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Recent observations of $r$-process material in ultra-faint dwarf galaxies(UFDs) shed light on the sources of these elements. Strong upper limits on theEu mass in some UFDs combined with detections of much larger masses in a UFD,Reticulum II, and other dwarf galaxies imply that Eu production is dominated byrare events, and that the minimal Eu mass observed in any UFD is approximatelythe amount of Eu mass produced per event. This is consistent with otherindependent observations in the Galaxy. We estimate, using a model independentlikelihood analysis, the rate and Eu (Fe) mass produced per $r$-process (Feproduction) event in dwarf galaxies including classical dwarfs and UFDs. Themass and rate of the Fe production events are consistent with the normalcore-collapse supernova~(ccSN) scenario. The Eu mass per event is $3\times10^{-5}M_{\odot}<\tilde{m}_{\rm Eu}<2\times 10^{-4}M_{\odot}$, corresponding toa total $r$-process mass per event of $6\times10^{-3}M_{\odot}<\tilde{m}_{r-process}<4\times 10^{-2}M_{\odot}$. The rate of$r$-process events is $2.5\times 10^{-4}<R_{rp/SN}<1.4\times 10^{-3}$ ascompared with the ccSNe rate. These values are consistent with the total Eumass observed in our own Galaxy, suggesting that the same mechanism is behindthe production of $r$-process events in both dwarf galaxies and the Milky Way,and that it may be the dominant mechanism for production of $r$-processelements in the Universe. The results are consistent with neutron star mergersestimates, but cannot rule out other rare core collapse scenarios, providedthat they produce a significant amounts of $r$-process material per event.

r-process Production Sites as inferred from Eu Abundances in Dwarf Galaxies