In terms of mass, solid dust particles make up an insignificant part of the Universe, but it is thanks to interstellar dust that stars, planets and people who study space and simply admire the stars arose and continue to appear. What kind of substance is this cosmic dust? What makes people equip expeditions into space costing the annual budget of a small state in the hope, and not in the firm confidence, of extracting and bringing back to Earth at least a tiny handful of interstellar dust?
Between stars and planets
In astronomy, dust refers to small, fractions of a micron in size, solid particles flying in outer space. Cosmic dust is often conventionally divided into interplanetary and interstellar, although, obviously, interstellar entry into interplanetary space is not prohibited. It’s not easy to just find it there, among the “local” dust, the probability is low, and its properties near the Sun can change significantly. Now, if you fly further away, to the borders of the solar system, there is a very high probability of catching real interstellar dust. The ideal option is to go beyond the solar system altogether.
Interplanetary dust, at least in comparative proximity to the Earth, is a fairly well-studied matter. Filling the entire space of the Solar System and concentrated in the plane of its equator, it was born largely as a result of random collisions of asteroids and the destruction of comets approaching the Sun. The composition of the dust, in fact, does not differ from the composition of meteorites falling on the Earth: it is very interesting to study it, and there are still many discoveries to be made in this area, but there seems to be no particular intrigue here. But thanks to this particular dust, in good weather in the west immediately after sunset or in the east before sunrise, you can admire a pale cone of light above the horizon. This is the so-called zodiacal sunlight, scattered by small cosmic dust particles.
Interstellar dust is much more interesting. Its distinctive feature is the presence of a solid core and shell. The core appears to be composed mainly of carbon, silicon and metals. And the shell is predominantly made up of gaseous elements frozen onto the surface of the core, crystallized under the conditions of “deep freezing” of interstellar space, and this is about 10 kelvins, hydrogen and oxygen. However, there are impurities of molecules that are more complex. These are ammonia, methane and even polyatomic organic molecules that stick to a speck of dust or form on its surface during wanderings. Some of these substances, of course, fly away from its surface, for example, under the influence of ultraviolet radiation, but this process is reversible - some fly away, others freeze or are synthesized.
Now in the space between stars or near them, the following have already been found, of course, not by chemical, but by physical, that is, spectroscopic, methods: water, oxides of carbon, nitrogen, sulfur and silicon, hydrogen chloride, ammonia, acetylene, organic acids such as formic and acetic acid, ethyl and methyl alcohols, benzene, naphthalene. They even found the amino acid glycine!
It would be interesting to catch and study interstellar dust penetrating into the solar system and probably falling to Earth. The problem of “catching” it is not easy, because few interstellar dust particles manage to preserve their icy “coat” in the sun’s rays, especially in the Earth’s atmosphere. Large ones heat up too much; their escape velocity cannot be quickly extinguished, and the dust grains “burn out.” Small ones, however, glide in the atmosphere for years, preserving part of the shell, but here the problem arises of finding them and identifying them.
There is one more, very intriguing detail. It concerns dust whose nuclei are made of carbon. Carbon synthesized in the cores of stars and released into space, for example, from the atmosphere of aging (such as red giants) stars, flying into interstellar space, cools and condenses in much the same way as after a hot day, fog from cooled water vapor collects in the lowlands. Depending on the crystallization conditions, layered structures of graphite, diamond crystals (just imagine whole clouds of tiny diamonds!) and even hollow balls of carbon atoms (fullerenes) can be obtained. And in them, perhaps, like in a safe or container, particles of the atmosphere of a very ancient star are stored. Finding such specks of dust would be a huge success.
Where is cosmic dust found?
It must be said that the very concept of the cosmic vacuum as something completely empty has long remained only a poetic metaphor. In fact, the entire space of the Universe, both between stars and between galaxies, is filled with matter, flows of elementary particles, radiation and fields - magnetic, electric and gravitational. All that can be touched, relatively speaking, is gas, dust and plasma, the contribution of which to the total mass of the Universe, according to various estimates, is only about 12% with an average density of about 10-24 g/cm 3 . There is most gas in space, almost 99%. This is mainly hydrogen (up to 77.4%) and helium (21%), the rest accounting for less than two percent of the mass. And then there is dust; its mass is almost a hundred times less than gas.
Although sometimes the emptiness in interstellar and intergalactic space is almost ideal: sometimes there is 1 liter of space per atom of matter! There is no such vacuum either in terrestrial laboratories or within the solar system. For comparison, we can give the following example: in 1 cm 3 of the air we breathe, there are approximately 30,000,000,000,000,000,000 molecules.
This matter is distributed very unevenly in interstellar space. Most of the interstellar gas and dust forms a gas-dust layer near the plane of symmetry of the Galaxy's disk. Its thickness in our Galaxy is several hundred light years. Most of the gas and dust in its spiral branches (arms) and core are concentrated mainly in giant molecular clouds ranging in size from 5 to 50 parsecs (16 x 160 light years) and weighing tens of thousands and even millions of solar masses. But inside these clouds the matter is also distributed non-uniformly. In the main volume of the cloud, the so-called fur coat, mainly made of molecular hydrogen, the density of particles is about 100 pieces per 1 cm 3. In the densities inside the cloud, it reaches tens of thousands of particles per 1 cm3, and in the cores of these densities, generally millions of particles per 1 cm3. It is this uneven distribution of matter in the Universe that owes the existence of stars, planets and, ultimately, ourselves. Because it is in molecular clouds, dense and relatively cold, that stars are born.
What’s interesting is that the higher the density of the cloud, the more diverse its composition. In this case, there is a correspondence between the density and temperature of the cloud (or its individual parts) and those substances whose molecules are found there. On the one hand, this is convenient for studying clouds: by observing their individual components in different spectral ranges along the characteristic lines of the spectrum, for example CO, OH or NH 3, you can “peek” into one or another part of it. On the other hand, data on the composition of the cloud allows us to learn a lot about the processes occurring in it.
In addition, in interstellar space, judging by the spectra, there are substances whose existence under terrestrial conditions is simply impossible. These are ions and radicals. Their chemical activity is so high that on Earth they immediately react. And in the rarefied cold space of space they live for a long time and quite freely.
In general, gas in interstellar space is not only atomic. Where it is colder, no more than 50 kelvins, atoms manage to stay together, forming molecules. However, a large mass of interstellar gas is still in the atomic state. It is mainly hydrogen; its neutral form was discovered relatively recently - in 1951. As is known, it emits radio waves 21 cm long (frequency 1,420 MHz), based on the intensity of which it was determined how much there is in the Galaxy. By the way, it is not uniformly distributed in space between stars. In clouds of atomic hydrogen its concentration reaches several atoms per 1 cm3, but between clouds it is orders of magnitude lower.
Finally, near hot stars, gas exists in the form of ions. Powerful ultraviolet radiation heats and ionizes the gas, causing it to glow. This is why areas with a high concentration of hot gas, with a temperature of about 10,000 K, appear as luminous clouds. They are called light gas nebulae.
And in any nebula, in greater or lesser quantities, there is interstellar dust. Despite the fact that nebulae are conventionally divided into dust and gas nebulae, there is dust in both. And in any case, it is dust that apparently helps stars form in the depths of nebulae.
Foggy objects
Among all cosmic objects, nebulae are perhaps the most beautiful. True, dark nebulae in the visible range simply look like black blots in the sky; they are best observed against the background of the Milky Way. But in other ranges of electromagnetic waves, for example infrared, they are visible very well and the pictures turn out to be very unusual.
Nebulae are clusters of gas and dust that are isolated in space and bound by gravity or external pressure. Their mass can be from 0.1 to 10,000 solar masses, and their size can be from 1 to 10 parsecs.
At first, nebulae irritated astronomers. Until the middle of the 19th century, discovered nebulae were viewed as an annoying nuisance that prevented the observation of stars and the search for new comets. In 1714, the Englishman Edmond Halley, whose name is the famous comet, even compiled a “black list” of six nebulae so that they would not mislead “comet catchers,” and the Frenchman Charles Messier expanded this list to 103 objects. Fortunately, the musician Sir William Herschel, who was in love with astronomy, and his sister and son became interested in the nebulae. Observing the sky with the help of telescopes they built with their own hands, they left behind a catalog of nebulae and star clusters, containing information about 5,079 space objects!
The Herschels practically exhausted the capabilities of optical telescopes of those years. However, the invention of photography and long exposure times made it possible to find very faintly luminous objects. A little later, spectral methods of analysis and observations in various ranges of electromagnetic waves made it possible in the future not only to detect many new nebulae, but also to determine their structure and properties.
An interstellar nebula appears bright in two cases: either it is so hot that its gas itself glows, such nebulae are called emission nebulae; or the nebula itself is cold, but its dust scatters the light of a nearby bright star - it is a reflection nebula.
Dark nebulae are also interstellar accumulations of gas and dust. But unlike light gaseous nebulae, which are sometimes visible even with strong binoculars or a telescope, such as the Orion Nebula, dark nebulae do not emit light, but absorb it. When starlight passes through such nebulae, dust can completely absorb it, converting it into infrared radiation that is invisible to the eye. Therefore, such nebulae look like starless holes in the sky. V. Herschel called them “holes in the sky.” Perhaps the most spectacular of these is the Horsehead Nebula.
However, dust grains may not completely absorb the light of stars, but only partially scatter it, and selectively. The fact is that the size of interstellar dust particles is close to the wavelength of blue light, so it is scattered and absorbed more strongly, and the “red” part of star light reaches us better. By the way, this is a good way to estimate the size of dust grains by how they attenuate light of different wavelengths.
Star from the cloud
The reasons why stars arise have not been precisely established; there are only models that more or less reliably explain experimental data. In addition, the formation paths, properties and further fate of stars are very diverse and depend on many factors. However, there is an established concept, or rather, the most developed hypothesis, the essence of which, in the most general terms, is that stars are formed from interstellar gas in areas with an increased density of matter, that is, in the depths of interstellar clouds. Dust as a material could be ignored, but its role in the formation of stars is enormous.
