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1.
The CORONAS-I and CORONAS-F data on variations in the ionizing shortwave ultraviolet (UV) solar radiation (EUV radiation) at wavelengths of less than 130 nm and near the H Lyman-alpha line are presented. The CORONAS-I data refer to the period close to solar minimum (the index F 10.7 = 80?100), and the CORONAS-F measurements were held close to solar maximum (F10.7 = 140?280). The UV data are compared to those from the UARS and SOHO satellites and to the results obtained from the ionospheric measurements of ionosphere critical frequencies.  相似文献   

2.
The paper reviews observations and the most important results obtained with the CORONAS-F satellite over more than three years of its orbiting in 2001–2004. The observations and the related new results concern global oscillations of the Sun, active regions and solar flares, the lower corona, ultraviolet and X-ray solar radiation, and solar cosmic rays.  相似文献   

3.
The results of measuring UV radiation onboard the CORONAS-F spacecraft during solar flares in 2001–2003 are considered. Some conclusions from the analysis of variations of solar-flare emission in several spectral intervals, namely, in soft X-rays, in the 10-to 130-nm range, and in the band near 120 nm, are discussed. The data were obtained by the VUSS-L and SUFR instruments. Time and energy characteristics of flares recorded onboard the CORONAS-F spacecraft are compared to the GOES measurements in the interval 0.1–0.8 nm and to the SOHO measurements of UV radiation in the 26-to 34-nm band. In particular, it is demonstrated that UV radiation is generated several (1–10) minutes before X-ray emission for most flares considered in the study. It is shown that the energy of flare emission in the extreme ultraviolet is usually not greater than ～10% of its preflare level and that energy fluxes in different wavelength ranges are related by a power law. Such an analysis makes it possible to better understand the mechanism of flare development.  相似文献   

4.
Accurate measurements of the solar spectral irradiance (SSI) and its temporal variations are of primary interest to better understand solar mechanisms, and the links between solar variability and Earth’s atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to carry out SSI measurements from 165 to 3088 nm. We focus here on the ultraviolet (UV) part of the measured solar spectrum (wavelengths less than 400 nm) because the UV part is potentially important for understanding the solar forcing of Earth’s atmosphere and climate. We present here SOLAR/SOLSPEC UV data obtained since 2008, and their variations in three spectral bands during Solar Cycle 24. They are compared with previously reported UV measurements and model reconstructions, and differences are discussed.  相似文献   

5.
The dynamics of energetic radiation, i.e., particles of radiation belts and galactic and solar cosmic rays in Earth’s environment during solar and geomagnetic disturbances, is analyzed in a review based on the CORONAS-F experimental data.  相似文献   

6.
The results of an experimental study of the variations in the intensity of the fluxes of the Earth radiation belt (ERB) particles in 0.3–6 and 1–50 MeV energy intervals for electrons and protons, respectively, are reported. ERBs were studied during strong magnetic storms from August 2001 through November 2003. The results of the CORONAS-F mission obtained during the magnetic storms of November 6 (D st = ?257 nT) and November 24, 2001 (D st = ?221 nT), October 29–30 (D st = ?400 nT) and November 20, 2003 (D st = ?465 nT) are analyzed. The electron flux is found to decrease abruptly in the outer radiation belt during the main phase of the magnetic storms under consideration. During the recovery phase, the outer radiation belt is found to recover much closer to Earth, near the boundary of the penetration of solar electrons during the main phase of the magnetic storm. We associate the decrease in the electron flux with the abrupt decrease of the size of the magnetosphere during the main phase of the storm. Note that, in all cases studied, the Earth radiation belts exhibited rather long (several days) variations. In those cases where solar cosmic-ray fluxes were observed during the storm, protons with energies 1–5 MeV could be trapped to form an additional maximum of protons with such energies at L >2.  相似文献   

7.
The dynamics of the boundary of the penetration of solar energetic particles (electrons and protons) to Earth’s magnetosphere during solar flares and related geomagnetic disturbances in November 2001 and October–November 2003 is analyzed using CORONAS-F data. The relationship between the penetration boundary, the geomagnetic activity indices, and the local magnetic time is investigated. The correlation coefficient between the invariant latitude of the penetration boundary and the K p and D st indices for electrons with energies ranging from 0.3 to 0.6 MeV in the dayside sector is demonstrated to be higher than that in the nightside sector. The correlation coefficient for protons with energies from 1 to 5 MeV is higher in the nightside sector as compared to the dayside sector. For protons with energies from 50 to 90 MeV, the correlation is high at all MLT.  相似文献   

