"Questions on astronomy" - Image transmission. M.V. Lomonosov. What astronomical signs are depicted on the flags. Saturn. Cacconi at Morrison came up with a very neat idea. Solve the crossword puzzle. Jupiter. The planet of the solar system has the smallest dimensions. This physical parameter of any body is equal to zero. On October 4, 1957, with the help of a powerful rocket, he reached a speed of 28,000 km / h.
"Astronomical Conference" - XI conference "Physics of the Galaxy" was held at the camp site "Khrustalnaya" in the picturesque surroundings of Sverdlovsk. Unforgettable meetings with V.S. Oskanyan, N.S. P.E.Zakharova Ural State University.
"Methods of astronomy" - Radiation in radio lines. Auxiliary tools and methods of astronomy. extragalactic research. T. Matthews and A. Sandage. observational grounds. Theory of radial pulsations. Hendrik van de Hulst. Extragalactic radio astronomy. Robert Trumpler. Solar flares. I.S. Shklovsky. B.V. Kukarkin.
"Astrophysics" - Discovery of Uranus. First parallax measurements. We got a completely different picture of the world. Hubble pictures. An unexpected discovery. How it works. Which exoplanet was discovered first. The discovery pushed the boundaries of the solar system. Discovery of the interstellar medium. For the first time, the scale of interstellar distances was reliably set.
"Galactic cosmic rays" - Earth's magnetosphere. Ground installations. An example of an optical detector. History of the discovery of cosmic rays. Radiation. Particles. Bruno Rossi. Satellites. Discharging an electroscope. Solar prominence. The first scientific hypotheses. Cosmic rays. EAS registration on the ground. USA. Experiments. Skobeltsyn. Measurement results.
"Cosmic rays" - Educational process. Central part. Berkeley Lab Cosmic Ray Detector. scintillation detector. Cosmic rays. Re-emitters. Storm installation. Scintillation assembly. Thermal stabilization in action. Detector electronics. EAS registration technique. Communications. Scheme of the detector scintillation assembly.
Total in the topic 23 presentations
Presentation: Nebulae and star clusters zelobservatory.ru.
Nebula? Nebula is a plot interstellar environments, which is distinguished by its emission or absorption ... around itself a significant amount interstellar hydrogen (and become dark... stars, magnetic field and interstellar environments. In the picture: The structure of a symmetrical ...
Stars with planetary systems, clouds interstellar gas, core. Galaxy, in ... part of the stars and almost everything interstellar matter is concentrated in a disk... thousands of solar radii. 3. Interstellar gas - component interstellar environments, which also consists of dust particles ...
Presentation: What are galaxies? Galaxies are large star systems in which stars are connected to each other by gravitational forces. Based on the expanding theory.
And the main part of this interstellar environments also moves in circles... and in the atmospheres of planets, interstellar Wednesday densest at the bottom .... However, up to 10% interstellar environments is outside the disk and... looked similar but moved among stars. Previously, they did not know ...
Presentation: ...) gravitationally bound system of stars, interstellar
...) a gravitationally bound system of stars, interstellar gas, dust and dark matter... as a rule, they have a lot of interstellar gas, up to 50% of the mass... galaxies Unusual galaxies Unusual galaxies Among There are some galaxies that...
Presentation: Solar family. solar system solar system planetary system that includes the central star the sun and all natural space objects,
local bubble" zone of dispersed high-temperature interstellar gas. Of the stars belonging to 50 ... planetology. Venus has the densest among other earth-like planets atmosphere, ... . Venus has the densest among other Earth-like planets atmosphere, ...
The origin of the universe. Worked on the presentation: Mezhuev Eduard Mezhuev Eduard Palitsyn Denis Palitsyn Denis Manuylov Alexey Manuylov Alexey MOU secondary school 1
The birth of stars. Opening interstellar substances. Opening interstellar substances. From what are formed ... notice. But apart from gas interstellar environment in a small amount (about 1 ... notice. But in addition to gas in interstellar environment in small quantities (about 1 ...
Galaxy Galaxy (ancient Greek Γαλαξίας Milky Way) is a gravitationally bound system of stars, interstellar gas, dust and dark matter.
system of stars interstellar gas, dust and... WEDNESDAY Interstellar gas is a rarefied gas Wednesday filling all the space between the stars. Interstellar... the gas is transparent. Full mass interstellar ...
interstellar gas, dust, dark matter and...
called big system from the stars interstellar gas, dust, dark matter and... called a large system of stars, interstellar gas, dust, dark matter and... . In addition to individual stars and rarefied interstellar environments, most galaxies contain many ...
« Interstellar Wednesday"Performed by a student of the 7" C "class of the NIS FMN, Astana Akzhigitov Dulat.
« Interstellar Wednesday"Completed student 7" C ... substances from the stars in interstellar space. Substance from... attraction and ejected into interstellar space. It comes in... but skipping red. Conclusion: Interstellar Wednesday essential for evolution...
Usually galaxies contain from 10 million to several trillion stars, orbiting around a common center of gravity. In addition to individual stars, and sparse.
