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What is a star? A star is a massive gas ball that emits light and is held in a state of equilibrium by its own gravity and internal pressure, in the depths of which thermonuclear fusion reactions take place (or have happened before).
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Stars are formed from a gas-dust environment as a result of gravitational compression. The energy of the vast majority of stars is released as a result of thermonuclear reactions the conversion of hydrogen into helium, occurring at high temperatures in the interior. Stars are often called the main bodies of the universe, since they contain the bulk of the luminous matter in nature. It is noteworthy that stars have a negative heat capacity.
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The closest star to the Sun is Proxima Centauri. It is located 4.2 light years (4.2 light years = 39 Pm = 39 trillion km = 3.9 × 1013 km) from the center solar system
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Comparison of the sizes and masses of the largest stars: the star with the largest diameter in the figure is VY Big Dog(17 ± 8 Mʘ); others are ρ Cassiopeia (14-30 Mʘ), Betelgeuse (11.6 ± 5.0 Mʘ) and the very massive blue star Pistol (27.5 Mʘ). The sun at this scale takes up 1 pixel in the full size image (2876 × 2068 pixels).
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With the naked eye, about 6,000 stars are visible in the sky, 3,000 in each hemisphere. With the exception of supernovae, all stars visible from the Earth (including those visible in the most powerful telescopes) are in the local group of galaxies. Local group of galaxies - a gravitationally bound group of galaxies, including Milky Way, the Andromeda Galaxy (M31) and the Triangulum Galaxy (M33).
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Units of measurement Most stellar characteristics are usually expressed in SI, but CGS is also used. To indicate the distance to the stars, units such as a light year and a parsec are adopted. Large distances, such as the radius of giant stars or the semi-major axis of binary star systems, are often expressed using an astronomical unit (AU), equal to the average distance between the Earth and the Sun (about 150 million km).
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Types of stars Types of line spectra At the beginning of the 20th century, Hertzsprung and Russell plotted various stars on the "Absolute Magnitude" - "Spectral Class" diagram, and it turned out that most of them were grouped along a narrow curve. Later, this diagram (now called the Hertzsprung-Russell diagram) turned out to be the key to understanding and studying the processes occurring inside the star.
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Absolute magnitude - physical quantity characterizing the luminosity of an astronomical object. For different types of objects, different definitions of the absolute value are used.
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How a star is structured Structure In the general case, a star located on the main sequence can be divided into three internal zones: the core, the convective zone, and the radiative transport zone. The core is the central region of a star in which nuclear reactions take place. Convective zone - a zone in which the transfer of energy occurs due to convection. For stars with a mass less than 0.5 M☉, it occupies the entire space from the surface of the core to the surface of the photosphere. For stars with a mass comparable to the sun, the convective part is at the very top, above the radiant zone. And for massive stars, it is inside, under the radiant zone. The location of the radiant zone and the convection zone in stars of different masses The radiant zone is the zone in which energy transfer occurs due to the emission of photons. For massive stars, this zone is located between the core and the convective zone, for low-mass stars it is absent, and for stars more than the mass of the Sun is near the surface.
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Above the surface of a star is an atmosphere, usually composed of three parts: photospheres of the coronal chromosphere The photosphere is the deepest part of the atmosphere; a continuous spectrum is formed in its lower layers.
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Brown dwarfs Brown dwarfs are a type of star in which nuclear reactions have never been able to compensate for the energy lost to radiation. Their existence was predicted in the middle of the 20th century, based on ideas about the processes that occur during the formation of stars. However, in 1995, a brown dwarf was first discovered. Their spectral class is M - T. In theory, another class is distinguished - designated Y (in 2011 its existence was confirmed by the discovery of several stars with a temperature of 300-500 K) WISE J014807.25−720258.8, WISE J041022.71+150248.5, WISE J140518. 40+553421.5, WISE J154151.65−225025.2, WISE J173835.52+273258.9, WISE J1828+2650 WISE J205628.90+145953.3 Comparative sizes of brown dwarfs Gliese 229B and Teide 1 with Jupiter and the Sun.