8.
We study the sources and components of the solar-wind spatial stream structure at the maximum of the solar cycle 23. In our analysis, we use several independent sets of experimental data: radio-astronomical observations of scattered radiation from compact sources with the determination of the distance from the Sun to the inner boundary of the transonic-flow transition region (Rin); calculated data on the magnetic-field intensity and structure in the solar corona, in the solar-wind source region, obtained from optical measurements of the photospheric magnetic-field intensity at the Stanford Solar Observatory (USA); and observations of the white-light corona with the LASCO coronograph onboard the SOHO spacecraft. We show that at the solar maximum, low-speed streams with a transition region located far from the Sun dominate in the solar-wind structure. A correlation analysis of the location of the inner boundary Rin and the source-surface magnetic-field intensity |B R | on a sphere R=2.5RS (RS is the solar radius) has revealed the previously unknown lowest-speed streams, which do not fit into the regular relationship between the parameters Rin and |B R |. In the white-light corona, the sources of these streams are located near the dark strip, a coronal region with a greatly reduced density; the nonstandard parameters of the streams probably result from the interaction of several discrete sources of different types.  相似文献   

9.
The current fleet of space-based solar observatories offers us a wealth of opportunities to study solar flares over a range of wavelengths. Significant advances in our understanding of flare physics often come from coordinated observations between multiple instruments. Consequently, considerable efforts have been, and continue to be, made to coordinate observations among instruments (e.g. through the Max Millennium Program of Solar Flare Research). However, there has been no study to date that quantifies how many flares have been observed by combinations of various instruments. Here we describe a technique that retrospectively searches archival databases for flares jointly observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Solar Dynamics Observatory (SDO)/EUV Variability Experiment (EVE – Multiple EUV Grating Spectrograph (MEGS)-A and -B, Hinode/(EUV Imaging Spectrometer, Solar Optical Telescope, and X-Ray Telescope), and Interface Region Imaging Spectrograph (IRIS). Out of the 6953 flares of GOES magnitude C1 or greater that we consider over the 6.5 years after the launch of SDO, 40 have been observed by 6 or more instruments simultaneously. Using each instrument’s individual rate of success in observing flares, we show that the numbers of flares co-observed by 3 or more instruments are higher than the number expected under the assumption that the instruments operated independently of one another. In particular, the number of flares observed by larger numbers of instruments is much higher than expected. Our study illustrates that these missions often acted in cooperation, or at least had aligned goals. We also provide details on an interactive widget (Solar Flare Finder), now available in SSWIDL, which allows a user to search for flaring events that have been observed by a chosen set of instruments. This provides access to a broader range of events in order to answer specific science questions. The difficulty in scheduling coordinated observations for solar-flare research is discussed with respect to instruments projected to begin operations during Solar Cycle 25, such as the Daniel K. Inouye Solar Telescope, Solar Orbiter, and Parker Solar Probe.  相似文献   

10.
The solar neutron detector Space Environment Data Acquisition Equipment – Attached Payload (SEDA-FIB) onboard the International Space Station (ISS) detected several events from the solar direction associated with three large solar flares observed on 05 (X1.1), 07 (X5.4), and 09 (M6.3) March 2012. In this study, we focus on the interesting event of 05 March, present the temporal profiles of the neutrons, and discuss the physics that may be related to a possible acceleration scenario for ions above the solar surface. We compare our data with images of the flares obtained by the ultraviolet telescope Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO).  相似文献   

11.
Spectra of an Ellerman bomb in the NOAA 11024 active region were obtained in spectropolarimetric observations with the French–Italian THEMIS telescope (Tenerife, Spain). The variations of profiles of the Stokes parameters I, Q, U, and V of photospheric lines were analyzed. The chosen lines had different intensities and magnetic-field sensitivities. It was found that the photospheric line profiles in the Ellerman bomb spectra differed greatly from the profiles for the quiet photosphere outside the active region. The Stokes I profiles of photospheric lines in the Ellerman bomb spectra were much weaker. The largest values of the Stokes parameters Q, U, and V were derived for the Fe I λ 630.25 nm magnetosensitive line. The Stokes parameter V was the highest in the central region of the Ellerman bomb, while the maximum Q and U parameters were observed at one of the edges of the Ellerman bomb. It follows from the comparison of the Stokes parameters for the Ellerman bomb and microflares that the Q, U, and V parameters for the bomb are much higher than those for flares.  相似文献   

12.
Quasi-periodic pulsations (QPPs) are intrinsically connected to the mechanism of solar flares. They are regularly observed in the impulsive phase of flares since the 1970s. In the past years, the studies of QPPs regained interest with the advent of a new generation of soft X-ray/extreme ultraviolet radiometers that pave the way for statistical surveys. Since the amplitude of QPPs in these wavelengths is rather small, detecting them implies that the overall trend of the time series needs to be removed before applying any Fourier or wavelet transform. This detrending process is known to produce artificial detection of periods that must then be distinguished from real ones. In this paper, we propose a set of criteria to help identify real periods and discard artifacts. We apply these criteria to data taken by the Extreme Ultraviolet Variability Experiment (EVE)/ESP onboard the Solar Dynamics Observatory (SDO) and the Large Yield Radiometer (LYRA) onboard the PRoject for On-Board Autonomy 2 (PROBA2) to search for QPPs in flares stronger than M5.0 that occurred during Solar Cycle 24.  相似文献   

