Atomic Processes in the Sun

Abstract

Publisher Summary The Sun is a unique astronomical object in that its proximity allows its electromagnetic spectrum to be observed from the γ ray to the radio regions, corresponding to 18 decades in energy. For significant portions of this range, it is possible to combine high spectral, temporal, and spatial resolutions. The spectroscopic information available for the sun is more detailed than that for any other astronomical plasma. When attempting to interpret the UV and X-ray region of the solar spectrum it is essential to have a comprehensive knowledge of the wavelengths of the spectral lines of each ion. Primarily the energy structure is used to identify the rich emission line spectra, and hence it is important to know the energy structure to very high accuracy. To interpret the solar spectrum, it is important to have an accurate knowledge of the basic atomic processes producing the radiation. This chapter attempts to discuss recent advances that have been made in theoretical calculations of basic atomic data, which are relevant in the analysis of solar emission line spectra. The best theoretical calculations are estimated to be accurate to better than 5%, although such results are only available at present for a small number of ions. It is envisaged that in the future precise theoretical data for many other ions will become available and will be used in interpreting the large amount of observational data obtained from rocket- and satellite-borne solar instruments. Additionally, high-quality observations of the solar emission spectrum should provide some of the most rigorous checks on the accuracy of the theoretical calculations.