Cosmic dust particles of matter in interstellar and interplanetary space. Light-absorbing condensations of cosmic rays are visible as dark spots in photographs of the Milky Way. Attenuation of light due to the influence of K. p. - the so-called. interstellar absorption, or extinction, is not the same for electromagnetic waves of different lengths λ
, as a result of which reddening of the stars is observed. In the visible region, the extinction is approximately proportional to λ -1, in the near ultraviolet region it is almost independent of the wavelength, but about 1400 Å there is an additional absorption maximum. Most of the extinction is due to light scattering, not absorption. This follows from observations of reflective nebulae that contain cosmic rays and are visible around stars of spectral class B and some other stars bright enough to illuminate dust. A comparison of the brightness of the nebulae and the stars illuminating them shows that the Albedo of the dust is large. The observed extinction and albedo lead to the conclusion that the crystal field consists of dielectric particles with an admixture of metals with a size slightly less than 1 microns. The ultraviolet extinction maximum can be explained by the fact that inside the dust grains there are graphite flakes about 0.05 × 0.05 × 0.01 microns. Due to the diffraction of light on a particle, the size of which is comparable to the wavelength, light is scattered mainly forward. Interstellar absorption often leads to polarization of light, which is explained by the anisotropy of the properties of dust grains (elongated shape in dielectric particles or anisotropy of the conductivity of graphite) and their ordered orientation in space. The latter is explained by the action of a weak interstellar field, which orients the dust grains with their long axis perpendicular to the field line. Thus, observing the polarized light of distant celestial bodies, one can judge the orientation of the field in interstellar space. The relative amount of dust is determined from the value of the average absorption of light in the plane of the Galaxy - from 0.5 to several stellar magnitudes per kiloParsec in the visual region of the spectrum. The mass of dust is about 1% of the mass of interstellar matter. Dust, like gas, is not uniformly distributed, forming clouds and denser formations - Globules. In globules, dust acts as a cooling factor, shielding the light of stars and emitting in the infrared range the energy received by a grain of dust from inelastic collisions with gas atoms. On the surface of the dust, atoms are combined into molecules: dust is a catalyst. S. B. Pikelner.
Great Soviet Encyclopedia. - M .: Soviet encyclopedia. 1969-1978 .
See what "Stardust" is in other dictionaries:
Particles of condensed matter in interstellar and interplanetary space. According to modern concepts, cosmic dust consists of particles with a size of approx. 1 μm with a graphite or silicate core. In the Galaxy, cosmic dust forms ... ... Big Encyclopedic Dictionary
SPACE DUST, very small particles of solid matter found in any part of the Universe, including meteorite dust and interstellar matter that can absorb starlight and form dark fogs in galaxies. Spherical ... ... Scientific and technical encyclopedic dictionary
COSMIC DUST- meteoric dust, as well as the smallest particles of matter that form dust and other nebulae in interstellar space ... Big Polytechnic Encyclopedia
cosmic dust- Very small particles of solid matter present in space and falling to the Earth ... Geography Dictionary
Particles of condensed matter in interstellar and interplanetary space. According to modern concepts, cosmic dust consists of particles about 1 micron in size with a core of graphite or silicate. In the Galaxy, cosmic dust forms ... ... encyclopedic Dictionary
It is formed in space by particles ranging in size from a few molecules to 0.1 mm. 40 kilotons of cosmic dust is deposited on planet Earth every year. Stardust can also be distinguished by its astronomical position, for example: intergalactic dust, ... ... Wikipedia
cosmic dust- kosminės dulkės statusas T sritis fizika atitikmenys: angl. cosmic dust; interstellar dust; space dust vok. interstellarer Staub, m; kosmische Staubteilchen, m rus. cosmic dust, f; interstellar dust, f pranc. poussière cosmique, f; poussière ... ... Fizikos terminų žodynas
cosmic dust- kosminės dulkės statusas T sritis ekologija ir aplinkotyra apibrėžtis Atmosferoje susidarančios meteorinės dulkės. atitikmenys: angl. cosmic dust vok. kosmischer Staub, m rus. cosmic dust, f ... Ekologijos terminų aiškinamasis žodynas
Particles condensed into VA in interstellar and interplanetary space. According to modern representations, K. the item consists of particles with a size of apprx. 1 μm with a graphite or silicate core. In the Galaxy, the cosmic ray forms condensations of clouds and globules. Calls ... ... Natural science. encyclopedic Dictionary
Particles of condensed matter in interstellar and interplanetary space. It consists of particles about 1 micron in size with a core of graphite or silicate, forms clouds in the Galaxy, which cause weakening of the light emitted by stars and ... ... Astronomical Dictionary
Books
- 99 secrets of astronomy, Serdtseva N .. This book contains 99 secrets of astronomy. Open it and learn about how the universe works, what cosmic dust is made of and where black holes come from. ... Funny and simple texts ...
Hello. In this lecture, we will talk with you about dust. But not about the one that accumulates in your rooms, but about cosmic dust. What is it?