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Asteroid disk around a brown dwarf. View from a hypothetical planet from a distance of about 3 million kilometers.
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Spectral Types of Brown Dwarfs Spectral Type M Brown dwarfs that are close in mass to red dwarfs may have a spectral type of M6.5 or dimmer in their early stages after formation. Such stars are also sometimes called "late M-dwarfs". Cooling down, they gradually pass into the class L more characteristic of brown dwarfs. Spectral class L In terms of spectral lines, it is completely different from M. In the red optical spectrum, the lines of titanium and vanadium oxides are were still strong, but there were also strong lines of metal hydrides, such as FeH, CrH, MgH, CaH. There were also strong lines alkali metals and iodine.
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Spectral type T The brown dwarf Gliese 229 B is the prototype of the second new spectral type, which has been called the T dwarf. While the near-infrared (NIR) spectrum of L-dwarfs is dominated by absorption bands of water and carbon monoxide (CO), the NIR spectrum of Gliese 229 B is dominated by methane (CH4) bands. Similar characteristics have previously been found outside the Earth only in the gas giants of the solar system and Saturn's moon Titan. In the red part of the spectrum, instead of the FeH and CrH bands characteristic of L-dwarfs, the spectra of alkali metals - sodium and potassium - are observed. Only comparatively low-mass brown dwarfs can be T-dwarfs. The mass of a T-dwarf usually does not exceed 7% of the mass of the Sun or 70 masses of Jupiter. In their properties, class T dwarfs are similar to gas giant planets.
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Other cool brown dwarfs (CFBDS J005910.90-011401.3, ULAS J133553.45+113005.2 and ULAS J003402.77-005206.7) have a surface temperature of 500-600 K (200-300 °C) and belong to the T9 spectral class. Their absorption spectrum is at 1.55 µm wavelength (infrared) Spectral type Y This spectral type has been modeled for ultra-cool brown dwarfs. The surface temperature should theoretically have been below 700 K (or 400 °C), which made such brown dwarfs invisible in the optical range, and also significantly colder than "hot Jupiters". In August 2011, American astronomers reported the discovery of seven ultracold brown dwarfs with effective temperatures in the range of 300-500 K. Of these, 6 were classified as Y-class. WISE temperature 1828+2650 ~ 25 °C. The brown dwarf WISE 1541-2250 of spectral type Y0.5 is located at 18.6 ly. years (5.7 pc) from the Sun, a brown dwarf fairly close to the Sun, located in the constellation Libra. The main criterion that separates the spectral class T from Y is the presence of ammonia absorption bands in the spectrum. However, it is difficult to identify whether these bands are there or not, since substances such as methane and water can also absorb.
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Ways to distinguish a brown dwarf from a planet: Density measurement. All brown dwarfs have approximately the same radius and volume. The presence of X-ray and infrared radiation. Some brown dwarfs emit X-rays. All "warm" dwarfs radiate in the red and infrared ranges until they cool down to a temperature comparable to the planetary temperature (up to 1000 K).
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White dwarfs White dwarfs are evolved stars with a mass not exceeding the Chandrasekhar limit, devoid of their own sources of thermonuclear energy. The average density of matter in white dwarfs within their photospheres is 105-109 g/cm³, which is almost a million times higher than the density of main sequence stars. By prevalence, white dwarfs make up, according to various estimates, 3-10% of the stellar population of our Galaxy.
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The history of the discovery The first discovered white dwarf was the star 40 Eridani B in the triple system 40 Eridani, which, back in 1785, William Herschel included in the catalog of double stars 40 Eridani or omicron² Eridani - a triple star system close to Earth in the constellation Eridani. Located at a distance of 16.45 St. years (5.04 pc) from the Sun.
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The color temperature of the light source: characterizes the spectral composition of the radiation of the light source, is the basis for the objectivity of the impression of the color of reflecting objects and light sources.
