[Si/Mg] as a function of SN progenitor mass. The measured [Si/Mg] abundance ratios are compared to theoretical nucleosynthetic yields from SN models across a range of progenitor masses. Circles, squares, and diamonds denote the predicted yields for CCSNe, HNe, and PISNe, respectively, based on Nomoto et al. (2013). The shaded bands represent the 68% credible intervals of the inferred [Si/Mg] ratios for NGC 1277 (pink) and the sample of local massive XTGs (cyan), derived from the Bayesian hierarchical analysis (Table 2). The solid lines mark the corresponding posterior medians.