Results for the radiative transfer and excitation analysis toward the sample of AGB stars. Fractional abundance f₀ derived for SiC₂ obtained byMassalkhi et al. (2018) for C-rich AGB stars (upper left), fractional abundance for SiO (upper middle), fractional abundance for CS (upper right), and fractional abundance for SiS (lower left) as a function of density measure Ṁ ∕V_exp for oxygen stars (blue) and carbon stars (red; Massalkhi et al. 2019). Fractional abundance for SO (lower middle) and for SO₂ (lower right)in O-rich envelopes as a function of density measure Ṁ∕V_exp. Downward arrows represent upper limits to f₀.