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Stars The universe is made up of 98% stars. They are also the main element of the galaxy. “Stars are huge balls of helium and hydrogen, as well as other gases. Gravity pulls them in, and the hot gas pressure pushes them out, creating balance. The energy of a star is contained in its core, where every second helium interacts with hydrogen.”
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The life of stars life path separate organism. Astronomers are unable to trace the life of a single star from beginning to end. Even the shortest-lived stars exist for millions of years - longer than the life of not only one person, but of all mankind. However, scientists can observe many stars at various stages of their development - just born and dying. Based on numerous stellar portraits, they are trying to reconstruct the evolutionary path of each star and write its biography.
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Regions of star formation Regions of star formation. Giant molecular clouds with masses greater than 105 solar masses (more than 6,000 of them are known in the Galaxy) The Eagle Nebula, 6000 light-years away, is a young open star cluster in the constellation Serpens, dark regions in the nebula are protostars
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The Orion Nebula The Orion Nebula is a luminous emission nebula with a greenish tint and lies below Orion's Belt and can even be seen naked eye 1300 light years from us, and a magnitude of 33 light years
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Gravitational contraction Gravitational contraction Compression is a consequence of gravitational instability, Newton's idea. Jeans later determined the minimum size of clouds in which spontaneous contraction can begin. A rather effective cooling of the medium takes place: the released energy of gravity goes into infrared radiation, which goes into outer space.
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Protostar Protostar As the density of the cloud increases, it becomes opaque to radiation. The temperature of the inner regions begins to rise. The temperature in the interior of a protostar reaches the threshold of thermonuclear fusion reactions. Compression stops for a while.
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Stationary state young star came to the main sequence H-R diagrams the process of hydrogen burnout has begun - the main stellar nuclear fuel is practically not compressed, and energy reserves no longer change slow change chemical composition in its central regions, due to the conversion of hydrogen into helium, the star passes into a stationary state
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Giants and supergiants When hydrogen is completely burnt out, the star leaves the main sequence in the region of giants or, with large masses, supergiants Giants and supergiants
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Gravitational contraction mass of a star< 1,4 массы Солнца: БЕЛЫЙ КАРЛИК электроны обобществляются, образуя вырожденный электронный газ гравитационное сжатие останавливается плотность становится до нескольких тонн в см3 еще сохраняет Т=10^4 К постепенно остывает и медленно сжимается(миллионы лет) окончательно остывают и превращаются в ЧЕРНЫХ КАРЛИКОВ Когда все ядерное топливо выгорело, начинается процесс гравитационного сжатия.
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Dwarfs A white dwarf in a cloud of interstellar dust Two young black dwarfs in the constellation Taurus
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The mass of the star the mass of the star > 1.4 solar masses: the forces of gravitational compression are very high the density of matter reaches a million tons per cm3 huge energy is released - 10 ^ 45 J temperature - 10 ^ 11 K supernova explosion most of the star is ejected into outer space at a speed of 1000 -5000 km / s neutrino flows cool the core of a star - Neutron star
Cousin Sofya and Shevyako Anna
Astronomy, as a subject, is derived from school curriculum. However, in physics of grade 11 under the program of the Federal State Educational Standard there is a chapter "Structure of the Universe". This chapter has lessons physical characteristics stars" and "Evolution of the stars". This presentation, made by the students, is additional material for these lessons. The work is done aesthetically, colorfully, competently and the material proposed in it goes beyond the scope of the program.
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The birth and evolution of stars The work was done by: students of grade 11 "L" MBOU "Secondary School No. 37", Kemerovo Kuzina Sofya and Shevyako Anna. Leader: Shinkorenko Olga Vladimirovna, teacher of physics.
The birth of a star Space is often called airless space, believing it to be empty. However, it is not. In interstellar space there is dust and gas, mainly helium and hydrogen, with the latter much more abundant. There are even entire clouds of dust and gas in the universe that can collapse under the influence of gravitational forces.
The birth of a star In the process of contraction, part of the cloud will heat up and condense. If the mass of the compressing matter is sufficient for nuclear reactions to begin to occur inside it during the compression process, then a star is obtained from such a cloud.
Birth of a star Each "newborn" star, depending on its initial mass, occupies a certain place on the Hertzsprung-Russell diagram - a graph, on one axis of which the color index of the star is plotted, and on the other - its luminosity, i.e. the amount of energy emitted per second. The color index of a star is related to the temperature of its surface layers - the lower the temperature, the redder the star, and its color index is greater.
Life of a star In the process of evolution, stars change their position on the "spectrum-luminosity" diagram, moving from one group to another. A star spends most of its life on the Main Sequence. To the right and up from it are both the youngest stars and stars that have advanced far along their evolutionary path.
