Interstellar SiC grains

Abstract

Silicon carbide (SiC) is one of the major components of cosmic dust. Small silicon carbide dust particles show a prominent lattice vibrational band at ~11.3 m m. In the 1960s, Friedemann et al. (1969) first predicted that SiC condenses in carbon-rich stellar ejecta. Later, SiC was detected in the circumstellar envelopes around evolved C stars through the 11.3 m m spectral feature. The existence of SiC in the interstellar medium (ISM) was established through the detection of presolar SiC grains in primitive meteorites based on the isotopic anomaly. However, the 11.3 m m absorption feature of SiC is surprisingly not seen in the ISM. This work mainly introduces the optical properties of silicon carbide, the observed characteristics of silicon carbon in a series of astrophysical environment, and abundance of silicon carbide in interstellar space and the underlying physics.