We present high-precision VI photometry of stars from the middle of the giant branch to about 5 magnitudes below the main-sequence turnoff in the globular cluster Palomar 13 based on images obtained with the Keck II 10m telescope .
We tabulate a complete sample of blue stragglers in the cluster out to about 18 core radii .
The blue straggler population is significantly more centrally concentrated than the giant star sample , which is in turn significantly more centrally concentrated than the main-sequence star sample .
Palomar 13 has one of the highest specific frequencies of blue stragglers of any known globular cluster , but the specific frequency of blue stragglers in the outskirts of the cluster does not increase as has been seen in denser clusters .
We also identify a group of faint blue stragglers ( bluer than the turnoff , but having about the same magnitude ) that outnumbers the brighter stragglers by more than a factor of 2 .
The cluster ’ s color-magnitude diagram shows a large excess of stars to the red of the main sequence , indicating that the cluster ’ s binary fraction is at least ( 30 \pm 4 ) % , which appears to be similar to that of the low-mass cluster E3 but significantly higher than that of the more massive clusters Pal 5 and NGC 288 .