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The second and third discovered white dwarfs were Sirius B and Procyon B. In 1844, the director of the Königsberg Observatory, Friedrich Bessel, analyzing the observational data that had been conducted since 1755, found that Sirius, brightest star Earth's sky, and Procyon periodically, albeit very weakly, deviate from a rectilinear trajectory of movement along the celestial sphere .. Bessel came to the conclusion that each of them must have a close satellite. Sirius A and B. Image of the Hubble telescope. Interestingly, this implies that Sirius B must have been much more massive than Sirius A in the past, since it had already left the main sequence in the process of evolution.
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In 1917, Adrian van Maanen discovered another white dwarf - van Maanen's star in the constellation Pisces. In 1922, Willem Jakob Leuten suggested calling such stars "white dwarfs". Star of Leuthen
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Procyon B is a dim white dwarf ≈16 AU distant from Procyon A. (distance from the Sun to Uranus). According to its characteristics, it is similar to the white dwarf near Sirius, but it is more difficult to find it in amateur telescopes. The mass of Procyon B is less than that of Sirius B. Its existence was predicted in 1844 by F. Bessel based on an analysis of the secular motion of Procyon A across the celestial sphere. Discovered in 1896 by the American astronomer D. M. Sheberle.
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Shortly after a helium flash, carbon and oxygen "light up"; the restructuring of the star and its rapid movement along the Hertzsprung-Russell diagram takes place. The size of the star's atmosphere increases even more, and it begins to intensively lose gas in the form of expanding stellar wind streams. The vast majority of stars end their evolution by shrinking until the pressure of degenerate electrons balances gravity. When the size of a star decreases by a factor of a hundred, and the density becomes a million times higher than that of water, the star is called a white dwarf. It is deprived of sources of energy and, gradually cooling down, becomes dark and invisible.
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Mass - radius dependence for white dwarfs. The vertical asymptote corresponds to the Chandrasekhar limit, the pressure drop and gravitational forces are equally dependent on the radius, but differently dependent on the mass - both respectively. with increasing mass white dwarf its radius decreases. If the mass is greater than a certain limit (the Chandrasekhar limit), then the star collapses. for white dwarfs, there is also a lower limit: the rate of evolution of stars is proportional to their mass, then we can observe low-mass white dwarfs as the remains of only those stars that managed to evolve during the time from the initial period of star formation of the Universe to the present day.
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A population of white dwarfs in the globular star cluster NGC 6397. Blue squares are helium white dwarfs, purple circles are "normal" high carbon white dwarfs
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White dwarfs are allocated to a separate spectral class D; currently, a classification is used that reflects the features of the spectra of white dwarfs, proposed in 1983 by Edward Sion; in this classification, the spectral class is written in the following format: Subclasses: DA - lines of the Balmer series of hydrogen are present in the spectrum, lines of helium are not observed; DB - helium He I lines are present in the spectrum, hydrogen or metal lines are absent; DC - continuous spectrum without absorption lines; DO - strong helium He II lines are present in the spectrum, He I and H lines may also be present; DZ - only metal lines, no H or He lines; DQ - lines of carbon, including molecular C2; and spectral features: P - observed polarization of light in a magnetic field; H - polarization if present magnetic field not visible; V - ZZ Ceti type stars or other variable white dwarfs; X - Peculiar or unclassified spectra.
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Red giants A red giant is a star of late spectral types with high luminosity and extended envelopes. Examples of red giants are Arcturus, Aldebaran, Gacrux, and Mira A.
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Mira with a "tail" (fragment of a photo taken by the GALEX telescope). Aldebaran Arcturus
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Evolutionary tracks of stars of different masses during the formation of red giants on the Hertzsprung-Russell diagram
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A planetary nebula is an astronomical object consisting of an ionized gas envelope and a central star, a white dwarf. Planetary nebulae are formed during the ejection of the outer layers (shells) of red giants and supergiants with a mass of 0.8 to 8 solar masses at the final stage of their evolution. A planetary nebula is a fast-moving (by astronomical standards) phenomenon lasting only a few tens of thousands of years, while the lifespan of the ancestor star is several billion years. Currently, about 1500 planetary nebulae are known in our galaxy.