Apparently this happens (in the most primitive version, for a single star). First, a protostellar cloud condenses from the interstellar medium, which may be due to gravitational instability, but the reasons may be different and are not yet completely clear. One way or another, it contracts and attracts matter from the surrounding space. The temperature and pressure at its center increase until the molecules at the center of this collapsing ball of gas begin to break apart into atoms and then into ions. This process cools the gas, and the pressure inside the core drops sharply. The core contracts, and a shock wave propagates inside the cloud, throwing off its outer layers. A protostar is formed, which continues to contract under the influence of gravity until thermonuclear fusion reactions begin in its center - the conversion of hydrogen into helium. The compression continues for some time until the forces of gravitational compression are balanced by the forces of gas and radiant pressure.
It is clear that the mass of the resulting star is always less than the mass of the nebula that “gave birth” to it. During this process, part of the matter that did not have time to fall onto the core is “swept out” by a shock wave, radiation and particle flows simply into the surrounding space.
The process of formation of stars and stellar systems is influenced by many factors, including the magnetic field, which often contributes to the “tearing” of the protostellar cloud into two, rarely three fragments, each of which is compressed under the influence of gravity into its own protostar. This is how, for example, many binary star systems arise - two stars that orbit a common center of mass and move in space as a single whole.
As nuclear fuel ages, the nuclear fuel in the interior of stars gradually burns out, and the larger the star, the faster it gets. In this case, the hydrogen cycle of reactions is replaced by the helium cycle, then, as a result of nuclear fusion reactions, increasingly heavier chemical elements are formed, up to iron. In the end, the nucleus, which no longer receives energy from thermonuclear reactions, sharply decreases in size, loses its stability, and its substance seems to fall on itself. A powerful explosion occurs, during which the substance can heat up to billions of degrees, and interactions between nuclei lead to the formation of new chemical elements, up to the heaviest. The explosion is accompanied by a sharp release of energy and the release of matter. A star explodes, a process called a supernova. Ultimately, the star, depending on its mass, will turn into a neutron star or a black hole.
This is probably what actually happens. In any case, there is no doubt that young, that is, hot, stars and their clusters are most numerous in nebulae, that is, in areas with an increased density of gas and dust. This is clearly visible in photographs taken by telescopes in different wavelength ranges.
Of course, this is nothing more than the crudest summary of the sequence of events. For us, two points are fundamentally important. First, what is the role of dust in the process of star formation? And secondly, where does it actually come from?
Universal coolant
In the total mass of cosmic matter, dust itself, that is, atoms of carbon, silicon and some other elements combined into solid particles, is so small that, in any case, as a building material for stars, it would seem that they can not be taken into account. However, in fact, their role is great - it is they who cool the hot interstellar gas, turning it into that very cold dense cloud from which stars are then formed.
The fact is that interstellar gas itself cannot cool. The electronic structure of the hydrogen atom is such that it can give up excess energy, if any, by emitting light in the visible and ultraviolet regions of the spectrum, but not in the infrared range. Figuratively speaking, hydrogen cannot radiate heat. To cool down properly, it needs a “refrigerator”, the role of which is played by interstellar dust particles.
During a collision with dust grains at high speed unlike heavier and slower dust grains, gas molecules fly quickly they lose speed and their kinetic energy is transferred to the dust grain. It also heats up and gives off this excess heat to the surrounding space, including in the form of infrared radiation, while it itself cools down. Thus, by absorbing the heat of interstellar molecules, dust acts as a kind of radiator, cooling the gas cloud. It is not much in mass - about 1% of the mass of the entire cloud matter, but this is enough to remove excess heat over millions of years.
When the temperature of the cloud drops, the pressure also drops, the cloud condenses and stars can be born from it. The remains of the material from which the star was born are, in turn, the starting material for the formation of planets. They already contain dust particles, and in larger quantities. Because, having been born, a star heats up and accelerates all the gas around itself, while dust remains flying nearby. After all, it is capable of cooling and is attracted to the new star much stronger than individual gas molecules. In the end, there is a dust cloud near the newborn star, and dust-rich gas at the periphery.
Gas planets such as Saturn, Uranus and Neptune are born there. Well, rocky planets appear near the star. For us it is Mars, Earth, Venus and Mercury. It turns out a fairly clear division into two zones: gas planets and solid ones. So the Earth turned out to be largely made of interstellar dust grains. Metal dust particles became part of the planet's core, and now the Earth has a huge iron core.
The Mystery of the Young Universe
If a galaxy has formed, then where does the dust come from? In principle, scientists understand. Its most significant sources are novae and supernovae, which lose part of their mass, “dropping” the shell into the surrounding space. In addition, dust is also born in the expanding atmosphere of red giants, from where it is literally swept away by radiation pressure. In their cool, by the standards of stars, atmosphere (about 2.5 3 thousand kelvins) there are quite a lot of relatively complex molecules.
But here is a mystery that has not yet been solved. It has always been believed that dust is a product of the evolution of stars. In other words, stars must be born, exist for some time, grow old and, say, produce dust in the last supernova explosion. But what came first - the egg or the chicken? The first dust necessary for the birth of a star, or the first star, which for some reason was born without the help of dust, grew old, exploded, forming the very first dust.
What happened in the beginning? After all, when the Big Bang occurred 14 billion years ago, there were only hydrogen and helium in the Universe, no other elements! It was then that the first galaxies began to emerge from them, huge clouds, and in them the first stars, which had to go through a long life path. Thermonuclear reactions in the cores of stars should have “cooked” more complex chemical elements, turning hydrogen and helium into carbon, nitrogen, oxygen, and so on, and after that the star should have thrown it all into space, exploding or gradually shedding its shell. This mass then had to cool, cool down and finally turn into dust. But already 2 billion years after the Big Bang, in the earliest galaxies, there was dust! Using telescopes, it was discovered in galaxies 12 billion light years away from ours. At the same time, 2 billion years is too short a period for the full life cycle of a star: during this time, most stars do not have time to grow old. Where the dust came from in the young Galaxy, if there should be nothing there except hydrogen and helium, is a mystery.
Mote reactor
Not only does interstellar dust act as a kind of universal coolant, but perhaps it is thanks to dust that complex molecules appear in space.
The fact is that the surface of a dust grain can serve both as a reactor in which molecules are formed from atoms and as a catalyst for the reactions of their synthesis. After all, the probability that many atoms of different elements will collide at one point, and even interact with each other at a temperature just above absolute zero, is unimaginably small. But the probability that a grain of dust will sequentially collide with various atoms or molecules in flight, especially inside a cold dense cloud, is quite high. Actually, this is what happens - this is how a shell of interstellar dust grains is formed from the encountered atoms and molecules frozen onto it.
On a solid surface, the atoms are close together. Migrating along the surface of a dust grain in search of the most energetically favorable position, atoms meet and, finding themselves in close proximity, are able to react with each other. Of course, very slowly in accordance with the temperature of the dust particle. The surface of particles, especially those containing a metal core, can exhibit catalyst properties. Chemists on Earth know well that the most effective catalysts are precisely particles a fraction of a micron in size on which molecules, which under normal conditions are completely “indifferent” to each other, gather and then react. Apparently, this is how molecular hydrogen is formed: its atoms “stick” to a speck of dust, and then fly away from it, but in pairs, in the form of molecules.
It may very well be that small interstellar dust particles, having retained a few organic molecules in their shells, including the simplest amino acids, brought the first “seeds of life” to Earth about 4 billion years ago. This, of course, is nothing more than a beautiful hypothesis. But what speaks in its favor is that the amino acid glycine was found in cold gas and dust clouds. Maybe there are others, it’s just that the capabilities of telescopes do not yet allow them to be detected.
Dust Hunt
The properties of interstellar dust can, of course, be studied at a distance using telescopes and other instruments located on Earth or on its satellites. But it is much more tempting to catch interstellar dust particles, and then study them in detail, find out, not theoretically, but practically, what they consist of and how they are structured. There are two options here. You can reach the depths of space, collect interstellar dust there, bring it to Earth and analyze it in all possible ways. Or you can try to fly outside the solar system and analyze dust along the way directly on board the spacecraft, sending the resulting data to Earth.
The first attempt to bring samples of interstellar dust, and substances of the interstellar medium in general, was made several years ago by NASA. The spacecraft was equipped with special traps - collectors for collecting interstellar dust and cosmic wind particles. To catch dust particles without losing their shell, the traps were filled with a special substance, the so-called airgel. This very light foamy substance (the composition of which is a trade secret) resembles jelly. Once inside, the dust particles get stuck, and then, as in any trap, the lid slams shut to be opened on Earth.
This project was called Stardust Stardust. His program is grandiose. After launching in February 1999, the equipment on board will eventually collect samples of interstellar dust and separately from dust in the immediate vicinity of Comet Wild-2, which flew near Earth last February. Now with containers filled with this valuable cargo, the ship flies home to land on January 15, 2006 in Utah, near Salt Lake City (USA). That’s when astronomers will finally see with their own eyes (with the help of a microscope, of course) those very dust grains whose composition and structure models they have already predicted.
And in August 2001, Genesis flew to collect samples of matter from deep space. This NASA project was aimed primarily at capturing particles from the solar wind. After spending 1,127 days in outer space, during which it flew about 32 million km, the ship returned and dropped a capsule with the resulting samples - traps with ions and solar wind particles - to Earth. Alas, a misfortune happened - the parachute did not open, and the capsule hit the ground with all its might. And crashed. Of course, the debris was collected and carefully studied. However, in March 2005, at a conference in Houston, program participant Don Barnetti said that four collectors with solar wind particles were not damaged, and their contents, 0.4 mg of captured solar wind, were being actively studied by scientists in Houston.
However, NASA is now preparing a third project, even more ambitious. This will be the Interstellar Probe space mission. This time the spacecraft will move away to a distance of 200 AU. e. from the Earth (a.e. distance from the Earth to the Sun). This ship will never return, but it will be “stuffed” with a wide variety of equipment, including for analyzing samples of interstellar dust. If everything works out, interstellar dust grains from deep space will finally be captured, photographed and analyzed automatically, right on board the spacecraft.
