Space object made of gas and dust. "Spots on the Milky Way"

By mass, solid particles of dust make up a negligible part of the Universe, but it is thanks to interstellar dust that stars, planets and people studying space and simply admiring the stars have arisen and continue to appear. What kind of substance is this - cosmic dust? What makes people equip expeditions into space worth the annual budget of a small state in the hope of only, and not in firm certainty, to extract and bring to Earth at least a tiny handful of interstellar dust?

Between stars and planets

Dust in astronomy is called small, fractions of a micron in size, solid particles flying in outer space. Cosmic dust is often conditionally divided into interplanetary and interstellar dust, although, obviously, interstellar entry into interplanetary space is not prohibited. Just finding it there, among the “local” dust, is not easy, the probability is low, and its properties near the Sun can change significantly. Now, if you fly away, to the borders solar system, where the probability of catching real interstellar dust is very high. Perfect option- generally go beyond the solar system.

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 for the most part as a result of random collisions of asteroids and the destruction of comets approaching the Sun. The composition of dust, in fact, does not differ from the composition of meteorites falling to the Earth: it is very interesting to study it, and there are still many discoveries to be made in this area, but it seems that there is no particular intrigue here. But thanks to this particular dust, in fine 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 zodiac sunlight scattered by small cosmic dust particles.

Much more interesting is interstellar dust. Its distinctive feature is the presence of a solid core and shell. The core appears to consist mainly of carbon, silicon, and metals. And the shell is mainly made of gaseous elements frozen on the surface of the nucleus, crystallized in the conditions of “deep freezing” of interstellar space, and this is about 10 kelvins, hydrogen and oxygen. However, there are impurities of molecules in it and more complicated. These are ammonia, methane, and even polyatomic organic molecules that stick to a grain of dust or form on its surface during wanderings. Some of these substances, of course, fly away from its surface, for example, under the action 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, they have already found, of course, not by chemical, but by physical, that is, by spectroscopic methods: water, oxides of carbon, nitrogen, sulfur and silicon, hydrogen chloride, ammonia, acetylene, organic acids, such as formic and acetic, ethyl and methyl alcohols, benzene, naphthalene. They even found an amino acid - glycine!

It would be interesting to catch and study the interstellar dust penetrating the solar system and probably falling to the Earth. The problem of "catching" it is not easy, because few interstellar dust particles manage to keep their ice "coat" in the sun, especially in the Earth's atmosphere. Large ones heat up too much - their cosmic speed cannot be quickly extinguished, and the dust particles "burn". Small ones, however, plan in the atmosphere for years, retaining part of the shell, but here the problem arises of finding and identifying them.

There is another very intriguing detail. It concerns the dust, the nuclei of which are composed of carbon. Carbon synthesized in the cores of stars and leaving into space, for example, from the atmosphere of aging (like red giants) stars, flying out 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 a container, particles of the atmosphere of a very ancient star are stored. Finding such dust particles would be a huge success.

Where is space dust found?

It must be said that the very concept of 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 galaxies, is filled with matter, flows elementary particles, radiation and fields - magnetic, electric and gravitational. All that can be touched, relatively speaking, is gas, dust and plasma, whose contribution to the total mass of the Universe, according to various estimates, is only about 1-2% with an average density of about 10-24 g/cm 3 . Gas in space is the most, almost 99%. This is mainly hydrogen (up to 77.4%) and helium (21%), the rest account 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 for one 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 in interstellar space very unevenly. Most of the interstellar gas and dust forms a gas and dust layer near the plane of symmetry of the Galactic 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 (16-160 light years) and weighing tens of thousands and even millions of solar masses. But even within these clouds, the matter is also distributed inhomogeneously. In the main volume of the cloud, the so-called fur coat, mainly from molecular hydrogen, the particle density is about 100 pieces per 1 cm 3. In densifications inside the cloud, it reaches tens of thousands of particles per 1 cm 3 , and in the cores of these densifications, in general, millions of particles per 1 cm 3 . It is this unevenness in the 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 is interesting: the higher the density of the cloud, the more diverse it is in composition. In this case, there is a correspondence between the density and temperature of the cloud (or its individual parts) and those substances, the molecules of which 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 "look" into one or another part of it. And on the other hand, data on the composition of the cloud allows you to learn a lot about the processes taking place in it.

