The atmosphere of the Sun is 90% hydrogen. Its part farthest from the surface is called the solar corona; it is clearly visible at full solar eclipses. The temperature of the corona reaches 1.5-2 million K, and the corona gas is completely ionized. At this plasma temperature, the thermal speed of protons is about 100 km/s, and that of electrons is several thousand kilometers per second. To overcome solar attraction is sufficient starting speed 618 km/s, second escape velocity Sun. Therefore, plasma constantly leaks from the solar corona into space. This flow of protons and electrons is called the solar wind.
Having overcome the gravity of the Sun, solar wind particles fly along straight trajectories. The speed of each particle almost does not change with distance, but it can be different. This speed depends mainly on the condition solar surface, from the “weather” on the Sun. On average it is equal to v ≈ 470 km/s. The solar wind travels the distance to Earth in 3-4 days. In this case, the density of particles in it decreases in inverse proportion to the square of the distance to the Sun. On distance, equal to the radius earth's orbit, in 1 cm 3 there are on average 4 protons and 4 electrons.
sunny wind reduces the mass of our star - the Sun - by 10 9 kg per second. Although this number seems large on a terrestrial scale, in reality it is small: the loss of solar mass can only be noticed over times thousands of times longer than modern age The Sun, which is approximately 5 billion years old.
The interaction of the solar wind with the magnetic field is interesting and unusual. It is known that charged particles usually move in a magnetic field H in a circle or along helical lines. This is true, however, only when the magnetic field is strong enough. More precisely, for charged particles to move in a circle, it is necessary that the energy density magnetic field H 2 /8π was greater than the density kinetic energy moving plasma ρv 2 /2. In the solar wind the situation is the opposite: the magnetic field is weak. Therefore, charged particles move in straight lines, and the magnetic field is not constant, it moves along with the flow of particles, as if carried away by this flow to the periphery of the Solar system. The direction of the magnetic field throughout interplanetary space remains the same as it was on the surface of the Sun at the moment the solar wind plasma emerged.
When traveling along the equator of the Sun, the magnetic field usually changes its direction 4 times. The sun rotates: points on the equator complete a revolution in T = 27 days. Therefore, the interplanetary magnetic field is directed in spirals (see figure), and the entire pattern of this figure rotates following the rotation of the solar surface. The angle of rotation of the Sun changes as φ = 2π/T. The distance from the Sun increases with the speed of the solar wind: r = vt. Hence the equation of the spirals in Fig. has the form: φ = 2πr/vT. At a distance of the earth's orbit (r = 1.5 10 11 m), the angle of inclination of the magnetic field to the radius vector is, as can be easily verified, 50°. On average, this angle is measured spaceships, but not quite close to Earth. Near the planets, the magnetic field is structured differently (see Magnetosphere).
sunny wind
- continuous plasma flow solar origin, spreading approximately radially from the Sun and filling with itself solar system to heliocentric distances ~100 AU S.v. is formed during gas-dynamic. expansion into interplanetary space. At high temperatures, which exist in the solar corona (K), the pressure of the overlying layers cannot balance the gas pressure of the corona matter, and the corona expands.First evidence of existence constant flow plasmas from the Sun were obtained by L. Biermann (Germany) in the 1950s. on the analysis of forces acting on the plasma tails of comets. In 1957, Yu. Parker (USA), analyzing the equilibrium conditions of the corona matter, showed that the corona cannot be in hydrostatic conditions. equilibrium, as previously assumed, but should expand, and this expansion given the existing boundary conditions should lead to the acceleration of coronal matter to supersonic speeds.
Average characteristics of S.v. are given in table. 1. For the first time, a plasma flow of solar origin was recorded on the second Soviet spacecraft. rocket "Luna-2" in 1959. The existence of a constant outflow of plasma from the Sun was proven as a result of many months of measurements in America. AMS Mariner 2 in 1962
Table 1. Average characteristics of the solar wind in Earth orbit
| Speed | 400 km/s |
| Proton Density | 6 cm -3 |
| Proton temperature | TO |
| Electron temperature | TO |
| Magnetic field strength | E |
| Proton flux density | cm -2 s -1 |
| Kinetic energy flux density | 0.3 ergsm -2 s -1 |
Streams N.v. can be divided into two classes: slow - with a speed of km/s and fast - with a speed of 600-700 km/s. Fast flows come from those regions of the corona where the magnetic field is close to radial. Some of these areas are . Slow currents N.W. are apparently associated with the areas of the crown where there is meaning. tangential component mag. fields.
