We have searched for compact stellar structures within 17 tidal tails in 13 different interacting galaxies using F606W - and F814W - band images from the Wide Field Planetary Camera 2 ( WFPC2 ) on the Hubble Space Telescope ( HST ) .
The sample of tidal tails includes a diverse population of optical properties , merging galaxy mass ratios , H i content , and ages .
Combining our tail sample with Knierman et al .
( 2003 ) , we find evidence of star clusters formed in situ with M _ { V } < -8.5 and V - I < 2.0 in 10 of 23 tidal tails ; we are able to identify cluster candidates to M _ { V } = -6.5 in the closest tails .
Three tails offer clear examples of “ beads on a string ” star formation morphology in V - I color maps .
Two tails present both tidal dwarf galaxy ( TDG ) candidates and cluster candidates .
Statistical diagnostics indicate that clusters in tidal tails may be drawn from the same power-law luminosity functions ( with logarithmic slopes \approx -2 – -2.5 ) found in quiescent spiral galaxies and the interiors of interacting systems .
We find that the tail regions with the largest number of observable clusters are relatively young ( \lesssim 250 Myr old ) and bright ( V \lesssim 24 mag arcsec ^ { -2 } ) , probably attributed to the strong bursts of star formation in interacting systems soon after periapse .
Otherwise , we find no statistical difference between cluster-rich and cluster-poor tails in terms of many observable characteristics , though this analysis suffers from complex , unresolved gas dynamics and projection effects .