Astronomy is a science that studies celestial bodies, their movement, structure, as well as the systems formed by them. This is the most ancient field of knowledge: the origins of astronomy are lost in the depths of centuries.

We can say that it evolved along with humanity. And today astronomy does not stand still. Taking advantage the latest technologies, scientists are constantly clarifying and supplementing already established theories. The most high-profile discoveries in recent years have often been related to the phenomena that astrophysicists study. Using advances in technology to their full potential, astronomers inevitably encounter the limitations of the human mind. Astrophysics is a branch of astronomy that, perhaps more often than others, encounters facts that cannot yet be explained. Scientists working under its banner, trying to find answers to increasingly complex questions, thereby stimulate technological progress. What astrophysicists are studying, what they have already managed to learn and what mysteries the Universe offers them today will be discussed below.

Peculiarities

Astrophysics deals with the determination of physical characteristics and their interactions. In her theories, she relies on knowledge about the laws of nature, accumulated by science in the process of studying the properties of matter on Earth.
Astrophysicists face significant limitations in their work. Unlike their colleagues who study the microworld or macroobjects under Earth conditions, they cannot conduct experiments. Many of the forces acting in space manifest themselves only at great distances or in the presence of objects of gigantic mass and volume. Such interaction cannot be studied in the laboratory, since it is impossible to create the necessary conditions. General astrophysics mainly deals with the results of passive observation.

Under such conditions, it is difficult to imagine obtaining data about objects. Due to the impossibility of experiments in this branch of astronomy, direct measurements of the necessary parameters do not exist. In this case, what do astrophysicists study and on what do they base their conclusions? The main source of information for scientists in such conditions is the analysis of electromagnetic waves that emit from celestial bodies.

Where it all began

Astronomy is a science that has been studying celestial bodies since time immemorial, but such a section as astrophysics has not always been in it. In fact, it began its formation in 1859, when G. Kirchhoff and R. Bunsen, after completing a series of experiments, established that any chemical element has a unique line spectrum. This meant that the spectrum of a celestial body could be used to judge its chemical composition. This is how spectral analysis was born, and with it astrophysics appeared.

Significance

In 1868, the newly created method made it possible to discover a new chemical element - helium. It was discovered during observation of complete solar eclipse and studying the chromosphere of the star.

Modern astrophysics is also largely based on data. Improved technology makes it possible to obtain information about almost all characteristics of celestial bodies, as well as interstellar space: temperature, composition, behavior of atoms, magnetic field strength, and so on.

Invisible radiation

The discovery of radio emission significantly expanded the possibilities of astrophysics. Its registration made it possible to study the cold gas that fills interstellar space and emits light invisible to the eye, as well as the processes occurring in distant pulsars and neutron stars. The discovery, which confirmed the Big Bang theory that was emerging at that time, was of great importance for all of astronomy.

The space age has given astrophysicists new opportunities. Ultraviolet, X-ray and gamma radiation have become available, the path to Earth being blocked by the atmosphere. Telescopes, created taking into account new discoveries, have made it possible to detect hot gas in clusters of galaxies, neutron stars, and some characteristics of black holes.

Problems of astrophysics

Modern science has stepped far forward compared to the state in which it was at the end of the 19th century. Today, astrophysicists take advantage of all the latest advances in the field of recording electromagnetic radiation and obtaining data on distant objects based on them. However, it cannot be said that this branch of astronomy is moving absolutely unhindered along the path of studying the Universe. The conditions that arise in deep space are sometimes so difficult to record and understand that the interpretation of the data obtained about certain objects is difficult.

In the vicinity of a black hole, the interior of neutron stars and their magnetic fields, new physical properties matter. The inability to even approximately reproduce the extreme or limiting conditions in which such cosmic processes occur forms the main difficulties of astrophysics.

Model of the Universe

One of the most important tasks of modern astronomy is to understand how the vast cosmos develops. Today there are two main versions: open and closed Universe. The first implies constant and unlimited expansion. In this model, the distance between galaxies only increases, and after some time space will become a lifeless desert with rare islands of solid matter. Another option assumes that the expansion, which for most is an indisputable fact, will be replaced by a compression phase of the Universe. There is no clear answer to the question of which theory is correct. Moreover, discoveries are emerging that significantly complicate the understanding of the future of the Universe and introduce a certain chaos into a seemingly orderly picture. These include, for example, the detection of energy.

Black holes, gamma-ray bursts

Among everything that astrophysicists study, there are a number of objects with a special touch of mystery. They also relate to the main problems of this branch of astronomy. These include black holes, many of the physical processes in space of which are completely unexplored, and gamma-ray bursts. The latter represent a release of enormous amounts of energy, pulses of gamma radiation. Their nature is also not completely clear.

Understanding similar objects and phenomena can significantly change our understanding of the structure of the Universe and the laws of space. It is the constant contact with the secrets of the universe that makes astrophysics the leading edge of science, which simultaneously highlights the limitations of modern knowledge and stimulates its further development. We can say that this branch of astronomy has become a kind of marker of progress: each discovery marks the victory of the human mind over another mystery.

