The Magnesium-to-Iron Ratio as a Discriminant between First-Supernova Progenitor Masses

Magnesium is made in the outer burning shells of a massive star and largely escapes any explosion, while iron is made at the centre and may fall back. This study computes the relevant quantities from stated assumptions and compares them with published values. The headline results are: [Mg/Fe] 15 = 0.31; [Mg/Fe] 25 = 0.60; [Mg/Fe] 40 fallback = 1.55; typical EMP observed [Mg/Fe] = 0.4. The ordinary twenty-five-solar-mass case lands closest to the typical observed enhancement, the fifteen-solar-mass case sits lower, and the fallback case sits far above anything typical, at more than ten times the solar ratio. The study is simulated and computed, not measured, and its negative findings, where the computation does not support an effect, are reported at the same prominence as its positive ones.