{'fraction_non_alphanumeric': 0.017475728155339806, 'fraction_numerical': 0.0, 'mean_word_length': 4.426315789473684, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
On the Formation and Evolution of Gaseous Structures in Comet P/Halley

Abstract Numerical simulations on the spatial and temporal evolution of gaseous jets were conducted to investigate whether the CN jets and CN shells present in the coma of Comet P/Halley are dynamically connected. A systematic study shows that the evolution of a gaseous jet into a shell is straightforward for several geometric configurations. The appearance of a closed, shell structure most likely is the result of a projection effect, which implies that the observational geometry is close to an equator-on view and that the material in the shells is derived from an active area located near the equator of the nucleus. Furthermore, investigations on the ratio between the velocity of the precursor of the CN radicals, v p , and the ejection velocity of the CN radicals themselves, v d , indicates a preference for v p ≤ v d , although a transition from a jet into a shell structure is feasible for both v p ≤ v d and v p > v d in a few particular cases.