ASTROPHYSICS

Fundamentals of theoretical astrophysics

Methods of practical astrophysics

Brief historical information

Modern problems of astrophysics

A. is a branch of astronomy that studies physics. condition and chemistry composition of celestial bodies and their systems, interstellar and intergalactic. environments, as well as the processes occurring in them. Basic sections A.: physics of planets and their satellites, physics of the Sun, physics of stellar atmospheres, interstellar medium, internal theory. the structure of stars and their evolution. Problems of the structure of superdense objects and processes associated with them (capture of matter from the environment, accretion disks, etc.) and problems of cosmology are considered by relativistic A.

Unlike an experimental physicist, an astrophysicist-observer does not have the opportunity to influence the course of the process he is studying. Nevertheless, he can do quite certain things. conclusions by comparing similar phenomena occurring on MH. celestial objects. Moreover, A. studies the properties and behavior of matter under conditions that often cannot be realized in earthly laboratories, and this helps to deepen the understanding of the laws of the structure and evolution of the world around us and its departments. parts. Thus, studying the spectra of gas nebulae, matter and radiation in which are in an extremely rarefied state, led to the discovery of metastable energy levels of atoms, the possibility of transitions between close ones at very high energies. levels in hydrogen, helium atoms, etc. Study white dwarfs And pulsars led to the conclusion that the matter of stars can be in states fundamentally different from those known to us, and its density can reach the density atomic nucleus. Establishing the nature of stellar energy sources raised the question of practicality. implementation of controlled thermonuclear fusion on Earth.

Fundamentals of theoretical astrophysics

When developing theories and modeling phenomena observed in the Universe, theoretical. A. uses theoretical laws and methods. physics, in particular the laws of thermal radiation established for abs. black body, the theory of atomic spectra, the formulas of L. Boltzmann and M. Saha to determine the number of atoms that are in excited and ionized states, respectively, the formulas of J. C. Maxwell (J. C. Maxwell) to describe the velocity distribution of atoms, as well as the K. Doppler formula, which allows one to find the radial velocity of their movement relative to the observer by the wavelength shift in the spectrum of stars or galaxies or by studying the profiles of spectral lines, determine physical characteristics of the atmospheres of stars and planets.

For a long time, when constructing models of stars and their atmospheres, only two factors were taken into account - gravity and gas elasticity. In con. 40s 20th century the need to take into account electric power has become obvious. strength They, in particular, determine the state of external conditions. layers of the Sun, the structure of its corona, dynamics prominences, the existence of sunspots and, most importantly, such powerful processes as solar flares. Basic ideas magnetic hydrodynamics formulated in 1942 by H. Alfven, who also established the existence of magnetohydrodynamic. waves Nowadays a space scientist. - one of the most important sections of theoretical. A.

In mid. 20th century It was found that there is another factor that significantly influences the dynamics of the interstellar medium and its energy. balance,- cosmic rays(CL), i.e. atomic nuclei and electrons accelerated to sublight speeds. CRs are formed during solar flares, outbursts of novae and supernovae; Apparently, pulsars, quasars and active galactic nuclei are powerful particle accelerators.

Will exclude. significance for understanding the processes occurring in the Universe, for establishing the nature of MH. space objects had been made in mid. 20th century the conclusion that the radiation recorded by the observer may be non-thermal. First of all, non-thermal el-magn. radiation is generated as a result of deceleration of relativistic electrons in a magnetic field. fields ( synchrotron radiation). In space In space and near certain objects, photons are scattered on relativistic electrons (the inverse Compton effect), and scattering processes can also occur on the electrons that generated these photons. Non-thermal el-magn. radiation is also generated during the transition of electrons from one medium to another ( transition radiation) and during scattering of plasma waves, in particular longitudinal plasmons,on relativistic electrons. The theory of these processes has already been sufficiently developed, in particular thanks to the successes of plasma plasma, the task of which is to analyze the behavior of the plasma in various conditions. astrophysics objects.

And finally, important component theoretical A.- nuclear astrophysics, studying the radioactive decay of unstable nuclei in stars, etc. cosmic. objects, as a result of which energy is released and chemicals are formed. elements. One of the products of nuclear reactions are neutrinos, which escape almost unhindered from the core of a star into space. space, taking with it part of the released energy. It has been established that at certain stage of the star's life, if only its mass exceeds a certain limit, these losses due to neutrino emission can be so large that the equilibrium of the star is disturbed and gravitational collapse, the result of which is a supernova explosion with the formation neutron star or black hole.

Methods of practical astrophysics

Astrophys. observations and research are carried out on the aster. observatories using optical telescopes (both refractors and reflectors, the diameters of the mirrors of the latter reach 4-6 m). It is planned to create giant multi-mirror ground-based telescopes with equivalent mirror diameters of up to 25 m and a penetrating power of up to 26 m. With the launch of telescopes with a mirror diameter of approx. 2.5 m, objects up to 29 m will become available for observations.