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NGC 6543, Cat's Eye Nebula - inner region, pseudo color image (red - Hα; blue - neutral oxygen, 630 nm; green - ionized nitrogen, 658.4 nm)
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An international team of astronomers at the European Southern Observatory have discovered the largest and hottest binary star system with the Largest Telescope ever. Two stars are at such a small distance that they practically touch each other, exchanging matter. The future of this system is most likely sad - the luminaries will either collapse and create one big star or form a binary black hole.
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VFTS 352, the largest binary star system known to date, lies 160,000 light-years from Earth in the Tarantula Nebula in the constellation Dorado. This was reported on the website of the European Southern Observatory (ESO).
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“If the stars mix well enough, then perhaps they will retain their sizes. Then the VFTS 352 system will avoid merging and becoming a giant megastar. This will lead the luminaries to a new evolutionary path, which is fundamentally different from the classical development of stars. But in the case of VFTS 352, the components of the system are likely to end their lives in a supernova explosion and turn into a pair of black holes that will become the source of the strongest gravity, ”said Selma de Mink from the University of Amsterdam. The most massive star known to science. Refers to the blue hypergiants. The star is also one of the brightest, emitting light, according to the highest estimates, up to 10 million times more than the Sun.
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Presentation on the topic: “Internal structure of the C sun" Completed by student 11 "a" class GBOU secondary school 1924 Gubernatorov Anton
The internal structure of the Sun.
The Sun is the only star in the solar system around which other objects of this system revolve: planets and their satellites, dwarf planets and their satellites, asteroids, meteoroids, comets and cosmic dust.
Structure of the Sun: -Solar core. - Radiant transfer zone. - The convective zone of the Sun.
Solar core. The central part of the Sun with a radius of about 150,000 kilometers, in which thermonuclear reactions take place, is called the solar core. The density of matter in the core is approximately 150,000 kg/m³ (150 times higher than the density of water and ~6.6 times higher than the density of the dense metal on Earth - osmium), and the temperature in the center of the nucleus is more than 14 million degrees.
Radiant transfer zone. Above the core, at distances of about 0.2-0.7 of the Sun's radius from its center, there is a radiative transfer zone, in which there are no macroscopic movements, energy is transferred using photon re-emission.
convective zone of the sun. Closer to the surface of the Sun, vortex mixing of the plasma occurs, and the transfer of energy to the surface occurs mainly by the motions of the matter itself. This method of energy transfer is called convection, and the subsurface layer of the Sun, approximately 200,000 km thick, where it occurs, is called the convective zone. According to modern data, its role in the physics of solar processes is exceptionally great, since it is in it that various motions of solar matter and magnetic fields originate.
Atmosphere of the Sun: -Photosphere. -Chromosphere. -Crown. -Sunny wind.
Photosphere of the Sun. The photosphere (a layer that emits light) forms the visible surface of the Sun, from which the dimensions of the Sun, the distance from the surface of the Sun, etc. are determined. The temperature in the photosphere reaches an average of 5800 K. Here, the average gas density is less than 1/1000 of the density of terrestrial air.
Chromosphere of the Sun. The chromosphere is the outer shell of the Sun with a thickness of about 10,000 km, surrounding the photosphere. The origin of the name of this part of the solar atmosphere is associated with its reddish color. The upper boundary of the chromosphere does not have a pronounced smooth surface; hot ejections, called spicules, constantly occur from it. The temperature of the chromosphere increases with altitude from 4,000 to 15,000 degrees.
Crown of the Sun. The corona is the last outer shell of the Sun. Despite its very high temperature, between 600,000 and 5,000,000 degrees, it is only visible to the naked eye during a total solar eclipse.
Sunny wind. Many natural phenomena on Earth are associated with disturbances in the solar wind, including geomagnetic storms and auroras.
