Physics and chemistry of the late stages of stellar evolution — an introduction

[摘要] The stellar evolution from the asymptotic giant branch (AGB) to planetary nebulae (PN) contains some of the most interesting physical and chemical processes in the Universe. Within a time period of one million years starting from the nucleosynthesis of carbon in the core, we witness the chemical synthesis of molecules in the atmosphere, followed by the condensation of minerals and organics in the stellar outflow. Different phases of supersonic stellar winds, both spherical symmetric and highly collimated, and their interactions lead to a series of dynamical processes and morphological transformation of the stellar ejecta. Most interestingly, PN are now known to be major sources of complex organics in the Galaxy. Organic compounds of mixed aromatic and aliphatic structures have been observed to form in the post-AGB evolution over time scales as short as hundreds of years. There is likely that these stellar organics journeyed through the Galaxy and were embedded in early Solar System.

[发布机构] Laboratory for Space Research, Faculty of Science, University of Hong Kong, Hong Kong, Hong Kong^1

[效力级别] 天文学 [学科分类] 天文学(综合)

[关键词] Aliphatic structures;Asymptotic giant branch;Chemical process;Dynamical process;Early solar systems;Morphological transformations;Planetary nebulae;Stellar evolutions