In addition to the main components of S.v. - protons and electrons; - particles, highly ionized ions of oxygen, silicon, sulfur, and iron were also found in its composition (Fig. 1). When analyzing gases trapped in foils exposed on the Moon, Ne and Ar atoms were found. Average chem. composition of S.v. is given in table. 2.Table 2. Relative chemical composition solar wind
| Element | Relative content |
| H | 0,96 |
| 3 He | |
| 4 He | 0,04 |
| O | |
| Ne | |
| Si | |
| Ar | |
| Fe |
Ionization state of matter S.v. corresponds to the level in the corona where the recombination time becomes small compared to the expansion time, i.e. on distance . Ionization measurements ion temperatures S.v. make it possible to determine the electron temperature of the solar corona.
S.v. carries the coronal magnetic field with it into the interplanetary medium. field. Frozen into plasma power lines This field forms an interplanetary magnetic field. field (MMP). Although the IMF intensity is low and its energy density is approx. 1% of kinetic energy S.V., it plays big role in thermodynamics S.v. and in the dynamics of interactions between S.v. with the bodies of the Solar System and the streams of the North. between themselves. Combination of expansion S.v. with the rotation of the Sun leads to the fact that the mag. power lyoniums frozen in the S.V. have a shape close to Archimedes’ spirals (Fig. 2). Radial and azimuthal component of mag. fields near the ecliptic plane change with distance:,
Where R- heliocentric distance, - angular velocity rotation of the sun, u R- radial velocity component S.v., index “0” corresponds to the initial level. At the distance of the Earth's orbit, the angle between the magnetic directions. fields and direction to the Sun, on large heliocentric. IMF distances are almost perpendicular to the direction to the Sun.
S.v., arising over regions of the Sun with different magnetic orientations. fields, forms flows in differently oriented permafrost - the so-called. interplanetary magnetic field.
In N.v. observed Various types waves: Langmuir, whistlers, ion-sonic, magnetosonic, etc. (see). Some waves are generated on the Sun, some are excited in the interplanetary medium. The generation of waves smoothes out deviations of the particle distribution function from the Maxwellian one and leads to the fact that the S.V. Behave like continuum. Alfvén-type waves play a large role in the acceleration of small components of the S.V. and in the formation of the proton distribution function. In N.v. Contact and rotational discontinuities, characteristic of magnetized plasma, are also observed.
Stream N.w. yavl. supersonic in relation to the speed of those types of waves that provide effective transfer of energy into the S.V. (Alfvén, sound and magnetosonic waves), Alfvén and sound Mach numbers S.v. in Earth orbit. When trimming the S.V. obstacles that can effectively deflect S.v. (magnetic fields of Mercury, Earth, Jupiter, Staurn or the conducting ionospheres of Venus and, apparently, Mars), a bow shock wave is formed. S.v. slows down and heats up at the front of the shock wave, which allows it to flow around the obstacle. At the same time, in N.v. a cavity is formed - the magnetosphere (either its own or induced), the shape and size of the structure is determined by the balance of magnetic pressure. fields of the planet and the pressure of the flowing plasma flow (see). The layer of heated plasma between the shock wave and the streamlined obstacle is called. transition region. The temperatures of ions at the front of the shock wave can increase by 10-20 times, electrons - by 1.5-2 times. Shock wave phenomenon. , the thermalization of the flow is ensured by collective plasma processes. The thickness of the shock wave front is ~100 km and is determined by the growth rate (magnetosonic and/or lower hybrid) during the interaction of the oncoming flow and part of the ion flow reflected from the front. In case of interaction between S.v. with a non-conducting body (the Moon), a shock wave does not arise: the plasma flow is absorbed by the surface, and behind the body a SW is formed which is gradually filled with plasma. cavity.On stationary process The outflow of the corona plasma is superimposed by non-stationary processes associated with. During strong solar flares, matter is released from lower regions corona into the interplanetary medium. In this case, a shock wave is also formed (Fig. 3), the edges gradually slow down when moving through the plasma of the SW. The arrival of a shock wave to the Earth leads to compression of the magnetosphere, after which the development of magnetism usually begins. storms
