Molecular Chemistry around Carbon Stars: An ALMA View

AGB stars contribute substantially to the chemical enrichment of galaxies by feeding back nucleosynthesized material to the ISM through their stellar winds. The chemical characterisation of AGB outflows is hence crucial for unravelling the astrochemical networks that lead to the formation of complex molecules and dust. However, the chemistry in circumstellar envelopes (CSEs) of carbon-rich AGB stars remains poorly constrained, with our current understanding currently based almost exclusively on observations of a single star, IRC +10216.  With the high sensitivity and unprecedented angular resolution of ALMA, we can now finally probe the CSEs of farther away AGB stars as well, opening up the possibility to determine whether IRC +10 216 indeed is the ‘archetype’ carbon star as conventionally assumed. In this talk, I will provide an overview of the current knowledge about carbon star chemistry, and present our recent results from our ongoing comparative study of the circumstellar chemical content of three C-type AGB stars.