In addition, in interstellar space, judging by the spectra, there are also 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 long and quite freely.

In general, gas in interstellar space is not only atomic. Where it is colder, no more than 50 kelvins, the atoms manage to stay together, forming molecules. However, a large mass of interstellar gas is still in the atomic state. This is mainly hydrogen, its neutral form was discovered relatively recently - in 1951. As you know, it emits radio waves with a length of 21 cm (frequency 1420 MHz), the intensity of which determined how much it is in the Galaxy. Incidentally, it is distributed inhomogeneously in the space between the stars. In the clouds atomic hydrogen its concentration reaches several atoms per 1 cm 3 , but between clouds it is orders of magnitude less.

Finally, near hot stars, gas exists in the form of ions. Powerful ultraviolet radiation heats and ionizes the gas, and it begins to glow. That is why areas with a high concentration of hot gas, with a temperature of about 10,000 K, look like luminous clouds. They are called light gas nebulae.

And in any nebula, to a greater or lesser extent, there is interstellar dust. Despite the fact that nebulae are conditionally divided into dusty and gaseous, there is dust in both of them. And in any case, it is dust that apparently helps stars form in the depths of nebulae.

fog objects

Among all space objects, nebulae are perhaps the most beautiful. True, dark nebulae in the visible range look just like black blobs in the sky - they are best observed against the background of the Milky Way. But in other ranges electromagnetic waves, for example infrared, they are visible very well - and the pictures are very unusual.

Nebulae are isolated in space, connected by gravitational forces or external pressure, accumulations of gas and dust. Their mass can be from 0.1 to 10,000 solar masses, and their size can be from 1 to 10 parsecs.

At first, astronomers were annoyed by nebulae. Until the middle of the 19th century, the discovered nebulae were considered as an annoying hindrance that prevented observing stars and searching for new comets. In 1714, the Englishman Edmond Halley, whose name the famous comet bears, even compiled a “black list” of six nebulae so that they would not mislead the “comet catchers”, and the Frenchman Charles Messier expanded this list to 103 objects. Fortunately, musician Sir William Herschel, his sister and son, who was in love with astronomy, became interested in nebulae. Observing the sky with their own built telescopes, they left behind a catalog of nebulae and star clusters, numbering information about 5,079 space objects!

The Herschels practically exhausted the possibilities of optical telescopes of those years. However, the invention of photography and the long exposure time made it possible to find very faintly luminous objects. A little later, spectral methods of analysis, 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 looks 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 - this is a reflection nebula.

Dark nebulae are also interstellar accumulations of gas and dust. But unlike light gaseous nebulae, sometimes visible even with strong binoculars or a telescope, such as the Orion Nebula, dark nebulae do not emit light, but absorb it. When the light of a star passes through such nebulae, the dust can completely absorb it, converting it into infrared radiation invisible to the eye. Therefore, such nebulae look like starless dips in the sky. V. Herschel called them "holes in the sky." Perhaps the most spectacular of these is the Horsehead Nebula.

However, dust particles may not completely absorb the light of stars, but only partially scatter it, while 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 the light of stars reaches us better. By the way, this good way estimate the size of dust grains by how they attenuate light of different wavelengths.

star from the cloud

The reasons for the formation of stars have not been precisely established - there are only models that more or less reliably explain the experimental data. In addition, the ways of formation, properties and further fate stars are very diverse and depend on many factors. However, there is a well-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.

This happens (in the most primitive version, for a single star), apparently, like this. 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 fully understood. One way or another, it contracts and attracts matter from the surrounding space. The temperature and pressure at its center rise until the molecules at the center of this shrinking ball of gas begin to disintegrate into atoms and then into ions. Such a process cools the gas, and the pressure inside the core drops sharply. The core is compressed, and a shock wave propagates inside the cloud, discarding its outer layers. A protostar is formed, which continues to shrink under the influence of gravitational forces until thermonuclear fusion reactions begin in its center - the conversion of hydrogen into helium. 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 formed star is always less than the mass of the nebula that "produced" it. Part of the matter that did not have time to fall onto the nucleus is “swept out” by the shock wave, radiation and particle flows simply into the surrounding space during this process.

The process of formation of stars and stellar systems is influenced by many factors, including the magnetic field, which often contributes to the "break" of the protostellar cloud into two, less often three fragments, each of which is compressed into its own protostar under the influence of gravity. This is how, for example, many binary star systems arise - two stars that revolve around a common center of mass and move in space as a single whole.