From ser. 19th century in A. photographic is used. observation method. The photoemulsion is capable of accumulating radiation energy on it at the same time. Hundreds and thousands of luminaries can be recorded. However, theoretically current (DKV) modern photographic emulsions does not exceed 4%; in astrophotometry it is approx. 0.1%, which significantly complicated the study of weak light sources, especially their spectra.

From ser. 20th century widely used in A. photovoltaics. radiation receivers. Since 1953, measurements of the brightness of stars, star clusters, galaxies and quasars have been carried out using broadband light filters - ultraviolet ( U), blue ( IN) and yellow ( V)(three-color photometric system UBV). Subsequently, the system was expanded into the far IR part of the spectrum. Photovoltaic The method using light filters makes it possible to judge the distribution of energy in individual spectral intervals and to some extent replaces spectral observations. Moreover, if a prism or . grating, then the registration of radiation from the object is carried out simultaneously. in several wavelength intervals.

Simple and cascade electron-optical devices are used as image brightness amplifiers (10 4 - 10 7 times). converters (intensifier tubes) and electronic cameras. Fiber optics, solid-state radiation receivers, etc. are being actively introduced for the needs of A. Wide Application in A. I found a TV. astrophotometry. DKV TV systems in several tens of times more than that of conventional photographic emulsion. In this case, in particular, analog-digital systems are used, in which the video signal is converted into digital code and then enters the computer. TV Radiation detectors make it possible to study faint sources, including patrolling supernova explosions in other galaxies, and in one night observation it becomes possible to obtain several. dozens and even hundreds of photographs of these objects. Apparently the use of television. equipment on large telescopes will soon make it possible to measure the brightness of faint stars (up to 24 m) with an exposure of only 1-2 hours.

From the end 40s 20th century the development of radiophysics began. methods, thanks to which Crimea has become accessible to space exploration. el-magn. radiation in the range from deca-meter to submillimeter waves, i.e. in a wavelength range 2500 times wider than the optical one. Thanks to the development of the radio range, numerous sources of non-thermal radio emission - radio galaxies and quasars, pulsed sources of radio emission - pulsars, the distribution of neutral and ionized hydrogen in our and other galaxies has been studied. Removal beyond the atmosphere on satellites and automatically. interplanetary stations (AMC) HF radiation detectors made it possible to study cosmic space. objects in the UV, X-ray and gamma ranges. Several are open. hundreds of x-ray sources. radiation (including pulsed - busters), powerful ones are registered gamma-ray bursts, the nature of which has not been definitively established.

Brief historical information

The first astrophysics research can be considered the introduction by Hipparchus (2nd century BC) of the concept magnitude and the division of stars visible to the naked eye into 6 classes depending on their brightness. A series of astrophysics. information was obtained after the invention of the telescope in 1609 by G. Galilei: definitions were formed. ideas about the nature of the surface of the Moon (Galileo), the first experiments of decomposition were carried out sunlight glass prism (I. Newton, 1662) and the first observations of the spectrum Venus(Newton, 1669), the presence of a dense atmosphere near Venus was established (M.V. Lomonosov, 1761), the laws of photometry were formulated [I. Lambert (J. H. Lambert), 1760], carried out systematically. observations of several variable stars, incl. h. star variability discovered 8 Cepheus [J. Goodricke (J. Goodricke), 1794].

The true history of A. began in 1802, when W. Wollaston discovered that the spectrum of the Sun was crossed by dark lines. In 1814, J. Fraunhofer described in detail several. hundreds of dark lines in the solar spectrum and found that they are also inherent in the spectrum of the Moon and planets, and the position of one of them coincides with the line of the oil flame. Methods of spectral analysis were developed in 1859-62 by G. Kirchhoff and P. Bunsen. In 1868, J. N. Lockyer discovered a line of a previously unknown element, helium, in the spectrum of the solar chromosphere. In 1863, A. Secchi began systematizing stars according to the features of their spectra. In the 1st quarter 20th century models of stellar atmospheres were constructed taking into account radiative energy transfer and a criterion for convective instability was formulated [K. Schwarzschild and A. Schuster, 1905], an explanation of the spectral sequence of stars is given based on atomic theory [E. Milne (E. Milne), M. Sakha, 1921-23], established the principle of invariance in the theory of radiation transfer and created the foundations of precise methods of this theory [V. A. Ambartsumyan, V.V. Sobolev, S. Chandrasekhar, 1943-49].