The equation describing the expansion of the solar corona can be obtained from the system of conservation equations for mass and angular momentum. The solutions to this equation, which describe the different nature of the change in speed with distance, are shown in Fig. 4. Solutions 1 and 2 correspond to low velocities at the base of the crown. The choice between these two solutions is determined by the conditions at infinity. Solution 1 corresponds to low rates of coronal expansion (“solar breeze”, according to J. Chamberlain, USA) and gives large values pressure at infinity, i.e. encounters the same difficulties as the static model. crowns Solution 2 corresponds to the transition of the expansion rate through the speed of sound ( v K) on a certain rum critical. distance R K and subsequent expansion at supersonic speed. This solution gives a vanishingly small value of pressure at infinity, which makes it possible to reconcile it with the low pressure of the interstellar medium. Parker called this type of current the solar wind. Critical the point is above the surface of the Sun if the temperature of the corona is less than a certain critical value. values , where m- proton mass, - adiabatic index. In Fig. Figure 5 shows the change in expansion rate from heliocentric. distance depending on isothermal temperature. isotropic corona. Subsequent models of S.v. take into account variations in the coronal temperature with distance, the two-liquid nature of the medium (electron and proton gases), thermal conductivity, viscosity, and the nonspherical nature of the expansion. Approach to substance S.v. how to a continuous medium is justified by the presence of the IMF and the collective nature of the interaction of the SW plasma, caused by various types of instabilities. S.v. provides the basic outflow of thermal energy from the corona, because heat transfer to the chromosphere, electromagnet. radiation from highly ionized corona matter and electronic thermal conductivity of solar energy. insufficient to establish thermal balance of the crown. Electronic thermal conductivity ensures a slow decrease in the ambient temperature. with distance. S.v. does not play any noticeable role in the energy of the Sun as a whole, because the energy flux carried away by it is ~ 10 -8Constant radial flow of solar plasma. crowns in interplanetary production. The flow of energy coming from the depths of the Sun heats the corona plasma to 1.5-2 million K. DC. heating is not balanced by energy loss due to radiation, since the corona is small. Excess energy means. degrees are carried away by the S. century. (=1027-1029 erg/s). The crown, therefore, is not in a hydrostatic position. equilibrium, it continuously expands. According to the composition of the S. century. does not differ from corona plasma (solar plasma contains mainly protons, electrons, some helium nuclei, oxygen, silicon, sulfur, and iron ions). At the base of the corona (10 thousand km from the photosphere of the Sun), particles have a radial radial of the order of hundreds of m/s, at a distance of several. solar radii it reaches the speed of sound in plasma (100 -150 km/s), near the Earth's orbit the speed of protons is 300-750 km/s, and their spaces. - from several h-ts to several tens of hours in 1 cm3. With the help of interplanetary space. stations it was established that up to the orbit of Saturn the density flow h-c S.v. decreases according to the law (r0/r)2, where r is the distance from the Sun, r0 is the initial level. S.v. carries with it the loops of the solar power lines. mag. fields, which form the interplanetary magnetic field. . Combination of radial movements h-ts S.v. with the rotation of the Sun it gives these lines the shape of spirals. Large-scale structure of mag. The fields in the vicinity of the Sun have the form of sectors, in which the field is directed from the Sun or towards it. The size of the cavity occupied by the S. v. is not precisely known (its radius is apparently no less than 100 AU). At the boundaries of this cavity there is a dynamic S.v. must be balanced by the pressure of interstellar gas, galactic. mag. fields and galactic space rays. In the vicinity of the Earth, the collision of the flow of h-c S. v. with geomagnetic field generates a stationary shock wave in front of the earth's magnetosphere (from the side of the Sun, Fig.).
S.v. flows around the magnetosphere, as it were, limiting its extent in space. Changes in solar intensity associated with solar flares, phenomena. basic cause of geomagnetic disturbances. fields and magnetosphere (magnetic storms).
