Stellar ISM dust sources: Carbide dust formation

尘埃粒子在星际介质(ISM)的天体物理中扮演着核心角色--从气体的化学和热力学到恒星形成的动力学。星际尘埃的生命周期始于恒定的风或恒星的爆炸性喷发中颗粒的成核和生长。渐近巨星分支(AGB)恒星和II型超新星(SNS)尤其富含探测到的尘埃化合物。因此，低质量和中等质量恒星是星系星际介质中最重要的尘埃来源之一，从这些恒星喷出的尘埃的组成会影响ISM中的尘埃组成。在这种星际包层中形成的尘埃颗粒是几种化学元素的混合物，许多对陨石中的太阳系前星尘颗粒的研究证实，这些尘埃颗粒在富碳和富氧的固体物质中是不同的。本研究的主要目的是详细地从理论上研究碳化物尘埃粒子在星周环境中的形成，主要集中在成核和颗粒生长过程的微物理方面。在这方面，特别讨论了碳化钛和碳化硅在碳尘形成中的作用和重要性。该研究项目的独特之处在于，将复杂的多组分粉尘生长与冷凝材料不同成核过程的竞争处理结合在一起。这些过程的知识对于理解其他尘埃天体物理环境也很重要。

Dust particles play a central role in the astrophysics of the interstellar medium (ISM) - from chemistry and thermodynamics of the gas up to the dynamics of star formation. The lifecycle of the interstellar dust starts with the nucleation and growth of grains in steady winds or explosive ejecta of stars. Asymptotic giant branch (AGB) stars and type II supernovae (SNs) are particularly rich in detected dust compounds. Low and intermediate mass stars are thus among the most important dust sources in the interstellar medium of galaxies and the composition of dust ejected from these stars affect those in the ISM. Dust grains formed in such circumstellar envelopes are rather a mixture of several chemical elements as verified by many investigations of presolar stardust grains enclosed in meteorites, which are differentiated in carbon–rich and oxygen–rich solid materials.The main objective of this research project is the detailed theoretical study of the formation of carbide dust particles in circumstellar environments focussing mainly on the microphysical aspects of the nucleation and grain growth processes. In this context especially the role and importance of titanium carbide and silicon carbide in carbon dust formation is addressed. The unique characteristic of this research project is thereby that the complex multi–component dust growth is combined with the competitive treatment of different nucleation processes of the condensing materials. The knowledge of these processes is also important for understanding other dusty astrophysical environments.