In addition to individual stars, and rarefied interstellar environments, a large Galaxy is a large system ... of stars, interstellar part of the galaxies contains many multiple ... stars with planetary systems, clouds interstellar gas, core. Galaxy in...
Completed by: Filatova Galina Petrovna, teacher of physics, municipal educational institution "Koltalovskaya secondary school" of the Kalinin district of the Tver region.
Behind her the solar wind and interstellar matter mix, mutually dissolving ... further than Pluto and is considered the beginning interstellar environments. However, it is assumed that the region ... ends the solar system and begins interstellar space is ambiguous. Sedna (...
Ministry of Housing, Communal Services and Energy of the Kamchatka Territory state-financed organization“Regional Center for Energy Development.
Bubble" zone of dispersed high-temperature interstellar gas The average distance of the Sun from ... photosynthesis from inorganic elements of the environment environments– H2O water and dioxide... its implementation: Creation of a favorable economic environments including: shaping...
... called a large system of stars, interstellar gas, dust and dark matter...
In addition to individual stars, and rarefied interstellar environments, most galaxies contain many ... thousands of light years. Interstellar gas is rarefied gas Wednesday filling all space...
the beginning interstellar environments. However, it is assumed that the region in which gravity is the gravity of the Heliosphere Interstellar Wednesday in... several recent supernovae Local interstellar cloud local bubble interstellar environment Relatively few stars...
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MUNICIPAL BUDGET GENERAL EDUCATIONAL INSTITUTION LYCEUM №11 OF THE CITY OF CHELYABINSK
abstract
nbut the topic:
"Gas and dust complexes. interstellar medium»
Performed:
11th grade student
Kiseleva Polina Olegovna
Checked:
Lykasova Alevtina Pavlovna
Chelyabinsk 2015
OHEAD
Introduction
1. History of ISM research
2. Main components of the ISM
2.1 Interstellar gas
2.2 Interstellar dust
2.3 Interstellar cloud
2.4 Cosmic rays
2.5 Interstellar magnetic field
3. Physical features of the ISM
4. Nebulae
4.1 Diffuse (bright) nebula
4.2 Dark Nebula
5. Radiation
6. Evolution of the interstellar medium
Conclusion
List of sources
INTRODUCTION
The universe, at its core, is almost empty space. It was only comparatively recently that it was possible to prove that stars do not exist in absolute emptiness and that outer space is not completely transparent. Stars occupy only a small part of the vast universe. The matter and fields that fill the interstellar space inside galaxies are called the interstellar medium (ISM). The nature of the interstellar medium has attracted the attention of astronomers and scientists for centuries. The term "interstellar medium" was first used by F. Bacon in 1626.
1. HISTORY OF RESEARCHMZS
Back in the middle of the 19th century. Russian astronomer V. Struve tried by scientific methods to find indisputable evidence that space is not empty, and light from distant stars is absorbed in it, but to no avail. interstellar medium cloud gas
Later German astrophysicist F. Hartman conducted a study of the spectrum of Delta Orion and studied the orbital motion of the companions of the Delta Orion system and the light coming from the star. Realizing that some of the light is absorbed on its way to Earth, Hartmann wrote that "the absorption line of calcium is very weak", and also that "it turned out to be somewhat surprising that the calcium lines at a wavelength of 393.4 nanometers do not move in a periodic divergence of lines spectrum that is present in spectroscopic binary stars. The stationary nature of these lines allowed Hartmann to suggest that the gas responsible for the absorption is not present in the atmosphere of Delta Orion, but, on the contrary, is located outside the star and is located between the star and the observer. This study was the beginning of the study of the interstellar medium.
Intensive studies of interstellar matter have made it possible W. Pickering in 1912 to state that "the interstellar absorbing medium, which, as shown Captain, absorbs only at some wavelengths, may indicate the presence of gas and gaseous molecules that are ejected by the Sun and stars.
In the same year 1912 AT.hess discovered cosmic rays, energetic charged particles that bombard the Earth from space. This allowed some researchers to state that they also fill the interstellar medium.
After Hartmann's research, in 1919, Eger while studying absorption lines at wavelengths of 589.0 and 589.6 nanometers in the Delta Orion and Beta Scorpio systems, he discovered sodium in the interstellar medium.
The presence of an absorbing rarefied medium was convincingly shown less than a hundred years ago, in the first half of the 20th century, by comparing the observed properties of distant star clusters at different distances from us. It was done independently by an American astronomer Robert Trumpler(1896-1956) and Soviet astronomer B.A.Vorontsov-Velyaminov(1904-1994). Rather, this is how one of the components of the interstellar medium was discovered - fine dust, due to which the interstellar medium is not completely transparent, especially in directions close to the direction of the Milky Way. The presence of dust meant that both the apparent brightness and the observed color of distant stars were distorted, and in order to know their true values, a rather complicated calculation of extinction was needed. Dust, thus, was perceived by astronomers as an unfortunate hindrance, interfering with the study of distant objects. But at the same time, interest arose in the study of dust as a physical medium - scientists began to find out how dust grains arise and collapse, how dust reacts to radiation, and what role dust plays in the formation of stars.
