RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 9, ES3004, doi:10.2205/2007ES000276, 2007
From the geophysical to heliophysical year: The results of the CORONAS-F projectV. D. Kuznetsov Pushkov Institute of the Earth Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences (IZMIRAN), Troitsk, RussiaContents
Abstract[1] The main and most significant results of the CORONAS-F space project are presented. In the scope of this project observations of solar activity and its impact on the Earth were carried out from July 2001 to December 2005. The remote observation devices studied the localization and morphology of solar activity in the second half of the 23rd solar cycle. High-temperature plasma formations are found and studied in the solar corona, eruptive phenomena, processes of particle acceleration, and atomic and nuclear processes in solar flares are investigated. The devices of the "Solar Cosmic Ray" complex studied manifestations of solar activity in the near-Earth environment, dynamics of the radiation belts of the Earth, and rebuilding of the magnetosphere structure in the periods of magnetic storms caused by active events on the Sun. Results related to the upper atmosphere of the Earth and helioseismology are also presented. 1. Introduction[2] During 50 years of the space era, the Russian space science passed in studies of solar activity and its influence on the Earth a way from the first artificial satellite to the CORONAS-F satellite, a multifunctional solar space laboratory. The space researches were the very activity that provided the most important input in the knowledge and ideas on solar activity and solar-terrestrial relations what we currently have. Currently it is impossible to consider the very concept of geophysics without a relation to heliophysics, the science studying the Sun and heliosphere filled by the solar wind. The fact that 2007 was claimed as Heliophysical Year once more emphasizes not only the importance of researches in this region for the Humanity, but the broadening of the frames and deepening of our knowledge from geophysics to heliophysics during the passed years of studies. Actually, a lot of new information was obtained concerning space, Sun, and its impact on the Earth and various spheres of human activity both, on the Earth and in space. The state of our knowledge reached the level when we are able to predict with a significant probability solar activity and its influence on the Earth and characterize all this by the term space weather which more and more enters our everyday life. [3] The CORONAS-F is the second satellite of the CORONAS Program (Complex Orbital Near-Earth Observations) which has been developed by the Physical Science Division of the Russian Academy of Sciences and is realized in the frame of the Federal Space Program. During the period of observations from July 2001 to December 2005, broad-scale durable continuous observations of solar activity and registration of its manifestations in the near-Earth environment were performed. The scientific payload of the satellite including 15 scientific devices registered electromagnetic and corpuscular radiation of the Sun within a wide spectral range (from optical to gamma emission) and within the energy range from a few keV to hundreds of MeV. The initial altitude and the inclination of the satellite orbit were approximately 500 km and 86o, respectively. The observational period fell on the phases of the maximum and decay of the 23rd cycle of solar activity, when a whole series of extreme events (powerful flares and ejections what provided obtaining the most detailed information on these events and study their manifestations in the near-Earth environment: in the dynamics of the Earth's radiation belts and structural rebuilding of the magnetosphere) occurred on the Sun. 2. Observations of the Sun and Its Activity2.1. Global Oscillations of the Sun
2.2. X-ray Solar Images[5] The entire complex of unique studies was carried out [Zhitnik et al., 2005] using the multi-channel X-ray telescope. Numerous images of the Sun with high spatial resolution in various spectral lines corresponding to different temperature layers of the solar atmosphere made it possible to localize and study the morphology of various active phenomena.
[9] Observations by the X-ray telescope operating in the coronagraph regime made it possible for the first time to obtain data on the solar corona dynamics at distances up to three solar radii. This region is important for understanding of the nature of many phenomena, but is not observed by other devices, because it is an intermediate region between the near-limb region observed by telescopes and the far corona observed in the white light by coronagraphs. It this region of the corona, loops and magnetic field arches, aligned streamers, and jets of the elapsing solar wind are distinctly seen, whereas mass ejections and eruptive filaments at these altitudes were observed for the first time. The X-ray coronagraph obtained also for the first time maps of the distribution of the hard X-ray radiation for quiet and disturbed corona in the presence at the limb of bright active regions which illustrate visually the magnetic heating of the corona over active regions.
