Public Seminar of Research Postgraduate Programmes Student:- Solar Wind Charge Exchange in Comets
Study of cometary solar wind charge exchange(SWCX) plays an important role in understanding the process itself, the stellar wind represented by the solar wind, the nature and structure of comets, and so on. Given these importances, the University of Hong Kong and Nanjing University plan to launch X-ray and EUV space telescopes in the near future, and list study on cometary SWCX as one of their scientific goals. Making use of this observation window, this proposed research plans to study cometary SWCX both theoretically and observationally. Some preparation work has been done, such as theoretically refining design parameters of the planned EUV telescope by predicting cometary spectra. In this study, codes of Gu L. et al(2016) are used to iteratively fit spectra of five comets observed by ACIS-S3 of Chandra X-ray observatory. Taking into account the coronal mass ejection(CME), another three free parameters, abundance of magnesium, silicon, and iron, were introduced into the comet 153P/2002 to re-fit. Obtained fitting results of five comets were then used to predict the spectral lines of comets in EUV band. Finally, by comparing with data in AtomDB, we identified some strong EUV emission lines, and gave a proposal for the design of the detector by statistics: Select different energy band according to the possible resolution, and at the same time pay attention to the detector’s effective area. Some other studies such as calibration are also ongoing.