[⁹⁴Mo/⁹⁶Mo] vs [⁹²Mo/⁹⁶Mo] from SiC grain data as dark grey circles MS grains and downward and upward triangles for Y and Z grains, respectively, with 1σ error bars (from Barzyk 2007; Liu et al. 2017b, 2019; Stephan et al. 2019) compared to the surface evolution of Set 0 and Set 1 stellar models of solar (left panel) and of double-solar metallicity (right panel) of different masses (see legend). Circles (Set 0) and triangles (Set 1) on the lines represent the composition after each TDU after the envelope becomes C-rich. The solid black line represents the linear regression from δ⁹⁴Mo₉₆ vs δ⁹²Mo₉₆, while the dashed black line represents the [⁹⁴Mo/⁹⁶Mo] = [⁹²Mo/⁹⁶Mo] line.