With the development of radio astronomy in the second half of the 20th century. it became possible to study the interstellar medium by its radio emission. As a result of purposeful searches, radiation of neutral hydrogen atoms was discovered in interstellar space at a frequency of 1420 MHz (which corresponds to a wavelength of 21 cm). Radiation at this frequency (or, as they say, in the radio line) was predicted by the Dutch astronomer Hendrik van de Hulst in 1944 on the basis of quantum mechanics, and it was discovered in 1951 after the calculation of its expected intensity by a Soviet astrophysicist I.S. Shklovsky. Shklovsky also pointed out the possibility of observing radiation various molecules in the radio range, which, indeed, was later discovered. The mass of interstellar gas, consisting of neutral atoms and very cold molecular gas, turned out to be about a hundred times greater than the mass of rarefied dust. But the gas is completely transparent to visible light, so it could not be detected by the same methods that dust was discovered.
With the advent of X-ray telescopes installed on space observatories, another, the hottest component of the interstellar medium, was discovered - a very rarefied gas with a temperature of millions and tens of millions of degrees. It is impossible to “see” this gas either by optical observations or by observations in radio lines - the medium is too rarefied and completely ionized, but, nevertheless, it fills a significant fraction of the volume of our entire Galaxy.
The rapid development of astrophysics, which studies the interaction of matter and radiation in outer space, as well as the emergence of new observational possibilities, made it possible to study in detail the physical processes in the interstellar medium. Entire scientific fields have emerged space gas dynamics and space electrodynamics who study the properties of rarefied space media. Astronomers have learned to determine the distance to gas clouds, to measure the temperature, density and pressure of the gas, its chemical composition, to estimate the speed of movement of matter. In the second half of the 20th century revealed a complex picture of the spatial distribution of the interstellar medium and its interaction with stars. It turned out that the possibility of the birth of stars depends on the density and amount of interstellar gas and dust, and the stars (first of all, the most massive of them), in turn, change the properties of the surrounding interstellar medium - they heat it, support the constant movement of gas, replenish the medium with their substance change its chemical composition.
2. MAIN COMPONENTS OF MLT
The interstellar medium includes interstellar gas, dust (1% of the gas mass), interstellar magnetic fields, interstellar cloud, cosmic rays, and dark matter. The chemical composition of the interstellar medium is a product of primary nucleosynthesis and nuclear fusion in stars.
2 .1 Interstellar gas
Interstellar gas is a rarefied gaseous medium that fills all the space between stars. Interstellar gas is transparent. The total mass of interstellar gas in the Galaxy exceeds 10 billion solar masses, or a few percent of the total mass of all the stars in our Galaxy. The average concentration of interstellar gas atoms is less than 1 atom per cm3. The average density of the gas is about 10–21 kg/m3. The chemical composition is about the same as that of most stars: it consists of hydrogen and helium with a small admixture of heavier elements. Depending on temperature and density, interstellar gas is in molecular, atomic or ionized states. Ultraviolet rays, unlike visible light rays, are absorbed by the gas and give it their energy. Due to this, hot stars with their ultraviolet radiation heat the surrounding gas to a temperature of about 10,000 K. The heated gas begins to emit light itself, and we observe it as a bright gaseous nebula. The colder, "invisible" gas is observed by radio astronomical methods. Hydrogen atoms in a rarefied medium emit radio waves at a wavelength of about 21 cm. Therefore, streams of radio waves propagate continuously from regions of interstellar gas. By receiving and analyzing this radiation, scientists learn about the density, temperature and movement of interstellar gas in outer space.
2 .2 Interstellar dust
Interstellar dust is solid microscopic particles that, along with interstellar gas, fill the space between stars. It is currently believed that dust particles have a refractory core surrounded by organic matter or ice shell. The chemical composition of the nucleus is determined by the atmosphere in which stars they condensed. For example, in the case of carbon stars, they will be composed of graphite and silicon carbide.
The typical particle size of interstellar dust is from 0.01 to 0.2 microns, the total mass of dust is about 1% of the total mass of gas. Starlight heats interstellar dust up to several tens of K, due to which interstellar dust is a source of long-wave infrared radiation.
Dust also affects the chemical processes taking place in the interstellar medium: dust granules contain heavy elements that are used as a catalyst in various chemical processes. Dust granules are also involved in the formation of hydrogen molecules, which increases the rate of star formation in metal-poor clouds.
2 .3 interstellar cloud
The interstellar cloud is the general name for accumulations of gas, plasma and dust in our and other galaxies. In other words, the interstellar cloud has a higher density than the average density of the interstellar medium. Depending on the density, size and temperature of a given cloud, the hydrogen in it can be neutral, ionized (that is, in the form of plasma) or molecular. Neutral and ionized clouds are sometimes called diffuse clouds, while molecular clouds are called dense clouds.
Analysis of the composition of interstellar clouds is carried out by studying their electromagnetic radiation using large radio telescopes. By examining the emission spectrum of an interstellar cloud and comparing it with the spectrum of specific chemical elements, one can determine the chemical composition of the cloud.
