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Proton acceleration in flares and magnetohydrodynamic solar activity
Solar Physics, 1993
The possibility of accelerated protons in solar flares having a sharp change in their spectral index is discussed. The analysis is based on the Tsytovich (1982, 1984, 1987a, b, c) acceleration model by MHD turbulence, which is shown to have different resonant conditions for non-relativistic and relativistic particles. The different resonant condition is shown to result in a sharp change in the accelerated proton spectral index, even in the absence of any peculiarity in the spectra of the MHD turbulence. Time scales for accelerated protons to relativistic energies are also derived, and shown to be consistent with observations. We also show that the threshold energy for electron acceleration by low frequency MHD turbulence is much greater than for proton acceleration. The turbulence therefore preferentially accelerates protons.
Journal of Atmospheric and Solar-Terrestrial Physics, 2018
We present the comparative analysis of the solar energetic particle (SEP) event properties and the indicators of acceleration processes in solar flares − the hard X-rays (HXR) and radio emission from microwaves to the meter-range. We focus our study on the two SEP events associated with solar flares with similar characteristics in HXR emission and the close location on solar disk. The proton
High Energetic Solar Proton Flares on 26 and 28 October 2003
Proceedings of the International …, 2004
Abstract. During the period from 19 October to 4 November 2003, there was a sudden and high Solar activity. During this period the sunspot area increased from 1110 10E-6 Hemisphere on 19 October to 5690 10E-6 Hemisphere on 30 October, then decreased to 1110 10 E-6 ...
Chinese Journal of Geophysics, 2004
The solar flare occurred on 2 April 2001 is the biggest flare in the 23rd cycle of solar activity, which is companied by a big solar proton event. The study was made to this event by combining the observation results from SZ2/XD and CBERS-1/CBMC. SZ2 has the orbit with 400km height and inclination of 42 • , and CBERS-1 is a satellite with solar-synchronous orbit and 780km to the Earth surface. The results show that after this flare CBERS-1/CBMC detected the flare particles in the polar cap region and XD observed an increase of energetic electron flux near the latitude 42 • . Morphological analysis of the temporal and spatial variations of energetic particles after this flare indicates that particles in different regions have varied origins. Those in the polar cap region come from the Earth's open field lines and those in the auroral oval and mid-latitudes near 42 • are particles of the earth's outer radiation belt. Data analysis and comparison show that the intensity of Solar Proton Event is not proportional to the X-ray flux of the related solar flare. The response of energetic particles in the near earth space is not solely related with solar X-ray intensity.
Information on particle acceleration and transport derived from solar flare spectropolarimetry
Advances in Space Research, 2005
The hydrogen Ha line has been found to be linearly polarized at some locations and times during a June 15th 2001 flare observed with THEMIS. This flare was accompanied by radio pulses and hard X-ray emission. Linear polarization is below the noise level in the flare kernels. However, it is present at the edges of these kernels, in the line center and near wings where the polarization degree exceeds 4%. The directions of polarization are not random but close within ±15°to the tangential and radial directions. This polarization can be due either to electron beams and their associated return currents or to electron and proton beams.
The Astrophysical Journal, 2000
Observations of polarization of chromospheric lines in solar Ñares can constrain the energy Ñux in accelerated protons. In this paper we analyze recently reported observations of Ha linear polarization obtained during a rather well observed Ñare on 1989 June 20. Modeling of the magnitude and orientation of the Ha polarization provides a constraint on the Ñux of low energy keV) protons, while (Z200 simultaneous gamma-ray and hard X-ray observations provide constraints on the Ñuxes of MeV Z10 protons and keV electrons, respectively. These, plus information on the energetics of the low-Z50 temperature and high-temperature thermal emissions, permit evaluation of both the absolute and relative roles of electrons and protons in the Ñare energy budget. We Ðnd that accelerated protons with energies keV can contain a signiÐcant portion of the total energy released during the Ñare, consistent with Z200 a steep extrapolation of the proton spectrum to such relatively low energies. We discuss these results in light of a uniÐed electron/proton stochastic particle acceleration model and show that the energetics are indeed consistent with this large proton energy content.
2020
Abstract. Solar Particle Events (SPEs) of the 23rd Solar Cycle detected by the ESA Standard Radiation Environment Monitor (SREM) onboard the INTEGRAL satellite have been studied in order to find their connection to solar sources. X-ray, optical and radio data of solar flares that were observed by several space-based instruments during the aforementioned solar cycle have been selected. The data were reduced and thoroughly analyzed in order to establish the corresponding solar origin of the selected SPEs. The extensive scientific analysis has produced clear correlations with X class solar flares for the events of the October-November 2003, January 2005 and December 2006 periods while for the events that occurred during September 2005, correlations with X class flares are possible but not straightforward due to the complexity of the registered solar particle fluxes.
2003
Charged particles are recorded onboard Coronas-F with the following instruments: MKL records electrons in the energy range 0.3-12 MeV and protons in the energy range 1-90 MeV; SKI-3 measures the chemical (charge) composition of solar cosmic rays (SCRs) for the elements from H to Si in the range 4-40 MeV/nucleon. These instruments were also described by Kuznetsov et al. (1995). MKL was slightly upgraded in comparison with the above description: the geometric factor of the detector for 14-90 MeV protons was reduced by half; the geometric factor of the detector for 1-4 MeV protons and 0.3-12 MeV electrons was reduced by a factor of 1.4. SCRs can be recorded in the polar caps in which the satellite stays for ~15 min with a time interval of ~47 min. MKL and SKI-3 were oriented in the antisolar direction.