Behind the Sun it loses from the north. =2X10-14 part of its mass Msol. It is natural to assume that the outflow of matter, similar to the S.E., also exists in other stars (""). It should be especially intense massive stars(with mass = several tenths of Msolns) and with a high surface temperature (= 30-50 thousand K) and for stars with an extended atmosphere (red giants), since in the first case there is a highly developed stellar crowns have enough high energy, to overcome the gravity of the star, and in the second - low parabolic. speed (escaping speed; (see SPACE SPEEDS)). Means. Mass losses with stellar wind (= 10-6 Msol/year and more) can significantly affect the evolution of stars. In turn, the stellar wind creates “bubbles” of hot gas in the interstellar medium - sources of X-rays. radiation.
Physical encyclopedic Dictionary. - M.: Soviet Encyclopedia. . 1983 .
SOLAR WIND - a continuous flow of plasma of solar origin, the Sun) into interplanetary space. At high temperatures, which exist in the solar corona (1.5 * 10 9 K), the pressure of the overlying layers cannot balance the gas pressure of the corona substance, and the corona expands.
The first evidence of the existence of post. plasma flows from the Sun were obtained by L. L. Biermann in the 1950s. on the analysis of forces acting on the plasma tails of comets. In 1957, Yu. Parker (E. Parker), analyzing the conditions of equilibrium of the corona matter, showed that the corona cannot be in hydrostatic conditions. Wed. characteristics of S. v. are given in table. 1. S. flows. can be divided into two classes: slow - with a speed of 300 km/s and fast - with a speed of 600-700 km/s. Fast flows come from regions of the solar corona, where the structure of the magnetic field. fields are close to radial. coronal holes. Slow streamspp. V. are apparently associated with the areas of the crown, in which there is, therefore, Table 1. - Average characteristics of the solar wind in Earth orbit
Speed | |
Proton concentration | |
Proton temperature | |
Electron temperature | |
Magnetic field strength | |
Python flux density.... | 2.4*10 8 cm -2 *c -1 |
Kinetic energy flux density | 0.3 erg*cm -2 *s -1 |
Table 2.- Relative chemical composition of the solar wind
Relative content |
|
Relative content |
|
In addition to the main components of solar water - protons and electrons; particles were also found in its composition. Measurements of ionization. temperature of ions S. v. make it possible to determine the electron temperature of the solar corona.
In the N. century. differences are observed. types of waves: Langmuir, whistlers, ion-acoustic, waves in plasma). Some of the Alfven type waves are generated on the Sun, and some are excited in the interplanetary medium. The generation of waves smoothes out deviations of the particle distribution function from the Maxwellian one and, in combination with the influence of magnetism. fields to plasma leads to the fact that S. v. behaves like a continuous medium. Alfvén-type waves play a large role in the acceleration of small components of S. 
Rice. 1. Massive solar wind. Along the horizontal axis is the ratio of the mass of a particle to its charge, along the vertical axis is the number of particles registered in the energy window of the device in 10 s. Numbers with a “+” sign indicate the charge of the ion.
Stream N. in. is supersonic in relation to the speeds of those types of waves that provide eff. transfer of energy to the S. century. (Alfven, sound). Alfven and sound Mach number C. V. 7. When flowing around the north side. obstacles capable of effectively deflecting it (magnetic fields of Mercury, Earth, Jupiter, Saturn or the conducting ionospheres of Venus and, apparently, Mars), a departing bow shock wave is formed. waves, which allows it to flow around an obstacle. At the same time, in the North century. a cavity is formed - the magnetosphere (either its own or induced), the shape and dimensions of the shape are determined by the magnetic pressure balance. fields of the planet and the pressure of the flowing plasma flow (see. Magnetosphere of the Earth, Magnetospheres of the planets). In case of interaction with S. v. with a non-conducting body (for example, the Moon), a shock wave does not occur. The plasma flow is absorbed by the surface, and a cavity is formed behind the body, gradually filled with plasma C. V.
The stationary process of corona plasma outflow is superimposed by non-stationary processes associated with flares on the Sun. During strong flares, substances are released from the bottom. corona regions into the interplanetary medium. Magnetic variations). 