Usually about 70% of the mass of an interstellar cloud is hydrogen, the rest is mainly helium. Clouds also contain traces of heavy elements: metals such as calcium, neutral or in the form of Ca+ (90%) and Ca++ (9%) cations, and inorganic compounds such as water, carbon monoxide, hydrogen sulfide, ammonia and hydrogen cyanide.
2 .4 Cosmic rays
Cosmic rays - elementary particles and nuclei of atoms moving with high energies in outer space. Their main (but not the only) source is supernova explosions.
Extragalactic and galactic rays are usually called primary. It is customary to call secondary flows of particles passing and transforming in the Earth's atmosphere.
Cosmic rays are a component of natural radiation (background radiation) on the Earth's surface and in the atmosphere.
The chemical spectrum of cosmic rays in terms of energy per nucleon consists of more than 94% of protons, another 4% of helium nuclei (alpha particles). There are also nuclei of other elements, but their share is much smaller.
In terms of particle number, cosmic rays are 90 percent protons, 7 percent helium nuclei, about 1 percent heavier elements, and about 1 percent electrons.
2 .5 Interstellar magnetic field
The particles move in the weak magnetic field of interstellar space, the induction of which is about a hundred thousand times less than that of the Earth's magnetic field. The interstellar magnetic field, acting on charged particles with a force that depends on their energy, "confuses" the trajectories of particles, and they continuously change the direction of their movement in the Galaxy. Charged particles flying in the interstellar magnetic field deviate from straight trajectories under the influence of the Lorentz force. Their trajectories seem to "wind" on the lines of magnetic induction.
3. PHYSICAL FEATURES OF THE ISM
· Lack of local thermodynamic equilibrium(LTR)- With the state of a system in which the macroscopic quantities of this system (temperature, pressure, volume, entropy) remain unchanged in time under conditions of isolation from environment.
· Thermal instability
The condition of thermal equilibrium may not be fulfilled at all. There is a magnetic field that resists compression unless it occurs along field lines. Secondly, the interstellar medium is in constant motion and its local properties are constantly changing, new sources of energy appear in it and old ones disappear. Thirdly, in addition to thermodynamic instability, there are gravitational and magnetohydrodynamic ones. And this is without taking into account any kind of cataclysms in the form of supernova explosions, tidal influences passing in the neighborhood of galaxies, or the passage of the gas itself through the spiral branches of the Galaxy.
· Forbidden lines and 21cm line
A distinctive feature of an optically thin medium is radiation in prohibited lines. Forbidden lines are called lines that are forbidden by the selection rules, that is, they come from metastable levels (quasi-stable equilibrium). The characteristic lifetime of an electron at this level is from s to several days. At high concentrations of particles, their collision removes the excitation and the lines are not observed due to extreme weakness. At and low densities, the line intensity does not depend on the transition probability, since the low probability is compensated by a large number of atoms in the metastable state. If there is no LTE, then the population of energy levels should be calculated from the balance of elementary processes of excitation and deactivation.
The most important forbidden line of the ISM is atomic hydrogen radio link 21cm. This line arises during the transition between sublevels of the hyperfine structure of the hydrogen level, associated with the presence of spin in the electron and proton. The probability of this transition (that is, 1 time in 11 million years).
Studies of the 21 cm radio line made it possible to establish that the neutral hydrogen in the galaxy is mainly enclosed in a very thin, 400 pc thick, layer near the plane of the Galaxy.
· Frozenness of the magnetic field.
Frozenness of the magnetic field means the preservation of the magnetic flux through any closed conducting circuit when it is deformed. Under laboratory conditions, the magnetic flux can be considered conserved in media with high electrical conductivity. In the limit of infinite electrical conductivity, the infinitesimal electric field would cause the current to rise to an infinite value. Therefore, an ideal conductor should not cross magnetic lines of force, and thus excite the electric field, but on the contrary, it should drag along the lines of the magnetic field, the magnetic field turns out to be, as it were, frozen into the conductor.
Real space plasma is far from ideal, and freezing should be understood in the sense that it takes a very long time to change the flow through the loop. In practice, this means that we can consider the field to be constant while the cloud contracts, rotates, etc.
4. Nebulae
Nebula- a section of the interstellar medium, distinguished by its radiation or absorption of radiation against the general background of the sky. Nebulae are made up of dust, gas, and plasma.
The primary feature used in the classification of nebulae is absorption, or emission or scattering of light by them, that is, according to this criterion, nebulae are divided into dark and light.
The division of nebulae into gaseous and dusty ones is largely arbitrary: all nebulae contain both dust and gas. This division is historically different ways observations and emission mechanisms: the presence of dust is most clearly observed when dark nebulae absorb radiation from sources located behind them and when reflection or scattering, or re-emission, contained in the dust of radiation from stars located nearby or in the nebula itself; The intrinsic radiation of the gaseous component of a nebula is observed when it is ionized by ultraviolet radiation from a hot star located in the nebula (H II emission regions of ionized hydrogen around stellar associations or planetary nebulae) or when the interstellar medium is heated by a shock wave due to a supernova explosion or the impact of a powerful stellar wind of Wolf-type stars -- Raye.
