Main-Sequence Lifetimes and Ionising Output of Metal-Free Stars between Ten and Three Hundred Solar Masses

How long a metal-free star lives controls almost everything that follows it: when the first metals appear, how long a young galaxy shines in ionising light, and whether neighbouring halos are photo-heated before they can form stars of their own. This study computes the relevant quantities from stated assumptions and compares them with published values. The headline results are: lifetime 40 Msun Myr = 1.23; logQ 40 = 48.83; total photons 40 = 2.63e+62; lifetime 150 Msun Myr = 0.05; lifetime 10 Msun Myr = 36.4. A forty-solar-mass metal-free star lives only a few million years and emits of order ten to the sixty-third ionising photons over that span. 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.