Rice. 2. Propagation of an interplanetary shock wave and ejecta from a solar flare. The arrows indicate the direction of motion of the solar wind plasma,
Rice. 3. Types of solutions to the corona expansion equation. The speed and distance are normalized to the critical speed vk and the critical distanceRk. Solution 2 corresponds to the solar wind.
The expansion of the solar corona is described by a system of mass conservation equations, v k) at some critical point. distance R to and subsequent expansion at supersonic speed. This solution gives a vanishingly small value of pressure at infinity, which makes it possible to reconcile it with the low pressure of the interstellar medium. This type of flow was called S. by Yu. Parker. 
, where m is the proton mass, is the adiabatic exponent, and is the mass of the Sun. In Fig. Figure 4 shows the change in expansion rate from heliocentric. thermal conductivity, viscosity, 
Rice. 4. Solar wind speed profiles for the isothermic corona model at different meanings coronal temperature.
S.v. provides the basic outflow of thermal energy from the corona, since heat transfer to the chromosphere, el.-magn. coronas and electronic thermal conductivitypp. V. insufficient to establish heat balance crowns Electronic thermal conductivity ensures a slow decrease in the ambient temperature. with distance. luminosity of the Sun.
S.v. carries the coronal magnetic field with it into the interplanetary medium. field. The force lines of this field frozen into the plasma form an interplanetary magnetic field. field (IMF). Although the intensity of the IMF is low and its energy density is about 1% of the kinetic density. energy of solar energy, it plays an important role in thermodynamics. V. and in the dynamics of interactions of S. v. with the bodies of the solar system, as well as the streams of the north. between themselves. Combination of expansion of the S. century. with the rotation of the Sun leads to the fact that the mag. the lines of force frozen into the north of the century have the form B R and azimuthal magnetic components. fields change differently with distance near the ecliptic plane: 
where is ang. speed of rotation of the Sun, And - radial component of velocityC. c., index 0 corresponds to the initial level. At the distance of the Earth's orbit, the angle between the magnetic direction. fields and R about 45°. At large L magnetic. 
Rice. 5. Shape of the interplanetary magnetic field line. - angular velocity of rotation of the Sun, and - radial component of plasma velocity, R - heliocentric distance.
S. v., arising over regions of the Sun with different. magnetic orientation fields, speed, temp-pa, particle concentration, etc.) also in cf. change naturally in the cross section of each sector, which is associated with the existence of a fast flow of solar water within the sector. The boundaries of the sectors are usually located within the slow flow of the North century. Most often, 2 or 4 sectors are observed, rotating with the Sun. This structure, formed when the S. is pulled out. large-scalemagn. corona fields, can be observed for several. revolutions of the Sun. The sector structure of the IMF is a consequence of the existence of a current sheet (CS) in the interplanetary medium, which rotates together with the Sun. TS creates a magnetic surge. fields - radial IMF have different signs By different sides TS. This TC, predicted by H. Alfven, passes through those parts of the solar corona that are associated with active regions on the Sun, and separates these regions from the different ones. signs of the radial component of the solar magnet. fields. The TS is located approximately in the plane of the solar equator and has a folded structure. The rotation of the Sun leads to the twisting of the folds of the TC into a spiral (Fig. 6). Being near the ecliptic plane, the observer finds himself either above or below the TS, due to which he falls into sectors with different signs of the IMF radial component.
Near the Sun in the north. there are longitudinal and latitudinal gradients of the velocity of collisionless shock waves (Fig. 7). First, a shock wave is formed, propagating forward from the boundary of the sectors (direct shock wave), and then a reverse shock wave is formed, propagating towards the Sun. 
Rice. 6. Shape of the heliospheric current layer. Its intersection with the ecliptic plane (inclined to the solar equator at an angle of ~ 7°) gives the observed sector structure of the interplanetary magnetic field.
Rice. 7. Structure of the interplanetary magnetic field sector. Short arrows show the direction of the solar wind, arrowed lines indicate magnetic field lines, dash-dotted lines indicate the boundaries of the sector (the intersection of the drawing plane with the current layer).
Since the speed of the shock wave is less than the speed of the solar energy, it carries the reverse shock wave in the direction away from the Sun. Shock waves near sector boundaries are formed at distances of ~1 AU. e. and can be traced to distances of several. A. e. These shock waves, as well as interplanetary shock waves from solar flares and circumplanetary shock waves, accelerate particles and are, therefore, a source of energetic particles.
