During 2003–2008 a group of Russian and Austrian scientists, with the participation of Heinz Kohlmann, a famous paleontologist, curator of the Eisenwurzen National Park, studied the catastrophe that happened 65 million years ago, when more than 75% of all organisms died out on Earth, including dinosaurs. Most researchers believe that the extinction was due to the fall of an asteroid, although there are other points of view.
Traces of this catastrophe in geological sections are represented by a thin layer of black clay with a thickness of 1 to 5 cm. One of these sections is located in Austria, in the Eastern Alps, in national park near the small town of Gams, located 200 km southwest of Vienna. As a result of studying samples from this section using a scanning electron microscope particles of unusual shape and composition were found, which are not formed under terrestrial conditions and belong to cosmic dust.
Cosmic dust on the ground
For the first time, traces of cosmic matter on Earth were discovered in red deep-sea clays by an English expedition that explored the bottom of the World Ocean on the Challenger ship (1872–1876). They were described by Murray and Renard in 1891. At two stations in the southern part Pacific Ocean during dredging from a depth of 4300 m, samples of ferromanganese nodules and magnetic microspheres with a diameter of up to 100 microns were raised, which later received the name "cosmic balls". However, iron microspheres recovered by the Challenger expedition were studied in detail only in last years. It turned out that the balls are 90% composed of metallic iron, 10% nickel, and their surface is covered with a thin crust of iron oxide.
Rice. 1. Monolith from the Gams 1 section, prepared for sampling. Layers are marked in Latin letters different ages. The transitional clay layer between the Cretaceous and Paleogene periods (about 65 million years old), in which an accumulation of metal microspheres and plates was found, is marked with the letter "J". Photo by A.F. Grachev
With the discovery of mysterious balls in deep-sea clays, in fact, the beginning of the study of cosmic matter on Earth is connected. However, an explosion of researchers' interest in this problem occurred after the first launches. spacecraft, with the help of which it became possible to select lunar soil and samples of dust particles from different parts of the solar system. Importance also had works by K.P. Florensky (1963), who studied the traces of the Tunguska catastrophe, and E.L. Krinov (1971), who studied meteoric dust at the site of the fall of the Sikhote-Alin meteorite.
The interest of researchers in metallic microspheres has led to their discovery in sedimentary rocks of different ages and origins. Metal microspheres have been found in the ice of Antarctica and Greenland, in deep ocean sediments and manganese nodules, in the sands of deserts and coastal beaches. They are often found in meteorite craters and next to them.
AT last decade metal microspheres extraterrestrial origin found in sedimentary rocks of different ages: from the lower Cambrian (about 500 million years ago) to modern formations.
Data on microspheres and other particles from ancient deposits make it possible to judge the volumes, as well as the uniformity or unevenness of the supply of cosmic matter to the Earth, the change in the composition of particles that came to Earth from space, and the primary sources of this matter. This is important because these processes affect the development of life on Earth. Many of these questions are still far from being resolved, but the accumulation of data and their comprehensive study will undoubtedly make it possible to answer them.
It is now known that total weight dust circulating inside the earth's orbit is about 1015 tons. Every year, from 4 to 10 thousand tons of cosmic matter falls on the Earth's surface. 95% of the matter falling on the Earth's surface are particles with a size of 50-400 microns. The question of how the rate of arrival of cosmic matter to the Earth changes with time remains controversial until now, despite the many studies carried out in the last 10 years.
Based on the size of cosmic dust particles, interplanetary cosmic dust with a size of less than 30 microns and micrometeorites larger than 50 microns are currently distinguished. Even earlier, E.L. Krinov suggested that the smallest fragments of a meteoroid melted from the surface be called micrometeorites.
Strict criteria for distinguishing between cosmic dust and meteorite particles have not yet been developed, and even using the example of the Hams section studied by us, it has been shown that metal particles and microspheres are more diverse in shape and composition than provided by the existing classifications. Almost perfect spherical shape, metallic luster and magnetic properties particles were seen as evidence of their cosmic origin. According to geochemist E.V. Sobotovich, "the only morphological criterion assessment of the cosmogenicity of the material under study is the presence of melted balls, including magnetic ones. However, in addition to the extremely diverse form, the chemical composition of the substance is fundamentally important. The researchers found that, along with microspheres of cosmic origin, there is great amount balls of a different genesis - associated with volcanic activity, the vital activity of bacteria or metamorphism. There is evidence that ferruginous microspheres of volcanic origin are much less likely to have an ideal spherical shape and, moreover, have an increased admixture of titanium (Ti) (more than 10%).