Life of a star The life of a star depends mainly on its mass. According to theoretical calculations, the mass of a star can vary from 0.08 to 100 solar masses. The greater the mass of a star, the faster hydrogen burns out, and the heavier elements can be formed in the process of thermonuclear fusion in its depths. At a late stage of evolution, when helium burning begins in the central part of the star, it descends from the Main Sequence, becoming, depending on the mass, a blue or red giant.
The life of a star But there comes a time when a star is on the verge of a crisis, it can no longer produce the necessary amount of energy to maintain internal pressure and resist the forces of gravity. The process of uncontrollable compression (collapse) begins. As a result of the collapse, stars with a huge density (white dwarfs) are formed. Simultaneously with the formation of a superdense core, the star sheds its outer shell, which turns into a gas cloud - a planetary nebula and gradually dissipates in space. A star of greater mass can shrink to a radius of 10 km, turning into a neutron star. One tablespoon of a neutron star weighs 1 billion tons! The last stage in the evolution of an even more massive star is the formation of a black hole. The star shrinks to such a size that the second space velocity becomes equal to the speed of light. In the region of a black hole, space is strongly curved, and time slows down.
Life of a star The formation of neutron stars and black holes is necessarily associated with a powerful explosion. A bright point appears in the sky, almost as bright as the galaxy in which it flared up. This is a supernova. Mentions found in ancient chronicles about the appearance in the sky the brightest stars, this is nothing but evidence of colossal cosmic explosions.
The death of a star The star loses its entire outer shell, which, expanding at high speed, dissolves without a trace in the interstellar medium after hundreds of thousands of years, and before that we observe it as an expanding gaseous nebula. For the first 20,000 years, the expansion of the gas envelope is accompanied by powerful radio emission. During this time, it is a hot plasma ball that has a magnetic field that holds the high-energy charged particles formed in the supernova. The more time has passed since the explosion, the weaker the radio emission and the lower the plasma temperature.
Examples of stars Galaxy in the constellation Ursa Major Ursa Major
Examples of the main constellations Andromeda
Used literature Karpenkov S. Kh. Concepts modern natural science. - M., 1997. Shklovsky IS Stars: their birth, life and death. - M.: Nauka, Main edition of physical and mathematical literature, 1984. - 384 p. Vladimir Surdin How Stars Are Born - Rubric "Planetarium", Around the World, No. 2 (2809), February 2008 Karpenkov S.Kh. Basic concepts of natural science. - M., 1998. Novikov ID Evolution of the Universe. - M., 1990. Rovinsky RE Developing Universe. - M., 1995.
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Origin and evolution of galaxies and stars Star formation region - Orion Nebula (M42), Mr. Alnitak Alnilam
Star Formation Model The radius of the visible part of the Universe - the Metagalaxy - cannot exceed the distance that radiation travels in a time equal to the age of the Universe - 13.7 ± 2 billion years according to modern concepts. Therefore, galaxies born almost 0.5 billion years from big bang, have an age of over 13 billion years. The oldest stars with an age of over 10 billion years are part of globular star clusters (population type 2 with a low abundance of elements heavier than He). They most likely formed at the same time as galaxies. Globular star cluster M80 in the constellation Scorpio at 8280 pc.
Age of the Universe and galaxies a) The age of our Galaxy is 13.7 billion years (1% accuracy). b) The universe consists of - 4% of the atoms of visible matter; - 23% is dark matter; - the remaining 73% is the mysterious "anti-gravity" (dark energy), which causes the Universe to expand. Galaxies began to form 100 million years after the Big Bang and in the next 3-5 billion years they formed and grouped into clusters. Therefore, the age of the oldest elliptical galaxies is about 14 billion years. The first stars appear 1 million years after the Big Bang, so there must be stars with an age of about 14 billion years. On June 30, 2001, the NASA astronomical apparatus "MAP" ("Microwave Anisotropy Probe") with a mass of 840 kg and a cost of $ 145 million was launched from Cape Canaveral and on October 1, 2001 it reached the point of libration L2 (gravitational balance between the Sun, Earth and Moon), 1.5 million kilometers from Earth. The purpose of the spacecraft is to compile a three-dimensional picture of the explosion and look at a time when stars and galaxies have not yet arisen. WMAP: 1-balancing weights of the precision stabilization system, 2-navigation system sensor, 3-receiving electronics unit, 4-waveguide, 5-omnidirectional antenna, 6-mirror 1.4*1.6 m, 7-second reflector, 8- cooling, 9-mounting platform, 10-electronics, 11-shield from sunlight. By using spacecraft NASA WMAP collecting data on microwave background radiation, by 2006 found:
Short story development of the Universe TimeTemperatureState of the Universe secMore KInflationary expansion secMore KThe appearance of quarks and electrons sec10 12 KFormation of protons and neutrons sec - 3 min KThe formation of nuclei of deuterium, helium and lithium 400 thousand years 4000 KFormation of atoms 15 million years300 KContinuation of the expansion of the gas cloud 1 billion years20 KThe birth of the first stars and galaxies 3 billion years10 K Formation of heavy nuclei in star explosions billion years3 KThe appearance of planets and intelligent life years 10 -2 KCessation of the process of birth of stars years KDepletion of energy of all stars years-20K Evaporation of black holes and birth elementary particles years KCompletion of evaporation of all black holes
