We used high-quality images acquired with the WFC3 on board the HST to probe the blue straggler star ( BSS ) population of the Galactic globular cluster NGC 362 .
We have found two distinct sequences of BSS : this is the second case , after M 30 , where such a feature has been observed .
Indeed the BSS location , their extension in magnitude and color and their radial distribution within the cluster nicely resemble those observed in M 30 , thus suggesting that the same interpretative scenario can be applied : the red BSS sub-population is generated by mass transfer binaries , the blue one by collisions .
The discovery of four new W UMa stars , three of which lying along the red-BSS sequence , further supports this scenario .
We also found that the inner portion of the density profile deviates from a King model and is well reproduced by either a mild power-law ( \alpha \sim - 0.2 ) or a double King profile .
This feature supports the hypothesis that the cluster is currently undergoing the core collapse phase .
Moreover , the BSS radial distribution shows a central peak and monotonically decreases outward without any evidence of an external rising branch .
This evidence is a further indication of the advanced dynamical age of NGC 362 : in fact , together with M 30 , NGC 362 belongs to the family of dynamically old clusters ( Family III ) in the ” dynamical clock ” classification proposed by Ferraro et al .
( 2012 ) .
The observational evidence presented here strengthens the possible connection between the existence of a double BSS sequence and a quite advanced dynamical status of the parent cluster .