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The maximum energy for cosmic ray acceleration at supernova shock fronts is usually thought to be limited to around 1014 –1015 eV by the size of the shock and the time for which it propagates at high velocity. We show that the magnetic field can be amplified non-linearly by the cosmic rays to many times the pre-shock value, thus increasing the acceleration rate and facilitating acceleration to energies well above 1015 eV. A supernova remnant expanding into a uniform circumstellar medium may accelerate protons to 1017 eV and heavy ions, with charge Ze , to Z ×1017 eV. Expansion into a pre-existing stellar wind may increase the maximum cosmic ray energy by a further factor of 10. 相似文献
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O. G. Den 《Astronomy Letters》2002,28(5):345-352
We propose a method for solving the Neumann boundary-value problem using the known magnetic-field component at the boundary in a specified direction (the oblique-derivative problem). The method allows the normal field component at the boundary to be directly determined from the measured line-of-sight component. This makes it possible to calculate the potential magnetic field in the corona above a region far removed from the solar-disk center. A model potential magnetic field is used as an example to test our method. 相似文献
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A numerical technique of time-longitude analysis has been developed by studying the fine structure of temporal variations in total solar irradiance (TSI). This analysis produces maps of large-scale thermal inhomogeneities on the Sun and reveals corresponding patterns of radiative excess and deficit relative to the unperturbed solar photosphere. These patterns are organized in two-and four-sector structures and exhibit the effects of both activity complexes and the active longitudes. Large-scale patterns with radiative excess show a facular macrostructure caused by the relaxation of large-scale thermo-magnetic perturbations and/or energy output due to very large-scale solar convection. These thermal patterns are related to long-lived magnetic fields that are characterized by rigid rotation. The patterns with radiative excess tend to concentrate around the active longitudes and are centered at 103° and 277° in the Carrington system when averaged over the time-longitude distribution of thermal inhomogeneities during activity cycles 21–23. 相似文献
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