Limits on Surviving Low-Mass First Stars from Their Absence in Halo Surveys

A metal-free star below about eight tenths of a solar mass would still be shining today, unchanged, in the Galactic halo. This study computes the relevant quantities from stated assumptions and compares them with published values. The headline results are: survey sample [Fe/H] below minus3 = 500; zero metal stars found = 0; upper fraction percent 95 = 0.6; low mass fraction if IMF extended percent = 18; exclusion factor = 30. The survey limit sits near half a percent, while an unbroken mass function would place roughly a fifth of first stars below the survival mass — a discrepancy of a factor of about thirty. 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.