4 .1 Diffuse(light)nebula
Diffuse (light) nebula -- In astronomy, a general term used to refer to light-emitting nebulae. The three types of diffuse nebulae are the reflection nebula, the emission nebula (of which the protoplanetary, planetary, and H II regions are varieties), and the supernova remnant.
· reflection nebula
Reflection nebulae are clouds of gas and dust illuminated by stars. If the star(s) is in or near an interstellar cloud, but is not hot enough (hot) to ionize a significant amount of interstellar hydrogen around it, then the main source of optical radiation from the nebula is stellar light scattered by interstellar dust.
The spectrum of the reflection nebula is the same as that of the star that illuminates it. Among the microscopic particles responsible for light scattering are particles of carbon (sometimes called diamond dust), as well as particles of iron and nickel. The last two interact with the galactic magnetic field, and therefore the reflected light is slightly polarized.
Reflection nebulae usually have a blue tint because blue is more efficiently scattered than red (this is one of the reasons why the sky is blue).
Currently, about 500 reflection nebulae are known, the most famous of which is around the Pleiades (star cluster). The giant red (spectral class M1) star Antares is surrounded by a large red reflection nebula. Reflection nebulae are also often found at star-forming sites.
In 1922, Hubble published the results of studies of some bright nebulae. In this work, Hubble derived the luminosity law for a reflection nebula, which establishes the relationship between the angular size of the nebula ( R) and the apparent magnitude of the illuminating star ( m):
where is a constant depending on the sensitivity of the measurement.
· emission nebula
An emission nebula is a cloud of ionized gas (plasma) emitting in the visible color range of the spectrum. Ionization occurs due to high-energy photons emitted by the nearest hot star. There are several types of emission nebulae. Among them are the H II regions, in which the formation of new stars occurs, and the sources of ionizing photons are young, massive stars, as well as planetary nebulae, in which the dying star has discarded its upper layers, and the exposed hot core ionizes them.
Planetmrye fogmness- an astronomical object consisting of an ionized gas shell 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 2.5–8 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.
The process of formation of planetary nebulae, along with supernova explosions, plays an important role in the chemical evolution of galaxies, throwing into interstellar space material enriched with heavy elements - products of stellar nucleosynthesis (in astronomy, all elements are considered heavy, with the exception of the products of the primary nucleosynthesis of the Big Bang - hydrogen and helium such as carbon, nitrogen, oxygen and calcium).
In recent years, with the help of images taken by the Hubble Space Telescope, it was possible to find out that many planetary nebulae have a very complex and peculiar structure. Although about a fifth of them are circumspherical, most do not have any spherical symmetry. The mechanisms by which the formation of such a variety of forms is possible remain to date not fully elucidated. It is believed that the interaction of the stellar wind and binary stars, the magnetic field and the interstellar medium can play a large role in this.
Planetary nebulae are mostly dim objects and are generally not visible to the naked eye. The first planetary nebula to be discovered was nebula dumbbell in the constellation Vulpecula.
The unusual nature of planetary nebulae was discovered in the middle of the 19th century, with the beginning of the use of the spectroscopy method in observations. William Huggins became the first astronomer to obtain the spectra of planetary nebulae - objects that stood out for their unusualness. When Huggins studied the spectra of nebulae NGC6543 (Cat's Eye), M27 (Dumbbell), M57 (ring nebula in Lyra) and a number of others, it turned out that their spectrum is extremely different from the spectra of stars: all the spectra of stars obtained by that time were absorption spectra (a continuous spectrum with a large number of dark lines), while the spectra of planetary nebulae turned out to be emission spectra with a small number of emission lines , which indicated their nature, which is fundamentally different from the nature of stars.
Planetary nebulae represent the final stage of evolution for many stars. A typical planetary nebula has an average length of one light year and consists of highly rarefied gas with a density of about 1000 particles per cm3, which is negligible in comparison, for example, with the density of the Earth's atmosphere, but about 10-100 times greater than the density of interplanetary space. at the distance of the Earth's orbit from the Sun. Young planetary nebulae have the highest density, sometimes reaching 10 6 particles per cm. As nebulae age, their expansion leads to a decrease in density. Most planetary nebulae are symmetrical and almost spherical in appearance, which does not prevent them from having many very complex shapes. Approximately 10% of planetary nebulae are practically bipolar, and only a small number are asymmetric. Even a rectangular planetary nebula is known.
protoplanetary nebula is an astronomical object that does not exist for long between the time a medium-mass star (1-8 solar masses) has left the asymptotic giant branch (AGB) and the subsequent planetary nebula (PT) phase. The protoplanetary nebula shines primarily in the infrared and is a subtype of reflection nebula.
RegionHII is a cloud of hot gas and plasma, reaching several hundred light-years across, which is an area of active star formation. Young hot bluish-white stars are born in this region, which emit abundant ultraviolet light, thereby ionizing the surrounding nebula.
H II regions can give birth to thousands of stars over a period of just a few million years. Eventually, supernova explosions and powerful stellar winds from the most massive stars in the resulting star cluster scatter the region's gases, and it turns into a Pleiades-like group.