Russian-Austrian group of geologists and film crew of the Vienna Television on the Gams section in the Eastern Alps. In the foreground - A.F. Grachev
Origin of cosmic dust
The question of the origin of cosmic dust is still a subject of debate. Professor E.V. Sobotovich believed that cosmic dust could represent the remnants of the original protoplanetary cloud, which was objected to in 1973 by B.Yu. Levin and A.N. Simonenko, believing that a finely dispersed substance could not be preserved for a long time (Earth and Universe, 1980, No. 6).
There is another explanation: the formation of cosmic dust is associated with the destruction of asteroids and comets. As noted by E.V. Sobotovich, if the amount of cosmic dust entering the Earth does not change in time, then B.Yu. Levin and A.N. Simonenko.
In spite of big number research, the answer to this fundamental question cannot currently be given, because quantitative assessments very few, and their accuracy is debatable. AT recent times data from isotope studies on NASA program Cosmic dust particles sampled in the stratosphere suggest the existence of particles of pre-solar origin. Minerals such as diamond, moissanite (silicon carbide) and corundum were found in this dust, which, using carbon and nitrogen isotopes, allow us to attribute their formation to the time before the formation of the solar system.
The importance of studying cosmic dust in the geological section is obvious. This article presents the first results of a study of cosmic matter in the transitional clay layer at the Cretaceous-Paleogene boundary (65 million years ago) from the Gams section, in the Eastern Alps (Austria).
General characteristics of the Gams section
Particles of cosmic origin were obtained from several sections of the transitional layers between the Cretaceous and Paleogene (in the Germanic literature - the K / T boundary), located near the Alpine village of Gams, where the river of the same name in several places reveals this boundary.
In section Gams 1, a monolith was cut from the outcrop, in which the K/T boundary is very well expressed. Its height is 46 cm, width is 30 cm at the bottom and 22 cm at the top, thickness is 4 cm. For general study section, the monolith was divided after 2 cm (from bottom to top) into layers, indicated by letters Latin alphabet(A, B, C…W), and within each layer, the numbers (1, 2, 3, etc.) were also marked every 2 cm. The transition layer J at the K/T interface was studied in more detail, where six sublayers with a thickness of about 3 mm were identified.
The results of the studies obtained in the Gams 1 section are largely repeated in the study of another section - Gams 2. The complex of studies included the study of thin sections and monomineral fractions, their chemical analysis, as well as X-ray fluorescence, neutron activation and X-ray structural analyzes, analysis of helium, carbon and oxygen, determination of the composition of minerals on a microprobe, magnetomineralogical analysis.
Variety of microparticles
Iron and nickel microspheres from the transitional layer between the Cretaceous and Paleogene in the Gams section: 1 – Fe microsphere with a rough reticulate-hummocky surface ( top part transition layer J); 2 – Fe microsphere with a rough longitudinally parallel surface ( Bottom part transition layer J); 3 – Fe microsphere with elements of crystallographic faceting and coarse cellular-network surface texture (layer M); 4 – Fe microsphere with a thin network surface (upper part of transition layer J); 5 – Ni microsphere with crystallites on the surface (upper part of transition layer J); 6 – aggregate of sintered Ni microspheres with crystallites on the surface (upper part of transition layer J); 7 – aggregate of Ni microspheres with microdiamonds (C; upper part of the transition layer J); 8, 9 - characteristic forms metal particles from the transitional layer between Cretaceous and Paleogene in the Gams section in the Eastern Alps.
In the transition layer of clay between two geological boundaries– Cretaceous and Paleogene, as well as at two levels in the overlying deposits of the Paleocene in the Gams section, a lot of metal particles and microspheres of cosmic origin were found. They are much more diverse in form, surface texture, and chemical composition than all known so far in transitional clay layers of this age in other regions of the world.
In the Gams section, cosmic matter is represented by fine particles various shapes, among which the most common are magnetic microspheres ranging in size from 0.7 to 100 microns, consisting of 98% pure iron. Such particles in the form of spherules or microspherules are found in large quantities not only in layer J, but also higher, in clays of the Paleocene (layers K and M).
