rus
Issue #5/2019
Earth In The Arms Of The Sun: Heliophysics And Space Weather
The regular meeting of the Scientific session of the Department of Physical Sciences (supervised by R. A. Suris, academician of the RAS) was held on June 5, 2019. The topic has combined the reports on the latest results in research on the Sun and its effect on space weather.
DOI: 10.22184/1993-7296.FRos.2019.13.5.504.506
DOI: 10.22184/1993-7296.FRos.2019.13.5.504.506
Earth in the Arms of the Sun: Heliophysics and Space Weather
The regular meeting of the Scientific session of the Department of Physical Sciences (supervised by R. A. Suris, academician of the RAS) was held on June 5, 2019. The topic has combined the reports on the latest results in research on the Sun and its effect on space weather.
S. A. Bogachev, Doctor of Technical Sciences (Lebedev Physical Institute, Moscow), spoke about the new results of observing the Sun with ultra-high spatial resolution. Long studies of the Sun have led to the generally accepted conclusion that the energy of the observed solar activity is insufficient to explain the fundamental properties of the solar corona – above all, its high temperature. In 1988, the American astronomer Eugene Parker suggested the existence of so-called nano-flares on the Sun – events whose power is 6–9 orders of magnitude lower than the power of a large flare, but whose integrated energy release can be orders of magnitude higher than the large-scale activity component. Over the past 10–15 years, solar nano-flares, as well as an intermediate class – microflares – have become an observable phenomenon.
At the same time, evidence appeared of the existence of a much wider set of small-scale phenomena on the Sun – bright X‑ray points, spicules of various types, Ellerman bombs. The report presents the results of domestic space experiments conducted by the Russian Academy of Sciences and the Russian Space Agency, as well as the latest data from foreign space observatories. Within the framework of the Federal Space Program of the Russian Federation for 2016–2025, it is planned to create a specialized solar observatory «ARKA», which is to provide images of the corona of the Sun with an angular resolution of 0.1 arc seconds (less than 100 km) for the first time. It is hoped that the information obtained will make it possible to make decisive progress in understanding the balance between large-scale and small-scale energy in the Sun, and maybe finally answer the fundamental question – what warms the corona of the Sun.
The report «Modern Look at the Solar Wind, from Micro to Macro Scales» (A. A. Petrukovich, M. O. Ryazantseva, H. V. Malova, Space Research Institute of RAS, Moscow) was devoted to one of the most important elements of the solar system – the solar wind. Solar wind plasma is a unique laboratory of a specific astrophysical medium with the dominance of flowing energy. A review of current results on the study of the origin and dynamics of the solar wind covered the structure of several scientific fields at once, emphasizing the logic of research. At the microscale, the spectral structure of flow turbulence was determined, new types of isolated nonlinear structures with characteristic sizes of the order of the ionic kinetic scale were revealed. Collisions of solar wind flows between themselves and with planets form shock waves. Multipoint satellite observations make it possible to determine the mode of plasma oscillations responsible for creating a collisionless wavefront. At medium scales (up to a million kilometers), structures that originate on the Sun and are modified during propagation dominate. These structures play an important role in the generation of magnetic activity on Earth. An analysis of the dynamics of such structures shows an interesting possibility of improving the forecast of their development with an increase in their size, which is of practical importance for forecasting magnetic storms for monitoring solar wind. At macroscales of the order of the heliosphere, the structure of the solar wind is determined by the configuration of the main magnetic field of the Sun and can be traced on interplanetary spacecraft.
V. D. Kuznetsov (Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk) made a review «Heliophysics: From Observations to Models and Applications». Based on observations and building physical models, he considered the problematic issues of solar physics – global fluctuations in the interior of the sun, trigger mechanisms of the most powerful manifestations of solar activity – flares and mass ejections, heating of the solar corona, shock waves in a collisionless solar wind plasma. The studied phenomena of solar activity are considered as sources of space weather in near-Earth outer space were considered in the appendix to the practical issues of the impact of its factors on the spheres of human activity on Earth and in space. The report examined the structure of scientific problems aimed at solving such urgent problems of solar physics as the variability of the duration and height of solar cycles, the trigger mechanisms of solar flares and mass ejections, the mechanisms of particle acceleration in the solar atmosphere and heliosphere, the heating of the solar corona and the acceleration of the solar wind, and some others. These tasks are being addressed within the framework of the Intergeliozond space project of the Federal Space Program of the Russian Federation.
M. I. Panasyuk (SINP MSU, Moscow) spoke about the existing radiation fields in space and the need in connection with their magnitudes of planning space missions. For on-board electronics and long-term manned flights, the problems associated with the presence of the heavy component of charged particles and secondary neutron fields in cosmic radiation are becoming increasingly relevant. The presence of radiation in outer space is due to the existence of radiation fields. These include: the Earth“s radiation belts (ERB) and some other planets of the solar system, galactic cosmic rays (GCR) and solar cosmic rays (SCR). These radiation components are composed of various particles, including protons, electrons and heavy nuclei (ions) of chemical elements:
It has been established that the energy range and level of particle fluxes in radiation fields, and, consequently, the level of radiation hazard vary significantly, due to both the spatially inhomogeneous distribution of these fluxes in interplanetary and near-Earth space, and the changes in these fluxes in time due to the temporal variability of physical processes in the galaxy and the solar system. In this regard, the development of space radiation monitoring systems with the ability to evaluate radiation conditions in real time is extremely important. For practical applications, the established physical parameters of the fluxes of particles of GCR, ERB, and SCR and the laws of their variations are generalized using physical and mathematical models and are also an integral component of calculations in assessing radiation hazard. The report gave an overview of the current state of the problems of experimental research, monitoring and modeling of radiation fields in space, relevant for the implementation of long-term near-Earth and future space missions for the exploration of the Moon and Mars.