Stardust is very small particles of solid matter found in any part of the universe, including meteorite dust and interstellar matter that can absorb starlight and form dark nebulae in galaxies. Spherical dust particles with a diameter of about 0.05 mm are found in some marine sediments; it is believed that these are the remnants of the 5,000 tons of cosmic dust that fall on the globe every year.
Scientists believe that cosmic dust is formed not only from collisions, destruction of small solids, but also due to the thickening of interstellar gas. Cosmic dust is distinguished by its origin: dust is intergalactic, interstellar, interplanetary and near-planetary (usually in a ring system).
Cosmic dust particles arise mainly in the slowly flowing atmospheres of stars - red dwarfs, as well as in explosive processes on stars and a violent outburst of gas from galactic nuclei. Other sources of cosmic dust formation are planetary and protostellar nebulae, stellar atmospheres and interstellar clouds.
Whole clouds of cosmic dust, which are in the layer of stars that form the Milky Way, prevent us from observing distant star clusters. A star cluster like the Pleiades is completely submerged in a dust cloud. The brightest stars in this cluster illuminate the dust like a lantern illuminates fog at night. Stardust can only shine with reflected light.
Blue rays of light, passing through cosmic dust, are weakened more than red ones, so the light of stars reaching us appears yellowish and even reddish. Entire areas of world space remain closed to observation precisely because of cosmic dust.
The dust is interplanetary, at least in comparative proximity to the Earth - the matter is quite studied. Filling the entire space of the solar system and concentrated in the plane of its equator, it was born mostly as a result of accidental collisions of asteroids and the destruction of comets that approached the Sun. The composition of the 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 a lot of discoveries in this area, but there seems to be no special 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 the pale cone of light above the horizon. This is the so-called zodiacal - sunlight scattered by small cosmic dust particles.
Much more interesting is interstellar dust. Its distinctive feature is the presence of a hard core and shell. The core appears to be composed primarily of carbon, silicon, and metals. And the shell is predominantly of gaseous elements frozen on the surface of the core, crystallized in the conditions of "deep freezing" of interstellar space, and this is about 10 kelvin, hydrogen and oxygen. However, there are also more complex admixtures of molecules in it. These are ammonia, methane and even polyatomic organic molecules that stick to a speck of dust or are formed 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.
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, "throwing" the shell into the surrounding space. In addition, dust is born in the expanding atmosphere of the red giants, from where it is literally swept away by the pressure of radiation. In their cool, by the standards of stars, atmosphere (about 2.5 - 3 thousand Kelvin) there are quite a lot of relatively complex molecules.
But here is a riddle 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 should be born, exist for some time, grow old and, say, produce dust in the last supernova explosion. But what came first - an egg or a 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, aged, exploded, forming the very first dust.
What happened 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 from them that the first galaxies, huge clouds began to emerge, 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, to convert hydrogen and helium into carbon, nitrogen, oxygen, and so on, and after that the star should have thrown all this into space, exploding or gradually shedding its envelope. 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 distant 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 did the dust come from in the young Galaxy, if there should be nothing but hydrogen and helium, is a mystery.
Looking at the time, the professor smiled slightly.
But you will try to solve this mystery at home. Let's write down the task.
Homework.
1. Try to speculate, what appeared earlier, the first star or is it dust?
Additional task.
1. A report on any kind of dust (interstellar, interplanetary, near-planetary, intergalactic)
2. Composition. Imagine yourself as a scientist tasked with researching cosmic dust.
3. Pictures.
Homemade assignment for students:
1. Why do we need dust in space?
Additional task.
1. Report on any kind of dust. Former students of the school remember the rules.
2. Composition. Disappearance of cosmic dust.
3. Pictures.
In interstellar and interplanetary space, there are small particles of solids - what in everyday life we call dust. We call the accumulation of these particles cosmic dust to distinguish it from dust in the terrestrial sense, although their physical structure is similar. These are particles ranging in size from 0.000001 centimeters to 0.001 centimeters, the chemical composition of which, in general, is still unknown.
These particles often form clouds, which are detected in different ways. For example, in our planetary system, the presence of cosmic dust was discovered due to the fact that sunlight, scattering on it, causes a phenomenon that has long been known as "zodiacal light". We observe the zodiacal light on exceptionally clear nights in the form of a weakly luminous strip stretching in the sky along the zodiac, it gradually weakens as we move away from the sun (which is at this time beyond the horizon). Measurements of the intensity of the zodiacal light and the study of its spectrum show that it comes from the scattering of sunlight on particles that form a cloud of cosmic dust, surrounding the Sun and reaching the orbit of Mars (the Earth is thus inside a cloud of cosmic dust).
The presence of cosmic dust clouds in interstellar space is detected in the same way.
If any cloud of dust finds itself near a relatively bright star, then the light from this star will be scattered on the cloud. We then find this dust cloud in the form of a bright speck, called an "irregular nebula" (diffuse nebula).