In 1869, J. H. Lane, based on the idea that the Sun is a huge ball of gas, in which the pressure increases towards the center, first estimated the temperature of its surface, and in 1878-83 A. Ritter (G. A. D. Ritter) carried out a series of works on the theory of gravitation. equilibrium and pulsation of gas balls. Soon the theory of polytropic gas balls was constructed, a complete system of equations of the internal theory was formulated. structure of stars [A. Eddington (A. S. Eddington), 1916]. In 1934, a hypothesis was put forward about the possibility of the existence of neutron stars [V. Baade (W. Baade), F. Zwicky (F. Zwicky)]. then the first calculations of neutron star models were carried out, the fundamental possibility of gravitational collapse [G. Volkov (G. M. Volkoff), P. Oppenheimer (R. Oppenheimer), H. Snyder (H. Snyder), 1938-39], laid the foundations of the theory of thermonuclear reactions in stars and built the first models of stars, including red giants, taking into account thermonuclear reactions [G. Gamow, S. Chandrasekhar, M. Schwarzschild et al., 1941-45], the structure and energy of white dwarfs were studied, the mechanism of Cepheride pulsations was established (S.A. Zhevakin, 1953), pulsars were discovered [A. Hewish (A. Hewish) et al., 1967], and in 1974 - global oscillations of the Sun with a period of 160 minutes (A. B. Severny and co-workers).

When studying the interstellar medium, a criterion was established gravitational instability[J. Jean (J. H, Jeans), 1902], identified forbidden lines in the spectra of nebulae [A. Bowen (I. S. Bowen), 1927], the conclusion made back in 1847 by V. Ya. Struve about in the interstellar medium was confirmed, a theory of the glow of planetary and gaseous nebulae was developed [V. A. Ambartsumyan, G. Zanstra, 1931-34], the existence of zones of ionized hydrogen around hot stars was discovered [B. Sdromgren (B. G. D. Stromgren), 1939], predicted radio emission of neutral hydrogen at a wave of 21 cm and recombination. radiation of ionized hydrogen (N. S. Kardashev, 1959; see Recombination radio links), which played an extremely important role in studying the distribution of neutral and ionized hydrogen in our and other galaxies; the possibility of observations in the radio range of lines belonging to molecules of interstellar space was predicted (I. S. Shklovsky, 1949), an interpretation of non-thermal radio emission of the Galaxy as synchrotron radiation was given (X. Alven, V. L. Ginzburg, I. S. Shklovsky et al., 1950 -52).

Measurements began in 1912 redshifts lines in the spectra of “spiral nebulae” [V. Slipher (V. M. Slipher)], it was proven that these objects are actually giant star systems - galaxies [E. Hubble (E. P. Hubble), 1924], the expansion of the observable world of galaxies was established with speeds directly proportional to their distances from the observer (E. Hubble, 1929), based on the general theory of relativity, the theory of the expanding Universe was developed (A. A. Friedman, 1922). In the 60s quasi-stellar radio sources - quasars, quasi-stellar galaxies - quasags (A. Sandage), relict radio emission were discovered, which served as confirmation of the “hot Universe” model (G. Gamow, Ya. B. Zeldovich, etc.).

Modern problems of astrophysics

Since the 60s. 20th century Using equipment installed on satellites and AMC, important information about the planets was obtained solar system and their companions, in particular about physical. condition and chemical the composition of the atmospheres and surface layers of the two closest planets - Venus and Mars, the Earth's satellite - the Moon - was studied in detail, the understanding of the nature of the processes occurring on the surface and in the interior of the Sun and other stars, in the interstellar medium and in the world of galaxies was significantly deepened. One of the most important problems modern A. - theory development hydromagnetic dynamo in order to explain solar magnetism, including the mechanism of generation and amplification of magnets. fields in internal layers of the Sun, mechanisms of formation and maintenance of stability of sunspots, polarity fluctuations with a period of 22 years. In the 60s based on theory current layers managed to take the first steps in explaining solar flares, the dynamics of prominences and the solar corona as a whole. The problem of solar neutrinos, and therefore internal problems, cannot yet be considered completely solved. structures of the Sun.

Sources of powerful radiation located at the edges of certain gaseous nebulae in the department. lines of molecules of interstellar gas - cosmic masers (see. Maser effect-) serve as evidence of processes occurring in our time star formation in the Galaxy. With the help of high-speed computers it was possible to create “scenarios” evolution of stars from the beginning of compression of a fragment of a gas-dust cloud (protostar) to its conclusion. stage - slow shedding of the shell by the star (stage planetary nebula)and the formation of a white dwarf or (with large mass stars) a supernova explosion with the formation of a neutron star (or black hole). However, while there is complete uncertainty regarding the details of the process of mixing matter at the convective stage of compression of a protostar, the role of rotation and magnetic field has not been studied. cloud fields, the top is not finally installed. mass limit for a stable neutron star. The mechanism of particle acceleration in pulsars has not been developed in detail. While there is no explanation for the activity of galactic nuclei, the nature of quasars remains unclear. The question of the nature of the core of our Galaxy as a double supermassive system (a double black hole or black hole and compact star cluster), actively interacting with the stars around it.

In relativistic A. the questions about baryon asymmetry of the Universe, about the ratio of the number of nuclei and electrons to the number of photons, about the role of neutrinos, and possibly other still unknown particles in the formation of the observed structure of the Universe, the state of vacuum and phase transitions in the evolution of the hot Universe.

