The Abundance of SiC2 in Carbon Star Envelopes

Silicon carbide dust grains are ubiquitous in circumstellar envelopes around C-rich AGB stars. However, the main gas-phase precursors leading to the formation of SiC dust have not yet been identified. To date, only three molecules containing an Si-C bond have been identified to have significant abundances in C-rich AGB stars: SiC₂, SiC, and Si₂C. The ring molecule SiC₂ has been observed in a handful of evolved stars, while SiC and Si₂C have only been detected in the C-star envelope IRC +10216. We aim to study how widespread and abundant SiC₂, SiC, and Si₂C are in envelopes around C-rich AGB stars and whether or not these species play an active role as gas-phase precursors of silicon carbide dust in the ejecta of carbon stars.