Population synthesis models of nucleosynthesis ejecta in a 10⁴ M_⊙ star group based on yield models by Limongi & Chieffi (2006, LC06) or Limongi & Chieffi (2018, LC18) as indicated in subcaptions. Different panels illustrate the impact of the physical parameters (a) IMF, (b) metallicity, (c) explodability, and (d) stellar rotation. Each panel shows the time evolution of the ejection of ²⁶Al (upper), ⁶⁰Fe (middle), and their average mass ratio (bottom). In each case, coeval star formation is assumed and the shaded regions indicate the 68th percentiles derived from 10³ Monte Carlo runs.