The microspheres are composed of pure iron or magnetite, some of them have impurities of chromium (Cr), an alloy of iron and nickel (avaruite), and pure nickel (Ni). Some Fe-Ni particles contain an admixture of molybdenum (Mo). In the transitional clay layer between the Cretaceous and Paleogene, all of them were discovered for the first time.
Never before have come across particles with high content nickel and a significant admixture of molybdenum, microspheres with the presence of chromium and pieces of spiral iron. In addition to metallic microspheres and particles, Ni-spinel, microdiamonds with microspheres of pure Ni, as well as torn plates of Au and Cu, which were not found in the underlying and overlying deposits, were found in the transitional clay layer in Gams.
Characterization of microparticles
Metallic microspheres in the Gams section are present at three stratigraphic levels: ferruginous particles of various shapes are concentrated in the transitional clay layer, in the overlying fine-grained sandstones of layer K, and the third level is formed by siltstones of layer M.
Some spheres have a smooth surface, others have a reticulate-hilly surface, and others are covered with a network of small polygonal cracks or a system of parallel cracks extending from one main crack. They are hollow, shell-like, filled with a clay mineral, and may also have an internal concentric structure. Metal particles and Fe microspheres are found throughout the transitional clay layer, but are mainly concentrated in the lower and middle horizons.
Micrometeorites are melted particles of pure iron or Fe-Ni iron-nickel alloy (awaruite); their sizes are from 5 to 20 microns. Numerous awaruite particles are confined to the upper level of the transition layer J, while purely ferruginous particles are present in the lower and upper parts of the transition layer.
Particles in the form of plates with a transversely bumpy surface consist only of iron, their width is 10–20 µm, and their length is up to 150 µm. They are slightly arcuately curved and occur at the base of the transition layer J. In its lower part, there are also Fe-Ni plates with an admixture of Mo.
Plates made of an alloy of iron and nickel have an elongated shape, slightly curved, with longitudinal grooves on the surface, the dimensions vary in length from 70 to 150 microns with a width of about 20 microns. They are more common in the lower and middle parts of the transition layer.
Iron plates with longitudinal grooves are identical in shape and size to Ni-Fe alloy plates. They are confined to the lower and middle parts of the transition layer.
Of particular interest are particles of pure iron, having the shape of a regular spiral and bent in the form of a hook. They mainly consist of pure Fe, rarely it is an Fe-Ni-Mo alloy. Spiral iron particles occur in the upper part of the J layer and in the overlying sandstone layer (K layer). A spiral Fe-Ni-Mo particle was found at the base of the transition layer J.
In the upper part of the transition layer J, there were several grains of microdiamonds sintered with Ni microspheres. Microprobe studies of nickel balls carried out on two instruments (with wave and energy dispersive spectrometers) showed that these balls consist of almost pure nickel under a thin film of nickel oxide. The surface of all nickel balls is dotted with distinct crystallites with pronounced twins 1–2 µm in size. Such pure nickel in the form of balls with a well-crystallized surface is not found in igneous rocks, nor in meteorites, where nickel necessarily contains a significant amount of impurities.
When studying a monolith from the Gams 1 section, pure Ni balls were found only in the uppermost part of the transition layer J (in its uppermost part, a very thin sedimentary layer J 6, whose thickness does not exceed 200 μm), and according to thermal magnetic analysis data, metallic nickel is present in transitional layer, starting from sublayer J4. Here, along with Ni balls, diamonds were also found. In a layer taken from a cube with an area of 1 cm2, the number of diamond grains found is in the tens (from fractions of microns to tens of microns in size), and hundreds of nickel balls of the same size.
Samples from the upper part of the transition layer taken directly from the outcrop contained diamonds with small particles nickel on the grain surface. It is significant that the presence of the mineral moissanite was also revealed during the study of samples from this part of layer J. Previously, microdiamonds were found in the transitional layer at the Cretaceous-Paleogene boundary in Mexico.
Finds in other areas
Hams microspheres with concentric internal structure similar to those that were mined by the Challenger expedition in the deep-sea clays of the Pacific Ocean.
iron particles irregular shape with melted edges, as well as in the form of spirals and curved hooks and plates, they are very similar to the destruction products of meteorites falling to the Earth, they can be considered as meteoric iron. Avaruite and pure nickel particles can be assigned to the same category.
