Carbon molecules in the inner wind of the oxygen-rich Mira IK Tauri

The gas-phase non-equilibrium chemistry of the inner wind of the oxygen-ric h Mira variable IK Tau (MML Tau) is investigated using a physio-chemical mo del describing the periodically shocked gas close to the stellar photospher e. We predict the formation in large amounts of a few carbon species in the inner envelope, in particular CO2, which has been recently detected with I SO in the spectra of several oxygen-rich semi-regular and Mira stars. The t heoretical abundances are also in excellent agreement with values derived f rom millimeter and sub-millimeter observations, pointing to the fact that s ome carbon species in oxygen stars do form from shock chemistry in the inne r layers and travel the envelope as "parent" species.