Formation of young stars
1. A giant galactic molecular cloud with a size of 100 parsecs, a mass of 100,000 suns, a temperature of 50 K, and a density of 10 2 particles/cm 3 . Inside this cloud there are large-scale condensations - diffuse gas and dust nebulae (1 x 10 pc, 10,000 suns, 20 K, 10 3 particles/cm 3) and small condensations - gas and dust nebulae (up to 1 pc, 100 x 1,000 suns, 20 K, 10 4 particles/cm 3). Inside the latter there are precisely clumps of globules with a size of 0.1 pc, a mass of 1 x 10 suns and a density of 10 x 10 6 particles / cm 3, where new stars are formed
2. The birth of a star inside a cloud of gas and dust
3. The new star, with its radiation and stellar wind, disperses the surrounding gas away from itself
4. A young star emerges into space that is clean and free of gas and dust, pushing aside the nebula that gave birth to it
Stages of “embryonic” development of a star with a mass equal to the Sun
5. The origin of a gravitationally unstable cloud with a size of 2,000,000 suns, with a temperature of about 15 K and an initial density of 10 -19 g/cm 3
6. After several hundred thousand years, this cloud will form a core with a temperature of about 200 K and the size of 100 suns, its mass is still only 0.05 of the solar
7. At this stage, the core with a temperature of up to 2,000 K sharply contracts due to the ionization of hydrogen and simultaneously heats up to 20,000 K, the speed of matter falling onto the growing star reaches 100 km/s
8. A protostar the size of two suns with a temperature at the center of 2x10 5 K, and at the surface 3x10 3 K
9. The last stage of the pre-evolution of a star is slow compression, during which lithium and beryllium isotopes burn out. Only after the temperature rises to 6x10 6 K, thermonuclear reactions of helium synthesis from hydrogen are started in the interior of the star. The total duration of the birth cycle of a star like our Sun is 50 million years, after which such a star can burn quietly for billions of years
Olga Maksimenko, Candidate of Chemical Sciences
Cosmic factors are of cosmic origin. These include the flow of cosmic dust, cosmic rays, etc. The most important cosmic factor is solar radiation. The sun's rays are a source of energy used by plants in the process of photosynthesis. Crop production can be considered as a system of measures to intensify photosynthesis of cultivated plants.[...]
Space resources, such as solar radiation, tidal energy and the like, are practically inexhaustible, and their protection (for example, the Sun) cannot be the subject of environmental protection, since humanity does not have such capabilities. However, the supply of solar energy to the surface of the Earth depends on the state of the atmosphere, the degree of its pollution - those factors that can be controlled by humans.[...]
FACTOR [lat. factor doing, producing] - a driving force of ongoing processes or a condition influencing processes. F. anthropogenic - a factor that owes its origin to human activity. F. climatic - a factor associated with the characteristics of the supply of solar energy, the circulation of air masses, the balance of heat and moisture, atmospheric pressure and other climatic processes. F. cosmic factor, the source of which are processes occurring outside the Earth (changes in solar activity, the flow of cosmic rays, etc.). F. transformative - 1) any internal or external influence in relation to the individual that causes persistent processes of adaptation. [...]
Space medicine is a complex of sciences covering medical, biological and other scientific research and activities aimed at ensuring safety and creating optimal conditions for human life during space flight and when entering outer space. Its sections include: study of the influence of space flight conditions and factors on the human body, elimination of their adverse effects and development of preventive measures and means; justification and formulation of medical requirements for life support systems of habitable space objects; prevention and treatment of diseases; medical justification for the rational construction of space object control systems; development of medical methods for selecting and training cosmonauts.[...]
The cosmic impact on the biosphere is evidenced by the law of refraction of cosmic impacts: cosmic factors, having an impact on the biosphere and especially its subdivisions, are subject to change by the ecosphere of the planet and therefore, in terms of strength and time, manifestations can be weakened and shifted or even completely lose their effect. The generalization here is important due to the fact that there is often a flow of synchronous effects of solar activity and other cosmic factors on the Earth’s ecosystems and the organisms inhabiting it (Fig. 12.57).[...]
The role of factors independent of population density in the formation of cycles of population dynamics is associated with the cyclical nature of long-term changes in climate and weather types. On this basis, the hypothesis of “climatic cycles” of abundance arose (Ch. Currently, this hypothesis has received a “rebirth” in the form of “the concept of connecting the dynamics of animal abundance with eleven-year cycles of solar activity. In particular, in a number of cases the coincidence of mammalian abundance cycles (mainly rodents) and solar activity can be recorded objectively. Thus, a correlation between the levels of solar activity and long-term changes in the abundance of the California vole Micmtus califomicus was discovered; it is believed that this may be the result of both the direct effect of the cosmic factor and secondary factors correlated with solar activity, in particular climate The direct influence of weather in these observations was also noted on smaller time scales.[...]
On board a spacecraft, the astronaut’s body is continuously affected by a factor unusual for the inhabitants of the Earth - weightlessness. There are no forces of attraction, the body becomes unusually light, and the blood also becomes weightless.[...]
The main factor influencing and influencing the atmosphere and the Earth in general is, of course, the Sun. The atmosphere, its structure and composition largely depend on solar electromagnetic radiation as the main external source of energy. The atmosphere is also significantly affected by the corpuscular flows of the solar wind, solar and galactic cosmic rays. Other external factors also noticeably affect the atmosphere, such as the gravitational influences of the Sun and Moon, magnetic and electric fields of the Earth, etc. [...]
External factors include: changes in illumination (photoperiodism), temperature (thermoperiodism), magnetic field, intensity of cosmic radiation, tides, seasonal and solar-lunar influences. [...]
ATMOSPHERE IONIZERS. Factors leading to the formation of light ions in the atmosphere (see ionization of the atmosphere). These factors are: radioactive radiation associated with radioactive elements in soil and rocks and their emanations; ultraviolet and X-ray solar radiation, cosmic and solar corpuscular radiation (in the ionosphere). Quiet electrical discharges and combustion are of secondary importance.[...]
Many environmental factors on our planet, primarily light conditions, temperature, air pressure and humidity, atmospheric electromagnetic field, sea tides, etc., naturally change under the influence of this rotation. Living organisms are also affected by cosmic rhythms such as periodic changes in solar activity. The Sun is characterized by an 11-year and a number of other cycles. Changes in solar radiation have a significant impact on the climate of our planet. In addition to the cyclical influence of abiotic factors, external rhythms for any organism are also natural changes in activity, as well as the behavior of other living beings.[...]
ENVIRONMENTAL CONDITIONS - a set of factors - from the cosmic impacts of the Universe on the Solar System to the direct impact of the environment on an individual, population or community.[...]
LIGHT is the most important environmental factor of cosmic nature, which provides energy for the production of primary organic matter by photoautotrophs (chlorophyll-containing green plants and cyanobacteria) and is an inexhaustible resource, as it constantly enters the Earth as a result of solar radiation..[...]
Establishment of A.L. Chizhevsky’s influence of cosmic factors on earthly processes put him in this direction of scientific research on a par with the pioneers of cosmic natural science - A. Humboldt, K.E. Tsiolkovsky, V.I. Vernadsky.[...]
The main stages of preparation and execution of space flights, which determine the degree of material and physical factors of impact on the ecosphere and near-Earth space, are: construction and operation of spaceports; pre-launch preparation and maintenance; active and passive flight phases; correction and maneuvering of the spacecraft on the flight path; additional insertion of the spacecraft from the intermediate orbit to the working orbit; flight and maneuvering of spacecraft in outer space and return to Earth.[...]
The peculiarities of the impact on the biosphere from cosmic factors and manifestations of solar activity are that the surface of our planet (where the “film of life” is concentrated) is, as it were, separated from Space by a thick layer of matter in a gaseous state, i.e., the atmosphere. The abiotic component of the terrestrial environment includes a set of climatic, hydrological, soil and ground conditions, i.e., many elements that are dynamic in time and space, interconnected and influencing living organisms. The atmosphere, as a medium that perceives cosmic and solar-related factors, has the most important climate-forming function.[...]
The reaction of the animal body to an informational environmental factor depends not only on its quality, but also on its quantity (intensity). An example is the response of animals to the influence of a sound alarm (noise). Natural background noise has a beneficial effect on organisms - it is one of the important factors in the optimal functioning of individuals, populations and biocenoses. Natural noise is considered equal to the sounds that arise from the flow of rivers, the movement of wind, the rustling of leaves, the breathing of animals, etc. A sharp decrease or, conversely, an increase in background noise is a limiting factor that negatively affects the body. Dead silence in a spacecraft negatively affects the psychological state of astronauts and their clinical and physiological status. Excessive noise also has a negative effect on the body. They have an irritating effect and disrupt the functioning of the digestive and metabolic organs in mammals and birds.[...]
Immediately after its formation, the young Earth was a cold cosmic body, and in its depths the temperature never exceeded the melting point of the substance. This, in particular, is evidenced by the complete absence on Earth of very ancient igneous (and any other) rocks with an age older than 4 billion years, as well as lead isotope ratios, showing that the processes of differentiation of terrestrial matter began noticeably later than the time of the formation of the Earth itself and proceeded without significant melting. In addition, there were no oceans or atmosphere on the earth's surface at that time. Therefore, the effective mechanical quality factor of the Earth in that early period of its development, which we will further call Katarchean, was relatively high. According to seismic data, in the developed oceanic lithosphere, i.e. in cold terrestrial matter of mantle composition, the quality factor ranges from 1000 to 2000, while in the partially molten asthenosphere under volcanoes its value drops to 100.[...]
But, moreover, a biologist cannot help but take into account one factor that he leaves aside. This factor is the main form of energy that manifests itself in the biosphere and underlies all its geological phenomena, including living matter. This energy is not only the energy of the Sun, which seems to us geologically eternal and in which fluctuations are imperceptible during the evolutionary process, but also other cosmic energy, which, apparently, inevitably changes in its intensity during the evolutionary process.[...]