2.3. Solar Flares[12] During the period of the observations by the CORONAS-F devices with high time and spectral resolution in the broad energy range, a vast amount of new information on various physical processes in flares was obtained. The information concerns spectral, energetic, polarization, and dynamical characteristics of flare emissions, spectra of accelerated particles, gamma lines etc.[13] On the basis of the observations with high time resolution in the X-ray range (3-40 keV) using the flare spectrometer IRIS and spectral analysis, characteristic periods of plasma oscillations in active regions before the flare, during the flare, and after the flare were determined [Dmitriev et al., 2002, 2006]. These periods differ considerably (from a few seconds to tens of seconds), this fact manifesting changes in the resonant properties of the magnetic configuration of active regions. Such signs could be used for forecasting of solar flares on the basis of the observed X-ray emission and for creation of a model of the flare process. 2.4. Impulsive Phase of a Flare[14] The impulsive phase of a flare is characterized by an energy release which (as we see it in the X-ray radiation) has an oscillation (saw-like) character [Dmitriev et al., 2002]. The beams of charged particles accelerated in the flare inject into the dense layers of the solar atmosphere and form peaks of the X-ray emission with characteristic intervals of 20 s. Quite similar picture of the energy release in the form of saw-like oscillations is observed also in tokomaks during an instability break related to reconnection of magnetic field lines [Prist and Forbes, 2000]. [15] The hard X-ray emission generated at the interaction of directed beams of accelerated particles with the dense solar atmosphere should be linearly polarized. Attempts to measure this polarization for a long time were failing. A considerable linear polarization in the flare maximum was for the first time measured by the SPR-N specropolarimeter at the CORONAS-F satellite for one of the most powerful flares on 29 November 2003 (class X-10) [Zhitnik et al., 2006]. This is a direct proof not only of the existence of the accelerated particle beams themselves, but a confirmation of the fact that these particles are accelerated by the pulse electric field during the magnetic reconnection, but not by some stochastic mechanism. [16] The impulsive character of the energy release and particle acceleration was registered also in the time profiles and dynamic spectra of the hard X-ray emission of flares in 8 energetic channels (26-380 keV) of the HELICON gamma spectrometer. On the basis of these observations, the dynamics of hard emission spectrum (characteristic times and values of the spectrum slope change) was determined. The most hard spectrum is realized in the flare maximum. 2.5. Atomic Processes in Flares
2.6. Nuclear Processes in Flares[18] In powerful flares, the accelerated protons and nuclei with an energy above a few MeV cause numerous nuclear reactions at collisions with nuclei of the medium. The gamma radiation, gamma lines of excited nuclei, annihilation electron-positron lines, and neutrons formed in the reactions bring important diagnostic information on the acceleration process and the composition of the solar atmosphere. These processes were registered by the devices of the gamma range: the amplitude-time spectrometer AVS-F and the spectrometer of solar neutrons and gamma radiation, SONG.
[20] The line of the annihilation of electrons and positrons was observed in the energy range of 0.5 MeV in the spectrum of the gamma radiation of the flare by the amplitude-time spectrometer AVS-F. The line appears only in powerful flares when sufficient number of positrons is formed from the radioactive nuclei born in the flare.
2.7. Ultraviolet Emission of Solar Flares
3. Registration of Solar Activity Manifestations in the Near-Earth Space Environment
3.1. Magnetosphere and Radiation Belts[23] Conducting measurements of solar cosmic rays along the orbit of the CORONAS-F satellite by the SCR (Solar Cosmic Ray) equipment, a continuous series of the data on the fluxes of energetic solar particles was obtained, the data on the fluxes of solar electrons with energies above 300 keV being unique, because no other measurements has been conducted in this period.[24] The conducted measurements of solar cosmic rays made it possible to study the dynamics of the magnetosphere and radiation belts of the Earth and also changes in the boundaries of penetration of energetic solar particles into the magnetosphere in the periods of strong geomagnetic disturbances [Kuznetsov et al., 2007a, 2007b].