Curved iron particles are close to the various forms of Pele's tears - lava drops (lapilli) that are thrown into liquid state volcanoes from the vent during eruptions.
Thus, the transitional clay layer in Gams has a heterogeneous structure and is distinctly divided into two parts. Iron particles and microspheres predominate in the lower and middle parts, while the upper part of the layer is enriched in nickel: awaruite particles and nickel microspheres with diamonds. This is confirmed not only by the distribution of iron and nickel particles in the clay, but also by the data of chemical and thermomagnetic analyses.
Comparison of the data of thermomagnetic analysis and microprobe analysis indicates an extreme inhomogeneity in the distribution of nickel, iron, and their alloy within layer J; however, according to the results of thermomagnetic analysis, pure nickel is recorded only from layer J4. It is also noteworthy that helical iron occurs mainly in the upper part of layer J and continues to occur in the overlying layer K, where, however, there are few Fe, Fe-Ni particles of isometric or lamellar shape.
We emphasize that such a clear differentiation in terms of iron, nickel, and iridium, which is manifested in the transitional clay layer in Gamsa, also exists in other regions. For example, in the American state of New Jersey, in the transitional (6 cm) spherule layer, the iridium anomaly manifested itself sharply at its base, while impact minerals are concentrated only in the upper (1 cm) part of this layer. In Haiti, at the Cretaceous–Paleogene boundary and in the uppermost part of the spherule layer, there is a sharp enrichment in Ni and impact quartz.
Background phenomenon for the Earth
Many features of the found Fe and Fe-Ni spherules are similar to the balls discovered by the Challenger expedition in the deep-sea clays of the Pacific Ocean, in the area of the Tunguska catastrophe and the impact sites of the Sikhote-Alin meteorite and the Nio meteorite in Japan, as well as in sedimentary rocks of different ages from many parts of the world. Except for the areas of the Tunguska catastrophe and the fall of the Sikhote-Alin meteorite, in all other cases the formation of not only spherules, but also particles of various morphologies, consisting of pure iron (sometimes containing chromium) and nickel-iron alloy, has no connection with the impact event. We consider the appearance of such particles as a result of the fall of cosmic interplanetary dust onto the Earth's surface - a process that has been continuously ongoing since the formation of the Earth and is a kind of background phenomenon.
Many particles studied in the Gams section are close in composition to the bulk chemical composition of the meteorite substance at the site of the fall of the Sikhote-Alin meteorite (according to E.L. Krinov, these are 93.29% iron, 5.94% nickel, 0.38% cobalt).
The presence of molybdenum in some of the particles is not unexpected, as many types of meteorites include it. The content of molybdenum in meteorites (iron, stone and carbonaceous chondrites) ranges from 6 to 7 g/t. The most important was the discovery of molybdenite in the Allende meteorite as an inclusion in a metal alloy of the following composition (wt %): Fe—31.1, Ni—64.5, Co—2.0, Cr—0.3, V—0.5, P—0.1. It should be noted that native molybdenum and molybdenite were also found in lunar dust sampled automatic stations"Luna-16", "Luna-20" and "Luna-24".
The balls of pure nickel with a well-crystallized surface found for the first time are not known either in igneous rocks or in meteorites, where nickel necessarily contains a significant amount of impurities. Such a surface structure of nickel balls could have arisen in the event of an asteroid (meteorite) fall, which led to the release of energy, which made it possible not only to melt the material fallen body but also evaporate it. Metal vapors could be raised by the explosion to great height(probably tens of kilometers), where crystallization took place.
Particles consisting of awaruite (Ni3Fe) are found together with metallic nickel balls. They belong to meteor dust, and melted iron particles (micrometeorites) should be considered as "meteorite dust" (according to the terminology of E.L. Krinov). The diamond crystals encountered together with the nickel balls probably arose as a result of the ablation (melting and evaporation) of the meteorite from the same vapor cloud during its subsequent cooling. It is known that synthetic diamonds are obtained by spontaneous crystallization from a carbon solution in a melt of metals (Ni, Fe) above the graphite–diamond phase equilibrium line in the form of single crystals, their intergrowths, twins, polycrystalline aggregates, framework crystals, needle-shaped crystals, and irregular grains. Almost all of the listed typomorphic features of diamond crystals were found in the studied sample.