S.v. extends to distances of ~100 AU. e., where the pressure of the interstellar medium balances the dynamic. blood pressure The cavity swept by the S. v. Interplanetary environment). ExpandingS. V. along with the magnet frozen into it. field prevents the penetration of galactic particles into the solar system. space rays of low energies and leads to cosmic variations. high energy rays. A phenomenon similar to the S.V. has been discovered in some other stars (see. Stellar wind).
Lit.: Parker E. N., Dynamics in the interplanetary medium, O. L. Weisberg.
Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Chief Editor A. M. Prokhorov. 1988 .
See what "SOLAR WIND" is in other dictionaries:
SOLAR WIND, a stream of plasma from the solar corona that fills the Solar System up to a distance of 100 astronomical units from the Sun, where the pressure of the interstellar medium balances the dynamic pressure of the flow. The main composition is protons, electrons, nuclei... Modern encyclopedia
SOLAR WIND, a steady stream of charged particles (mainly protons and electrons) accelerated high temperature solar CORONA to speeds high enough for the particles to overcome the Sun's gravity. The solar wind deflects... Scientific and technical encyclopedic dictionary
SUNNY WIND- a continuous stream of solar origin, spreading approximately radially from the Sun and filling the Solar System to the heliocentric. distances R ~ 100 a. e. S. v. is formed during gas-dynamic. expansion of the solar corona (see Sun )into interplanetary space. At high temperatures, which exist in the solar corona (1.5 * 10 9 K), the pressure of the overlying layers cannot balance the gas pressure of the corona matter, and the corona expands.
The first evidence of the existence of post. plasma flows from the Sun were obtained by L. Biermann in the 1950s. on the analysis of forces acting on the plasma tails of comets. In 1957, Yu. Parker (E. Parker), analyzing the equilibrium conditions of the corona matter, showed that the corona cannot be in hydrostatic conditions. equilibrium, as was previously assumed, but should expand, and this expansion, under the existing boundary conditions, should lead to the acceleration of coronal matter to supersonic speeds (see below). For the first time, a plasma flow of solar origin was recorded in the Soviet spacecraft. spacecraft "Luna-2" in 1959. Existence post. the outflow of plasma from the Sun was proven as a result of many months of measurements in America. space the Mariner 2 apparatus in 1962.
Wed. characteristics of S. v. are given in table. 1. S. flows. can be divided into two classes: slow - with a speed of 300 km/s and fast - with a speed of 600-700 km/s. Fast flows come from regions of the solar corona, where the structure of the magnetic field. fields are close to radial. Some of these areas are coronal holes . Slow flows of the North century. are apparently connected with the regions of the crown, in which there is, therefore, a tangential magnetic component. fields.
Table 1.- Average characteristics of the solar wind in Earth orbit
|
Speed |
|
|
Proton concentration |
|
|
Proton temperature |
|
|
Electron temperature |
|
|
Magnetic field strength |
|
|
Python flux density.... |
2.4*10 8 cm -2 *c -1 |
|
Kinetic energy flux density |
0.3 erg*cm -2 *s -1 |
Table 2.- Relative chemical composition of the solar wind
|
Relative content |
|
|
Relative content |
|
In addition to the main components of solar water are protons and electrons; highly ionized particles are also found in its composition. ions of oxygen, silicon, sulfur, iron (Fig. 1). When analyzing gases trapped in foils exposed on the Moon, Ne and Ar atoms were found. Wed. relative chem. composition of S. v. is given in table. 2. Ionization. state of matter S. v. corresponds to the level in the corona where the recombination time is short compared to the expansion time 
Ionization measurements temperature of ions S. v. make it possible to determine the electron temperature of the solar corona.
In the N. century. differences are observed. types of waves: Langmuir, whistlers, ion-sonic, magnetosonic, Alfven, etc. (see. Waves in plasma
Some of the Alfvén-type waves are generated on the Sun, and some are excited in the interplanetary medium. The generation of waves smoothes out deviations of the particle distribution function from the Maxwellian one and, in combination with the influence of magnetism. fields on the plasma leads to the fact that S. v. behaves like a continuous medium. Alfvén-type waves play a large role in the acceleration of small components of solar waves. and in the formation of the proton distribution function. In the N. century. contact and rotational discontinuities characteristic of magnetized plasma are also observed. 
