太阳耀斑伽马射线计算及其观测  

The Calculation and Observation of Gamma-Rays from Solar Flares

作　　者：陈维[1] 

机构地区：[1]中国科学院紫金山天文台,南京210008

出　　处：《天文学报》2013年第5期491-492,共2页Acta Astronomica Sinica

摘　　要：耀斑加速粒子与太阳大气介质原子的核反应碰撞过程产生大量的伽马射线、中子、正电子以及丌介子，这些辐射在许多耀斑中被观测到．产生耀斑伽马射线的主要机制是原子核退激发、质子俘获中子和正负电子湮灭．核退激发谱包括加速轻离子（质子和Q粒子）与太阳大气重原子核碰撞产生的窄线和加速重核与周围大气的H、He原子碰撞产生的宽线以及核连续谱（包括大量不可分辨的弱线、复合反应连续谱和预平衡反应连续谱）．Nuclear reactions, due to the interactions of the flare-accelerated particles with the ambi- ent solar atmosphere, produce a wealth of gamma-ray line, neutron, positron, and 7r-meson emissions. Such emissions have been observed in many solar flares. The principal mecha- nisms for the production of solar gamma-ray lines are nuclear deexcitation, neutron capture by proton, and positron-electron annihilation. The nuclear deexcitation spectrum consists of narrow lines resulting from the accelerated light-weight ions （protons and a-particles） interacting with the ambient heavy nuclei, broad lines resulting from the accelerated heavy nuclei interacting with ambient H and He atoms, and nuclear continuum which includes a series of unresolved weak lines, compound continuum, and pre-equilibrium continuum. The solar gamma-rays are the most direct diagnostic tool for studying the acceleration and transportation of energetic particles in solar flares, especially for protons and heavy ions. They provide a wealth of information about the nature of accelerated particles, as well as the physical properties of ambient medium. TALYS is an efficient code for simulating nuclear reactions, and it can provide detailed calculations for all the information, including cross sections. Based on TALYS, we develop a new program of gamma-ray production, which improves the completeness and accuracy of the previous calculations. The theoretical frame of gamma-ray production in solar flares is treated in detail in the first half of the thesis. In addition, we take the 4.438 MeV line as an example to calculate the shapes of strong gamma-ray lines under different conditions. By comparison, we find that the shapes of gamma-ray lines （including Doppler width and shift） are closely related to the energy spectrum and angular distribution of accelerated ions, the solar atmospheric element abundance, and flare location, etc. As a result, the observation and analysis of spectral line shape will help us to obtain these physical parameters. In th

关 键 词：太阳耀斑 伽马射线 观测 原子核碰撞 计算 正负电子湮灭 大气介质 加速粒子 

分 类 号：P182.52[天文地球—天文学]