As the "aging" of nuclear fuel in the bowels of stars gradually burns out, and the faster, the more star. In this case, the hydrogen cycle of reactions is replaced by helium, then, as a result of nuclear fusion reactions, increasingly heavier chemical elements are formed, up to iron. In the end, the nucleus, which does not receive more energy from thermonuclear reactions, sharply decreases in size, loses its stability, and its substance, as it were, falls on itself. A powerful explosion occurs, during which the substance can heat up to billions of degrees, and the interactions between the nuclei lead to the formation of new chemical elements up to the most severe. The explosion is accompanied by a sharp release of energy and the release of matter. A star explodes - this process is called a supernova explosion. Ultimately, the star, depending on the mass, will turn into 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 of all just in nebulae, that is, in areas with an increased density of gas and dust. This is clearly seen 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 formation of stars? And the second - where, in fact, does it 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 obtained.

The fact is that interstellar gas cannot cool itself. 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. In order to cool down properly, it needs a “refrigerator”, the role of which is precisely played by particles of interstellar dust.

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 transferred to the dust. It also heats up and gives off this excess heat to the surrounding space, including in the form of infrared radiation, while itself cools down. So, taking on the heat of interstellar molecules, the dust acts as a kind of radiator, cooling the gas cloud. There is not much of it by mass - about 1% of the mass of the entire substance of the cloud, but this is enough to remove excess heat over millions of years.

When the temperature of the cloud drops, so does the pressure, the cloud condenses and stars can already be born from it. The remnants of the material from which the star was born are, in turn, the source for the formation of planets. Here, dust particles are already included in their composition, and in more. Because, having been born, the star heats up and accelerates all the gas around it, and the dust remains to fly nearby. After all, it is able to cool and is attracted to a new star much stronger than individual gas molecules. In the end, next to the newborn star is a dust cloud, and on the periphery - dust-saturated gas.

There are born gas planets such as Saturn, Uranus and Neptune. Well, solid planets appear near the star. We have 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 particles. Metallic dust particles have become part of the planet's core, and now the Earth has a huge iron core.

Mystery of the young universe

If the 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, "dumping" 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's a mystery that hasn't been solved yet. 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. 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 was in the beginning? After all, when the Big Bang happened 14 billion years ago, there were only hydrogen and helium in the Universe, no other elements! It was then that the first galaxies, huge clouds, began to emerge from them, and in them the first stars that had to go through a long life path. Thermonuclear reactions in the cores of stars were supposed to “weld” more complex chemical elements, turn hydrogen and helium into carbon, nitrogen, oxygen, and so on, and only after that the star had to throw it all into space, exploding or gradually dropping the shell. Then this mass 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! With the help of telescopes, it was discovered in galaxies that are 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 but hydrogen and helium, is a mystery.

Dust - reactor

Not only does interstellar dust act as a kind of universal refrigerant, it is perhaps thanks to dust that complex molecules appear in space.

The fact is that the surface of a grain of dust can simultaneously serve 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 once at one point, and even interact with each other at a temperature slightly above absolute zero, is unimaginably small. On the other hand, the probability that a grain of dust will sequentially collide in flight with various atoms or molecules, especially inside a cold dense cloud, is quite high. Actually, this is what happens - this is how the shell of interstellar dust grains is formed from the met atoms and molecules frozen on it.

On a solid surface, atoms are side by side. Migrating over the surface of a dust grain in search of the most energetically favorable position, atoms meet and, being in close proximity, get the opportunity to react with each other. Of course, very slowly - in accordance with the temperature of the dust. The surface of particles, especially those containing a metal in the core, can exhibit the properties of a catalyst. Chemists on Earth are well aware that the most effective catalysts are just particles a fraction of a micron in size, on which molecules are assembled and then react, which, under normal conditions, are completely “indifferent” to each other. Apparently, molecular hydrogen is also formed in this way: its atoms "stick" to a grain of dust, and then fly away from it - but already in pairs, in the form of molecules.

It is very possible that small interstellar dust grains, having retained in their shells a few organic molecules, 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 in its favor is the fact that an amino acid, glycine, was found in the composition of cold gas and dust clouds. Maybe there are others, just so far the capabilities of telescopes do not allow them to be detected.