The ionization of the lower and middle atmosphere is determined mainly by the following factors: cosmic rays, ionizing the entire atmosphere; UV and X-ray radiation from the Sun. The ionizing effect of UV and X-ray radiation manifests itself at altitudes above 50-60 km.[...]
Changes in the ionosphere in the polar regions of the Earth are also associated with solar cosmic rays, which cause ionization. During powerful flares of solar activity, exposure to solar cosmic rays may briefly exceed the normal background of galactic cosmic rays. Currently, science has accumulated a lot of factual materials illustrating the influence of cosmic factors on biosphere processes. In particular, the sensitivity of invertebrate animals to changes in solar activity has been proven, a correlation of its variations with the dynamics of the nervous and cardiovascular systems of humans, as well as with the dynamics of diseases - hereditary, oncological, infectious, etc., has been established [...]
The quantity and infinitely varied quality of the physical and chemical factors surrounding us from all sides - nature - are infinitely large. Powerful interacting forces come from outer space. The Sun, Moon, planets and an infinite number of celestial bodies are connected to the Earth by invisible bonds. The movement of the Earth is controlled by gravitational forces, which cause a number of deformations in the air, liquid and solid shells of our planet, make them pulsate, and produce tides. The position of the planets in the solar system affects the distribution and intensity of the Earth's electrical and magnetic forces.[...]
V.I. Vernadsky was one of the first to realize that humanity had become a powerful geological and, possibly, cosmic force, capable of transforming nature on a large scale. He noted that man has embraced the entire biosphere with his life and culture and strives to further deepen and expand the sphere of his influence. The biosphere, from his point of view, is gradually transformed into the noosphere - the sphere of reason. V.I. Vernadsky considered the noosphere as the highest stage of development of the biosphere, when intelligent human activity becomes the determining factor. He associated the transformation of the biosphere into the noosphere with the development of science, the deepening of scientific insight into the essence of processes occurring in nature and the organization of rational human activity on this basis. V.I. Vernadsky was convinced that noospheric humanity would find a way to restore and maintain ecological balance on the planet, develop and put into practice a strategy for the crisis-free development of nature and society. At the same time, he believed that man is quite capable of taking on the functions of managing the ecological development of the planet as a whole.[...]
After numerous international expeditions to Antarctica, it was found that, in addition to various physical and geographical factors, the main one is the presence of a significant amount of chlorofluorocarbons (CFCs) in the atmosphere. The latter are widely used in production and everyday life as refrigerants, foaming agents, solvents in aerosol packages, etc. Freons, rising into the upper layers of the atmosphere, undergo photochemical decomposition with the formation of chlorine oxide, which intensively destroys ozone. In total, about 1,300 thousand tons of ozone-depleting substances are produced in the world. In recent years, it has been established that emissions from supersonic aircraft can lead to the destruction of 10% of the ozone layer of the atmosphere, so one launch of a space shuttle type leads to the “quenching” of at least 10 million tons of ozone. Simultaneously with the depletion of the ozone layer in the stratosphere, there is an increase in the concentration of ozone in the troposphere near the Earth's surface, but this cannot compensate for the depletion of the ozone layer, since its mass in the troposphere is barely 10% of the mass in the ozonosphere. [...]
In 1975, the Section of Chemical, Technological and Chemical Sciences of the Presidium of the USSR Academy of Sciences, in its resolution, noted the importance of the problem “The influence of cosmic factors on processes occurring on Earth,” emphasizing that outstanding merit in the formulation and development of this problem “belongs to A.L. Chizhevsky, who first expressed the idea of the close dependence of phenomena occurring in the biosphere on cosmic factors, and Academician V.I. Vernadsky - the creator of the doctrine of the biosphere.”[...]
IRRADIATION - exposure of a living organism to any type of radiation: infrared (thermal radiation), visible and ultraviolet sunlight, cosmic rays and ionizing radiation of terrestrial origin. The biological effect of oxygen depends on the dose, type and energy of oxygen, accompanying factors and the physiological state of the body. O. external - irradiation of the body from sources of ionizing radiation located outside it. O. internal irradiation of the body from sources of ionizing radiation located inside it. O - modifying conditions - time, localization, accompanying factors. If the dose rate (the amount of radiation energy absorbed per unit of time) is very small, then even daily exposure throughout a person’s life will not be able to have a noticeably pronounced damaging effect.[... ]
The structure of the atmosphere discussed in Chapter 4 was formed as a result of the complex influence on the air shell of our planet of two factors - outer space, mainly on the upper layers, and the earth's surface through the lower layers. [...]
Impurities of natural origin, as a rule, are not air pollution, except in cases where they temporarily turn out to be either limiting factors in relation to living organisms, or significantly (but mostly locally) change some physicochemical properties of the atmosphere, for example, its transparency, reflectivity, thermal regime. Thus, cosmic dust (highly dispersed residues from the destruction and combustion of meteorite matter), smoke and soot from forest and steppe fires, dust from the weathering of rocks or surface masses of soil and sand captured by wind flows, including during dust and sand storms, tornadoes, hurricanes are not pollutants. Sometimes highly dispersed dust particles suspended in the air in calm conditions can serve as nuclei of moisture condensation and contribute to the formation of fog. As a result of the evaporation of splashes of water, tiny salt crystals are constantly present in the air above the surface of the seas and oceans. Multi-ton masses of solid matter erupt from the craters of active volcanoes.[...]
The removal of hydrogen from the cycle when it is bound into chemical compounds other than water (dispersed organic matter of rocks, supergene silicates), as well as when dissipated in outer space, is a very important factor from the point of view of the evolution of conditions on our planet. Without the removal of hydrogen, but only with its redistribution between reservoirs, changes in the redox balance towards the formation of an oxidizing environment on Earth could not occur.[...]
STRATOSPHERE AEROSOLS. Aerosol particles in the stratosphere, which are the result of volcanic eruptions, the introduction of condensation nuclei from the troposphere during strong convection, the actions of jet aircraft, etc., as well as particles of cosmic dust. Their increase increases the Earth's planetary albedo and lowers air temperature; therefore, S.A. are a global climate factor.[...]
Life on Earth was formed under the influence of environmental conditions. The latter is a collection of energy, material bodies, phenomena that are in interaction (direct and indirect). This concept is very broad: from the cosmic influences of the Universe on the solar system, the influence of the Sun as the main source of energy, on earthly processes to the direct effects of the environment (including humans) on an individual, population, community. The concept of environmental conditions includes components that do not or have little effect on the life activity of organisms (inert gases of the atmosphere, abiogenic elements of the earth’s crust) and those that significantly affect the life activity of biota. They are called environmental factors (light, temperature, water, air movement and its composition, soil properties, salinity, radioactivity, etc.). Environmental factors act together, although in some cases one factor predominates over the others and is decisive in the responses of living organisms (for example, temperature in the arctic and subarctic zones or deserts).[...]
The biodynamic farming system is used in Sweden, Denmark, and Germany. It incorporates basic principles common to other alternative farming systems. The difference between this farming system and others is that, in addition to bioinert elements, it takes into account cosmic factors and their rhythm, which influence the passage of phenophases of cultivated crops. [...]
In our country, a sufficient number of works are devoted to the problem of “human ecology”, but there is still no consensus regarding the legitimacy of such a science and its subject. Thus, G.I. Tsaregorodtsev (1976) used the term “human ecology” to mean “the interaction of humanity with natural environmental factors.” Yu. P. Lisitsin (1973), A. V. Katsura, I. V. Novik (1974), O. V. Baroyan (1975) and others believe that “human ecology” should study the optimal living conditions of man as a biological species (climatic, weather, space, etc.) and social being (psychological, social, economic, political, etc.).[...]
The atmosphere is the gaseous shell of the Earth. Composition of dry atmospheric air: nitrogen - 78.08%, oxygen - 20.94%, carbon dioxide - 0.033%, argon - 0.93%. The rest is impurities: neon, helium, hydrogen, etc. Water vapor makes up 3-4% of the volume of air. The density of the atmosphere at sea level is 0.001 g/cm'. The atmosphere protects living organisms from the harmful effects of cosmic rays and the ultraviolet spectrum of the sun, and also prevents sharp fluctuations in the temperature of the planet. At an altitude of 20-50 km, most of the energy from ultraviolet rays is absorbed by the conversion of oxygen into ozone, forming the ozone layer. The total ozone content is no more than 0.5% of the mass of the atmosphere, which is 5.15-1013 tons. The maximum ozone concentration is at an altitude of 20-25 km. The ozone shield is the most important factor in preserving life on Earth. The pressure in the troposphere (the surface layer of the atmosphere) decreases by 1 mm Hg. pillar when rising every 100 meters.[...]
For a long time it was believed that spontaneous mutations are causeless, but now there are other ideas on this issue, which boil down to the fact that spontaneous mutations are not causeless, that they are the result of natural processes occurring in cells. They arise in the natural radioactive background of the Earth in the form of cosmic radiation, radioactive elements on the surface of the Earth, radionuclides incorporated into the cells of organisms that cause these mutations or as a result of DNA replication errors. Factors in the natural radioactive background of the Earth cause changes in the sequence of bases or damage to bases, similar to the case of induced mutations (see below). [...]
Atmospheric aerosol, as a very small, but perhaps the most variable impurity in the atmosphere, plays an important role in a wide variety of scientific and applied issues of atmospheric physics. Practically, the aerosol entirely determines the optical weather and the extremely variable regime of direct and diffuse radiation in the atmosphere. The role of aerosol in the radiation regime of the atmosphere and in the information content of space optical methods for studying the Earth is increasingly being realized. Aerosol is an active participant and often the final product of complex cycles of chemical and photochemical reactions in the atmosphere. The role of aerosol as one of the ozone-active components of the atmosphere is great. Aerosol can be both a source and a sink of atmospheric ozone, for example, due to heterogeneous reactions of various gas impurities in the atmosphere. It is possible that it is the catalytic effect of the aerosol, which has a fine height distribution structure, that determines the correlation of aerosol and ozone layers observed by Rosen and Kondratieff. The spectral attenuation of aerosol from solar direct and scattered radiation is a very difficult factor to take into account for the correct determination of the content of atmospheric impurities by optical methods. Therefore, the study of aerosol and, above all, its spectral properties is a natural component of ozonometric research.[...]