Star formation Stars are always formed in groups (clusters) as a result of gravitational instability in cold (T = 10 K) and dense molecular clouds with a mass of at least 2000 M. GMOs with a mass of more than 10 5 M (more than 6000 are known) contain up to 90% of the total molecular gas of the Galaxy . Accumulation of cold gas and dust - globule B68 (Barnard's catalogue), GMO fragment. The mass of the globule can reach up to 100 M shock waves in the expansion of supernova remnants, spiral density waves and stellar winds from hot OB stars. The temperature of the matter during the transition from molecular clouds through the fragmentation of the cloud (the appearance of globules) to stars increases millions of times, and the density increases several times. The stage of development of a star, characterized by compression and not yet having thermonuclear sources of energy, is called a protostar (Greek protos "first").
Evolution of solar-type stars In the emerging protostar, the core draws in all, or almost all, matter, contracts, and when the temperature inside exceeds 10 million K, the process of hydrogen burning out (thermonuclear reaction) begins. For stars with M, 60 million years have passed from the very beginning. On the main sequence - the longest stage in life, solar-type stars are 9-10 billion years old. In the layer adjacent to the core, as a rule, hydrogen remains, proton-proton reactions resume, the pressure in the shell increases significantly, and the outer layers of the star increase sharply in size - the star shifts to the right - to the region of red giants, increasing in size by about 50 times. At the end of its life, after the stage of a red giant, the star shrinks turning into a white dwarf, sheds the shell (up to 30% of the mass) in the form of a planetary nebula. The white dwarf continues to glow faintly for a very long time, until its heat is completely used up, and it turns into a dead black dwarf. After the star uses up the hydrogen contained in the central part, the helium core will begin to shrink, its temperature will rise so much that reactions with a large energy release will begin (at a temperature of K, helium combustion begins - it is a tenth of the combustion of H).
Evolution of Massive Stars Two main factors leading to loss of stability and collapse are now known: > 13 4 He + 4n, = at higher temperatures - dissociation of helium 4 He > 2n + 2p and matter neutronization (capture of electrons by protons with the formation of neutrons). The shedding of the star shell is explained by the interaction of neutrinos with matter. The decay of nuclei requires a significant expenditure of energy, the substance loses its elasticity, the nucleus contracts, the temperature rises, but not so fast as to stop the compression. Most of the energy released during compression is carried away by neutrinos. As a result of the neutronization of matter and the dissociation of nuclei, there is a kind of explosion of the star inside - implosion. The matter of the central region of the star falls towards the center with a velocity free fall, drawing in successively more and more distant from the center layers of the star. The collapse that has begun can be stopped by the elasticity of a substance that has reached nuclear density and consists mainly of degenerate neutrons (neutron liquid). This creates a neutron star. The shell of the star acquires a huge momentum and is thrown into interstellar space at a speed of up to km/s. During the collapse of the cores of the most massive stars with a mass of more than 30 solar masses, the implosion of the core apparently leads to the formation of a black hole. In stars with a mass greater than 10M, thermonuclear reactions proceed under nondegenerate conditions up to the formation of the most stable elements of the iron peak (Fig.). The mass of the evolving core weakly depends on the total mass of the star and is 2–2.5 M. 13 4 He + 4n, = at higher temperatures - dissociation of helium 4 He > 2n + 2p and neutronization of matter (capture of electrons by protons with the formation of neutrons). The shedding of the star shell is explained by the interaction of neutrinos with matter. The decay of nuclei requires a significant expenditure of energy, the substance loses its elasticity, the nucleus contracts, the temperature rises, but not so fast as to stop the compression. Most of the energy released during compression is carried away by neutrinos. As a result of the neutronization of matter and the dissociation of nuclei, there is a kind of explosion of the star inside - implosion. The matter of the central region of the star falls towards the center at the speed of free fall, drawing in successively more and more distant from the center layers of the star. The collapse that has begun can be stopped by the elasticity of a substance that has reached nuclear density and consists mainly of degenerate neutrons (neutron liquid). This creates a neutron star. The shell of the star acquires a huge momentum and is thrown into interstellar space at a speed of up to 10,000 km/s. During the collapse of the cores of the most massive stars with a mass of more than 30 solar masses, the implosion of the core apparently leads to the formation of a black hole. In stars with a mass greater than 10M, thermonuclear reactions proceed under nondegenerate conditions up to the formation of the most stable elements of the iron peak (Fig.). The mass of the evolving core weakly depends on the total mass of the star and is 2–2.5 M."> 
The last stage in the evolution of stars, the Crab Nebula is the gaseous remnant of a supernova with core collapse, the explosion of which was observed in 1054. In the center is a neutron star ejecting particles that cause the gas to glow (blue). The outer filaments are mostly hydrogen and helium from the collapsed massive star. NGC 6543, Inner Cat's Eye Nebula, pseudocolor image (red Hα; blue neutral oxygen, 630 nm; green ionized nitrogen, nm). Planetary nebulae are formed during the ejection of the outer layers (shells) of red giants and supergiants with a mass of 2.58 solar masses at the final stage of their evolution. Image: hot plasma accretion disk orbiting a black hole
Presentation
Topic: Birth and evolution of stars
Rodkina L. R.