Hunting for dust

It is possible, of course, to study the properties of interstellar dust at a distance - with the help of telescopes and other instruments located on the Earth or on its satellites. But it is much more tempting to catch interstellar dust particles, and then to study in detail, to find out - not theoretically, but practically, what they consist of, how they are arranged. There are two options here. You can get to 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 out of the solar system and analyze the dust along the way right on board the spacecraft, sending the received data to Earth.

The first attempt to bring samples of interstellar dust, and in general the substance of the interstellar medium, was made by NASA several years ago. 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 (whose composition is a trade secret) resembles jelly. Once in it, dust particles get stuck, and then, as in any trap, the lid slams shut to be open already on Earth.

This project was called Stardust - Stardust. His program is great. After the launch in February 1999, the equipment on board will eventually collect samples of interstellar dust and, separately, dust in the immediate vicinity of the comet Wild-2, which flew near the Earth in February last year. Now with containers filled with this most valuable cargo, the ship is flying 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 particles, the models of the composition and structure of which they have already predicted.

And in August 2001, Genesis flew for samples of matter from deep space. This NASA project was aimed mainly at capturing solar wind particles. 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 obtained samples onto Earth - traps with ions, particles of the solar wind. Alas, a misfortune happened - the parachute did not open, and the capsule slammed to the ground with all its might. And crashed. Of course, the wreckage was collected and carefully studied. However, in March 2005, at a conference in Houston, a participant in the program, Don Barnetty, said that four collectors with solar wind particles were not affected, and scientists are actively studying their contents, 0.4 mg of the captured solar wind, in Houston.

However, now NASA is preparing a third project, even more grandiose. It will be space mission Interstellar Probe. This time spaceship will be removed at a distance of 200 a. e. from the Earth (a. e. - the distance from the Earth to the Sun). This ship will never return, but the whole will be “stuffed” with a wide variety of equipment, including for analyzing samples of interstellar dust. If all goes well, interstellar dust particles 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, a density of 10 2 particles / cm 3. Inside this cloud there are large-scale condensations - diffuse gas and dust nebulae (1-10 pc, 10,000 suns, 20 K, 103 particles/cm 4 particles/cm3). Inside the latter, there are clusters of globules with a size of 0.1 pc, a mass of 1-10 suns and a density of 10-10 6 particles / cm 3, where new stars are formed.

2. The birth of a star inside a gas and dust cloud

3. A new star with its radiation and stellar wind accelerates the surrounding gas away from itself

4. A young star enters space, clean and free of gas and dust, pushing the nebula that gave birth to it

Stages of the "embryonic" development of a star, equal in mass to the Sun

5. The origin of a gravitationally unstable cloud 2,000,000 suns in size, 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 forms a core with a temperature of about 200 K and a size of 100 suns, its mass is still only 0.05 of the solar

7. At this stage, the core with temperatures up to 2,000 K shrinks sharply due to hydrogen ionization and simultaneously heats up to 20,000 K, the velocity of matter falling onto a growing star reaches 100 km/s

8. A protostar the size of two suns with a temperature of 2x10 5 K at the center and 3x10 3 K on the surface

9. The last stage in 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 start 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 quietly burn for billions of years

Olga Maksimenko, Candidate of Chemical Sciences

Hello!

Today we will talk about a very interesting topic related to such a science as astronomy! Let's talk about space dust. I guess many of you have heard about it for the first time. So, you need to tell about her everything that only I know! At school - astronomy was one of my favorite subjects, I will say more - my favorite, because it was in astronomy that I passed the exam.

Although I got the 13th ticket, which was the most difficult, I passed the exam perfectly and was satisfied!

If it is quite accessible to say what cosmic dust is, then one can imagine all the fragments that are only in the Universe from cosmic matter, for example, from asteroids. And the Universe after all is not only Space! Do not confuse, my dear and good! The Universe is our whole world - our whole huge globe!

How is space dust formed?

For example, cosmic dust can be formed when two asteroids collide in space and during the collision, they break down into small particles. Many scientists are also inclined to believe that its formation is associated with when the interstellar gas thickens.

How is space dust created?

How it is formed, we just found out, now we will learn about how it arises. As a rule, these dust grains simply arise in the atmospheres of red stars, if you have heard, such red stars are also called dwarf stars; occur when various explosions occur on stars; when gas is actively ejected from the very nuclei of galaxies; protostellar and planetary nebula - also contributes to its occurrence, however, like the stellar atmosphere itself and interstellar clouds.