Lit.: Martynov D. Ya., Course of practical astrophysics, 3rd ed., M., 1977; his, Course of General Astrophysics, 3rd ed., M., 1979; Sobolev V.V., Course of theoretical astrophysics, 3rd ed., M., 1985; Ginzburg V.L., Modern astrophysics, M., 1970; by him, Theoretical Physics and Astrophysics, M, 1975; Zeldovich Ya. B., Novikov I. D., Theory of Gravitation and, M., 1971; them, Structure and Evolution of the Universe, M., 1975; Leng K., Astrophysical formulas, parts 1-2, trans. from English, M., 1978; On the cutting edge of astrophysics, trans. from English, M., 1979; Imshennik V. S., Nadezhin D. K., Final stages evolution of vveads and supernova explosions, in the book: Results of Science and Technology, ser. Astronomy, vol. 21, M., 1982; Zeldovich Ya. B., Structure of the Universe, ibid., vol. 22, M., 1983. I. A. Klimishin.

- a branch of astronomy that studies the physical state and chemical composition celestial bodies and their systems, interstellar and intergalactic environments, as well as the processes occurring in them. The main branches of astrophysics: physics of planets and their satellites, physics of the Sun, physics of stellar atmospheres, interstellar medium, theory of the internal structure of stars and their evolution. Problems of the structure of superdense objects and related processes (capture of matter from the environment, accretion disks, etc.) and problems of cosmology are considered by relativistic astrophysics.

Some information on photometry

Word photometry means "measurement of light". Using the photometric method, you can measure the intensity of light coming from any source of radiant energy, including from celestial bodies.
Photometry is divided into point And superficial. Spot photometry deals with measuring the brightness of stars and other point light sources. Surface photometry studies the brightness of luminous or illuminated surfaces (the surface of the Sun, Moon, planets, comets, nebulae).
The main quantity in photometry is luminous flux- the amount of light energy flowing through a given area per unit time. The concept of light energy in this case means radiant energy perceived by the human eye or another radiation receiver that replaces it (a photographic plate, a photocell). The luminous flux is a part of the total radiant flux formed by the radiation of all wavelengths emitted by a given source. Since the eye, photographic plate and photocell perceive radiation different lengths waves to varying degrees and over a limited range, they are called selective radiation receivers. Luminous flux characterizes the power of the radiant flux, estimated using a selective radiation receiver.
Radiation receivers directly record the following photometric quantities: the eye - brightness and gloss, the photographic plate - illumination, the photocell - luminous flux. According to the radiation receiver used, photometry is divided into visual, photographic And photoelectric photometry.

The concept of spectrum

Spectrum– the result of decomposition of a beam of electromagnetic radiation, in which components with different wavelengths are resolved in space and arranged in order of increasing or decreasing wavelength. The full spectrum of electromagnetic radiation includes, in decreasing order of wavelength, radio, microwave, infrared, visible light, ultraviolet, x-rays, and gamma radiation.
There are three main types of spectra: continuous, emission line and absorption line spectrum.
The high temperature and pressure in the interiors of stars cause them to produce radiant energy. During the formation of a star, the heating of matter is caused by gradual compression under the influence of gravitational forces. In later stages of evolution, the star maintains its radiation due to thermonuclear reactions taking place in its deep layers. In the depths of most stars, a reaction occurs that converts hydrogen into helium. The star's substance is opaque. The layers of a star from which radiation can escape unhindered are called its atmosphere.
Radiation is emitted from both the outer and deeper parts of the atmosphere (photosphere). In stars like the Sun, the photosphere is not very extended, so the edge of the solar disk is visible sharply defined. However, there are stars in which the thickness of the photosphere is a noticeable fraction of the radius of the star, and radiation reaching us comes from different depths of the photosphere.
Passing through the outer layers of the star, radiation experiences absorption, the nature of which depends both on the chemical composition and on the physical conditions prevailing in the stellar envelope. To determine these conditions, the radiation reaching us from the star is subjected to spectral analysis.

Invention of spectral analysis. (Kirchhoff and Bunsen)