The free surface of oceans and seas is called a flat surface. It is a surface perpendicular at each point to the direction of the resultant of all forces acting on it at a given location. The surface of the World Ocean, under the influence of various forces, experiences periodic, non-periodic and other fluctuations, deviating from the long-term average value closest to the geoid surface. The main forces causing these fluctuations can be combined into the following groups: a) cosmic - tidal forces; b) physical and mechanical, related to the distribution of solar radiation over the Earth’s surface and the impact of atmospheric processes, such as changes in the distribution of pressure and winds, precipitation, fluctuations in river flow and other hydrometeorological factors; c) geodynamic, associated with tectonic movements of the earth’s crust, seismic and geothermal phenomena.[...]
As already mentioned, the fresh waters of rivers and lakes, our main source of water supply, are different. This difference arose initially and is associated with the climatic zone and characteristics of the area in which the reservoir is located. Water is a universal solvent, which means that its saturation with minerals depends on the soil and the underlying rocks. In addition, water is mobile, and therefore its composition is affected by precipitation, snowmelt, floods and tributaries flowing into a larger river or lake. Take, for example, the Neva, the main source of drinking water in St. Petersburg: it is mainly fed by Lake Ladoga, one of the freshest lakes in the world. Ladoga water contains few calcium and magnesium salts, which makes it very soft; it contains little aluminum, manganese and nickel, but quite a lot of nitrogen, oxygen, silicon, and phosphorus. Finally, the microbiological composition of water depends on aquatic flora and fauna, on forests and meadows on the banks of a reservoir, and on many other reasons, not excluding cosmic factors. Thus, the pathogenicity of microbes increases sharply during years of solar activity: previously almost harmless ones become dangerous, and dangerous ones become simply fatal.
Cosmic dust, its composition and properties are little known to people not involved in the study of extraterrestrial space. However, such a phenomenon leaves its traces on our planet! Let's take a closer look at where it comes from and how it affects life on Earth.
Cosmic dust concept
Space dust on Earth is most often found in certain layers of the ocean floor, ice sheets of the planet's polar regions, peat deposits, hard-to-reach desert areas and meteorite craters. The size of this substance is less than 200 nm, which makes its study problematic.
Typically, the concept of cosmic dust includes a distinction between interstellar and interplanetary varieties. However, all this is very conditional. The most convenient option for studying such a phenomenon is considered to be the study of dust from space on the borders of the Solar system or beyond.
The reason for this problematic approach to studying the object is that the properties of extraterrestrial dust change dramatically when it is near a star such as the Sun.
Theories of the origin of cosmic dust
Streams of cosmic dust constantly attack the Earth's surface. The question arises where this substance comes from. Its origins give rise to much debate among experts in the field.
The following theories of the formation of cosmic dust are distinguished:
- Decay of celestial bodies. Some scientists believe that cosmic dust is nothing more than the result of the destruction of asteroids, comets and meteorites.
- Remnants of a protoplanetary type cloud. There is a version according to which cosmic dust is classified as microparticles of a protoplanetary cloud. However, this assumption raises some doubts due to the fragility of the finely dispersed substance.
- The result of an explosion on the stars. As a result of this process, according to some experts, a powerful release of energy and gas occurs, which leads to the formation of cosmic dust.
- Residual phenomena after the formation of new planets. The so-called construction “garbage” has become the basis for the emergence of dust.
The main types of cosmic dust
There is currently no specific classification of cosmic dust types. Subspecies can be distinguished by visual characteristics and location of these microparticles.
Let's consider seven groups of cosmic dust in the atmosphere, different in external indicators:
- Gray fragments of irregular shape. These are residual phenomena after the collision of meteorites, comets and asteroids no larger than 100-200 nm in size.
- Particles of slag-like and ash-like formation. Such objects are difficult to identify solely by external signs, because they have undergone changes after passing through the Earth's atmosphere.
- The grains are round in shape, with parameters similar to black sand. Outwardly, they resemble magnetite powder (magnetic iron ore).
- Small black circles with a characteristic shine. Their diameter does not exceed 20 nm, which makes studying them a painstaking task.
- Larger balls of the same color with a rough surface. Their size reaches 100 nm and makes it possible to study their composition in detail.
- Balls of a certain color with a predominance of black and white tones with inclusions of gas. These microparticles of cosmic origin consist of a silicate base.
- Balls of heterogeneous structure made of glass and metal. Such elements are characterized by microscopic sizes within 20 nm.
- Dust found in intergalactic space. This type can distort the dimensions of distances during certain calculations and is capable of changing the color of space objects.
- Formations within the Galaxy. The space within these limits is always filled with dust from the destruction of cosmic bodies.
- Matter concentrated between stars. It is most interesting due to the presence of a shell and a core of solid consistency.
- Dust located near a certain planet. It is usually located in the ring system of a celestial body.
- Clouds of dust around the stars. They circle along the orbital path of the star itself, reflecting its light and creating a nebula.
- Metal band. Representatives of this subspecies have a specific gravity of more than five grams per cubic centimeter, and their base consists mainly of iron.
- Silicate-based group. The base is transparent glass with a specific gravity of approximately three grams per cubic centimeter.
- Mixed group. The very name of this association indicates the presence of both glass and iron microparticles in the structure. The base also includes magnetic elements.
- Spherules with hollow filling. This species is often found in meteorite crash sites.
- Spherules of metallic formation. This subspecies has a core of cobalt and nickel, as well as a shell that has oxidized.
- Balls of homogeneous build. Such grains have an oxidized shell.
- Balls with a silicate base. The presence of gas inclusions gives them the appearance of ordinary slag, and sometimes foam.
It should be remembered that these classifications are very arbitrary, but serve as a certain guideline for designating the types of dust from space.
Composition and characteristics of cosmic dust components
Let's take a closer look at what cosmic dust consists of. There is a certain problem in determining the composition of these microparticles. Unlike gaseous substances, solids have a continuous spectrum with relatively few bands that are blurred. As a result, the identification of cosmic dust grains becomes difficult.
The composition of cosmic dust can be considered using the example of the main models of this substance. These include the following subspecies:
- Ice particles whose structure includes a core with a refractory characteristic. The shell of such a model consists of light elements. Large particles contain atoms with magnetic elements.
- The MRN model, the composition of which is determined by the presence of silicate and graphite inclusions.
- Oxide cosmic dust, which is based on diatomic oxides of magnesium, iron, calcium and silicon.
- Balls with metallic nature of formation. The composition of such microparticles includes an element such as nickel.
- Metal balls with the presence of iron and the absence of nickel.
- Silicone based circles.
- Iron-nickel balls of irregular shape.
The soils are fertile for the presence of cosmic material. A particularly large number of spherules were found in places where meteorites fell. The basis for them was nickel and iron, as well as various minerals such as troilite, cohenite, steatite and other components.
Glaciers also melt aliens from outer space in the form of dust in their blocks. Silicate, iron and nickel serve as the basis for the spherules found. All mined particles were classified into 10 clearly defined groups.
Difficulties in determining the composition of the object under study and differentiating it from impurities of terrestrial origin leave this issue open for further research.
The influence of cosmic dust on life processes
The influence of this substance has not been fully studied by specialists, which provides great opportunities for further activities in this direction. At a certain altitude, with the help of rockets, they discovered a specific belt consisting of cosmic dust. This gives grounds to assert that such extraterrestrial matter affects some processes occurring on planet Earth.
The influence of cosmic dust on the upper atmosphere
Recent studies indicate that the amount of cosmic dust can influence changes in the upper atmosphere. This process is very significant because it leads to certain fluctuations in the climatic characteristics of planet Earth.
A huge amount of dust resulting from asteroid collisions fills the space around our planet. Its quantity reaches almost 200 tons per day, which, according to scientists, cannot but leave its consequences.
The northern hemisphere, whose climate is prone to cold temperatures and dampness, is most susceptible to this attack, according to the same experts.
The impact of cosmic dust on cloud formation and climate change has not yet been sufficiently studied. New research in this area raises more and more questions, the answers to which have not yet been obtained.
The influence of dust from space on the transformation of oceanic silt
Irradiation of cosmic dust by the solar wind causes these particles to fall to Earth. Statistics show that the lightest of the three isotopes of helium enters ocean silt in huge quantities through dust grains from space.
The absorption of elements from outer space by minerals of ferromanganese origin served as the basis for the formation of unique ore formations on the ocean floor.
At the moment, the amount of manganese in areas that are close to the Arctic Circle is limited. All this is due to the fact that cosmic dust does not enter the World Ocean in those areas due to ice sheets.
The influence of cosmic dust on the composition of the water of the World Ocean
If we look at the glaciers of Antarctica, they are striking in the number of meteorite remains found in them and the presence of cosmic dust, which is a hundred times higher than the normal background.
The excessively increased concentration of the same helium-3, valuable metals in the form of cobalt, platinum and nickel allows us to confidently assert the fact of the interference of cosmic dust in the composition of the ice sheet. At the same time, the substance of extraterrestrial origin remains in its original form and not diluted by ocean waters, which in itself is a unique phenomenon.
According to some scientists, the amount of cosmic dust in such peculiar ice sheets over the last million years amounts to about several hundred trillion formations of meteorite origin. During the period of warming, these covers melt and carry elements of cosmic dust into the World Ocean.
Watch a video about cosmic dust:
This cosmic neoplasm and its influence on some factors of life on our planet have not yet been studied enough. It is important to remember that the substance can influence climate change, the structure of the ocean floor and the concentration of certain substances in the waters of the World Ocean. Photos of cosmic dust indicate how many more mysteries these microparticles conceal. All this makes studying this interesting and relevant!