Sometimes a cloud of cosmic dust becomes visible because it obscures the stars behind it. Then we distinguish it in the form of a relatively dark spot against the background of star-studded celestial space.
A third way to detect cosmic dust is by changing the color of stars. Stars behind a cloud of cosmic dust are generally more intensely red. Cosmic dust, just like terrestrial dust, causes "reddening" of the light that passes through it. We can often observe this phenomenon on Earth. On foggy nights, we see that the lights located in the distance are more red in color than the nearby lights, the light of which remains practically unchanged. We must, however, make a reservation: only dust consisting of small particles causes discoloration. And it is this kind of dust that is most often found in interstellar and interplanetary spaces. And from the fact that this dust causes the "reddening" of the light of the stars lying behind it, we conclude that the size of its particles is small, about 0.00001 cm.
We don't know exactly where the cosmic dust comes from. Most likely, it arises from those gases that are constantly ejected by stars, especially young ones. At low temperatures, gas freezes and turns into a solid - into particles of cosmic dust. And, conversely, part of this dust, finding itself in a relatively high temperature, for example, near some hot star, or during the collision of two clouds of cosmic dust, which, in general, is a frequent phenomenon in our region of the Universe, turns into gas again.
SPACE DUST, solid particles with characteristic sizes from about 0.001 microns to about 1 micron (and, possibly, up to 100 microns 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. Stardust scatters and absorbs incident radiation. Scattered radiation with the same wavelength as the incident radiation propagates in all directions. The radiation absorbed by a grain of dust is transformed into thermal energy, and the particle usually emits 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 studied in almost the entire range of electromagnetic waves - from X-ray to millimeter. The electric dipole radiation of rapidly rotating ultrafine particles seems to make some contribution to microwave radiation at frequencies of 10-60 GHz. An important role is played by laboratory experiments, in which they measure the refractive indices, as well as the absorption spectra and scattering matrices of particles - analogs 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.
Cosmic dust in various physical conditions is directly studied in the composition of meteorites that have fallen to the Earth's surface, in the upper layers of the earth's atmosphere (interplanetary dust and remnants of small comets), during spacecraft flights to planets, asteroids and comets (near-planetary and cometary dust) and after limits of the heliosphere (interstellar dust). Ground-based and space remote observations of cosmic dust cover the Solar System (interplanetary, near-planetary 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 distant objects (cosmological dust).
Space dust particles are mainly composed of carbonaceous substances (amorphous carbon, graphite) and magnesium-ferrous silicates (olivine, pyroxenes). They condense and grow in the atmospheres of stars of late spectral types 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 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 sputtering in shock waves arising after supernova explosions, or evaporation in the process of star formation, which began in a 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" (newly formed in their atmosphere), and around young stars - old (evolved as part of the interstellar medium). It is assumed that cosmological dust, possibly existing in distant galaxies, condensed in the ejections of matter after the explosions of massive supernovae.
Lit. see at Art. Interstellar dust.
The science
Scientists have noticed a large cloud of cosmic dust created by a supernova explosion.
Stardust can provide answers to questions about how life appeared on earth- whether it originated here or was brought in with comets that fell to the Earth, was there water from the very beginning, or was it also brought in from space.
A recent snapshot of a cloud of cosmic dust that occurred after a supernova explosion proves thatsupernovaecapable of producing enough cosmic dust to create planets like our Earth.
Moreover, scientists believe that this dust is enough to create thousands suchplanets like earth.
Telescope data show warm dust (white) that survived inside the supernova remnant. Supernova remnant cloud Sagittarius A East is shown in blue. Radio emission (red) indicates the collision of an expanding shock wave with surrounding interstellar clouds (green).
It is worth noting that cosmic dust participated in the creation of both our planet and many other cosmic bodies. Sheconsists of small particles up to 1 micrometer in size.
Today it is already known that comets contain primordial dust, which is billions of years old, and which played a major role in the formation of the solar system. By examining this dust, you can learn a lot about howhow the universe and our solar system began to be createdin particular, and also learn more about the composition of the first organic matter and water.
According to Ryan Lau of Cornell University in Ithaca, New York,flash,recentlycaptured by a telescope, occurred 10,000 years ago, and as a result, a dust cloud of sufficient size was formed toit turned out 7,000 planets similar to the Earth.
Supernova observations
Via Stratospheric Observatory for Infrared Astronomy (SOFIA), scientists studied the intensity of the radiation, and were able to calculate the total mass of cosmic dust in the cloud.
It should be noted that SOFIA is a joint a project of NASA and the German Center for Aviation and Astronautics... The goal of the project is to create and use a Cassegrain telescope on board a Boeing 474.
During the flight at an altitude of 12-14 kilometers, a telescope with a circumference of 2.5 meters is capable of creating photographs of space that are close in quality to photographs taken by space observatories.
Led by Lau, the team used the SOFIA telescope with a dedicated cameraFORCAST on board,to take infrared images of the cosmic dust cloud, also known as supernova remnant Sagittarius A Vostok. FORCAST isinfrared camera for detecting low-contrast objects.
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