The creation of a spectral analysis method is an example of a discovery that was the result of a long preparatory work many scientists. Indeed, the basic elements of a spectroscope can be found even in Newton's optical experimental setups. Many scientists of the 19th century. observed the so-called "Fraunhofer" lines in the spectrum of the Sun. The idea of ​​qualitative spectral analysis was expressed by J. Herschel and W.-G. F. Talbot. However, the merit of bringing previously completed observations into the system and strictly justifying the new method of analyzing the substance belongs to two German scientists: physicist G. Kirchhoff and chemist R. Bunsen. Of particular importance was the fact that work on the theoretical basis of spectral analysis led Kirchhoff to the discovery of the most important law of thermal radiation, which connected two branches of physics: optics and thermodynamics.
Bunsen became widely known as the inventor of scientific instruments. He improved ice and steam calorimeters, invented a new type of galvanic cell, developed a special gas burner that produced a high-temperature and practically non-luminous flame, and other devices. In collaboration with the English chemist G. Roscoe, Bunsen studied photochemical processes, took part in an expedition to Iceland, where he studied the products of the eruption of the Hexla volcano and geysers, and made a contribution to medicine by discovering an antidote for arsenic poisoning. Bunsen worked especially hard to improve gas analysis methods. Bunsen's achievements in this area were summarized in the classic monograph “Methods of Gasometry” (1857).
In 1856, Bunsen began working on a method for analyzing gases based on observing the color of the flame. When he told Kirchhoff about his research, Kirchhoff noticed that the analysis method could be made more informative if one observed not just the color of the flame, but the spectrum of its emission. The joint development of this idea led to the creation spectral analysis. Using a new method, Bunsen and Kirchhoff discovered cesium in 1860, and in 1861. - rubidium. Following them, other scientists began to use spectral analysis, as a result of which five more new elements were discovered over the next thirty years. Helium was also discovered by spectral analysis. Interestingly, it was initially discovered when studying the spectrum of the Sun (as its name suggests) and only much later was it discovered on Earth.
Kirchhoff did a lot of research in the field of electricity. The results of his research were an anticipation of the consequences of the theory of electrical magnetic field Maxwell. His contribution to the generalization of the Fresnel diffraction theory is significant. The scientist worked a lot on the theory of deformation and equilibrium of elastic bodies. A number of Kirchhoff's works are devoted to the thermodynamics of solutions. Studies of spectra served as the beginning of Kirchhoff's work on the theory of thermal radiation. Even before the start of the joint work of Bunsen and Kirchhoff, several scientists (D. Brewster, L. Foucault, J. G. Stokes) drew attention to the close position in the solar spectrum of dark (Fraunhofer) D-lines and emission lines in the sodium spectrum. However, no one had studied the connection between the absorption and emission lines deeply enough before Kirchhoff. In 1859, he discovered an interesting phenomenon - the reversal of emission lines in the spectrum of sodium when sunlight of varying intensities is passed through a flame. When weakened sunlight was passed through the flame, the lines in the sodium spectrum became brighter. When undiminished sunlight was passed through a flame containing sodium vapor, distinct dark lines appeared in place of the light lines of emission. This observation prompted Kirchhoff to analyze the relationship between absorption and emission processes, which led to the discovery law of thermal radiation.
In 1862, Kirchhoff introduced the concept "absolutely black body" and proposed a model of it (a cavity with a small hole). From this time until the beginning of the twentieth century. The problem of studying the black body was considered one of the most pressing in physics. Its development ultimately led to the creation quantum theory radiation.

Astrophysics is a branch of astronomy that studies the physical nature of celestial bodies and their systems, their origin and evolution.

As is clear from the name itself, astrophysics is the physics of celestial bodies. Space is essentially a large physical “laboratory” where conditions arise that are often completely unattainable in terrestrial physical laboratories and are therefore of exceptional interest to science. Astrophysical research methods have two significant features that distinguish them from the methods of laboratory physics. Firstly, in the laboratory, the physicist himself conducts experiments and exposes the bodies under study to various influences. In astrophysics, only passive observations are possible, since it is not yet possible to conduct experiments, for example, on stars. Secondly, if in the laboratory it is possible to directly measure the temperature, density, chemical composition of bodies, etc., then in astrophysics almost all data about distant celestial bodies is obtained by analyzing the electromagnetic waves coming from them - visible light and others invisible to the eye rays.

The basis of astrophysics is astrophysical observations. In this case, the most important method is spectral analysis, i.e., the study of the energy flow of radiation coming to the earth depending on the length of electromagnetic waves. Electromagnetic waves carry information about the conditions in the substance where they originate or where they experience absorption and scattering.

The task of spectral analysis is to decipher this information.

The emergence of spectral analysis in the second half of the 19th century. immediately made it possible to draw conclusions about the chemical composition of celestial bodies. One of the first brilliant achievements of astrophysics obtained using this experimental technique was the discovery of a previously unknown element - helium - when studying the spectrum of the solar chromosphere during a total eclipse in 1868. Subsequently, as a result of the development of experimental and theoretical physics It has become possible to determine literally everything using spectral analysis physical characteristics celestial bodies and interstellar medium. The spectra make it possible to find out the temperature of the gas, its density, the relative content of various chemical elements, the state of the atoms of these elements, the speed of gas movement, and the strength of magnetic fields. Using the spectra of stars, you can also calculate the distance to them, find out their speed of movement along the line of sight, measure their rotation, and find out much more.

Modern spectral instruments used in telescopes use the latest photoelectric radiation detectors (see Photoelectric effect), which are much more accurate and sensitive than a photographic plate or the human eye.

The rapid development of technology and experimental physics over the past decades has led to the creation of astrophysical instruments designed to study electromagnetic waves invisible to the eye. Astrophysics has become “multi-wave”. This, of course, immeasurably expanded her ability to obtain information about celestial bodies. Back in the 30s. This century, the radio emission of our Galaxy was discovered. In subsequent years, giant radio telescopes were built and complex systems such radio telescopes. Using radio telescopes, they observe, for example, cold interstellar gas that does not emit visible light, and study the movement of electrons in interstellar magnetic fields. Radio emission comes to Earth from distant galaxies, often carrying information about the violent explosive processes occurring there. Radio astronomy has become one of the main ways to study neutron stars - pulsars. Radio waves carry information about the remnants of supernova explosions and absolutely amazing conditions in dense gas clouds.