Energy sources of stars If the Sun consisted of hard coal and the source of its energy was combustion, then for while maintaining current level radiating energy from the Sun would completely burn out in 5000 years. But the Sun has been shining for billions of years already! If the Sun consisted of coal and the source of its energy was combustion, then in order to maintain the current level of radiation energy, the Sun would completely burn out in 5000 years. But the Sun has been shining for billions of years! The question of the energy sources of stars was raised by Newton. He assumed that the stars replenish their energy supply at the expense of falling comets. The question of the sources of stellar energy was raised by Newton. He assumed that the stars replenish their energy supply due to falling comets. In 1845, German. Physicist Robert Meyer () tried to prove that the Sun shines due to the fall of interstellar matter on it. In 1845, it. Physicist Robert Meyer () tried to prove that the Sun shines due to the fall of interstellar matter on it. Hermann Helmholtz suggested that the Sun radiates part of the energy released during its slow contraction. From simple calculations, you can find out that the Sun would completely disappear in 23 million years, which is too little. By the way, this source of energy, in principle, takes place before the stars enter the main sequence. Hermann Helmholtz suggested that the Sun radiates part of the energy released during its slow contraction. From simple calculations, you can find out that the Sun would completely disappear in 23 million years, which is too little. By the way, this source of energy, in principle, takes place before the exit of stars to the main sequence. Hermann Helmholtz (d.)
The internal structure of stars Energy sources of stars At high temperatures and masses of more than 1.5 solar masses, the carbon cycle (CNO) dominates. Reaction (4) is the slowest - it takes about 1 million years. In this case, slightly less energy is released, because. more than it is carried away by neutrinos. At high temperatures and masses of more than 1.5 solar masses, the carbon cycle (CNO) dominates. Reaction (4) is the slowest - it takes about 1 million years. In this case, slightly less energy is released, because. more of it is carried away by neutrinos. This cycle was independently developed by Hans Bethe and Carl Friedrich von Weizsacker in 1938. This cycle was independently developed by Hans Bethe and Carl Friedrich von Weizsacker in 1938.
The internal structure of stars Energy sources of stars When the combustion of helium in the interior of stars ends, at higher temperatures other reactions become possible in which more heavy elements up to iron and nickel. These are a-reactions, carbon combustion, oxygen combustion, silicon combustion ... When the combustion of helium in the interior of stars ends, at higher temperatures other reactions become possible in which heavier elements are synthesized, up to iron and nickel. These are a-reactions, carbon combustion, oxygen combustion, silicon combustion ... Thus, the Sun and planets were formed from the "ash" of long-exploded supernovae. Thus, the Sun and planets were formed from the "ash" of long-exploded supernovae.
The internal structure of stars Models of the structure of stars In 1926, Arthur Eddington's book "The Internal Structure of Stars" was published, with which, one might say, the study of the internal structure of stars began. In 1926, Arthur Eddington's book "The Internal Structure of Stars" was published, with which , one might say, the study of the internal structure of stars began. Eddington made an assumption about the equilibrium state of main sequence stars, i.e., about the equality of the energy flux generated in the interior of a star and the energy radiated from its surface. Eddington made an assumption about the equilibrium state of main sequence stars, i.e., about equality the flow of energy generated in the bowels of the star, and the energy radiated from its surface. Eddington did not imagine the source of this energy, but quite correctly placed this source in the hottest part of the star - its center and suggested that a large energy diffusion time (millions of years) would even out all changes except those that appear near the surface. Eddington did not represent the source of this energy, but correctly placed this source in the hottest part of the star - its center and assumed that a large time of energy diffusion (millions of years) would even out all changes, except for those that appear near the surface.
The internal structure of stars Models of the structure of stars Equilibrium imposes strict restrictions on the star, i.e., having come into a state of equilibrium, the star will have a strictly defined structure. At each point of the star, the balance of gravitational forces, thermal pressure, radiation pressure, etc. must be observed. Also, the temperature gradient must be such that the outward heat flux strictly corresponds to the observed radiation flux from the surface. Equilibrium imposes severe restrictions on the star, i.e., into a state of equilibrium, the star will have a strictly defined structure. At each point of the star, the balance of gravitational forces, thermal pressure, radiation pressure, etc. must be observed. Also, the temperature gradient must be such that the outward heat flux strictly corresponds to the observed radiation flux from the surface. All these conditions can be written in the form of mathematical equations (at least 7), the solution of which is possible only by numerical methods. All these conditions can be written in the form of mathematical equations (at least 7), the solution of which is possible only by numerical methods.
