Dissecting the colour-magnitude diagram: a homogeneous catalogue of stellar populations in globular clusters
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abstract
We present a homogeneous catalogue for blue straggler, red giant branch,
horizontal branch and main-sequence turn-off stars in a sample of 35 clusters
taken from the ACS Survey for Globular Clusters. As a result of the superior
photometry and relatively large field of view offered by the ACS data, this new
catalogue is a significant improvement upon the one presented in Leigh, Sills &
knigge (2007). Using our catalogue, we study and compare the radial
distributions of the different stellar populations.
We have confirmed our previous result (Knigge, Leigh & Sills 2009) that there
is a clear, but sub-linear, correlation between the number of blue stragglers
found in the cluster core and the total stellar mass contained within it. By
considering a larger spatial extent than just the core, our results suggest
that mass segregation is not the dominant effect contributing to the observed
sub-linearity. We also investigate the radial distributions of the different
stellar populations in our sample of clusters. Our results are consistent with
a linear relationship between the number of stars in these populations and the
total mass enclosed within the same radius. Therefore, we conclude that the
cluster dynamics does not significantly affect the relative distributions of
these populations in our sample.
