  Blue stragglers are anomalously luminous core hydrogen-burning stars formed
through mass-transfer in binary/triple systems and stellar collisions. Their
physical and evolutionary properties are largely unknown and unconstrained.
Here we analyze 320 high-resolution spectra of blue stragglers collected in
eight galactic globular clusters with different structural characteristics and
show evidence that the fraction of fast rotating blue stragglers (with
rotational velocities larger than 40 km/s) increases for decreasing central
density of the host system. This trend suggests that fast spinning blue
stragglers prefer low-density environments and promises to open an unexplored
route towards understanding the evolutionary processes of these stars. Since
large rotation rates are expected in the early stages of both formation
channels, our results provide direct evidence for recent blue straggler
formation activity in low-density environments and put strong constraints on
the timescale of the collisional blue straggler slow-down processes.
