首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Theoretical Siiv line ratios compared to extreme ultraviolet solar observations
Authors:F P Keenan  J G Doyle
Institution:(1) Department of Pure and Applied Physics, Queen's University, BT7 1NN Belfast, Northern Ireland;(2) Armagh Observatory, BT61 9DG Armagh, Northern Ireland
Abstract:New theoretical electron temperature sensitive emission line ratios in Siiv involving the 3d 2 D – 3p 2 P and 4s 2 S – 3p 2 P multiplets at sim1125 and 816 Å, respectively, are derived using recent R-matrix electron excitation rate calculations. A comparison of these with observational data for a solar active region at the limb obtained with the Harvard S-055 spectrometer on board Skylab reveals that there is good agreement between theory and observation for ratios that include the 2 D 3/2, 5/22 P 3/2 transition at 1128.3 Å. This is in contrast to the findings of Keenan, Dufton, and Kingston (1986) and provides support for the atomic data adopted in the calculations. However, the 2 D 3/22 P 1/2 line at 1122.5 Å appears to be severely blended, as suggested previously by Burton and Ridgeley (1970) and Feldman and Doschek (1977), as it leads to electron temperature estimates that differ significantly from that expected in ionisation equilibrium. The fact that the I(1122.5 Å)/I(1128.3 Å) intensity ratios determined from several flare spectra are closer to theory than that for the active region indicates that the blending is probably due to species with relatively low ionization potentials, as noted by Flower and Nussbaumer (1975). Electron temperatures deduced for a sunspot are much lower than that predicted from ionisation balance calculations, in agreement with earlier results, and imply that a cooling flow may be present.
Keywords:
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号