What types of cosmic dust can be distinguished, given its origin?

As for the species, regarding the origin, we distinguish the following species:

interstellar type of dust, when an explosion occurs on the stars, a huge release of gas and a powerful release of energy occur

intergalactic,

interplanetary,

circumplanetary: appeared as "garbage", remnants, after the formation of other planets.

Are there species that are classified not by origin, but by external features?

black circles, small, shiny

black circles, but larger in size, having a rough surface

circles balls black and white, which in their composition have a silicate base

circles, which consist of glass and metal, they are heterogeneous, and small (20 nm)

circles similar to magnetite powder, they are black and look like black sand

ash-like and slag-like circles

a species that was formed from the collision of asteroids, comets, meteorites

Lucky question! Of course it can. And from the collision of meteorites, too. From the collision of any celestial bodies its education is possible.

The question of the formation and origin of cosmic dust is still controversial, and different scientists put forward their points of view, but you can adhere to one or two points of view that are close to you on this issue. For example, the one that is more understandable.

After all, even with respect to its species there is no absolutely accurate classification!

balls, the basis of which is homogeneous; their shell is oxidized;

balls, the basis of which is silicate; since they have inclusions of gas, their appearance is often similar to slag or foam;

balls, the basis of which is metal with a core of nickel and cobalt; the shell is also oxidized;

circles whose filling is hollow.

they can be icy, and their shell consists of light elements; in large ice particles there are even atoms that have magnetic properties,

circles with silicate and graphite inclusions,

circles consisting of oxides, which are based on diatomic oxides:

Space dust is not fully understood! There are a lot of open questions, because they are controversial, but I think we still have the main ideas now!

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Many people admire with delight the beautiful spectacle of the starry sky, one of the greatest creations of nature. In the clear autumn sky, it is clearly visible how a faintly luminous band, called milky way, which has irregular outlines with different widths and brightness. If we look at the Milky Way, which forms our Galaxy, through a telescope, it will turn out that this bright band breaks up into many faintly luminous stars, which, to the naked eye, merge into a continuous radiance. It is now established that the Milky Way consists not only of stars and star clusters, but also of gas and dust clouds.

Cosmic dust occurs in many space objects, where there is a rapid outflow of matter, accompanied by cooling. It manifests itself in infrared radiation hot stars Wolf-Rayet with a very powerful stellar wind, planetary nebulae, supernova shells and new stars. A large amount of dust exists in the cores of many galaxies (for example, M82, NGC253), from which there is an intense outflow of gas. The influence of cosmic dust is most pronounced during the radiation of a new star. A few weeks after the maximum brightness of the nova, a strong excess of radiation in the infrared range appears in its spectrum, caused by the appearance of dust with a temperature of about K. Further

Interstellar dust is a product of various intensity processes occurring in all corners of the Universe, and its invisible particles even reach the surface of the Earth, flying in the atmosphere around us.

A repeatedly confirmed fact - nature does not like emptiness. interstellar space, which seems to us to be a vacuum, is actually filled with gas and microscopic, 0.01-0.2 microns in size, dust particles. The combination of these invisible elements gives rise to objects of enormous size, a kind of clouds of the Universe, capable of absorbing some types of spectral radiation from stars, sometimes completely hiding them from earthly researchers.

What is interstellar dust made of?

These microscopic particles have a nucleus, which is formed in the gaseous envelope of stars and depends entirely on its composition. For example, graphite dust is formed from grains of carbon luminaries, and silicate dust is formed from oxygen ones. This is an interesting process that lasts for decades: when the stars cool down, they lose their molecules, which, flying into space, combine into groups and become the basis of the core of a dust grain. Further, a shell of hydrogen atoms and more complex molecules is formed. At low temperatures, interstellar dust is in the form of ice crystals. Wandering around the Galaxy, little travelers lose part of the gas when heated, but new molecules take the place of the departed molecules.

Location and properties

The main part of the dust that falls on our Galaxy is concentrated in the region of the Milky Way. It stands out against the background of stars in the form of black stripes and spots. Despite the fact that the weight of dust is negligible compared to the weight of gas and is only 1%, it is able to hide celestial bodies from us. Although the particles are separated from each other by tens of meters, but even in such an amount, the densest regions absorb up to 95% of the light emitted by stars. The sizes of gas and dust clouds in our system are really huge, they are measured in hundreds of light years.