13.
The problem of particle acceleration in collapsing magnetic traps in the solar corona has been solved by taking into account the particle scattering and braking in the high-temperature plasma of solar flares. The Coulomb collisions are shown to be weak in traps with lifetimes t l < 10 s and strong for t l > 100 s. In the approximation of strong collisions, collapsing magnetic traps are capable of confining up to 20% of the injected particles in the corona for a long time. In the collisionless approximation, this value exceeds 90%. The question about the observational manifestations of collisions is examined. For collision times comparable to t l , the electron spectrumat energies above 10 keV is shown to be a double-power-law one. Such spectra were found by the RHESSI satellite in flares.  相似文献   

14.
During the GRIF experiment onboard the Mir orbiting station, the sky was monitored with a PX-2 wide-field (～1 sr) scintillation X-ray spectrometer to detect bursts in the photon energy range 10–300 keV. Because of the comprehensive instrumentation, which, apart from the X-ray and gamma-ray instruments, also included charged-particle detectors, the imitations of astrophysical bursts by magnetospheric electron precipitations and strongly ionizing nuclei were effectively filtered out. It was also possible to separate solar and atmospheric events. Several tens of bursts interpreted as being astrophysical were detected in the experiment at sensitivity levels S～10?7 erg cm?2 (for bursts whose spectra were characterized by effective temperatures kT～100 keV) and S～3×10?8 erg cm?2 (for bursts with kT～25 keV). Some of the soft gamma-ray or hard X-ray bursts with kT～10–50 keV were identified with the bursting pulsar GRO J1744-28. Our estimate of the detection rate for cosmological soft gamma-ray or hard X-ray bursts from the entire sky suggests that the distributions of long-duration (>1 s) gamma-ray bursts (GRBs) in characteristic energy kT and duration are inconsistent with the steady-state cosmological model in which the evolution of burst sources is disregarded. Based on GRIF and BATSE/CGRO data, we conclude that most of the GRB sources originate at redshifts 1<z<5.  相似文献   

15.
The results of simultaneous measurements of variations of UV radiation (in a band near the hydrogen Lα line, 121.6 nm) and hard X-ray and gamma-ray radiation (50 keV-200 MeV) performed by the VUSS-L and SONG instruments, respectively, onboard the CORONAS-F spacecraft are presented for periods of solar flares. Variations in the Lα ultraviolet radiation during the impulsive phase of a flare are shown to be synchronous with those of hard X-ray radiation. Temporal variations of UV and X-ray fluxes correspond to the progressive heating of higher and higher regions of the solar atmosphere and the energy transfer from the lower layers of the solar atmosphere to the coronal areas of flare regions. The energy of electrons in beams arising during the impulsive phase of flares can be as high as 500 keV. The velocity of the energy propagation from the regions of its release to the upper layers of the solar atmosphere can reach several tens of kilometers per second.  相似文献   

16.
Spectrally resolved measurements of individual solar active regions (ARs) in the soft X-ray (SXR) range are important for studying dynamic processes in the solar corona and their associated effects on the Earth’s upper atmosphere. They are also a means of evaluating atomic data and elemental abundances used in physics-based solar spectral models. However, very few such measurements are available. We present spectral measurements of two individual ARs in the 0.5 to 2.5 nm range obtained on the NASA 36.290 sounding rocket flight of 21 October 2013 (at about 18:30 UT) using the Solar Aspect Monitor (SAM), a channel of the Extreme Ultaviolet Variability Experiment (EVE) payload designed for underflight calibrations of the orbital EVE on the Solar Dynamics Observatory (SDO). The EVE rocket instrument is a duplicate of the EVE on SDO, except the SAM channel on the rocket version was modified in 2012 to include a freestanding transmission grating to provide spectrally resolved images of the solar disk with the best signal to noise ratio for the brightest features, such as ARs. Calibrations of the EVE sounding rocket instrument at the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility (NIST/SURF) have provided a measurement of the SAM absolute spectral response function and a mapping of wavelength separation in the grating diffraction pattern. We discuss techniques (incorporating the NIST/SURF data) for determining SXR spectra from the dispersed AR images as well as the resulting spectra for NOAA ARs 11877 and 11875 observed on the 2013 rocket flight. In comparisons with physics-based spectral models using the CHIANTI v8 atomic database we find that both AR spectra are in good agreement with isothermal spectra (4 MK), as well as spectra based on an AR differential emission measure (DEM) included with the CHIANTI distribution, with the exception of the relative intensities of strong Fe?xvii lines associated with \(2p^{6}\)–\(2p^{5}3{s}\) and \(2p^{6}\)–\(2p^{5}3{d}\) transitions at about 1.7 nm and 1.5 nm, respectively. The ratio of the Fe?xvii lines suggests that the AR 11877 is hotter than the AR 11875. This result is confirmed with analysis of the active regions imaged by X-ray Telescope (XRT) onboard Hinode.  相似文献   

