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The astrophysical production site of the heaviest elements in the universeremains a mystery. Incorporating heavy element signatures of metal-poor,$r$-process enhanced stars into theoretical studies of $r$-process productioncan offer crucial constraints on the origin of heavy elements. In this study,we introduce and apply the "Actinide-Dilution with Matching" model to a varietyof stellar groups ranging from actinide-deficient to actinide-enhanced toempirically characterize $r$-process ejecta mass as a function of electronfraction. We find that actinide-boost stars do not indicate the need for aunique and separate $r$-process progenitor. Rather, small variations of neutronrichness within the same type of $r$-process event can account for all observedlevels of actinide enhancements. The very low-$Y_e$, fission-cycling ejecta ofan $r$-process event need only constitute 10-30% of the total ejecta mass toaccommodate most actinide abundances of metal-poor stars. We find that ourempirical $Y_e$ distributions of ejecta are similar to those inferred fromstudies of GW170817 mass ejecta ratios, which is consistent with neutron-starmergers being a source of the heavy elements in metal-poor, $r$-processenhanced stars.

Actinide-rich and Actinide-poor $r$-Process Enhanced Metal-Poor Stars do not Require Separate $r$-Process Progenitors