Space exploration (meteor)dust on the surface of the Earth:problem overview
A.P.Boyarkina, L.M. Gindilis
Cosmic dust as an astronomical factor
Cosmic dust refers to particles of solid matter ranging in size from fractions of a micron to several microns. Dust matter is one of the important components of outer space. It fills interstellar, interplanetary and near-Earth space, penetrates the upper layers of the Earth's atmosphere and falls on the Earth's surface in the form of so-called meteor dust, being one of the forms of material (material and energy) exchange in the Space-Earth system. At the same time, it influences a number of processes occurring on Earth.
Dust matter in interstellar space
The interstellar medium consists of gas and dust mixed in a ratio of 100:1 (by mass), i.e. the mass of dust is 1% of the mass of the gas. The average gas density is 1 hydrogen atom per cubic centimeter or 10 -24 g/cm 3 . The density of dust is correspondingly 100 times less. Despite such an insignificant density, dust matter has a significant impact on the processes occurring in Space. First of all, interstellar dust absorbs light, which is why distant objects located near the galactic plane (where the dust concentration is greatest) are not visible in the optical region. For example, the center of our Galaxy is observed only in the infrared, radio and X-rays. And other galaxies can be observed in the optical range if they are located far from the galactic plane, at high galactic latitudes. The absorption of light by dust leads to distortion of distances to stars determined photometrically. Taking absorption into account is one of the most important problems in observational astronomy. When interacting with dust, the spectral composition and polarization of light changes.
Gas and dust in the galactic disk are distributed unevenly, forming separate gas and dust clouds; the concentration of dust in them is approximately 100 times higher than in the intercloud medium. Dense gas and dust clouds do not transmit the light of the stars behind them. Therefore, they appear as dark areas in the sky, which are called dark nebulae. An example is the Coalsack region in the Milky Way or the Horsehead Nebula in the constellation Orion. If there are bright stars near a gas and dust cloud, then due to the scattering of light on dust particles, such clouds glow; they are called reflection nebulae. An example is the reflection nebula in the Pleiades cluster. The most dense are clouds of molecular hydrogen H 2, their density is 10 4 -10 5 times higher than in clouds of atomic hydrogen. Accordingly, the density of dust is just as many times higher. In addition to hydrogen, molecular clouds contain dozens of other molecules. Dust particles are nuclei of condensation of molecules; chemical reactions occur on their surface with the formation of new, more complex molecules. Molecular clouds are regions of intense star formation.
In composition, interstellar particles consist of a refractory core (silicates, graphite, silicon carbide, iron) and a shell of volatile elements (H, H 2, O, OH, H 2 O). There are also very small silicate and graphite particles (without a shell) of the order of hundredths of a micron in size. According to the hypothesis of F. Hoyle and C. Wickramasing, a significant proportion of interstellar dust, up to 80%, consists of bacteria.
The interstellar medium is continuously replenished due to the influx of matter during the shedding of stellar shells in the later stages of their evolution (especially during supernova explosions). On the other hand, it itself is the source of the formation of stars and planetary systems.
Dust matter in interplanetary and near-Earth space
Interplanetary dust is formed mainly during the decay of periodic comets, as well as during the crushing of asteroids. Dust formation occurs continuously, and the process of dust grains falling onto the Sun under the influence of radiation braking also continues continuously. As a result, a constantly renewed dust environment is formed, filling interplanetary space and being in a state of dynamic equilibrium. Its density, although higher than in interstellar space, is still very small: 10 -23 -10 -21 g/cm 3 . However, it noticeably scatters sunlight. When it is scattered on particles of interplanetary dust, optical phenomena such as zodiacal light, the Fraunhofer component of the solar corona, the zodiacal band, and counter-radiance arise. The zodiacal component of the glow of the night sky is also determined by the scattering of dust particles.
Dust matter in the Solar System is highly concentrated towards the ecliptic. In the ecliptic plane, its density decreases approximately in proportion to the distance from the Sun. Near the Earth, as well as near other large planets, the concentration of dust increases under the influence of their gravity. Interplanetary dust particles move around the Sun in shrinking (due to radiation braking) elliptical orbits. Their speed of movement is several tens of kilometers per second. When colliding with solid bodies, including spacecraft, they cause noticeable surface erosion.
Colliding with the Earth and burning up in its atmosphere at an altitude of about 100 km, cosmic particles cause the well-known phenomenon of meteors (or “shooting stars”). On this basis, they were called meteoric particles, and the entire complex of interplanetary dust is often called meteoric matter or meteoric dust. Most meteor particles are loose bodies of cometary origin. Among them, two groups of particles are distinguished: porous particles with a density of 0.1 to 1 g/cm 3 and so-called dust lumps or fluffy flakes, reminiscent of snowflakes with a density of less than 0.1 g/cm 3 . In addition, denser asteroid-type particles with a density of more than 1 g/cm 3 are less common. At high altitudes, loose meteors predominate; at altitudes below 70 km, asteroid particles with an average density of 3.5 g/cm 3 prevail.
As a result of the fragmentation of loose meteoroids of cometary origin at altitudes of 100-400 km from the Earth's surface, a fairly dense dust shell is formed, the dust concentration in which is tens of thousands of times higher than in interplanetary space. The scattering of sunlight in this shell causes the twilight glow of the sky when the sun dips below the horizon below 100º.
The largest and smallest meteoroids of the asteroid type reach the Earth's surface. The first (meteorites) reach the surface due to the fact that they do not have time to completely collapse and burn when flying through the atmosphere; the latter - due to the fact that their interaction with the atmosphere, due to their insignificant mass (at a sufficiently high density), occurs without noticeable destruction.
The fall of cosmic dust onto the Earth's surface
While meteorites have long been in the field of view of science, cosmic dust has not attracted the attention of scientists for a long time.
The concept of cosmic (meteor) dust was introduced into science in the second half of the 19th century, when the famous Dutch polar explorer A.E. Nordenskjöld discovered dust of supposed cosmic origin on the surface of ice. Around the same time, in the mid-1970s, Murray (I. Murray) described rounded magnetite particles found in deep-sea sediments of the Pacific Ocean, the origin of which was also associated with cosmic dust. However, these assumptions were not confirmed for a long time, remaining within the framework of the hypothesis. At the same time, the scientific study of cosmic dust progressed extremely slowly, as pointed out by Academician V.I. Vernadsky in 1941.
He first drew attention to the problem of cosmic dust in 1908 and then returned to it in 1932 and 1941. In the work “On the Study of Cosmic Dust” V.I. Vernadsky wrote: “... The earth is connected with cosmic bodies and with outer space not only through the exchange of different forms of energy. It is closely connected with them materially... Among the material bodies falling onto our planet from outer space, predominantly meteorites and cosmic dust, which is usually included in them, are accessible to our direct study... Meteorites - and at least to some extent the fireballs associated with them - are always unexpected for us in their manifestation... Cosmic dust is a different matter: everything indicates that it falls continuously, and perhaps this continuity of fall exists at every point of the biosphere, distributed evenly over the entire planet. It is surprising that this phenomenon, one might say, has not been studied at all and completely disappears from scientific records.» .
Considering the largest known meteorites in this article, V.I. Vernadsky pays special attention to the Tunguska meteorite, the search for which was carried out by L.A. under his direct supervision. Sandpiper. Large fragments of the meteorite were not found, and in connection with this V.I. Vernadsky makes the assumption that he “... is a new phenomenon in the annals of science - the penetration into the region of earth's gravity not of a meteorite, but of a huge cloud or clouds of cosmic dust moving at cosmic speed» .
To the same topic V.I. Vernadsky returned in February 1941 in his report “On the need to organize scientific work on cosmic dust” at a meeting of the Committee on Meteorites of the USSR Academy of Sciences. In this document, along with theoretical reflections on the origin and role of cosmic dust in geology and especially in the geochemistry of the Earth, he substantiates in detail the program for searching and collecting material from cosmic dust that has fallen on the surface of the Earth, with the help of which, he believes, a number of problems can be solved scientific cosmogony about the qualitative composition and “dominant importance of cosmic dust in the structure of the Universe.” It is necessary to study cosmic dust and take it into account as a source of cosmic energy, continuously brought to us from the surrounding space. The mass of cosmic dust, noted V.I. Vernadsky, has atomic and other nuclear energy, which is not indifferent in its existence in Space and in its manifestation on our planet. To understand the role of cosmic dust, he emphasized, it is necessary to have sufficient material for its study. Organizing the collection of cosmic dust and scientific research of the collected material is the first task facing scientists. Promising for this purpose are V.I. Vernadsky considers snow and glacial natural plates of high-mountain and arctic regions remote from human industrial activity.
The Great Patriotic War and the death of V.I. Vernadsky, prevented the implementation of this program. However, it became relevant in the second half of the twentieth century and contributed to the intensification of research into meteoric dust in our country.
In 1946, on the initiative of Academician V.G. Fesenkov organized an expedition to the mountains of the Trans-Ili Ala-Tau (Northern Tien Shan), the task of which was to study solid particles with magnetic properties in snow deposits. The snow sampling site was chosen on the left side moraine of the Tuyuk-Su glacier (altitude 3500 m); most of the ridges surrounding the moraine were covered with snow, which reduced the possibility of contamination by earthly dust. It was also removed from sources of dust associated with human activity, and was surrounded on all sides by mountains.
The method for collecting cosmic dust in the snow cover was as follows. From a strip 0.5 m wide to a depth of 0.75 m, snow was collected with a wooden shovel, transferred and melted in an aluminum container, poured into a glass container, where the solid fraction precipitated within 5 hours. Then the upper part of the water was drained, a new batch of melted snow was added, etc. As a result, 85 buckets of snow were melted with a total area of 1.5 m2 and a volume of 1.1 m3. The resulting sediment was transferred to the laboratory of the Institute of Astronomy and Physics of the Academy of Sciences of the Kazakh SSR, where the water was evaporated and subjected to further analysis. However, since these studies did not give a definite result, N.B. Divari came to the conclusion that it would be better to use either very old compacted firns or open glaciers to take snow samples in this case.
