Are Blue Stragglers Mixed during Collisions?

The smoothed particle hydrodynamics (SPH) simulations of Benz & Hills led to the assumption that blue stragglers created by collisions are initially fully mixed. The theoretical models of stars created under this assumption fit the observed blue straggler sequences well. Recently, however, Lombardi, Rasio, & Shapiro performed SPH calculations of stellar collisions using a more realistic polytropic index for the structure of stars near the …