Investigation of unidentified lines in optical cometary spectra

Abstract

The first objective of this thesis focuses on enhancing the Atlas of cometary lines developed by Hardy and the ULiège COMETA team in 2022. This Atlas is based on the spectra of comets C/2002 T7 (LINEAR), C/2016 R2 (PANSTARRS), C/2002 X5 (Kudo-Fujikawa), and 8P/Tuttle obtained by the ULiège team using the high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES). The use of spectra that are centred and offset in the tail direction allows the identification of new lines, especially ionic ones. A total of 579 new lines have been identified in the spectra, among which 57 were previously unidentified lines in the Atlas. The remaining 522 lines are new lines that had not previously been detected in the version of the Atlas developed by Hardy. The second objective of the thesis focuses on developing a fluorescence model of imidogen (NH). We describe how the model was set up, and then present the results obtained from the model. The thesis ends with numerous perspectives on continuing the identification of new lines using different comparison techniques.