Associate Professor of the Department of Electronics IIBS
VSUES, 2009
The birth of the stars
Star life
White dwarfs and neutron holes
Black holes
The death of the stars
Goals and objectives
To acquaint with the action of gravitational forces in the Universe, which lead to the formation of stars.
Consider the process of evolution of stars.
Give the concept of the spatial velocity of stars.
Describe the physical nature of stars.
The birth of a star
The birth of a star
The birth of a star
Star life
Star life
The lifetime of a star depends mainly on its mass. According to theoretical calculations, the mass of a star can vary from 0,08 before 100 solar masses.
The greater the mass of a star, the faster hydrogen burns out, and the heavier elements can be formed in the process of thermonuclear fusion in its depths. At a late stage of evolution, when helium burning begins in the central part of the star, it descends from the Main Sequence, becoming, depending on the mass, a blue or red giant.
Star life
Star life
Star death
Bibliography:
Shklovsky I.S. Stars: their birth, life and death. - M.: Nauka, Main edition of physical and mathematical literature, 1984. - 384 p.
Vladimir Surdin How stars are born - Heading "Planetarium", Around the World, No. 2 (2809), February 2008
Control questions
Where do stars come from?
How do they arise?
Since the lifetime of stars is limited, they must also appear in a finite time. How can we learn anything about this process?
Is it possible to see how stars form in the sky?
Are we witnessing their birth?
Used Books
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slide 1
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The universe is made up of 98% stars. They are also the main element of the galaxy.
“Stars are huge balls of helium and hydrogen, as well as other gases. Gravity pulls them in, and the hot gas pressure pushes them out, creating balance. The energy of a star is contained in its core, where every second helium interacts with hydrogen.”
slide 3
The life path of the stars is a complete cycle - birth, growth, a period of relatively calm activity, agony, death, and resembles the life path of an individual organism.
Astronomers are unable to trace the life of a single star from beginning to end. Even the shortest-lived stars exist for millions of years - longer than the life of not only one person, but of all mankind. However, scientists can observe many stars at various stages of their development - just born and dying. Based on numerous stellar portraits, they are trying to reconstruct the evolutionary path of each star and write its biography.
slide 4
slide 5
Regions of star formation.
Giant molecular clouds with masses greater than 105 solar masses (more than 6,000 of them are known in the Galaxy)
Eagle Nebula
6000 light-years away a young open star cluster in the constellation Serpens dark regions in the nebula are protostars
slide 6
Orion Nebula
a luminous emission nebula with a greenish tint and located below Orion's Belt can be seen even with the naked eye at 1300 light years from us, and a magnitude of 33 light years
Slide 7
Gravitational contraction
Compression is a consequence of gravitational instability, Newton's idea. Jeans later determined the minimum size of clouds in which spontaneous contraction can begin.
A rather effective cooling of the medium takes place: the released energy of gravity goes into infrared radiation, which goes into outer space.
Slide 8
protostar
As the density of the cloud increases, it becomes opaque to radiation. The temperature of the inner regions begins to rise. The temperature in the interior of a protostar reaches the threshold of thermonuclear fusion reactions. Compression stops for a while.
Slide 9
a young star has entered the main sequence of the H-R diagram, the process of hydrogen burnout has begun - the main stellar nuclear fuel is practically not compressed, and energy reserves no longer change a slow change in the chemical composition in its central regions, due to the conversion of hydrogen into helium
The star goes into a stationary state
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when the hydrogen burns out completely, the star leaves the main sequence in the region of giants or, at high masses, supergiants
Giants and supergiants