Significant progress in the study of cosmic meteor dust came in the middle of the twentieth century, when, in connection with the launches of artificial Earth satellites, direct methods for studying meteor particles were developed - their direct registration by the number of collisions with a spacecraft or various types of traps (installed on satellites and geophysical rockets, launched to an altitude of several hundred kilometers). Analysis of the obtained materials made it possible, in particular, to detect the presence of a dust shell around the Earth at altitudes from 100 to 300 km above the surface (as discussed above).
Along with the study of dust using spacecraft, particles were studied in the lower atmosphere and various natural reservoirs: in high-mountain snow, in the Antarctic ice sheet, in the polar ice of the Arctic, in peat deposits and deep-sea silt. The latter are observed mainly in the form of so-called “magnetic balls,” that is, dense spherical particles with magnetic properties. The size of these particles is from 1 to 300 microns, weight from 10 -11 to 10 -6 g.
Another direction is related to the study of astrophysical and geophysical phenomena associated with cosmic dust; this includes various optical phenomena: the glow of the night sky, noctilucent clouds, zodiacal light, counter-radiance, etc. Their study also allows one to obtain important data about cosmic dust. Meteor research was included in the program of the International Geophysical Year 1957-1959 and 1964-1965.
As a result of these works, estimates of the total influx of cosmic dust onto the Earth's surface were refined. According to T.N. Nazarova, I.S. Astapovich and V.V. Fedynsky, the total influx of cosmic dust to Earth reaches up to 10 7 tons/year. According to A.N. Simonenko and B.Yu. Levin (according to data for 1972), the influx of cosmic dust to the surface of the Earth is 10 2 -10 9 t/year, according to other, more recent studies - 10 7 -10 8 t/year.
Research into meteor dust collection continued. At the suggestion of Academician A.P. Vinogradov, during the 14th Antarctic expedition (1968-1969), work was carried out to identify patterns of spatiotemporal distributions of extraterrestrial matter deposition in the Antarctic ice sheet. The surface layer of snow cover was studied in the areas of Molodezhnaya, Mirny, Vostok stations and in a section of about 1400 km between Mirny and Vostok stations. Snow sampling was carried out from pits 2-5 m deep at points remote from polar stations. The samples were packed in plastic bags or special plastic containers. Under stationary conditions, samples were melted in glass or aluminum containers. The resulting water was filtered using a collapsible funnel through membrane filters (pore size 0.7 μm). The filters were moistened with glycerol and the number of microparticles was determined in transmitted light at a magnification of 350X.
Polar ice, bottom sediments of the Pacific Ocean, sedimentary rocks, and salt deposits were also studied. At the same time, the search for melted microscopic spherical particles, which are quite easily identified among other dust fractions, has proven to be a promising direction.
In 1962, the Commission on Meteorites and Cosmic Dust was created at the Siberian Branch of the USSR Academy of Sciences, headed by Academician V.S. Sobolev, which existed until 1990 and whose creation was initiated by the problem of the Tunguska meteorite. Work on the study of cosmic dust was carried out under the leadership of Academician of the Russian Academy of Medical Sciences N.V. Vasilyeva.
When assessing cosmic dust fallout, along with other natural tablets, we used peat composed of brown sphagnum moss according to the method of Tomsk scientist Yu.A. Lvov. This moss is quite widespread in the middle zone of the globe; it receives mineral nutrition only from the atmosphere and has the ability to preserve it in the layer that was the surface when dust hit it. Layer-by-layer stratification and dating of peat allows us to give a retrospective assessment of its loss. Both spherical particles with a size of 7-100 microns and the microelement composition of the peat substrate were studied - a function of the dust it contained.
The method for isolating cosmic dust from peat is as follows. In an area of raised sphagnum bog, a site with a flat surface and a peat deposit composed of brown sphagnum moss (Sphagnum fuscum Klingr) is selected. Shrubs are cut from its surface at the level of the moss turf. A pit is laid to a depth of up to 60 cm, an area of the required size is marked at its side (for example, 10x10 cm), then a column of peat is exposed on two or three sides, cut into layers of 3 cm each, which are packed in plastic bags. The upper 6 layers (feather) are considered together and can serve to determine age characteristics according to the method of E.Ya. Muldiyarov and E.D. Lapshina. Each layer is washed under laboratory conditions through a sieve with a mesh diameter of 250 microns for at least 5 minutes. The humus with mineral particles that has passed through the sieve is allowed to settle until the sediment completely falls out, then the sediment is poured into a Petri dish, where it is dried. Packed in tracing paper, the dry sample is convenient for transportation and for further study. Under appropriate conditions, the sample is ashed in a crucible and muffle furnace for an hour at a temperature of 500-600 degrees. The ash residue is weighed and subjected to either inspection under a binocular microscope at 56 times magnification to identify spherical particles measuring 7-100 microns or more, or subjected to other types of analysis. Because This moss receives mineral nutrition only from the atmosphere, then its ash component may be a function of the cosmic dust included in its composition.
Thus, studies in the area of the fall of the Tunguska meteorite, many hundreds of kilometers away from sources of technogenic pollution, made it possible to estimate the influx of spherical particles with a size of 7-100 microns or more onto the Earth’s surface. The upper layers of peat provided an opportunity to estimate global aerosol deposition during the study period; layers dating back to 1908 - substances of the Tunguska meteorite; lower (pre-industrial) layers - cosmic dust. The influx of cosmic microspherules onto the Earth's surface is estimated at (2-4)·10 3 t/year, and in general of cosmic dust - 1.5·10 9 t/year. Analytical methods of analysis, in particular neutron activation, were used to determine the trace element composition of cosmic dust. According to these data, the following falls annually onto the Earth's surface from outer space (t/year): iron (2·10 6), cobalt (150), scandium (250).
Of great interest in terms of the above studies are the works of E.M. Kolesnikova and her co-authors, who discovered isotopic anomalies in the peat of the area where the Tunguska meteorite fell, dating back to 1908 and speaking, on the one hand, in favor of the comet hypothesis of this phenomenon, on the other hand, shedding light on the cometary substance that fell on the surface of the Earth.
The most complete review of the problem of the Tunguska meteorite, including its substance, for 2000 should be recognized as the monograph by V.A. Bronshten. The latest data on the substance of the Tunguska meteorite were reported and discussed at the International Conference “100 Years of the Tunguska Phenomenon”, Moscow, June 26-28, 2008. Despite the progress made in the study of cosmic dust, a number of problems still remain unresolved.
Sources of metascientific knowledge about cosmic dust
Along with the data obtained by modern research methods, of great interest is the information contained in non-scientific sources: “Letters of the Mahatmas”, the Teaching of Living Ethics, letters and works of E.I. Roerich (in particular, in her work “Study of Human Properties,” which provides an extensive program of scientific research for many years to come).
So in a letter from Koot Hoomi in 1882 to the editor of the influential English-language newspaper “Pioneer” A.P. Sinnett (the original letter is kept in the British Museum) provides the following data on cosmic dust:
- “High above our earth’s surface, the air is saturated and space is filled with magnetic and meteoric dust that does not even belong to our solar system”;
- “Snow, especially in our northern regions, is full of meteoric iron and magnetic particles, deposits of the latter are found even at the bottom of the oceans.” “Millions of such meteors and the finest particles reach us every year and every day”;
- “every atmospheric change on Earth and all perturbations occur from the combined magnetism” of two large “mass” - the Earth and meteoric dust;
There is "the terrestrial magnetic attraction of meteoric dust and the direct effect of the latter on sudden changes in temperature, especially in relation to heat and cold";
Because “our earth with all the other planets is rushing through space, it receives more of the cosmic dust on its northern hemisphere than on the southern”; “...this explains the quantitative predominance of continents in the northern hemisphere and the greater abundance of snow and dampness”;
- “The heat that the earth receives from the rays of the sun is, to the greatest extent, only a third, if not less, of the amount it receives directly from meteors”;
- “Powerful accumulations of meteoric matter” in interstellar space lead to a distortion of the observed intensity of starlight and, consequently, to a distortion of the distances to stars obtained by photometry.
A number of these provisions were ahead of the science of that time and were confirmed by subsequent research. Thus, studies of twilight atmospheric glow carried out in the 30-50s. XX century, showed that if at altitudes less than 100 km the glow is determined by the scattering of sunlight in a gaseous (air) medium, then at altitudes of more than 100 km the predominant role is played by scattering on dust particles. The first observations made with the help of artificial satellites led to the discovery of the dust shell of the Earth at altitudes of several hundred kilometers, as indicated in the mentioned letter from Kut Hoomi. Of particular interest are data on distortions of distances to stars obtained photometrically. Essentially, this was an indication of the presence of interstellar absorption, discovered in 1930 by Trempler, which is rightfully considered one of the most important astronomical discoveries of the 20th century. Taking into account interstellar absorption led to a reestimation of the astronomical distance scale and, as a consequence, to a change in the scale of the visible Universe.
Some provisions of this letter - about the influence of cosmic dust on processes in the atmosphere, in particular on the weather - have not yet found scientific confirmation. Further study is needed here.
Let us turn to another source of metascientific knowledge - the Teaching of Living Ethics, created by E.I. Roerich and N.K. Roerich in collaboration with the Himalayan Teachers - Mahatmas in the 20-30s of the twentieth century. The books of Living Ethics, originally published in Russian, have now been translated and published in many languages of the world. They pay great attention to scientific problems. In this case, we will be interested in everything related to cosmic dust.
The problem of cosmic dust, in particular its influx to the surface of the Earth, is given quite a lot of attention in the Teaching of Living Ethics.
“Pay attention to high places exposed to winds from snowy peaks. At the level of twenty-four thousand feet special deposits of meteoric dust can be observed" (1927-1929). “Aerolites are not studied enough, and even less attention is paid to cosmic dust on eternal snow and glaciers. Meanwhile, the Cosmic Ocean draws its rhythm on the peaks" (1930-1931). “Meteor dust is inaccessible to the eye, but produces very significant precipitation” (1932-1933). “In the purest place, the purest snow is saturated with earthly and cosmic dust - this is how space is filled even with rough observation” (1936).