These regions get their name from the large amount of ionized atomic hydrogen, referred to by astronomers as H II (the HI region is the zone of neutral hydrogen, and H 2 stands for molecular hydrogen). They can be seen at considerable distances throughout the universe, and the study of such regions located in other galaxies is important for determining the distance to the latter, as well as their chemical composition.
Examples are carina nebula, nebula Tarantula,NGC 604 , Trapeze of Orion, Barnard's loop.
· supernova remnant
supernova remnant(English) S uperN ova R emnant, SNR ) is a gas and dust formation, the result of a catastrophic explosion of a star that occurred many tens or hundreds of years ago and its transformation into a supernova. During the explosion, the supernova shell scatters in all directions, forming a shock wave expanding at a tremendous speed, which forms supernova remnant. The rest consists of stellar material ejected by the explosion and interstellar matter absorbed by the shock wave.
Probably the most beautiful and best studied young remnant formed by a supernova SN 1987 A in the Large Magellanic Cloud that erupted in 1987. Other well-known supernova remnants are crab nebula, remnant of a relatively recent explosion (1054), supernova remnant Quiet (SN 1572) , named after Tycho Brahe, who observed and recorded its initial brightness immediately after the outbreak in 1572, as well as the remainder Kepler's supernova (SN 1604) named after Johannes Kepler.
4 .2 Dark Nebula
A dark nebula is a type of interstellar cloud so dense that it absorbs visible light from emission or reflection nebulae (such as , Horsehead Nebula) or stars (for example, Coal Sack Nebula) behind it.
Light is absorbed by interstellar dust particles located in the coldest and densest parts of molecular clouds. Clusters and large complexes of dark nebulae are associated with giant molecular clouds (GMOs). Isolated dark nebulae are most often Bok globules.
Such clouds have a very irregular shape: they do not have clearly defined boundaries, sometimes they take on swirling snake-like images. The largest dark nebulae are visible to the naked eye, appearing as patches of black against the bright Milky Way.
In the inner parts of dark nebulae, active processes often take place: for example, the birth of stars or maser radiation.
5. RADIATION
Stellar wind- the process of outflow of matter from stars into interstellar space.
The substance of which stars are composed, under certain conditions, can overcome their attraction and be ejected into interstellar space. This happens when a particle in the atmosphere of a star accelerates to a speed exceeding the second cosmic velocity for this star. In fact, the speeds of the particles that make up the stellar wind are hundreds of kilometers per second.
The stellar wind can contain both charged particles and neutral ones.
Stellar wind is a constantly occurring process that leads to a decrease in the mass of a star. Quantitatively, this process can be characterized as the amount (mass) of matter that the star loses per unit time.
The stellar wind can play an important role in stellar evolution: since this process results in a decrease in the mass of a star, the lifespan of a star depends on its intensity.
The stellar wind is a way of transporting matter over considerable distances in space. In addition to the fact that it itself consists of matter flowing from stars, it can act on the surrounding interstellar matter, transferring to it part of its kinetic energy. Thus, the shape of the emission nebula NGC 7635 "Bubble" was formed as a result of such an impact.
In the case of the outflow of matter from several closely spaced stars, supplemented by the influence of the radiation of these stars, condensation of interstellar matter is possible with subsequent star formation.
With an active stellar wind, the amount of ejected matter may be sufficient to form a planetary nebula.
6. EVOLUTION OF THE INTERSTELLAR MEDIUM
The evolution of the interstellar medium, or to be more precise, the interstellar gas, is closely related to the chemical evolution of the entire Galaxy. It would seem that everything is simple: stars absorb gas, and then throw it back, enriching it with nuclear combustion products - heavy elements - thus the metallicity should gradually increase.
The Big Bang theory predicts that hydrogen, helium, deuterium, lithium, and other light nuclei were formed during primordial nucleosynthesis, which are still splitting on the Hayashi track or the protostar stage. In other words, we should observe long-lived G-dwarfs with zero metallicity. But none of these have been found in the Galaxy; moreover, most of them have an almost solar metallicity. According to indirect data, it can be judged that something similar exists in other galaxies. At the moment, the issue remains open and awaits a decision.
There was also no dust in the primordial interstellar gas. It is now believed that dust grains are formed on the surface of old cold stars and leave it together with the outflowing matter.
CONCLUSION
The study of such a complex system as "stars - interstellar medium" turned out to be a very difficult astrophysical task, especially considering that the total mass of the interstellar medium in the Galaxy and its chemical composition slowly change under the influence of various factors. Therefore, we can say that the entire history of our stellar system, lasting billions of years, is reflected in the interstellar medium.
