in Y03 and Y05 (38 stars). Unfortunately, observations of M 13 and the comparison field star HD 141531 did not incorporate the Rb line.

In Figure \[fig:rb\], we compare our Rb abundances with those measured in dwarfs and giants in the disk and halo (@gratton94 and @tomkin99), globular cluster giants (@gonzalez98 and @smith00), and carbon-rich AGB stars [@abia01]. (While we retain their stars in the plots, we note that the Abia sample contains very different objects that are difficult to analyze compared to the dwarfs and giants considered in the other studies.) Recall that we have made small adjustments to the Rb abundances in an attempt to place them onto a common scale. At the metallicity of NGC 6752 (\[Fe/H\] = $-$1.6), our two stars in NGC 6752 with the highest \[Rb/Fe\] ratios have abundances compatible with the lower envelope of the @tomkin99 sample. The two NGC 6752 stars also exhibit very similar abundances \[Rb/Fe\] to the @gonzalez98 and @smith00 globular cluster giants. Our three stars with the lower \[Rb/Fe\] ratios appear unusual compared to the @tomkin99 sample. Only 1 star in the @abia01 sample has \[Fe/H\] $< -1.0$ and it is interesting that it has an abundance ratio \[Rb/Fe\] 