Velilla-Prieto L, Cernicharo J, Agúndez M, Fonfría J P, Castro-Carrizo A, Quintana-Lacaci G, Marcelino N, McCarthy M C, Gottlieb C A, Sánchez Contreras C, Young K H, Patel N A, Joblin C, Martín-Gago J A
Instituto de Física Fundamental (IFF-CSIC), Serrano, 123, CP 28006, Madrid, Spain.
Dept. of Space, Earth and Environment, Chalmers Univ. of Technology, Onsala Space Observatory, 43992 Onsala, Sweden.
Proc Int Astron Union. 2018 Aug;14:535-537. doi: 10.1017/S1743921318005410. Epub 2019 Dec 30.
Silicon carbide together with amorphous carbon are the main components of dust grains in the atmospheres of C-rich AGB stars. Small gaseous Si-C bearing molecules (such as SiC, SiCSi, and SiC) are efficiently formed close to the stellar photosphere. They likely condense onto dust seeds owing to their highly refractory nature at the lower temperatures (i.e., below about 2500 K) in the dust growth zone which extends a few stellar radii from the photosphere. Beyond this region, the abundances of Si-C bearing molecules are expected to decrease until they are eventually reformed in the outer shells of the circumstellar envelope, owing to the interaction between the gas and the interstellar UV radiation field. Our goal is to understand the time-dependent chemical evolution of Si-C bond carriers probed by molecular spectral line emission in the circumstellar envelope of IRC+10216 at millimeter wavelengths.
碳化硅与无定形碳是富碳渐近巨星分支（AGB）恒星大气中尘埃颗粒的主要成分。含硅碳的小分子气态物质（如SiC、SiCSi和SiC）在靠近恒星光球层的区域高效形成。由于它们在尘埃生长区较低温度（即低于约2500K）下具有高耐火性，它们很可能凝结在尘埃种子上，尘埃生长区从光球层向外延伸几个恒星半径。在这个区域之外，预计含硅碳分子的丰度会降低，直到它们最终在星际包层的外壳中重新形成，这是由于气体与星际紫外线辐射场之间的相互作用。我们的目标是了解在毫米波长下，通过IRC+10216星际包层中的分子光谱线发射探测到的含硅碳键载体随时间的化学演化。
