We age-date the stellar populations associated with 12 historic nearby core-collapse supernovae ( CCSNe ) and 2 supernova impostors , and from these ages , we infer their initial masses and associated uncertainties .
To do this , we have obtained new HST imaging covering these CCSNe .
Using these images , we measure resolved stellar photometry for the stars surrounding the locations of the SNe .
We then fit the color-magnitude distributions of this photometry with stellar evolution models to determine the ages of any young existing populations present .
From these age distributions , we infer the most likely progenitor mass for all of the SNe in our sample .
We find ages between 4 and 50 Myr , corresponding to masses from 7.5 to 59 solar masses .
There were no SNe that lacked a young population within 50 pc .
Our sample contains 4 type Ib/c SNe ; their masses have a wide range of values , suggesting that the progenitors of stripped-envelope SNe are binary systems .
Both impostors have masses constrained to be \buildrel < \over { \sim } 7.5 solar masses .
In cases with precursor imaging measurements , we find that age-dating and precursor imaging give consistent progenitor masses .
This consistency implies that , although the uncertainties for each technique are significantly different , the results of both are reliable to the measured uncertainties .
We combine these new measurements with those from our previous work and find that the distribution of 25 core-collapse SNe progenitor masses is consistent with a standard Salpeter power-law mass function , no upper mass cutoff , and an assumed minimum mass for core-collapse of 7.5 M _ { \odot } .
The distribution is consistent with a minimum mass < 9.5 M _ { \odot } .