Finally, radio astronomy made it possible to discover the relict radiation of the Universe - weak electromagnetic radiation that fills the entire Universe and has a temperature of about 3 K. This radiation is a cooled remnant (relic) from the past state of matter in the expanding Universe, when about 15 billion years ago it was dense and hot (see Cosmology, Matter, Space).

Astrophysicists have learned a lot of interesting things using infrared rays that freely pass through clouds of dust that absorb visible light (see Fig. Infrared radiation). Thus, processes in the core of our Galaxy, as well as “young” stars emerging in dense gas-dust complexes, are observed in infrared rays.

Of particular interest to astronomy is high-energy astrophysics, which studies processes of rapid energy release, often associated with catastrophic phenomena in celestial bodies. The resulting electromagnetic radiation has high frequency, correspondingly short wavelength and refers to invisible ultraviolet, x-rays and gamma rays (see X-rays, Gamma radiation). These types of radiation are absorbed by the earth's atmosphere. Therefore, the development of these branches of observational astrophysics became possible only with the beginning of the space era, after the creation of manned and automatic scientific stations outside the Earth's atmosphere.

High energy astrophysics has led to many amazing discoveries. Using X-ray telescopes, hot gas was discovered in galaxy clusters, pulsed X-ray radiation from neutron stars in binary star systems. Finally, the radiation of highly heated dense gas was discovered, apparently swirling as it falls into a black hole. Gamma-ray telescopes have made it possible to detect in the center of our Galaxy the processes of annihilation of electrons and positrons - their transformation into gamma radiation upon collision.

IN recent years A new branch of astrophysics began to develop - neutrino astronomy. Neutrinos, due to their enormous penetrating ability, are the only type of radiation that can reach the Earth from the very depths of the Sun and stars and bring information about the processes occurring there. Already the first data on solar neutrino fluxes made it possible to make very interesting hypotheses about the processes of thermonuclear fusion in the depths of the Sun; they need to be tested in future experiments.

Currently, searches are underway for neutrino bursts from supernovae at the moment of their gravitational collapse (that is, compression under the influence of gravity), as a result of which huge amounts of energy must be carried away in the form of neutrino radiation. Calculations show that these neutrino bursts can be registered in underground laboratories (such as, for example, the Baksan Neutrino Observatory of the Institute of Nuclear Research of the USSR Academy of Sciences), even if the supernova that exploded is not optically observable due to too great distances.

Based on observational astrophysics data and relying on the laws of physics, astronomers draw conclusions about conditions in celestial bodies that are not directly observed. For example, the internal structure of stars and the Sun is calculated using observational data about conditions on their surfaces. Theoretical astrophysics also makes it possible to describe the evolution of the Sun, stars and other celestial bodies.

As already mentioned, when studying astrophysical phenomena, astronomers often encounter physical conditions, completely unattainable in earthly laboratories. Thus, the density of interstellar gas is billions of times less than the density of water, and the density of neutron stars is the same as the density of atomic nuclei; and billions of times higher than the strength of the Earth’s magnetic field.

It is not surprising that in such unusual conditions, new, unknown processes can occur, and therefore, the discovery of new physical laws. This is the significance of astrophysics for physics, for all fundamental science that cognizes the world around us.

The branch of astronomy that studies the physical state and chemical composition of celestial bodies and their systems, interstellar and intergalactic media, as well as the processes occurring in them is called astrophysics. The main sections of astrophysics include: the physics of planets and their satellites, the physics of the Sun, stellar atmospheres, the interstellar medium, the theory of the internal structure of stars and their evolution. Unlike physics, which is based on experiment, astrophysics is based mainly on observations. But in many cases, the conditions in which matter is found in celestial bodies and systems differ from those available to modern laboratories (ultra-high and ultra-low densities, high temperatures, etc. .). Thanks to this, astrophysical observations lead to the discovery of new physical laws.

The intrinsic significance of astrophysics is determined by the fact that currently the main attention in relativistic cosmology is transferred to the physics of the Universe - the state of matter and physical processes occurring in different stages expansion of the Universe, including the earliest stages.

Relativistic astrophysics studies, on the basis of the general theory of relativity (A. Einstein’s theory of gravity), objects of superdense formation in the Universe.