Impact on observations

Thackeray globules obscure the region of the sky behind them

Interstellar dust absorbs most of the radiation from stars, especially in the blue spectrum, it distorts their light and polarity. Short waves from distant sources receive the greatest distortion. Microparticles mixed with gas are visible as dark spots on the Milky Way.

In connection with this factor, the core of our Galaxy is completely hidden and is available for observation only in infrared rays. Clouds with a high concentration of dust become almost opaque, so the particles inside do not lose their icy shell. Modern researchers and scientists believe that it is they who stick together to form the nuclei of new comets.

Science has proven the influence of dust granules on the processes of star formation. These particles contain various substances, including metals, which act as catalysts for numerous chemical processes.

Our planet increases its mass every year due to falling interstellar dust. Of course, these microscopic particles are invisible, and in order to find and study them, they explore the ocean floor and meteorites. The collection and delivery of interstellar dust has become one of the functions of spacecraft and missions.

When entering the Earth's atmosphere, large particles lose their shell, and small ones invisibly circle around us for years. Cosmic dust is ubiquitous and similar in all galaxies, astronomers regularly observe dark lines on the face of distant worlds.

Cosmic dust, its composition and properties are little known to a person who is not associated with the study of extraterrestrial space. However, such a phenomenon leaves its traces on our planet! Let us consider in more detail where it comes from and how it affects life on Earth.

The concept of space dust

Cosmic dust on Earth is most often found in certain layers of the ocean floor, ice sheets of the polar regions of the planet, peat deposits, hard-to-reach places in the desert and meteorite craters. The size of this substance is less than 200 nm, which makes its study problematic.

Usually the concept of cosmic dust includes the delimitation of the interstellar and interplanetary varieties. However, all this is very conditional. The most convenient option for studying this phenomenon is the study of dust from space at the edges of the solar system or beyond.

The reason for this problematic approach to the study of the object is that the properties of extraterrestrial dust change dramatically when it is near a star like the Sun.

Theories on the origin of cosmic dust

Streams of cosmic dust constantly attack the surface of the Earth. The question arises where this substance comes from. Its origin gives rise to many discussions among specialists in this field.

There are such theories of the formation of cosmic dust:

• Decay of celestial bodies. Some scientists believe that space dust is nothing more than the result of the destruction of asteroids, comets and meteorites.
• The remnants of a protoplanetary type cloud. There is a version according to which cosmic dust is referred to as microparticles of a protoplanetary cloud. However, such an assumption raises some doubts due to the fragility of a finely dispersed substance.
• The result of the explosion on the stars. As a result of this process, according to some experts, there is a powerful release of energy and gas, 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 occurrence of dust.

According to some studies, a certain part of the cosmic dust component predated the formation of the solar system, which makes this material even more interesting for further study. It is worth paying attention to this when evaluating and analyzing such an extraterrestrial phenomenon.

The main types of cosmic dust

A specific classification of types of cosmic dust on this moment does not exist. Subspecies can be distinguished by visual characteristics and location of these microparticles.

Consider seven groups of cosmic dust in the atmosphere, different in external indicators:

1. 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.
2. 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.
3. The grains are round in shape, which are similar in parameters to black sand. Outwardly, they resemble powder of magnetite (magnetic iron ore).
4. Small black circles with a characteristic sheen. Their diameter does not exceed 20 nm, which makes their study a painstaking task.
5. 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.
6. 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.
7. Spheres of heterogeneous structure made of glass and metal. Such elements are characterized by microscopic dimensions within 20 nm.

According to the astronomical location, 5 groups of cosmic dust are distinguished:

• Dust found in intergalactic space. This view can distort the size of distances in certain calculations and is able to change 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 a 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 the orbital path of the star itself, reflecting its light and creating a nebula.

Three groups according to the total specific gravity of microparticles look like this:

1. metal group. Representatives of this subspecies have a specific gravity of more than five grams per cubic centimeter, and their basis consists mainly of iron.
2. silicate group. The base is clear glass with a specific gravity of approximately three grams per cubic centimeter.
3. Mixed group. The very name of this association indicates the presence of both glass and iron in the structure of microparticles. The base also includes magnetic elements.