LIST OF SOURCES
1) Materials taken from www.wikipedia.org
2) Materials taken from the site www.krugosvet.ru
3) Materials taken from www.bse.sci-lib.com
4) Materials taken from the site www.dic.academic.ru
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Stellar evolution - changes of a star during its life. Thermonuclear fusion and the birth of stars; planetary nebula, protostars. Characteristics of young stars, their maturity, later years, death. Neutron stars (pulsars), white dwarfs, black holes.
presentation, added 05/10/2012
Stages of formation of the solar system. The composition of the medium of the protoplanetary disk of the Sun, the study of its evolution using a numerical two-dimensional gas-dynamic model, which corresponds to the axisymmetric movement of the gaseous medium in a gravitational field.
term paper, added 05/29/2012
Characteristics of the stars. Stars in outer space. A star is a plasma ball. Dynamics of stellar processes. Solar system. Interstellar medium. The concept of stellar evolution. The process of star formation. Star as a dynamic self-regulating system.
abstract, added 10/17/2008
The eighth planet from the Sun. Some parameters of the planet Neptune. Chemical composition, physical conditions, structure, atmosphere. The temperature of the surface areas. Satellites of Neptune, their sizes, characteristics, history of discoveries. Rings of Neptune, magnetic field.
Interstellar gas and dust.
The interstellar medium is the matter and fields that fill the interstellar space inside galaxies. Composition: interstellar gas, dust (1% of the gas mass), interstellar magnetic fields, cosmic rays, and dark matter. The entire interstellar medium is permeated with magnetic fields, cosmic rays and electromagnetic radiation.
Interstellar gas is the main component of the interstellar medium. Interstellar gas is transparent. The total mass of interstellar gas in the Galaxy exceeds 10 billion solar masses, or a few percent of the total mass of all the stars in our Galaxy. The average concentration of atoms in interstellar gas is less than 1 atom per cm³. Its main mass is contained near the plane of the Galaxy in a layer several hundred parsecs thick. The average density of the gas is about 10 −21 kg/m³. The chemical composition is approximately the same as that of most stars: it consists of hydrogen and helium (90% and 10% by the number of atoms, respectively) with a small admixture of heavier elements (O, C, N, Ne, S, etc.).
Depending on temperature and density, interstellar gas is in molecular, atomic or ionized states.
The main data on interstellar gas were obtained by radio astronomical methods, after the radio emission of neutral atomic hydrogen at a wavelength of 21 cm was discovered in 1951. It turned out that atomic hydrogen, having a temperature of 100 K, forms a layer 200-300 pc thick in the disk of the Galaxy at a distance of 15 20 kpc from its center. By receiving and analyzing this radiation, scientists learn about the density, temperature and movement of interstellar gas in outer space.
About half of the interstellar gas is contained in giant molecular clouds with an average mass of 10 ^ 5 solar masses and a diameter of about 40 pc. Due to the low temperature (about 10 K) and high density (up to 10^3 particles in 1 cm^3), hydrogen and other elements in these clouds are combined into molecules.
There are about 4000 such molecular clouds in the Galaxy.
Regions of ionized hydrogen with a temperature of 8000-10000 K manifest themselves in the optical range as bright diffuse nebulae.
Ultraviolet rays, unlike visible light rays, are absorbed by the gas and give it their energy. Due to this, hot stars with their ultraviolet radiation heat the surrounding gas to a temperature of about 10,000 K. The heated gas begins to emit light itself, and we observe it as a bright gaseous nebula.
It is these nebulae that are indicators of the places of ongoing star formation.
So in the Great Nebula of Orion, using the Hubble Space Telescope, protostars surrounded by protoplanetary disks were discovered.
The Great Nebula of Orion is the brightest gaseous nebula. It is visible through binoculars or a small telescope.
A special type of nebulae are planetary nebulae, which appear as faintly luminous disks or rings resembling planetary disks. They were discovered in 1783 by W. Herschel, and now there are more than 1200 of them. In the center of such a nebula is the remnant of a dead red giant - a hot white dwarf or neutron star. Under the influence of the internal pressure of the gas, the planetary nebula expands at a speed of approximately 20-40 km/s, while the density of the gas decreases.
(Planetary nebula Hourglass picture)
Interstellar dust is solid microscopic particles that, along with interstellar gas, fill the space between stars. It is now believed that dust grains have a refractory core surrounded by organic matter or an ice shell. The chemical composition of the nucleus is determined by the atmosphere in which stars they condensed. For example, in the case of carbon stars, they will be composed of graphite and silicon carbide.
The typical particle size of interstellar dust is from 0.01 to 0.2 microns, the total mass of dust is about 1% of the total mass of gas. Starlight heats interstellar dust up to several tens of Kelvin, due to which interstellar dust is a source of long-wave infrared radiation.
Due to dust, the densest gas formations - molecular clouds - are practically opaque and look like dark regions in the sky, almost devoid of stars. Such formations are called dark diffuse nebulae. (picture)
Dust also affects the chemical processes taking place in the interstellar medium: dust granules contain heavy elements that are used as a catalyst in various chemical processes. Dust granules are also involved in the formation of hydrogen molecules, which increases the rate of star formation in metal-poor clouds.
Means of studying interstellar dust
- Distance learning.
- Studies of micrometeorites for the presence of inclusions of interstellar dust.
- Study of ocean sediments for the presence of cosmic dust particles.
- The study of cosmic dust particles present at high altitudes in the Earth's atmosphere.
- Launch of spacecraft to collect, study and deliver interstellar dust particles to Earth.
Interesting
- For a year on earth's surface more than 3 million tons of cosmic dust falls, as well as from 350 thousand to 10 million tons of meteorites - stone or metal bodies that fly into the atmosphere from space.