Rice. 1. Mass spectrum of the solar wind. Along the horizontal axis is the ratio of the mass of a particle to its charge, along the vertical axis is the number of particles registered in the energy window of the device in 10 s. Numbers with a “+” sign indicate the charge of the ion.
Stream N. in. is supersonic in relation to the speeds of those types of waves that provide eff. transfer of energy to the S. century. (Alfven, sound and magnetosonic waves). Alfven and sound Mach number WITH.V. in Earth's orbit 7. When flowing around the northeast. obstacles capable of effectively deflecting it (magnetic fields of Mercury, Earth, Jupiter, Saturn or the conducting ionospheres of Venus and, apparently, Mars), a departing bow shock wave is formed. S.v. slows down and heats up at the front of the shock wave, which allows it to flow around the obstacle. At the same time, in the North century. a cavity is formed - the magnetosphere (either its own or induced), the shape and dimensions of the shape are determined by the balance of magnetic pressure. fields of the planet and the pressure of the flowing plasma flow (see. Magnetosphere of the Earth, Magnetospheres of the planets). In case of interaction with S. v. with a non-conducting body (for example, the Moon), a shock wave does not occur. The plasma flow is absorbed by the surface, and a cavity is formed behind the body, which is gradually filled with plasma from the plasma.
The stationary process of corona plasma outflow is superimposed by non-stationary processes associated with solar flares
. During strong flares, substances are released from below. corona regions into the interplanetary medium. In this case, a shock wave is also formed (Fig. 2), which gradually slows down, spreading in the plasma of the solar system. The arrival of a shock wave to the Earth causes compression of the magnetosphere, after which the development of magnetism usually begins. storms (see Magnetic variations)
.
Rice. 2. Propagation of an interplanetary shock wave and ejection from a solar flare. The arrows show the direction of motion of the solar wind plasma, the lines without a caption are the magnetic field lines.
Rice. 3. Types of solutions to the corona expansion equation. Speed and distance are normalized to the critical speed vk and the critical distance Rk. Solution 2 corresponds to the solar wind.
The expansion of the solar corona is described by a system of equations of conservation of mass, angular momentum and energy equations. Solutions that meet various the nature of the change in speed with distance are shown in Fig. 3. Solutions 1 and 2 correspond to low velocities at the base of the crown. The choice between these two solutions is determined by the conditions at infinity. Solution 1 corresponds to low rates of expansion of the corona and gives large values of pressure at infinity, i.e., it encounters the same difficulties as the static model. crowns Solution 2 corresponds to the transition of the expansion rate through the speed of sound values ( v to) on some critical. distance R to and subsequent expansion at supersonic speed. This solution gives a vanishingly small value of pressure at infinity, which makes it possible to reconcile it with the low pressure of the interstellar medium. This type of flow was called S. by Yu. Parker. Critical the point is above the surface of the Sun if the temperature of the corona is less than a certain critical value. values 
, where m is the proton mass, is the adiabatic exponent, and is the mass of the Sun. In Fig. Figure 4 shows the change in expansion rate from heliocentric. distance depending on isothermal temperature. isotropic corona. Subsequent models of S. century. take into account variations in coronal temperature with distance, two-liquid nature of the medium (electron and proton gases), thermal conductivity, viscosity, non-spherical. nature of expansion. 
Rice. 4. Solar wind speed profiles for the isothermal corona model at different values of coronal temperature.
S.v. provides the basic outflow of thermal energy from the corona, since heat transfer to the chromosphere, el-magn. Corona radiation and electron thermal conductivity are insufficient to establish the thermal balance of the corona. Electronic thermal conductivity ensures a slow decrease in temperature. with distance. S.v. does not play any noticeable role in the energy of the Sun as a whole, since the energy flow carried away by it is ~10 -7 luminosity Sun.