17.
Results of calculations of the cross-sections of the basic processes forming continuous absorption in the photospheres of solar-type stars in the visible and infrared spectral ranges are reported. (These processes are photoionization of H– ions and excited hydrogen atoms, as well as absorption of photons by “free” electrons being in the partially ionized plasma of the photosphere.) The effective cross-section of hydrogen satisfying the observational data or the results of laboratory experiments was introduced, and its nonmonotonic behavior caused by photoionization of excited hydrogen atoms was ascertained in the spectral range of λ from 650 to 820 nm. For a plane-parallel model of the Sun, the continuous absorption coefficient κ c (λ|z) was calculated as a function of the wavelength and coordinate. Its spectral features caused by the effective cross-section structure in the above-mentioned spectral range were for the first time analyzed. The spectral dependence of the radiation intensity in the solar disk center in the continuous spectral range of λ from 600 to 900 nm was studied. The calculation results were compared to the currently available data of observations. It has been shown that the deviation of the observed radiation intensity from the Planck distribution (i.e., the depression) is caused by the processes of photoionization of the excited hydrogen atoms in the states with a principal quantum number n = 3. In the range of λ from 650 to 820 nm, the mean relative deviation is approximately 4%. It has been established that the magnitude of the depression effect significantly depends on the effective temperature of the photosphere of a solar-type star.  相似文献   

18.
The first scientific results of the analysis of the X-ray spectra of flares and active regions in the solar corona obtained by Polish-led spectrometers RESIK and DIOGENESS onboard the CORONAS-F satellite are presented. The instruments were designed and made in the Solar Physics Division of the Space Research Center of the Polish Academy of Sciences (SRC PAS, Wroclaw, Poland). The Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN, Russia) and the Astronomical Institute of the Czech Academy of Sciences also participated in designing the DIOGENESS spectrometer, while IZMIRAN (Russia), Mullard Space Science Laboratory (MSSL, Great Britain), Rutherford Appleton Laboratory (RAL, Great Britain), and Naval Research Laboratory (NRL, United States) contributed to the development of the RESIK spectrometer. In the paper, we give spectra obtained in a number of previously unstudied spectral ranges and a preliminary identification of new spectral lines. The results for the shifts of the X-ray spectral lines observed with the use of a so-called dopplerometer configuration are also presented. Methods for determining the abundances of the rare elements in the solar corona, including chlorine, potassium, and argon, are described.  相似文献   

19.
We study the formation of solar-wind streams in the years of maximum solar activity 2000–2002. We use observations of the scattering of radio emission by solar-wind streams at distances of ～4–60RS from the Sun, data on the magnetic field structure and strength in the source region (R ～ 2.5RS), and observations with the LASCO coronagraph onboard the SOHO spacecraft. Analysis of these data allowed us to investigate the changes in the structure of circumsolar plasma streams during the solar maximum. We constructed radio maps of the solar-wind transition, transonic region in which the heliolatitudinal stream structure is compared with the structure of the white-light corona. We show that the heliolatitudinal structure of the white-light corona largely determines the structure of the solar-wind transition region. We analyze the correlation between the location of the inner boundary of the transition region Rin and the magnetic field strength on the source surface |BR|. We discuss the peculiarities of the Rin = F(|BR|) correlation diagrams that distinguish them from similar diagrams at previous phases of the solar cycle.  相似文献   

20.
Onboard the International Space Station (ISS), two instruments are observing the solar spectral irradiance (SSI) at wavelengths from 16 to 2900 nm. Although the ISS platform orientation generally precludes pointing at the Sun more than 10?–?14 days per month, in November/December 2012 a continuous period of measurements was obtained by implementing an ISS ‘bridging’ maneuver. This enabled observations to be made of the solar spectral irradiance (SSI) during a complete solar rotation. We present these measurements, which quantify the impact of active regions on SSI, and compare them with data simultaneously gathered from other platforms, and with models of spectral irradiance variability. Our analysis demonstrates that the instruments onboard the ISS have the capability to measure SSI variations consistent with other instruments in space. A comparison among all available SSI measurements during November–December 2012 in absolute units with reconstructions using solar proxies and observed solar activity features is presented and discussed in terms of accuracy.  相似文献   

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