The internal structure of stars Models of the structure of stars Mechanical (hydrostatic) balance The force due to the pressure difference directed from the center must be equal to the force of gravity. d P/d r = M(r)G/r 2, where P is the pressure, is the density, M(r) is the mass within a sphere of radius r. Energy balance The increase in luminosity due to the source of energy contained in a layer of thickness dr at a distance from the center r is calculated by the formula dL/dr = 4 r 2 (r), where L is the luminosity, (r) is the specific energy release of nuclear reactions. Thermal equilibrium The temperature difference at the inner and outer boundaries of the layer must be constant, and the inner layers must be hotter.
The internal structure of stars 1. The core of the star (the zone of thermonuclear reactions). 2. The zone of radiative transfer of the energy released in the core to the outer layers of the star. 3. Zone of convection (convective mixing of matter). 4. Helium isothermal core from a degenerate electron gas. 5. Shell of an ideal gas.
The internal structure of stars The structure of stars up to the solar mass Stars with a mass of less than 0.3 solar masses are completely convective, due to their low temperatures and high extinction coefficients. Stars with a mass of less than 0.3 solar masses are completely convective, due to their low temperatures and high absorption coefficients. Solar-mass stars in the core undergo radiative transport, while in the outer layers it is convective. Solar-mass stars in the core undergo radiative transport, while in the outer layers it is convective. Moreover, the mass of the convective shell rapidly decreases when moving up the main sequence. Moreover, the mass of the convective shell rapidly decreases when moving up the main sequence.
The internal structure of stars The structure of degenerate stars The pressure in white dwarfs reaches hundreds of kilograms per cubic centimeter, while in pulsars it is several orders of magnitude higher. The pressure in white dwarfs reaches hundreds of kilograms per cubic centimeter, and in pulsars it is several orders of magnitude higher. At such densities, the behavior differs sharply from that of an ideal gas. Stops acting gas law Mendeleev-Clapeyron - pressure no longer depends on temperature, but is determined only by density. This is the state of degenerate matter. At such densities, the behavior differs sharply from that of an ideal gas. The Mendeleev-Clapeyron gas law ceases to operate - pressure no longer depends on temperature, but is determined only by density. This is the state of degenerate matter. The behavior of a degenerate gas, consisting of electrons, protons and neutrons, obeys quantum laws, in particular, the Pauli exclusion principle. He claims that no more than two particles can be in the same state, and their spins are directed oppositely. The behavior of a degenerate gas, consisting of electrons, protons and neutrons, obeys quantum laws, in particular, the Pauli exclusion principle. He claims that no more than two particles can be in the same state, and their spins are directed oppositely. In white dwarfs, the number of these possible states is limited, gravity tries to squeeze the electrons into the already occupied places. In this case, a specific force of counteraction to pressure arises. In this case, p ~ 5/3. In white dwarfs, the number of these possible states is limited, gravity trying to squeeze electrons into already occupied places. In this case, a specific force of counteraction to pressure arises. In this case, p ~ 5/3. At the same time, electrons have high speeds of movement, and the degenerate gas has high transparency due to the employment of all possible energy levels and the impossibility of the absorption-reradiation process. At the same time, electrons have high speeds of movement, and the degenerate gas has high transparency due to the employment of all possible energy levels and the impossibility of the absorption-reemission process.