S.v. carries the coronal magnetic field with it into the interplanetary medium. field. The field lines of this field frozen into the plasma form an interplanetary magnetic field. field (MMP). Although the IMF intensity is low and its energy density is approx. 1% of kinetic density energy of solar energy, it plays a large role in the thermodynamics of solar energy. and in the dynamics of interactions of S. v. with the bodies of the solar system, as well as the streams of the north. between themselves. Combination of expansion of the S. century. with the rotation of the Sun leads to the fact that the mag. the lines of force frozen into the north century have a shape close to the Archimedes spiral (Fig. 5). Radial B R and azimuthal magnetic components. fields change differently with distance near the ecliptic plane: 
where is ang. speed of rotation of the Sun, And- radial component of the velocity of the central air, index 0 corresponds to the initial level. At the distance of the Earth's orbit, the angle between the direction of the magnetic. fields and R about 45°. At large L magnetic. the field is almost perpendicular to R. 
Rice. 5. Shape of the interplanetary magnetic field line. - angular velocity of rotation of the Sun, and - radial component of plasma velocity, R - heliocentric distance.
S. v., arising over regions of the Sun with different. magnetic orientation fields, forms flows with differently oriented permafrost. Separation of the observed large-scale structure of the solar system. on even number sectors with different the direction of the radial component of the IMF is called. interplanetary sector structure. Characteristics of S. v. (speed, temp-pa, particle concentration, etc.) also on Wed. change naturally in the cross section of each sector, which is associated with the existence of a fast flow of solar water inside the sector. The boundaries of the sectors are usually located within the slow flow of the north. Most often, 2 or 4 sectors are observed, rotating with the Sun. This structure, formed when the S. is pulled out. large-scale mag. corona fields, can be observed for several. revolutions of the Sun. The sector structure of the IMF is a consequence of the existence of a current layer (CS) in the interplanetary medium, which rotates together with the Sun. TS creates a magnetic surge. fields - the radial components of the IMF have different signs on different sides of the vehicle. This TS, predicted by H. Alfven, passes through those parts of the solar corona that are associated with active regions on the Sun, and separates these regions from the various regions. signs of the radial component of the solar magnet. fields. The TS is located approximately in the plane of the solar equator and has a folded structure. The rotation of the Sun leads to the twisting of the folds of the TC into a spiral (Fig. 6). Being near the ecliptic plane, the observer finds himself either above or below the TS, due to which he ends up in sectors with different signs of the IMF radial component.
Near the Sun in the north. There are longitudinal and latitudinal velocity gradients caused by the difference in the velocities of fast and slow flows. As you move away from the Sun and the boundary between the streams in the north becomes steeper. radial velocity gradients arise, which lead to the formation collisionless shock waves(Fig. 7). First, a shock wave is formed, propagating forward from the boundary of the sectors (a forward shock wave), and then a reverse shock wave is formed, propagating towards the Sun. 
Rice. 6. Shape of the heliospheric current layer. Its intersection with the ecliptic plane (inclined to the solar equator at an angle of ~ 7°) gives the observed sector structure of the interplanetary magnetic field.
Rice. 7. Structure of the interplanetary magnetic field sector. Short arrows show the direction of solar wind plasma flow, lines with arrows - magnetic field lines, dash-dotted lines - sector boundaries (intersection of the drawing plane with the current layer).
Since the speed of the shock wave is less than the speed of the solar energy, the plasma entrains the reverse shock wave in the direction away from the Sun. Shock waves near the sector boundaries are formed at distances of ~1 AU. e. and can be traced to distances of several. A. e. These shock waves, as well as interplanetary shock waves from solar flares and circumplanetary shock waves, accelerate particles and are, therefore, a source of energetic particles.
S.v. extends to distances of ~100 AU. e., where the pressure of the interstellar medium balances the dynamic. blood pressure The cavity swept by the S. v. in the interstellar medium, forms the heliosphere (see. Interplanetary environment ). Expanding S. v. along with the magnet frozen into it. field prevents the penetration of galactic particles into the Solar System. space rays of low energies and leads to variations in cosmic. high energy rays. A phenomenon similar to the S.V. has also been discovered in certain other stars (see Stellar wind ).
Lit.: Parker E. N., Dynamic processes in the interplanetary medium, trans. from English, M., 1965; Brandt J., Solar Wind, trans. from English, M., 1973; Hundhausen A., Corona Expansion and the Solar Wind, trans. from English, M., 1976. O. L. Weisberg.