature similar to the Sun, also has two large planets. 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 this star used to have a much larger number of 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 a 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 - a letter of the Latin alphabet and the name of a 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 of Latin letters is provided for them - 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. Blue waves 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 make it possible to use spectral analysis to determine the temperature of a star, from which it is easy to calculate its age.
Video secrets of the stars watch online
There are a huge number of stars in space. Bright and huge ones can be seen with the naked eye, even if they are very far away, even by cosmic standards. But there are many more dwarf stars. It is almost impossible to see them with the naked eye. Among the dwarf stars there are red dwarfs that are already outliving their useful life. And brown dwarfs, which can hardly even be called stars. And already almost cooled white dwarfs, which will eventually turn into black ones.
On our planet there is a certain law of nature that the smaller the organism, the more of its individuals. This law also applies to the stars. This state of affairs raises many questions. After all, with living beings on Earth everything is extremely clear, but with the stars it’s not entirely clear. Scientists have solved this riddle halfway. In order to maintain themselves from gravitational collapse, stars with enormous weight need to heat up to high temperatures and, as a result, in a few million years they simply exhaust their energy supply, since in order to maintain a temperature in the center of hundreds of millions of degrees, very large expenditures of this energy are needed the energy itself. Dwarfs quietly smolder, stretching their “fuel” for tens of billions of years. Our Galaxy is only thirteen billion years old, therefore, whenever a dwarf appeared, it lives to this day. The second half of the question is that giant stars are born much less frequently than dwarfs. For every 100 stars like our Sun, only one star appears ten times more massive than . This is precisely the question that scientists have not yet answered. For a long time, among astronomical classifications there was no place for objects that were neither stars nor planets. The question of whether such objects exist has worried astronomers for decades. But in the mid-nineties, such planets were discovered outside the solar system. They turned out to be more massive than Jupiter, the largest planet in the solar system. 
But the question arose of where to draw the line between a planet and a star. It was believed that the star uses its main source of energy, i.e. thermonuclear reactions. Planets glow due to reflected Sveta and thermonuclear reactions do not occur in it. But it turned out that there are objects of thermonuclear reactions in which they occur, but are not the main source of energy. Astrophysicist Kumar calculated that if the mass of a cosmic body is 7.5% or more of the mass of the Sun, then at the center of such an object the temperature will be sufficient for the reaction to occur. This value was called the “hydrogen flammability limit.” For example, if a star has 8% the mass of the Sun, it will smolder for about six trillion years, which is 400 times the age of the Universe.
The search for brown dwarfs invented by Shiv Kumar continued for three decades. Although this scientist was a theorist, he also took up the telescope in the hope of finding such a star. It was immediately clear that we needed to search near other stars, to which the distance was already known. But this star should not be bright, since it will simply blind the telescope and prevent it from seeing the dim dwarf. Consequently, it was necessary to look near red stars, or already cooling white ones. But at that time these searches were unsuccessful.
It was only when more sensitive instruments became available that astronomers were able to detect very dim red dwarfs. Over time, it became clear that to detect the so-called “failed stars” it is not necessary to have huge telescopes.
From 1995 to 1997, many such objects were discovered, which made it possible to classify new objects located between planets and stars.
In the section on the question Please give an example of dwarf stars given by the author chevron the best answer is Dwarf STARS, the type of star most common in our Galaxy - 90% of stars, including the Sun, belong to it. They are also called main sequence stars, according to their position on the HERZSPRUNG-RUSSELL DIAGRAM. The name “dwarf” refers not so much to the size of the stars as to their LUMINOSITY, so this term does not have any diminutive connotation.
White dwarfs are very small stars that are in the last stage of evolution. Although their diameters are smaller than those of red dwarfs (no larger than the Earth), they have the same mass as the Sun. The brightest star in our night sky is Sirius (Dog Dawn among the ancient Egyptians). - double dawn: it includes a white dwarf, which is called Puppy (the Latin name for Sirius - “Vacation” - means “little dog”). The white dwarf Omicron-2 in the constellation Eridanus is one of the dwarfs that can be seen from Earth with the naked eye.
Red dwarfs are larger than Jupiter, but smaller than an average-sized star such as our Sun. Their luminosity is 0.01% of the luminosity of the Sun. Not a single red dwarf can be seen with the naked eye, even the closest one to us - Proxima Centauri.
Brown dwarfs are very cool cosmic objects, slightly larger than Jupiter. Brown dwarfs form in the same way as other stars, but their initial mass is insufficient for nuclear reactions to occur; Their lordship is very weak. Black dwarfs are small, cool, “dead” stars. Black dwarfs are not massive enough for nuclear reactions to take place in their depths, or all the nuclear fuel in them has burned out and they go out like burnt coal. The smallest stars are neutron stars.
Stars are the hottest objects not only in the Solar System, but in the entire Universe. Thermonuclear reactions constantly occur inside them, and as a result of these reactions a large amount of energy is released. The temperature of stars reaches gigantic values - from 2 to 60 thousand degrees Celsius. However, not all stars are alike. There are other, much cooler stars.
What class of objects do brown dwarfs belong to?
