The measurement of the electron radiation inside the satellite is important for engineering and space environment researches.The particle radiation detectors (PRD) on board CBERS-1 and CBERS-2 made great contribution ...The measurement of the electron radiation inside the satellite is important for engineering and space environment researches.The particle radiation detectors (PRD) on board CBERS-1 and CBERS-2 made great contribution to understanding of the space environment.Then,what is the radiation relationship between inside and outside the satellite? The Monte Carlo simula-tion with Geant4 was implemented to study the problem.The boundaries of the energy bins of 0.5 and 2 MeV were precisely corresponding to outside energies of 0.99 and 2.52 MeV,respectively.Besides the changes of the energy bins,the fluxes inside were smaller than those of the corresponding bins outside.The spectrum inside the satellite was harder than that outside.An indicator was that the flux ratio of the high energy bin to the low energy bin increased more than 20% from outside to inside.The geometric factor (GF) relates to the incident energy of electrons.By using the AE-8 model to derive the incident spec-trum,the GFs of the low and high energy bins were 1.15 and 0.70 cm2 sr,respectively.GF of the low energy bin was larger than that of the high energy bin.But they were both smaller than the previous results.It was due to the scattering,straggle and shielding effects.展开更多
In this review, we discuss whether the present solar dynamo models can be extrapolated to explain various aspects of stellar activity. We begin with a summary of the following kinds of data for solar-like stars:(i) da...In this review, we discuss whether the present solar dynamo models can be extrapolated to explain various aspects of stellar activity. We begin with a summary of the following kinds of data for solar-like stars:(i) data pertaining to stellar cycles from Ca H/K emission over many years;(ii) X-ray data indicating hot coronal activity;(iii) starspot data(especially about giant polar spots); and(iv) data pertaining to stellar superflares. Then we describe the current status of solar dynamo modelling—giving an introduction to the flux transport dynamo model, the currently favoured model for the solar cycle. While an extrapolation of this model to solar-like stars can explain some aspects of observational data, some other aspects of the data still remain to be theoretically explained. It is not clear right now whether we need a different kind of dynamo mechanism for stars having giant starspots or producing very strong superflares.展开更多
基金supported by the Special Foundation of China Meteorological Administration (Grant No. GYHY200706041)the Foundation of Coconstruction of Beijing Municipal Commission of Education (Grant No. XK100010404)
文摘The measurement of the electron radiation inside the satellite is important for engineering and space environment researches.The particle radiation detectors (PRD) on board CBERS-1 and CBERS-2 made great contribution to understanding of the space environment.Then,what is the radiation relationship between inside and outside the satellite? The Monte Carlo simula-tion with Geant4 was implemented to study the problem.The boundaries of the energy bins of 0.5 and 2 MeV were precisely corresponding to outside energies of 0.99 and 2.52 MeV,respectively.Besides the changes of the energy bins,the fluxes inside were smaller than those of the corresponding bins outside.The spectrum inside the satellite was harder than that outside.An indicator was that the flux ratio of the high energy bin to the low energy bin increased more than 20% from outside to inside.The geometric factor (GF) relates to the incident energy of electrons.By using the AE-8 model to derive the incident spec-trum,the GFs of the low and high energy bins were 1.15 and 0.70 cm2 sr,respectively.GF of the low energy bin was larger than that of the high energy bin.But they were both smaller than the previous results.It was due to the scattering,straggle and shielding effects.
基金provided by the J C Bose Fellowship awarded by the Department of Science and Technology, Government of India
文摘In this review, we discuss whether the present solar dynamo models can be extrapolated to explain various aspects of stellar activity. We begin with a summary of the following kinds of data for solar-like stars:(i) data pertaining to stellar cycles from Ca H/K emission over many years;(ii) X-ray data indicating hot coronal activity;(iii) starspot data(especially about giant polar spots); and(iv) data pertaining to stellar superflares. Then we describe the current status of solar dynamo modelling—giving an introduction to the flux transport dynamo model, the currently favoured model for the solar cycle. While an extrapolation of this model to solar-like stars can explain some aspects of observational data, some other aspects of the data still remain to be theoretically explained. It is not clear right now whether we need a different kind of dynamo mechanism for stars having giant starspots or producing very strong superflares.
