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1.
The excitation of the ballooning instability by the eigenoscillations of coronal loops is analyzed using the energy method. The second variation of the potential energy for the case of a plasma—plasma boundary is obtained via the linearized ideal MHD equations. It is shown that the eigenmodes of a magnetic tube and of a toroidal coronal loop coincide in a first approximation. The bending oscillations of the loops are able to excite the ballooning instability when β ? 1. The effects of the instability in solar coronal loops are discussed. 相似文献
2.
Astronomy Letters - Based on an analysis of the dynamic spectra for solar flares in the meter wavelength range obtained with the ground-based Radio Solar Telescope Network, we consider the... 相似文献
3.
Interaction of the 30–300 keV electrons with whistlers in solar coronal loops is studied using a quasi-linear approach. We show that the electron–whistler interaction may play a dominant role in the formation of fast electron spectra within the solar flare loops with the plasma temperature 107 K and plasma density 1011 cm–3. It is found that Landau damping of whistlers provides weak and intermediate pitch-angle diffusion regimes of fast electrons in coronal loops. The level of whistler turbulence in the weak diffusion regime under flare conditions is estimated as 10–7 of the energy density in the thermal particles. The `top – footpoint' relations between the hard X-ray flux densities and spectra are derived. The reason for a `broken' spectrum of the flare microwave emission is discussed. 相似文献
4.
On July 20, 1994, before the Q fragments of Comet Shoemaker-Levy 9 fell to Jupiter, more than 200 spectra of the Jovian features were obtained at the Crimean Astrophysical Observatory in the wavelength range 5700–7600 Å with a 26 s exposure time and a spectral resolution of 20 Å. We found a time-varying Na D line emission in the form of two components with Doppler shifts of about 30 Å. The brightest and most frequent sodium flares were detected when the Q fragments passed through the Jovian inner magnetosphere at a distance of about three the Jovian radii (3RJ) from its center, where they crossed the Io-Jupiter current tube. A frequency analysis of our data revealed a flare recurrence time scale of 1 min. We conclude that sodium was released from the cometary dust and from the surfaces of numerous cometary debris and that its amount was enough to produce the observed emission. The observed high-speed clouds of sodium atoms are assumed to have been formed through ionization, ion acceleration by the bidirectional electric fields of Alfvén waves in the Io-Jupiter current tube, and their neutralization. 相似文献
5.
6.
Based on the observations of solar eclipses performed on the RT-22 radio telescope at CrAO in the wavelength range 2.0–3.5
cm, we consider the fine spatial structure of the microwave emission from the quiet Sun. We have established that the positions
of compact radio sources with a typical size of about 7″.0 and coronal bright points coincide. The mean radio flux exceeds
the level of the quiet Sun by 0.28 sfu. The brightness temperatures increase with wavelength and lie within the range 0.3–2.7
MK. Evidence for a nonthermal nature of the emission from compact radio sources has been obtained. 相似文献
7.
Regularities have been searched for in the dynamics of characteristics of flare solar radiation during the development of the active region NOAA 0069 in the interval of August 14–24, 2002. The SONG (Solar Neutrons and Gamma rays) instrument onboard the Russian CORONAS-F Solar Observatory recorded hard X-ray and gamma-ray radiation in nine of the 30 flares of class above C5 in this active region within the indicated time interval. It was obtained that, in accordance with the development of the active region, the X- and gamma-ray flux tended to increase at the flare maxima while the hard X-ray spectral index tended to decrease; flares with a harder radiation spectrum occurred in the sunspot umbra, i.e., in the region with the strongest magnetic fields. 相似文献
8.
D. N. Rachkovsky T. T. Tsap V. G. Lozitsky 《Journal of Astrophysics and Astronomy》2005,26(4):435-445
We analyse different observational data related to the problem of intrinsic magnetic field strength in small-scale fluxtubes
outside sunspots. We conclude that the kG range of fluxtube fields follows from not only classical line ratio method, but
also from other old and new techniques. For the quiet regions on the Sun, the most probable mode of such fields has a magnetic
field strength of 1.2–1.5 kG assuming the rectangular field profile. To best interpret the observations, a weak background
field between fluxtubes should be assumed, and its magnetic field strength is expected to increase with the filling factor
of fluxtubes. The alternative point of view about subkilogauss fluxtube fields is critically examined, and possible sources
of different conclusions are presented. 相似文献
9.
Based on single-particle approximation, the peculiarities of electron acceleration by the sub-Dreicer electric field in solar atmosphere have been considered. The elastic and inelastic collisions of fast electrons with hydrogen atoms have been taken into account within the Born approximation. The rate of energy gain by accelerated electrons is inversely proportional to the mean free path of the thermal particles. Electron acceleration can be more effective in the transition region and chromosphere than in the corona. Chromospheric electrons can achieve several hundred keV energy at distances of a few tens of kilometers. 相似文献
10.
Tsap Yu. T. Stepanov A. V. Kopylova Yu. G. Khaneichuk O. V. 《Geomagnetism and Aeronomy》2020,60(4):446-451
Geomagnetism and Aeronomy - The propagation of linear Alfvén waves with periods of 10–200 s from the photosphere to the solar chromosphere under the conditions of an isothermal... 相似文献