We study the post-main sequence evolution of products of collisions between
main sequence stars (blue stragglers), with particular interest paid to the
horizontal branch and asymptotic giant branch phases. We found that the blue
straggler progeny populate the colour-magnitude diagram slightly blueward of
the red giant branch and between 0.2 and 1 magnitudes brighter than the
horizontal branch. We also found that the lifetimes of collision products on
the horizontal branch is consistent with the numbers of so-called "evolved blue
straggler stars" (E-BSS) identified by various authors in a number of globular
clusters, and is almost independent of mass or initial composition profile. The
observed ratio of the number of E-BSS to blue stragglers points to a main
sequence lifetime for blue stragglers of approximately 1-2 Gyr on average.Comment: accepted by the Astrophysical Journa