The report «X‑ray and Gamma Radiation of Solar Flares» (D. D. Frederiks, A. L. Lysenko, D. S. Svinkin, M. V. Ulanov, A. E. Tsvetkova, R. L. Aptekar, A. F. Ioffe Physics and Technical Institute, St. Petersburg) was devoted to a brief review of recent results on the observation of solar flares in the hard X‑ray and gamma-ray ranges. They are especially important for the diagnosis of accelerated particles, since it is in them that the bremsstrahlung of non-thermal electrons and gamma lines from nuclear reactions of accelerated ions are observed. Particle acceleration and plasma heating processes are typical of many astrophysical objects, and the Sun, the closest star to us, is a unique natural laboratory where they can be studied with unique spatial and temporal resolution. Although significant progress has been made in understanding the morphology of solar flares in the last decade, however, many unresolved issues remain in their physics, including, for example, elucidating the specific mechanisms of particle acceleration and the problem of heating the solar corona, whose temperature is orders of magnitude higher than the temperature photosphere.
The results obtained by the A. F. Ioffe Physics and Technical Institute of RAS during a joint Russian-American space experiment «Cone-Wind», which carries out continuous monitoring of flare solar activity in the range of 20 keV –15 MeV, since November 1994. The equipment of the experiment «Cone» consists of two scintillation gamma-spectrometer. They are mounted on the Wind satellite, stabilized by rotation in such a way that they constantly examine the entire celestial sphere. The satellite“s orbit is located completely in interplanetary space (at the so-called libration point L1, about 1.5 million kilometers from the Earth on the Earth-Sun line), i. e., outside the Earth“s radiation belts, which are dangerous for detectors. Also, thanks to this, the Earth does not close the detectors with an overview of any parts of the celestial sphere. An important objective of the experiment is to determine the coordinates of gamma-ray burst sources using the triangulation method according to the InterPlanetary Network (IPN) satellite with gamma-ray detectors on board.
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The regular meeting of the Scientific session of the Department of Physical Sciences (supervised by R. A. Suris, academician of the RAS) was held on June 5, 2019. The topic has combined the reports on the latest results in research on the Sun and its effect on space weather.
S. A. Bogachev, Doctor of Technical Sciences (Lebedev Physical Institute, Moscow), spoke about the new results of observing the Sun with ultra-high spatial resolution. Long studies of the Sun have led to the generally accepted conclusion that the energy of the observed solar activity is insufficient to explain the fundamental properties of the solar corona – above all, its high temperature. In 1988, the American astronomer Eugene Parker suggested the existence of so-called nano-flares on the Sun – events whose power is 6–9 orders of magnitude lower than the power of a large flare, but whose integrated energy release can be orders of magnitude higher than the large-scale activity component. Over the past 10–15 years, solar nano-flares, as well as an intermediate class – microflares – have become an observable phenomenon.
At the same time, evidence appeared of the existence of a much wider set of small-scale phenomena on the Sun – bright X‑ray points, spicules of various types, Ellerman bombs. The report presents the results of domestic space experiments conducted by the Russian Academy of Sciences and the Russian Space Agency, as well as the latest data from foreign space observatories. Within the framework of the Federal Space Program of the Russian Federation for 2016–2025, it is planned to create a specialized solar observatory «ARKA», which is to provide images of the corona of the Sun with an angular resolution of 0.1 arc seconds (less than 100 km) for the first time. It is hoped that the information obtained will make it possible to make decisive progress in understanding the balance between large-scale and small-scale energy in the Sun, and maybe finally answer the fundamental question – what warms the corona of the Sun.
The report «Modern Look at the Solar Wind, from Micro to Macro Scales» (A. A. Petrukovich, M. O. Ryazantseva, H. V. Malova, Space Research Institute of RAS, Moscow) was devoted to one of the most important elements of the solar system – the solar wind. Solar wind plasma is a unique laboratory of a specific astrophysical medium with the dominance of flowing energy. A review of current results on the study of the origin and dynamics of the solar wind covered the structure of several scientific fields at once, emphasizing the logic of research. At the microscale, the spectral structure of flow turbulence was determined, new types of isolated nonlinear structures with characteristic sizes of the order of the ionic kinetic scale were revealed. Collisions of solar wind flows between themselves and with planets form shock waves. Multipoint satellite observations make it possible to determine the mode of plasma oscillations responsible for creating a collisionless wavefront. At medium scales (up to a million kilometers), structures that originate on the Sun and are modified during propagation dominate. These structures play an important role in the generation of magnetic activity on Earth. An analysis of the dynamics of such structures shows an interesting possibility of improving the forecast of their development with an increase in their size, which is of practical importance for forecasting magnetic storms for monitoring solar wind. At macroscales of the order of the heliosphere, the structure of the solar wind is determined by the configuration of the main magnetic field of the Sun and can be traced on interplanetary spacecraft.
