Gradualism, definition correlation

Fig. 2 shows [Pd/Ba] as a function of [Sr/Ba] with our new data by Subaru HDS. By definition, [Sr/Ba] should increase with the fractional contribution of weak r-process to the stellar abundances. If Pd originates from weak r like Sr, [Pd/Ba] must show a correlation with the slope of unity to [Sr/Ba]. If Pd comes from main r like Ba, [Pd/Ba] must be constant. New data show a mild correlation with the slope less than unity, suggesting that the weak r-process fraction for Pd takes intermediate value between those of Sr and Ba 10%. Therefore, this implies that the weak r-process yield decreases gradually from Sr to Ba. 

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