Four similarity groups internal structure microparticles of cosmic dust:

• Spherules with hollow filling. This species is often found in places where meteorites fall.
• Spherules of metal formation. This subspecies has a core of cobalt and nickel, as well as a shell that has oxidized.
• Spheres of uniform addition. Such grains have an oxidized shell.
• Balls with a silicate base. The presence of gas inclusions gives them the appearance of ordinary slags, and sometimes foam.

It should be remembered that these classifications are very arbitrary, but they serve as a certain guideline for designating types of dust from space.

Composition and characteristics of the components of cosmic dust

Let's take a closer look at what cosmic dust is made of. There is a problem in determining the composition of these microparticles. Unlike gaseous substances, solid bodies have a continuous spectrum with relatively few bands that are blurred. As a result, the identification of cosmic dust grains is difficult.

The composition of cosmic dust can be considered on the example of the main models of this substance. These include the following subspecies:

1. Ice particles, the structure of which includes a core with a refractory characteristic. The shell of such a model consists of light elements. In particles of large size there are atoms with elements of magnetic property.
2. Model MRN, the composition of which is determined by the presence of silicate and graphite inclusions.
3. Oxide space dust, which is based on diatomic oxides of magnesium, iron, calcium and silicon.

General classification according to chemical composition space dust:

• Balls with a metallic nature of education. The composition of such microparticles includes such an element as nickel.
• Metal balls with the presence of iron and the absence of nickel.
• Circles on a silicone basis.
• Irregular-shaped iron-nickel balls.

More specifically, you can consider the composition of cosmic dust on the example found in oceanic silt, sedimentary rocks and glaciers. Their formula will differ little from one another. Findings in the study of the seabed are balls with a silicate and metal base with the presence of such chemical elements as nickel and cobalt. Also, microparticles with the presence of aluminum, silicon and magnesium were found in the bowels of the water element.

Soils are fertile for the presence of cosmic material. Especially a large number of spherules were found in places where meteorites fell. They were based on nickel and iron, as well as various minerals such as troilite, cohenite, steatite and other components.

Glaciers also hide aliens from outer space in the form of dust in their blocks. Silicate, iron and nickel serve as the basis for the found spherules. All mined particles were classified into 10 clearly demarcated groups.

Difficulties in determining the composition of the studied object 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 gives great opportunities in terms of further activities in this direction. At a certain height, using rockets, they discovered a specific belt consisting of cosmic dust. This gives grounds to assert that such an extraterrestrial substance affects some of the processes occurring on planet Earth.

Influence of cosmic dust on the upper atmosphere

Recent studies suggest that the amount of cosmic dust can affect the change upper layers atmosphere. This process is very significant, because it leads to certain fluctuations in the climatic characteristics of planet Earth.

A huge amount of dust from the collision of asteroids fills the space around our planet. Its amount reaches almost 200 tons per day, which, according to scientists, cannot but leave its consequences.

The most susceptible to this attack, according to the same experts, is the northern hemisphere, whose climate is predisposed to cold temperatures and dampness.

The impact of cosmic dust on cloud formation and climate change is not well understood. New research in this area gives rise to more and more questions, the answers to which have not yet been received.

Influence of dust from space on the transformation of oceanic silt

Irradiation of space dust solar wind leads to the fact that these particles fall on the Earth. Statistics show that the lightest of the three isotopes of helium in huge number falls through dust particles from space into oceanic silt.

The absorption of elements from 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.

Influence of cosmic dust on the composition of the ocean water

If we consider the glaciers of Antarctica, they amaze with the number of meteorite remains found in them and the presence of cosmic dust, which is a hundred times higher than the usual background.

An excessively high concentration of the same helium-3, valuable metals in the form of cobalt, platinum and nickel, makes it possible to assert with certainty the fact of the intervention 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 the waters of the ocean, which in itself is a unique phenomenon.

According to some scientists, the amount of cosmic dust in such peculiar ice sheets over the past million years is on the order of 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 space dust:

This cosmic neoplasm and its influence on some factors of the vital activity of our planet have not yet been studied enough. It is important to remember that the substance can affect climate change, the structure of the ocean floor and the concentration of certain substances in the waters of the oceans. Photographs of cosmic dust testify to how many more mysteries these microparticles are fraught with. All this makes the study of this interesting and relevant!