[26] Strong variations of the SCR penetration boundary were observed also during strong magnetic storms in November 2001. The variations of the penetration boundary of protons of SCR with an energy of 1-5 MeV and 50-90 MeV and electrons of SCR with an energy of 0.3-0.6 MeV as a function of the geomagnetic activity indices Kp and Dst for the dusk and dawn sectors of the magnetic local time (MLT) were observed. The stronger magnetic disturbances (larger values of Kp and larger negative values of Dst ) the lower the L value, and so solar energetic particles penetrate to lower latitudes and lower heights.
[27] The experimental dependence of the penetration boundary of solar cosmic rays on the
Dst and
Kp indices of geomagnetic activity was approximated by the analytical
formula in the form:
L = a + b
[28] International Space Station having the inclination of the orbit plane to the equatorial plane of
51o is able (taking into account the inclination of the magnetic dipole axis to the axis of the Earth's
rotation
[29] On the basis of the measurements by the CRM (Cosmic Ray Monitor) device of the SCR scientific equipment, the dynamics of the outer radiation belt of the Earth during strong magnetic storms caused by active events on the Sun is studied and the relation of its dynamics to the structural rebuilding of the magnetosphere is determined. The interaction of coronal mass ejections with the magnetosphere of the Earth led to a magnetic storm which was accompanied by a structural rebuilding of the magnetosphere: shrinking of the region of closed drift shells (region of the radiation belts), redistribution of the field lines into the magnetospheric tail, and increase in the polar cap dimensions.
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![]() ![]() ![]() ![]() ![]() ![]() ![]() [34] Thus the structural rebuilding of the magnetosphere during a magnetic storm leads to a shrinking of the region of the outer radiation belt. After the end of a magnetic storm (the recovery phase), the outer radiation belt recovers. First the electron fluxes increase at the boundary of the penetration of SCR electrons at the moment of the magnetic storm, then the fluxes of electrons with an energy of a few MeV increase, and so the radiation belt structure could have two maxima. [35] Thus it is proved on the basis of the conducted measurements that the effect of the disappearance of the outer radiation belt of electrons at the main phase of magnetic storms at the energies above 1.5 MeV is due to the shrinking of the region in which the captured radiation could exist. After the end of a magnetic storm, the region of existence of the captured radiation recovers up to the pre-storm state. 3.2. Upper Atmosphere of the Earth
[39] The observations of the upper atmosphere of the Earth carried out in the scope of the CORONAS-F project made it possible to obtain experimental data for creation of a modern model of the Earth's atmosphere. This is important in the light of the recent publication on the possible systematic trends in the parameters of the upper atmosphere and in relation to the global warming problem. 4. Conclusions[40] During the half-century period from the International Geophysical Year (1957) to the International Heliophysical Year (2007), from the first artificial satellite (1957) to the solar space observatory CORONAS-F (2001-2005), thanks to the entire series of solar and heliospheric space projects (SOHO, TRACE, ULYSSES, Solar A, RHESSI, and CORONAS-F) in the studies of solar activity and its impact on the Earth a considerable success was achieved in understanding of the main processes occurring in the Sun-Earth system. This understanding allows us to estimate correctly the influence of the space weather on the human activity on the Earth and in Space. It makes also possible to provide the necessary level of space weather