The interplanetary medium is matter and fields that fill the space inside the solar system (star system) from the solar corona (star corona) to the borders of the heliosphere with the exception of planets and bodies of the solar system. The interplanetary medium mainly includes the solar wind (the wind of the central star in the star system (starwind)), the interplanetary magnetic field, cosmic rays (high-energy charged particles), neutral gas, interplanetary dust, and electromagnetic radiation [1] . The interplanetary medium plays a key role in solar-terrestrial physics and its practical part - space weather .
Content
Solar wind
The solar wind (the wind of the central star in the star system (starwind)) is an expanding plasma of the solar corona, filling the entire heliosphere. The solar wind consists of electrons , protons , alpha particles and other ions of solar origin, as well as trapped ions formed from the neutral component as a result of interaction with radiation. The solar wind is a non-equilibrium system with a high level of turbulence. Large-scale structures and dynamic processes in the solar atmosphere are manifested in the existence in the solar wind up to distances of several large-scale astronomical units to various astronomical units, in which the values of the parameters may differ significantly. Near the maximum of the solar activity cycle, non-stationary types of solar wind can be about half the time of observations. At a distance of 1 a. e. the proton flux of the solar wind varies from before cm with and the speed is from 300 to 1000 km / s, the average temperature is K. With increasing distance from the Sun R, the proton flux decreases as , the speed remains almost constant, and the differences between the structures are reduced. The interaction of the solar wind with the planets and bodies of the Solar System determines the position and state of their outer plasma shells, the state of Cosmic weather.
Interplanetary Magnetic Field
The magnetic field of the solar corona is "frozen in" into the plasma and carried away by the solar wind, forming an interplanetary magnetic field (MMP). Magnetic field strength for 1 a. e. changes from before E, the maximum magnetic field is recorded in coronal mass ejection. The rotation of the Sun leads to the fact that the field lines of force in the stationary solar wind twist and take the form of a spiral. Near the ecliptic plane, a heliospheric current sheet (CTA) is observed, separating fields of opposite direction. GTS has the form of corrugations, therefore, spacecraft register the sector structure, that is 2, 4 or (less often) 6 sectors per revolution of the Sun, in which the MMP has one direction. The stationary solar wind at small heliolatitudes does not contain a noticeable normal to the ecliptic plane to the magnetic field component, therefore it is not geoeffective, and all disturbances of the Earth’s magnetosphere are caused by non-stationary types of solar wind. In coronal mass ejections, the field lines of force are twisted and look like a tow, one or both ends of which are connected to the Sun. In the areas of compression before the rapid flow of the solar wind or the ejection of the coronal mass, the initial magnetic field is compressed and deformed when different structures of the solar wind interact [2] .
Cosmic Rays
Cosmic rays (high-energy charged particles) have several types associated with their origin. Cosmic rays, despite their high energy, do not affect the local state of the solar wind plasma and the magnetic field due to their low concentration, but on a large scale, especially near the borders of the heliosphere, where the concentration of the solar wind drops, cosmic rays play an important role . Solar cosmic rays are accelerated during strong solar flares or during the propagation of shock waves in the corona and in the solar wind. In this case, protons with energies up to several hundred MeV and electrons up to several tens of keV are formed, in rare cases, relativistic electrons with energies of several MeV are formed. The composition of solar cosmic rays is close to the composition of the solar corona. The number of events with solar cosmic rays greatly increases near the maximum of the solar activity cycle. Galactic cosmic rays are born outside the heliosphere (during the explosion of new and supernovae). They are fully ionized nuclei of various elements with energy - eV. They are scattered by inhomogeneities of the interplanetary magnetic field, and their flux decreases on average with distance from the boundaries of the heliosphere. The flux also depends on time and falls both on scales of about a day when coronal mass ejection (Forbush decrease) passes through the heliosphere, and on scales of about a year (near the maximum of the solar activity cycle). Only the most high-energy particles (with an energy of more than several hundred MeV) reach the Earth's orbit. Anomalous cosmic rays are also observed, which, unlike ordinary GCSs, are singly (rarely doubly) ionized atoms, their appearance is associated with two possible mechanisms: (1) ionization of neutral atoms of the interstellar medium and their acceleration at the boundaries of the heliosphere (heliospheric interface) and ( 2) flashes on stars belonging to red and yellow dwarfs. Near the planets (especially the giant planets Jupiter and Saturn) there are less intense flows of energetic particles born on the head shock wave and inside the magnetosphere. The intensity of these flows depends on the conditions on the planets and often changes with the period of rotation of the planets.
Neutral Component
The heliosphere moves through the local interstellar cloud , which according to indirect observations is a partially ionized medium with a density of 0.2 cm and temperature K. The neutral component freely penetrates into the heliosphere and reaches the region near the Sun, where effective ionization begins when interacting with solar radiation and recharging when interacting with the solar wind and solar cosmic rays. A small part of the neutral component is associated with the loss of atoms by the planets and other bodies of the solar system.
Dust component
The dust component of the interplanetary medium consists mainly of particles from 1 nm to 100 μm, which have a charge and form a plasma-dust environment (or dusty plasma). Larger particles behave as test particles and are considered as "particles in a plasma". The dust component fills the entire heliosphere extremely non-uniformly and is concentrated mainly near the Sun in the inner heliosphere and near the ecliptic plane, and its distribution strongly depends on the size of the dust particles, since their trajectory is described by a balance of different forces that depend significantly on size. The dust component is the source of such phenomena as the sun's F-corona and zodiacal light . The main source of dust are cometary nuclei and asteroids, the smallest dust particles under the influence of the Pointing-Robertson effect approach the Sun and acquire a charge. Near the Sun, due to the high temperature, the sublimation process is important.
Electromagnetic Radiation
The interplanetary space is filled with electromagnetic radiation, mainly of solar origin. This radiation plays a significant role in the formation of other components of the interplanetary medium and is a source of secondary radiation, which serves as a source of experimental data on the interplanetary medium. Weaker streams of electromagnetic waves generate planets of the solar system, the boundaries of the heliosphere and other objects of the Universe.
Notes
- ↑ Yu. I. Ermolaev, Interplanetary Environment // Big Russian Encyclopedia, ed. Yu. S. Osipova, Moscow: BDT, vol. 19, 2012
- ↑ Interplanetary Magnetic Field | Vestishki.ru
Literature
- Solar and solar-terrestrial physics. Illustrated glossary of terms. from English, M., 1980.
- Interplanetary Environment / MS Burgin // Physics of the Cosmos: The Little Encyclopedia / Edited: R. A. Syunyaev (Gl. Ed.), And others. - 2nd ed. - M .: Soviet Encyclopedia , 1986. - p. 396-398. - 783 s. - 70 000 copies
- Plasma heliogeophysics / Ed. L. M. Zeleny, I. S. Veselovsky. In 2 tons. M .: Fiz-matlit, 2008. T. 1. 672 p .; T. 2. 560 s.