Brown dwarfs are one of the most mysterious objects in the Universe. Stars that weigh 10 times less than the Sun are classified as red dwarfs. But not a single scientist would admit the idea that a red dwarf is not a star. And in the mid-1990s, astronomers found objects that were called “black ghosts.” They had gigantic sizes and impressive gravity.
Mass measurement
The planet whose mass is usually compared to that of a brown dwarf is Jupiter. There are brown dwarfs that are 12 times larger than this planet. Scientists find it difficult to classify them as stars. But such a huge object cannot be called a planet. Currently, astronomers are actively discussing the question of whether gas giants and brown dwarfs should be classified into different categories (recall that the planet Jupiter is a gas giant).
Brown dwarfs are several dozen times larger than Jupiter, but at the same time, “black ghosts” are approximately a hundred times smaller than the Sun. Another name for brown dwarfs is brown dwarfs. Despite the fact that in science it is customary to call them substellar objects, they are still stars, although they have very unusual properties.
First guesses
Astronomers first began talking about this type of object in the 1960s. However, not a single assumption about their existence has been confirmed. Many ambitious scientists were intrigued and began to intensively study the immediate surroundings of the Universe, trying to find similar objects. But for as long as 35 years, no one was able to find an object even remotely resembling a brown dwarf. However, this outcome of events was quite natural - after all, this type of star does not emit its own light, or its luminosity is so low that it is simply impossible to notice. In addition, ground-based telescopes have low enough sensitivity to detect objects of this kind.
Properties of brown dwarfs
Astronomers cannot classify brown dwarfs either as planets or stars. The simplest definition would be: “a type of imperfect star.” They grew very poorly, barely able to reach a certain weight in their weight at which the processes of thermonuclear reactions would begin inside them, thanks to which ordinary stars shine in the sky. This is why brown dwarfs are not a source of light and heat. It is extremely difficult for astronomers to determine their location.
However, scientists always have a few secrets they can use. For example, traces of lithium are always present in the glow spectrum of brown dwarfs. This metal is often used in various types of industries, such as the production of batteries. But lithium is rare in outer space because it decays easily under such conditions. However, this metal is typical of brown dwarfs.
Atmosphere of cold stars
Another sign by which the location of such stars can be determined is the presence of methane. This gas cannot accumulate on ordinary stars due to their high temperatures. However, brown dwarfs are relatively cold, so methane easily accumulates in their atmosphere. The methane atmosphere of this type of star is very dense.
Violent winds rage on their surface, and the rays of other stars never penetrate here, and accordingly, the weather is never favorable. This is why brown dwarfs look inhospitable in photos. Space explorers never get close to these stars.
It is impossible to land a ship on their surface. The force of their gravity is so monstrous that the astronauts would immediately die in its clutches even before the ship turned into a pile of metal.
Many of the brown dwarfs are actively forming gas and dust clouds around themselves, from which, in turn, planets are formed. Such a planetary system was recently discovered in the constellation Chameleon.
Nearest object
And in 2014, all astronomical magazines were full of headlines: “A brown dwarf was found in the vicinity of the solar system.” The brown dwarf was named WISE J085510.83-071442.5. It is located approximately 7.2 light years from the Sun. For comparison: the closest system to us is Alpha Centauri, and it is located 4 light years from planet Earth. The mass of this brown dwarf has been estimated by scientists approximately. It is believed that this object is 3-10 times larger than the planet Jupiter. Some astronomers suggest that with such a mass, the brown dwarf could once have been classified as a gas giant, which was eventually thrown out of the solar system.
However, most researchers are still inclined to believe that this object belongs to the group of brown dwarfs. After all, they are quite common in the Universe. Subsequently, astronomer Kevin Luhmann, who analyzed photographs of this object, discovered two more brown dwarfs. They are located at a distance of 6.5 light years from our planet. Astronomers have not yet discovered any other brown dwarfs directly in the Solar System. Perhaps all these discoveries are yet to come in the future.
Mysterious satellite of the Sun
There is another assumption about the existence of a special brown dwarf in the solar system - Nemesis. This is a theoretically proposed star that was once a “companion” of the Sun. However, scientists are still arguing about which category it belongs to - brown, red or white dwarfs. The theory of the existence of Nemesis was put forward in order to explain the cyclical process of extinction of various biological species on Earth - according to scientists, this happened every 27 billion years.
However, astronomers have not yet found confirmation of the existence of Nemesis. It is believed that this star could be a satellite of the Sun and rotate in a more elongated orbit. The theory that there is another star revolving around the Sun was popular in scientific circles in the 70s and 80s of the last century. When the star approached the planets, it caused gravitational disturbances in their orbits, which could lead to mass extinction of species. In addition, the star could bring comets to earth from the Oort cloud, through which it passed every 27 billion years.
Brown dwarfs in the vicinity of the solar system
Not long ago, astronomers discovered a group of ultra-cold stars - brown dwarfs - near the solar system. The research was led by Montreal astronomer J. Robert. These discoveries will help scientists further determine how densely these objects are located near our star system, as well as in other nearby areas. Astronomer J. Robert's team discovered 165 brown dwarfs. A third of these supercool stars (a term meaning their surface temperatures are less than 2,200 Kelvin) have quite unusual chemical compositions. Scientists believe that the discovery of most stars of this type will only occur in the future, because previous scientists “overlooked” a large number of objects.
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