Stellar ISM dust sources: Carbide dust formation

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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.