V. D. Kuznetsov (Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk) made a review «Heliophysics: From Observations to Models and Applications». Based on observations and building physical models, he considered the problematic issues of solar physics – global fluctuations in the interior of the sun, trigger mechanisms of the most powerful manifestations of solar activity – flares and mass ejections, heating of the solar corona, shock waves in a collisionless solar wind plasma. The studied phenomena of solar activity are considered as sources of space weather in near-Earth outer space were considered in the appendix to the practical issues of the impact of its factors on the spheres of human activity on Earth and in space. The report examined the structure of scientific problems aimed at solving such urgent problems of solar physics as the variability of the duration and height of solar cycles, the trigger mechanisms of solar flares and mass ejections, the mechanisms of particle acceleration in the solar atmosphere and heliosphere, the heating of the solar corona and the acceleration of the solar wind, and some others. These tasks are being addressed within the framework of the Intergeliozond space project of the Federal Space Program of the Russian Federation.
M. I. Panasyuk (SINP MSU, Moscow) spoke about the existing radiation fields in space and the need in connection with their magnitudes of planning space missions. For on-board electronics and long-term manned flights, the problems associated with the presence of the heavy component of charged particles and secondary neutron fields in cosmic radiation are becoming increasingly relevant. The presence of radiation in outer space is due to the existence of radiation fields. These include: the Earth“s radiation belts (ERB) and some other planets of the solar system, galactic cosmic rays (GCR) and solar cosmic rays (SCR). These radiation components are composed of various particles, including protons, electrons and heavy nuclei (ions) of chemical elements:
- GCR, the flows of which penetrate into the solar system from our and other galaxies;
- SCR, which occasionally appear in the solar system as a result of the generation of chromospheric flares and coronal mass injections on the sun;
- ERBs trapped in the magnetic trap of the Earth“s magnetosphere, which holds particles of solar and atmospheric (ionospheric) origin, as well as nuclear reaction products resulting from the interaction of cosmic rays with the Earth“s atmosphere.
It has been established that the energy range and level of particle fluxes in radiation fields, and, consequently, the level of radiation hazard vary significantly, due to both the spatially inhomogeneous distribution of these fluxes in interplanetary and near-Earth space, and the changes in these fluxes in time due to the temporal variability of physical processes in the galaxy and the solar system. In this regard, the development of space radiation monitoring systems with the ability to evaluate radiation conditions in real time is extremely important. For practical applications, the established physical parameters of the fluxes of particles of GCR, ERB, and SCR and the laws of their variations are generalized using physical and mathematical models and are also an integral component of calculations in assessing radiation hazard. The report gave an overview of the current state of the problems of experimental research, monitoring and modeling of radiation fields in space, relevant for the implementation of long-term near-Earth and future space missions for the exploration of the Moon and Mars.
The report «X‑ray and Gamma Radiation of Solar Flares» (D. D. Frederiks, A. L. Lysenko, D. S. Svinkin, M. V. Ulanov, A. E. Tsvetkova, R. L. Aptekar, A. F. Ioffe Physics and Technical Institute, St. Petersburg) was devoted to a brief review of recent results on the observation of solar flares in the hard X‑ray and gamma-ray ranges. They are especially important for the diagnosis of accelerated particles, since it is in them that the bremsstrahlung of non-thermal electrons and gamma lines from nuclear reactions of accelerated ions are observed. Particle acceleration and plasma heating processes are typical of many astrophysical objects, and the Sun, the closest star to us, is a unique natural laboratory where they can be studied with unique spatial and temporal resolution. Although significant progress has been made in understanding the morphology of solar flares in the last decade, however, many unresolved issues remain in their physics, including, for example, elucidating the specific mechanisms of particle acceleration and the problem of heating the solar corona, whose temperature is orders of magnitude higher than the temperature photosphere.
The results obtained by the A. F. Ioffe Physics and Technical Institute of RAS during a joint Russian-American space experiment «Cone-Wind», which carries out continuous monitoring of flare solar activity in the range of 20 keV –15 MeV, since November 1994. The equipment of the experiment «Cone» consists of two scintillation gamma-spectrometer. They are mounted on the Wind satellite, stabilized by rotation in such a way that they constantly examine the entire celestial sphere. The satellite“s orbit is located completely in interplanetary space (at the so-called libration point L1, about 1.5 million kilometers from the Earth on the Earth-Sun line), i. e., outside the Earth“s radiation belts, which are dangerous for detectors. Also, thanks to this, the Earth does not close the detectors with an overview of any parts of the celestial sphere. An important objective of the experiment is to determine the coordinates of gamma-ray burst sources using the triangulation method according to the InterPlanetary Network (IPN) satellite with gamma-ray detectors on board.
gpad ac.ru
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