prediction needed to provide the safety of cosmonauts, space vehicles, communication and navigation systems, and extended ground-based communication and transport systems. [41] The acting (SOHO, STEREO, Hinode, TRACE, RHESSI), prepared to be launched (SDO, Solar probe, CORONAS-PHOTON, and others), and being developed (Interhelioprobe, Solar Orbiter, and others) heliospheric and solar space missions of various space agencies continue fundamental and vitally important solar-terrestrial studies. A start to these studies was given in 1957 by the launching of the first artificial satellite and by the wide program of the International Geophysical Year. [42] This paper presents only some of the most important results of the CORONAS-F project. One can find their more detailed description in the reviews [Kuznetsov, 2004, 2005, 2006a, 2006b; Kuznetsov et al., 2004, 2005; Oraevsky and Sobelman, 2002; Oraevsky et al., 2002, 2003] and in the references therein. Acknowledgments[43] The author thanks the leaders of the experiments on board the CORONAS-F satellite I. A. Zhitnik, , Yu. D. Kotov, V. M. Pankov, A. A. Nusinov, E. P. Mazets, and Ya. Sylwester for the presented information used at writing of this paper. ReferencesArkhangel'skaya, I. V., A. I. Arkhangel'skii, Yu. D. Kotov, S. N. Kuznetsov, and A. S. Glyanenko (2006), Studies of the gamma radiation of solar flares in October-November 2003 on the basis of the data of the AVS-F device on board the CORONAS-F satellite, Astronomical Transactions (in Russian), 40, (4), 331. Chertok, I. M., V. V. Grechnev, V. A. Slemzin, S. V. Kuzin, O. I. Bugaenko, I. A. Zhitnik, A. P. Ignat'ev, A. A. Pertsov, and J.-P. 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(2005a), RESIK: Bent crystal solar X-ray spectrometer for studies of Coronal Plasma Composition, Sol. Phys., 226, (1)), 45, doi:10.1007/s11207-005-6392-5. [CrossRef] Sylwester, Ya., B. Sylwester, K. J. X. Fillips, V. D. Kuznetsov, and S. I. Boldyrev (2005b), Observations of the solar X-ray spectra by the RESIK and DIAGENESS spectrometers on board the CORONAS-F satellite, Astronomical Transactions (in Russian), 39, (1-2), 537. Zhitnik, I. A., O. I. Bugaenko, A. P. Ignat'ev, V. V. Krutov, S. V. Kuzin, A. V. Mitrofanov, S. N. Oparin, A. A. Pertsov, V. A. Slemzin, and A. I. Stepanov (2003), Dynamic 10 MK plasma structures observed in monochromatic full-Sun images by the SPIRIT spectroheliograph on the CORONAS-F mission, Monthly Notice of Royal Astronomical Society, 338, (1), 67, doi:10.1046/j.1365-8711.2003.06014.x. [CrossRef] Zhitnik, I. A., S. V. Kuzin, I. I. Sobelman, O. I. Bugaenko, A. P. Ignat'ev, A. V. Mitrofanov, S. N. Oparin, A. Pertsov, V. A. Slemzin, and N. K. Sukhodrev (2005), The main results of the SPIRIT experiment on board the CORONAS-F satellite, Astronomical Transactions (in Russian), 39, (6), 495. Zhitnik, I. A., Yu. I. Logachev, A. V. Bogachev, Yu. I. Denisov, S. Kavanosyan, S. Kuznetsov, O. Morozov, I. Myagkova, S. I. Svertilov, and A. P. Ignat'ev (2006), Results of measurements of polarization, time, and spectral characteristics of the hard X-ray radiation of solar flares according to the data of the experiment with the SPR-N device on board the CORONAS-F satellite, Astronomical Transactions (in Russian), 40, (2), 108. Received 20 October 2007; accepted 15 November 2007; published 27 December 2007. Keywords: heliophysical year, CORONAS-F project, near-Earth environment, helioseismology. Index Terms: 2162 Interplanetary Physics: Solar cycle variations; 2164 Interplanetary Physics: Solar wind plasma; 2194 Interplanetary Physics: Instruments and techniques. ![]() Citation: 2007), From the geophysical to heliophysical year: The results of the CORONAS-F project, Russ. J. Earth Sci., 9, ES3004, doi:10.2205/2007ES000276. (Copyright 2007 by the Russian Journal of Earth SciencesPowered by TeXWeb (Win32, v.2.0). |