This allows us to conclude that the processes of crystallization of diamond in a cloud of nickel-carbon vapor during its cooling and spontaneous crystallization from a carbon solution in a nickel melt in experiments are similar. However, the final conclusion about the nature of diamond can be made after detailed isotopic studies, for which it is necessary to obtain a sufficiently large amount of the substance.
Thus, the study of cosmic matter in the transitional clay layer at the Cretaceous–Paleogene boundary showed its presence in all parts (from layer J1 to layer J6), but signs of an impact event are recorded only from layer J4, which is 65 million years old. This layer of cosmic dust can be compared with the time of the death of dinosaurs.
A.F. GRACHEV Doctor of Geological and Mineralogical Sciences, V.A. TSELMOVICH Candidate of Physical and Mathematical Sciences, Institute of Physics of the Earth RAS (IFZ RAS), OA KORCHAGIN Candidate of Geological and Mineralogical Sciences, Geological Institute of the Russian Academy of Sciences (GIN RAS).
Magazine "Earth and Universe" № 5 2008.
COSMIC DUST, solid particles with characteristic sizes from about 0.001 µm to about 1 µm (and possibly up to 100 µm or more in the interplanetary medium and protoplanetary disks), found in almost all astronomical objects: from the solar system to very distant galaxies and quasars. Dust characteristics (particle concentration, chemical composition, particle size, etc.) vary significantly from one object to another, even for objects of the same type. Cosmic dust scatters and absorbs incident radiation. Scattered radiation with the same wavelength as the incident radiation propagates in all directions. The radiation absorbed by the dust grain is transformed into thermal energy, and the particle usually radiates in a longer wavelength region of the spectrum compared to the incident radiation. Both processes contribute to extinction - the attenuation of the radiation of celestial bodies by dust located on the line of sight between the object and the observer.
Dust objects are explored in almost the entire range electromagnetic waves- from x-ray to millimeter. Electric dipole radiation from rapidly rotating ultrafine particles appears to make some contribution to microwave radiation at frequencies of 10-60 GHz. Important role play laboratory experiments, which measure the refractive indices, as well as the absorption spectra and scattering matrices of particles - analogues of cosmic dust grains, simulate the processes of formation and growth of refractory dust grains in the atmospheres of stars and protoplanetary disks, study the formation of molecules and the evolution of volatile dust components under conditions similar to those existing in dark interstellar clouds.
Space dust found in various physical conditions, directly studied in the composition of meteorites that fell to the Earth's surface, in the upper layers earth's atmosphere(interplanetary dust and remnants small comets), during spacecraft flights to planets, asteroids and comets (near planetary and cometary dust) and beyond the heliosphere (interstellar dust). Ground and space remote observations of cosmic dust cover the Solar System (interplanetary, circumplanetary and cometary dust, dust near the Sun), the interstellar medium of our Galaxy (interstellar, circumstellar and nebular dust) and other galaxies (extragalactic dust), as well as very remote objects(cosmological dust).
Cosmic dust particles mainly consist of carbonaceous substances (amorphous carbon, graphite) and magnesium-iron silicates (olivines, pyroxenes). They condense and grow in the atmospheres of stars of late spectral classes and in protoplanetary nebulae, and then are ejected into the interstellar medium by radiation pressure. In interstellar clouds, especially dense ones, refractory particles continue to grow as a result of the accretion of gas atoms, as well as when particles collide and stick together (coagulation). This leads to the appearance of shells of volatile substances (mainly ice) and to the formation of porous aggregate particles. The destruction of dust particles occurs as a result of spraying into shock waves, arising after bursts of supernovae, or evaporation in the process of star formation that began in the cloud. The remaining dust continues to evolve near the formed star and later manifests itself in the form of an interplanetary dust cloud or cometary nuclei. Paradoxically, dust around evolved (old) stars is “fresh” (recently formed in their atmosphere), and around young stars it is old (evolved in the composition of interstellar medium). It is assumed that cosmological dust, possibly existing in distant galaxies, condensed in the ejecta of matter after the explosions of massive supernovae.
Lit. see at st. Interstellar dust.
Space vacuum has long been a very conventional concept. The space between planets and even between stars is far from empty - it is filled with matter in the form of various radiations, fields, flows elementary particles and ... substances. Most of this substance - 99% - is gas (mainly hydrogen, in lesser degree helium), but there are also solid particles. These particles are also called cosmic dust.