Much attention is paid to issues of cosmic dust in the “Cosmological Records” of E.I. Roerich (1940). It should be borne in mind that E.I. Roerich closely followed the development of astronomy and was aware of its latest achievements; she critically assessed some theories of that time (20-30 years of the last century), for example in the field of cosmology, and her ideas have been confirmed in our time. The Teaching of Living Ethics and Cosmological Records of E.I. Roerich contain a number of provisions about those processes that are associated with the fall of cosmic dust on the surface of the Earth and which can be summarized as follows:
In addition to meteorites, material particles of cosmic dust constantly fall onto the Earth, which bring in cosmic matter that carries information about the Distant Worlds of outer space;
Cosmic dust changes the composition of soils, snow, natural waters and plants;
This especially applies to the locations of natural ores, which not only act as unique magnets that attract cosmic dust, but we should also expect some differentiation depending on the type of ore: “So iron and other metals attract meteors, especially when the ores are in their natural state and are not devoid of cosmic magnetism”;
Much attention in the Teaching of Living Ethics is paid to mountain peaks, which, according to E.I. Roerich “...are the greatest magnetic stations.” “...The Cosmic Ocean draws its rhythm on the peaks”;
The study of cosmic dust can lead to the discovery of new minerals that have not yet been discovered by modern science, in particular, a metal that has properties that help store vibrations with the distant worlds of outer space;
By studying cosmic dust, new types of microbes and bacteria may be discovered;
But what is especially important is that the Teaching of Living Ethics opens a new page of scientific knowledge - the impact of cosmic dust on living organisms, including humans and their energy. It can have various effects on the human body and some processes on the physical and, especially, subtle planes.
This information is beginning to be confirmed in modern scientific research. Thus, in recent years, complex organic compounds have been discovered on cosmic dust particles, and some scientists have started talking about cosmic microbes. In this regard, the work on bacterial paleontology carried out at the Institute of Paleontology of the Russian Academy of Sciences is of particular interest. In these works, in addition to terrestrial rocks, meteorites were studied. It has been shown that microfossils found in meteorites represent traces of the vital activity of microorganisms, some of which are similar to cyanobacteria. In a number of studies, it was possible to experimentally demonstrate the positive effect of cosmic matter on plant growth and substantiate the possibility of its influence on the human body.
The authors of the Teaching of Living Ethics strongly recommend organizing constant monitoring of cosmic dust fallout. And use glacial and snow deposits in the mountains at an altitude of over 7 thousand meters as its natural reservoir. The Roerichs, living for many years in the Himalayas, dreamed of creating a scientific station there. In a letter dated October 13, 1930, E.I. Roerich writes: “The station must develop into a City of Knowledge. We wish in this City to give a synthesis of achievements, therefore all areas of science should subsequently be represented in it... The study of new cosmic rays, giving humanity new valuable energies, only possible at altitudes, for all the subtlest and most valuable and powerful lies in the purer layers of the atmosphere. Also, aren’t all the meteoric precipitation deposited on the snowy peaks and carried into the valleys by mountain streams worthy of attention?” .
Conclusion
The study of cosmic dust has now become an independent field of modern astrophysics and geophysics. This problem is especially relevant since meteoric dust is a source of cosmic matter and energy that is continuously brought to Earth from outer space and actively influences geochemical and geophysical processes, as well as having a unique effect on biological objects, including humans. These processes have not yet been studied much. In the study of cosmic dust, a number of provisions contained in the sources of metascientific knowledge have not been properly applied. Meteor dust manifests itself in terrestrial conditions not only as a phenomenon of the physical world, but also as matter that carries the energy of outer space, including worlds of other dimensions and other states of matter. Taking these provisions into account requires the development of a completely new method for studying meteoric dust. But the most important task remains the collection and analysis of cosmic dust in various natural reservoirs.
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Cosmic X-ray background
Oscillations and waves: Characteristics of various oscillatory systems (oscillators).
Rupture of the Universe
Dust circumplanetary complexes: fig4
Properties of cosmic dust
| S. V. Bozhokin St. Petersburg State Technical University | Content |
Introduction
Many people admire with delight the beautiful spectacle of the starry sky, one of nature's greatest creations. In the clear autumn sky, it is clearly visible how a faintly luminous strip, called the Milky Way, runs across the entire sky, having irregular outlines with different widths and brightness. If we examine the Milky Way, which forms our Galaxy, through a telescope, it will turn out that this bright strip breaks up into many faintly luminous stars, which for the naked eye merge into a continuous glow. It is now established that the Milky Way consists not only of stars and star clusters, but also of gas and dust clouds.
Huge interstellar clouds of luminous rarefied gases got the name gaseous diffuse nebulae. One of the most famous is the nebula in Orion constellation, which is visible even to the naked eye near the middle of the three stars that form the “sword” of Orion. The gases that form it glow with cold light, re-emitting the light of neighboring hot stars. The composition of gaseous diffuse nebulae consists mainly of hydrogen, oxygen, helium and nitrogen. Such gaseous or diffuse nebulae serve as a cradle for young stars, which are born in the same way as ours was once born. solar system. The process of star formation is continuous, and stars continue to form today.
IN interstellar space Diffuse dust nebulae are also observed. These clouds are made up of tiny solid grains of dust. If there is a bright star near the dust nebula, then its light is scattered by this nebula and the dust nebula becomes directly observable(Fig. 1). Gas and dust nebulae can generally absorb the light of the stars behind them, so in sky photographs they are often visible as black, gaping holes against the background of the Milky Way. Such nebulae are called dark nebulae. There is one very large dark nebula in the sky of the southern hemisphere, which navigators nicknamed the Coal Sack. There is no clear boundary between gas and dust nebulae, so they are often observed together as gas and dust nebulae.
Diffuse nebulae are only densifications in that extremely rarefied interstellar matter, which was named interstellar gas. Interstellar gas is detected only when observing the spectra of distant stars, causing additional gas in them. Indeed, over a long distance, even such rarefied gas can absorb the radiation of stars. Emergence and rapid development radio astronomy made it possible to detect this invisible gas by the radio waves it emits. The huge, dark clouds of interstellar gas are composed mainly of hydrogen, which, even at low temperatures, emits radio waves at a length of 21 cm. These radio waves travel unimpeded through gas and dust. It was radio astronomy that helped us study the shape of the Milky Way. Today we know that gas and dust mixed with large clusters of stars form a spiral, the branches of which, emerging from the center of the Galaxy, wrap around its middle, creating something similar to a cuttlefish with long tentacles caught in a whirlpool.
Currently, a huge amount of matter in our Galaxy is in the form of gas and dust nebulae. Interstellar diffuse matter is concentrated in a relatively thin layer in equatorial plane our star system. Clouds of interstellar gas and dust block the center of the Galaxy from us. Due to clouds of cosmic dust, tens of thousands of open star clusters remain invisible to us. Fine cosmic dust not only weakens the light of stars, but also distorts them spectral composition. The fact is that when light radiation passes through cosmic dust, it not only weakens, but also changes color. The absorption of light by cosmic dust depends on the wavelength, so of all optical spectrum of a star Blue rays are absorbed more strongly and photons corresponding to red are absorbed more weakly. This effect leads to the phenomenon of reddening of the light of stars passing through the interstellar medium.
For astrophysicists, it is of great importance to study the properties of cosmic dust and determine the influence that this dust has when studying physical characteristics of astrophysical objects. Interstellar absorption and interstellar polarization of light, infrared radiation of neutral hydrogen regions, deficiency chemical elements in the interstellar medium, issues of the formation of molecules and the birth of stars - in all these problems, a huge role belongs to cosmic dust, the properties of which are discussed in this article.
Origin of cosmic dust
Cosmic dust grains arise mainly in the slowly expiring atmospheres of stars - red dwarfs, as well as during explosive processes on stars and violent ejections of gas from the cores of galaxies. Other sources of cosmic dust formation are planetary and protostellar nebulae , stellar atmospheres and interstellar clouds. In all processes of formation of cosmic dust grains, the gas temperature drops as the gas moves outward and at some point passes through the dew point, at which condensation of vapors of substances, forming the nuclei of dust grains. The centers of formation of a new phase are usually clusters. Clusters are small groups of atoms or molecules that form a stable quasi-molecule. When colliding with an already formed dust grain nucleus, atoms and molecules can join it, either entering into chemical reactions with the dust grain atoms (chemisorption) or completing the formation of the emerging cluster. In the densest regions of the interstellar medium, the concentration of particles in which is cm -3, the growth of dust grains can be associated with coagulation processes, in which dust grains can stick together without being destroyed. Coagulation processes, depending on the surface properties of dust grains and their temperatures, occur only when collisions between dust grains occur at low relative collision velocities.
In Fig. Figure 2 shows the process of growth of cosmic dust clusters using the addition of monomers. The resulting amorphous cosmic dust particle may be a cluster of atoms with fractal properties. Fractals are called geometric objects: lines, surfaces, spatial bodies that have a highly rugged shape and have the property of self-similarity. Self-similarity means the unchanged basic geometric characteristics fractal object when changing the scale. For example, images of many fractal objects turn out to be very similar when the resolution in a microscope increases. Fractal clusters are highly branched porous structures formed under highly nonequilibrium conditions when solid particles of similar sizes combine into one whole. Under terrestrial conditions, fractal aggregates are obtained when vapor relaxation metals in nonequilibrium conditions, during the formation of gels in solutions, during the coagulation of particles in smoke. The model of a fractal cosmic dust particle is shown in Fig. 3. Note that the processes of coagulation of dust grains occurring in protostellar clouds and gas and dust disks, are significantly enhanced by turbulent movement interstellar matter.
The nuclei of cosmic dust grains, consisting of refractory elements, hundreds of microns in size, are formed in the shells of cold stars during the smooth outflow of gas or during explosive processes. Such dust grain nuclei are resistant to many external influences.