- In the last 500 years alone, the mass of our planet has increased by a billion tons due to cosmic matter, which is only 1.7·10 -16% of the mass of the Earth. However, it apparently affects the annual and daily movement of our planet.
slide 2
GALAXY A galaxy is a large system of stars, interstellar gas, dust and dark matter, bound by gravitational forces. Usually galaxies contain from 10 million to several trillion stars, orbiting around a common center of gravity. In addition to individual stars and a rarefied interstellar medium, most galaxies contain many multiple star systems, star clusters, and various nebulae. As a rule, the diameter of galaxies ranges from several thousand to several hundred thousand light-years, and the distances between them are estimated at millions of light-years.
slide 3
There are countless stars in the sky. However, with the naked eye in clear weather, only about 2.5 thousand can be observed in each of the hemispheres. Stars are unevenly distributed in the Universe, forming galaxies consisting of a different number of stars: from tens of thousands to hundreds of billions. There are an innumerable number of galaxies throughout the Universe. The stars are so far away from us that even the most powerful telescope can be seen as dots. The closest star to the Sun, Proxima Centauri, is 4.25 light-years away, and the closest galaxy, the Sagittarius Dwarf Galaxy, is 80,000 light-years away. Stars
slide 4
Interstellar gas is a rarefied gaseous medium that fills all the space between stars. Interstellar gas is transparent. The total mass of interstellar gas in the Galaxy exceeds 10 billion solar masses, or a few percent of the total mass of all the stars in our Galaxy. The chemical composition is about the same as that of most stars: it consists of hydrogen and helium (90% and 10% by number of atoms, respectively) with a small admixture of heavier elements. Depending on temperature and density, interstellar gas is in molecular, atomic or ionized states. Interstellar Gas
slide 5
Interstellar dust is an admixture of solid microscopic particles in the interstellar gas. The total mass of interstellar dust is about 1% of the gas mass. The particle size of interstellar dust is from 0.01 to 0.02 microns. The dust grains probably have a refractory core (graphite, silicate, or metal) surrounded by organic matter or an ice shell. Recent studies indicate that dust particles are generally non-spherical in shape. Dust affects the optical emission of stars, leading to the absorption, reddening and polarization of starlight. Interstellar Dust
slide 6
General name for a collection of astronomical objects inaccessible to direct observation modern means astronomy (that is, not emitting electromagnetic radiation of sufficient intensity for observations), but observable indirectly by the gravitational effects exerted on the observed objects. The general problem of hidden mass consists of two problems: astrophysical, that is, the contradiction between the observed mass of gravitationally bound objects and their systems, such as galaxies and their clusters, with their observed parameters determined by gravitational effects; cosmological - contradictions in the observed cosmological parameters of the average density of the Universe obtained from astrophysical data. Dark matter
Slide 7
The sun - the central body of the solar system - is a hot ball of gas. It is 750 times more massive than all other bodies in the solar system combined. That is why everything in the solar system can be roughly considered to revolve around the sun. The sun outweighs the earth 330,000 times. A chain of 109 planets like ours could be placed on the solar diameter. The sun is the closest star to the Earth, it is the only star whose visible disk is visible to the naked eye. All other stars that are light years away from us, even when viewed through powerful telescopes, do not reveal any details of their surfaces. Light from the Sun reaches us in 8 and a third minutes. According to one of the hypotheses, it was together with the Sun that our planetary system, the Earth, and then life on it, formed. Sun
Slide 8
A parallel world is a reality that somehow exists simultaneously with ours, but independently of it. This self-contained reality can range in size from a small geographic area to an entire universe. In a parallel world, events take place in their own way, it can differ from our world both in individual details and radically, in almost everything. The physical laws of the parallel world are not necessarily similar to the laws of our world; in particular, the existence in parallel worlds of such phenomena as magic is sometimes allowed. A parallel world
Slide 9
The great cosmonaut Yuri Alekseevich Gagarin was born on March 9, 1934 in the village of Klushino in the Gzhatsky district of the Western region of the RSFSR, not far from the city of Gzhatsk (later renamed the city of Gagarin) in the Gagarinsky district of the Smolensk region. On April 12, 1961, the Vostok spacecraft was launched from the Baikonur Cosmodrome for the first time in the world, on board with pilot-cosmonaut Yuri Alekseevich Gagarin. For this feat he was awarded the title of Hero Soviet Union, and starting from April 12, 1962, the day of Gagarin's flight into space was declared a holiday - Cosmonautics Day. Yuri Alekseevich Gagarin THE FIRST COSMONAUT OF THE PLANET
Slide 10
Comets are small celestial bodies that have a hazy appearance, revolving around the Sun, usually in elongated orbits. When approaching the Sun, comets form a coma and sometimes a tail of gas and dust. The nucleus is the solid part of a comet, which has a relatively small size. A coma forms around the nucleus of an active comet (when it approaches the Sun). Comet nuclei are composed of ice with the addition of cosmic dust and frozen volatile compounds: carbon monoxide and carbon dioxide, methane, ammonia. Comets Ulyanovsk 2009
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