It is truly omnipresent: there is interstellar and interplanetary dust - however, it is not always easy to distinguish between them, because interstellar dust can also fall into interplanetary space... but if you go beyond the solar system, preferably farther away, you can find interstellar dust "in pure form", without an admixture of interplanetary ... Yes, what solar system- cosmic dust constantly settles on the Earth, and the count goes to tens of kilotons per year, there is even an assumption that 24% of the dust that settles in two weeks in a locked apartment is precisely cosmic dust!
What is cosmic dust? As already mentioned, these are solid particles scattered in outer space. Their size is small: the largest particles reach 0.1 micrometer (a thousandth of the length of a millimeter), and the smallest - in general, several molecules. Chemical composition interplanetary dust practically does not differ from the composition of meteorites that fall to Earth from time to time, but interstellar dust in this planet is more interesting. Its particles have - in addition to a solid core - also a shell that differs from the poison in composition. The core is carbon, silicon metals, it is surrounded by the nuclei of atoms of gaseous elements, which in the conditions of interstellar space quickly crystallize ("freeze" on the core) - this is the shell. However, crystallization processes can also affect the cores of dust particles, in particular those that consist of carbon. In this case, crystals of ... diamond can form (this is how the space pirate from the work of Kir Bulychev, who poured diamond dust into the lubricant of robots on the planet Shelezyak, is recalled!).
But this is not the greatest miracle that can occur during carbon crystallization - while carbon atoms can line up in hollow balls (so-called fullerenes), inside which particles of the atmosphere of ancient stars are enclosed ... the study of such a substance could shed light on many things!
Although the particles of cosmic dust are so small, it is difficult not to notice them if they collect in dust clouds. The thickness of the gas and dust layer of our galaxy is measured in hundreds of light years, most of the matter is concentrated in the spiral arms.
In a number of cases, dust clouds actually "obscure" the stars for us and even from the cluster, absorbing their light - in this case, the dust clouds look like black holes. Cosmic dust absorbs blue rays best of all, and red rays least of all, so the light of a star passing through the interstellar medium filled with cosmic dust “turns red”.
Where does all this splendor come from? Let's start with the fact that initially in the Universe there were only molecular clouds of hydrogen ... all other elements were born (and continue to be born) in the cores of stars - these grandiose " fusion reactors". Atmospheres of young stars - red dwarfs - slowly expire in space, old massive stars, exploding at the end of its " life cycle, throw out a huge amount of matter into space. In interstellar space, these substances (at first located in gaseous state) condense to form stable groups of atoms or even molecules. Other atoms or molecules join such groups, entering into chemical reaction with existing ones (this process is called chemisorption), and if the concentration of such particles is high enough, they can even stick together without breaking down.
This is how cosmic dust is born... and we can rightfully say that it has a great future: after all, it is from gas and dust clouds that new stars with planetary systems are born!
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 consider the Milky Way, which forms our Galaxy, through a telescope, it turns out that this bright band breaks up into many weakly glowing stars, which to the naked eye merge into a solid radiance. It is now established that the Milky Way consists not only of stars and star clusters, but also from gas and dust clouds.
Space 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, shells of supernovae and new stars. A large number of dust exists in the cores of many galaxies (for example, M82, NGC253), from which there is an intense outflow of gas. The effect of cosmic dust is most pronounced during radiation 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 outer space, which seems to us to be vacuum, is actually filled with gas and microscopic dust particles, 0.01-0.2 microns in size. The combination of these invisible elements gives rise to objects of enormous size, a kind of clouds of the Universe, capable of absorbing certain types of spectral radiation stars, sometimes completely hiding them from terrestrial researchers.
What is interstellar dust made of?
These microscopic particles have a nucleus, which is formed in gas envelope 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. it interesting process, lasting for whole decades: when cooling, the stars 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. In conditions low temperatures interstellar dust is in the form of ice crystals. Wandering around the Galaxy, small 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 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 from us celestial bodies. Although the particles are separated from each other by tens of meters, but even in this 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 stellar radiation, 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, sticking together, 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 that act as catalysts for numerous chemical processes.
Our planet every year increases its mass due to the falling inter stardust. 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.