The internal structure of stars The structure of a neutron star At densities above g / cm 3, the process of neutronization of matter occurs, the reactions + e n + At densities above g / cm 3, the process of neutronization of matter occurs, the reactions + e n + B in 1934 Fritz Zwicky and Walter Baarde were theoretically predicted the existence of neutron stars whose equilibrium is maintained by neutron gas pressure. In 1934, Fritz Zwicky and Walter Baarde theoretically predicted the existence of neutron stars whose equilibrium is maintained by neutron gas pressure. The mass of a neutron star cannot be less than 0.1M and more than 3M. The density in the center of a neutron star reaches g/cm3. The temperature in the interior of such a star is measured in hundreds of millions of degrees. The sizes of neutron stars do not exceed tens of kilometers. The magnetic field on the surface of neutron stars (a million times greater than that of the earth) is a source of radio emission. The mass of a neutron star cannot be less than 0.1M and greater than 3M. The density in the center of a neutron star reaches g/cm3. The temperature in the interior of such a star is measured in hundreds of millions of degrees. The sizes of neutron stars do not exceed tens of kilometers. The magnetic field on the surface of neutron stars (a million times greater than that of the earth) is a source of radio emission. On the surface of a neutron star, matter must have the properties solid body, i.e., neutron stars are surrounded by a solid crust several hundred meters thick. On the surface of a neutron star, the matter must have the properties of a solid body, i.e., neutron stars are surrounded by a solid crust several hundred meters thick.
MM.Dagaev and others. Astronomy - M.: Enlightenment, 1983 MM.Dagaev and others. Astronomy - M.: Education, 1983 P.G. Kulikovsky. Astronomy Amateur's Handbook - M.URSS, 2002 P.G. Kulikovsky. Astronomy Amateur's Handbook - M.URSS, 2002 M.M.Dagaev, V.M.Charugin Astrophysics. Reading book on astronomy - M.: Enlightenment, 1988 M.M.Dagaev, V.M.Charugin Astrophysics. Reading book on astronomy - M.: Enlightenment, 1988 A.I. Eremeeva, F.A. Tsitsin "History of Astronomy" - M.: Moscow State University, 1989 A.I. Eremeeva, F.A. Tsitsin "History of Astronomy" - M .: Moscow State University, 1989 W. Cooper, E. Walker "Measuring the light of stars" - M .: Mir, 1994 W. Cooper, E. Walker "Measuring the light of stars" - M. : World, 1994 R. Kippenhan. 100 billion suns. Birth, life and death of stars. M.: Mir, 1990. R. Kippenhan. 100 billion suns. Birth, life and death of stars. Moscow: Mir, 1990 Internal structure of stars References
"Black holes of the Universe" - The history of ideas about black holes. The question of the real existence of black holes. Detection of black holes. collapsing stars. Dark matter. Difficulty. Black holes and dark matter. Supermassive black holes. hot dark matter. Cold dark matter. Warm dark matter. Primitive black holes.
"The physical nature of the stars" - Betelgeuse. The luminosities of other stars are determined in relative units, compared with the luminosity of the Sun. Comparative sizes of the Sun and dwarfs. Stars can differ in luminosity by a billion times. Thus, the masses of the stars differ by only a few hundred times. Our Sun is a yellow star, the temperature of the photosphere of which is about 6000 K. The same color is Capella, the temperature of which is also about 6000 K.
"Evolution of the Stars" - Supernova explosion. The Orion Nebula. Compression is a consequence of gravitational instability, Newton's idea. The universe is made up of 98% stars. As the density of the cloud increases, it becomes opaque to radiation. Astronomers are unable to trace the life of a single star from beginning to end. Nebula Eagle.
"Stars on the sky" - general characteristics stars. The evolution of the stars. "Burnout" of hydrogen. Chemical composition. There are many legends about Ursa Major and Ursa Minor. Temperature determines the color of a star and its spectrum. star radius. The winter sky is richest in bright stars. What did the ancient Greeks say about bears?
"Distances to the stars" - Stars differ in color, brilliance. Even with the naked eye you can see that the world around us is extremely diverse. Hipparchus. 1 parsec = 3.26 light years = 206 265 astronomical units = 3.083 1015 m. From the spectral lines, you can estimate the luminosity of a star, and then find the distance to it.
"Starry sky" - Late at night in the sky you see a lot of stars. constellations. Name the constellations you know. Planet Earth. The earth is the habitat of man. Planets. Stars on the sky. Light from the Sun reaches the Earth in 8.5 minutes. A legend has come down to us from the ancient Greeks. In 1609, Galileo first looked at the moon through a telescope.
In total there are 17 presentations in the topic