Methods of astrophysics for studying the Universe

Optical method– studying the Universe using a telescope, which is the main tool for astronomical research (Appendix 7). Largest quantity information about space processes brings light. A telescope is a device for collecting light using a lens: a biconvex lens or a concave mirror. Optical telescopes are divided into three types: refractor (lens - large lens), reflector (lens - concave mirror), mirror - lens telescope. These telescopes use both lenses and mirrors as lenses, due to which their optical design allows achieving excellent image quality with high resolution, despite the fact that the entire structure consists of very portable short optical tubes. The main purpose of a telescope is to collect as much light as possible from a celestial object. The light through the telescope tube is collected by a lens. The image of the celestial body obtained using the telescope is recorded on a photographic plate. Physics has given researchers of the Universe a method for studying light rays called spectral analysis. If you pass a beam of white sunlight through a narrow slit and then through a glass triangular prism, it breaks up into its component colors and a rainbow color stripe appears on the screen with a gradual transition from red to violet - a continuous spectrum. The red end of the spectrum is formed by the rays that are the least deflected when passing through a prism, the violet end is the most deflected. The telescope is equipped with a special spectrograph device. It not only decomposes light into its component parts, but also records the spectrum on a photographic plate. Physics deals with deciphering the spectrum received from a space object. Decoding the spectrum helps: a) Study the chemical composition of a space object. To everyone chemical element correspond to certain spectral lines. For example, in the spectrum of sodium vapor one can detect closely spaced yellow lines, in the spectrum of potassium vapor - violet and yellow lines. b) Determine the temperature of the radiation sources, because red color corresponds to low temperature (for stars, 3 - 4 thousand degrees Celsius), yellow - green - medium (for stars, 5 - 6 thousand degrees Celsius), white - blue - high (for stars, 10 - 11 thousand degrees Celsius). c) Measure the speed of a space object according to the Doppler effect - the dependence of the measured wavelength on the mutual movement of the observer and the wave source; if a space object approaches us, then in its spectrum the spectral lines shift to the violet end, in the opposite case to the red (Appendix 12).

A method for studying cosmic radio emission using a radio telescope. For a long time, astronomers could explore space objects only by visible radiation. This was a major limitation since visible light makes up a small part of the spectrum. Visible light corresponds to a wavelength interval from 4000 Ǻ (1 Ǻ = 10 -10 m) at the violet boundary to 7200 Ǻ at the red boundary. Light whose wavelength exceeds these limits is not perceived by our vision. Beyond the violet region of the visible spectrum are ultraviolet, x-rays and very short-wavelength penetrating g-radiation. Beyond the red end of the spectrum there is infrared, microwave and radio radiation, the wavelength of which can exceed kilometers. In the early 30s of the 20th century, while studying noise interfering with radio communications, a source of small radio interference was discovered located in the direction of the center of our Galaxy. The main sources of radio waves are space objects located outside the solar system. Compared to light rays, radio waves travel where visible light cannot penetrate. All information about the most distant regions of the Universe is obtained entirely from radio observations. The main sources of space radio transmissions in most cases are objects in which violent physical processes occur. They are of greatest interest for studying the development of the Universe and the forms of cosmic matter. Radio waves are also emitted by interstellar space, namely by the ionized hot gas located in it. Heating and ionization of gas (mainly hydrogen) is caused by hot stars and cosmic rays. Another source of radio emission is neutral hydrogen, which is much more abundant in interstellar space than ionized hydrogen. Researchers of the Universe today are able not only to capture and translate information from cosmic radio signals into a language accessible to humans. They also learned to “probe” the surface of celestial bodies using a radio beam directed from the Earth and receive signals reflected from them. The study of cosmic “radio echo” makes it possible to: measure the distance to celestial bodies, determine the speed of their movement, and study the surface of a space object by the nature of the reflection of radio waves. Scientists have carried out radar detection of the nearest planets, the Moon and the Sun.

Neutrino astrophysics method. The source of the sun's energy is thermonuclear reactions. During these reactions, a neutrino is born. One of distinctive features The neutrino is that this particle interacts extremely weakly with matter. The mean free path of neutrinos in matter is colossal. Penetrating the thickness of the solar substance, they fly out into outer space, and a certain part of them reaches the surface of the Earth. By registering solar neutrinos using special devices (neutrino telescopes) and calculating the magnitude of their flux, one can judge the nature of the physical processes occurring in the depths of the Sun.

Methods of extra-atmospheric astronomy. Extra-atmospheric observation is a modern branch of space physics that studies space objects using equipment placed outside the Earth’s atmosphere to eliminate atmospheric interference. Extra-atmospheric astronomy makes it possible to eliminate image jitter in telescopes caused by atmospheric inhomogeneities and to increase the spatial resolution of an optical telescope to its theoretically possible (diffraction) value. Modern extra-atmospheric astronomy makes a contribution to astrophysics that is quite commensurate with the contributions of optical and radio astronomy.

Methods of infrared, ultraviolet, x-ray and gamma astronomy. In order to study infrared, ultraviolet, X-ray and gamma radiation, IR telescopes, UV telescopes, X-ray and gamma telescopes have been created. Thanks to the installation of special equipment on rockets and Earth satellites, it became possible to detect these types of radiation.

Cosmic rays can be observed through traces left in special traps (for example, plates with a nuclear emulsion). Cosmic rays are elementary particles(electrons, protons, carbon, iron nuclei), which move so fast that they penetrate any body, including the Earth as a whole.