Stellar Populations (2) ...

It is especially important to confirm that the stars in a globular are of the same age, as is widely believed, since this is a valuable clue to their formation. However there have been some surprises. There is a population of young blue stars in the globulars known as blue stragglers that are clearly much younger than the general population. This appears inconsistent with the idea of globular cluster formation at a single time.
Blue Stragglers in 47 Tucanae.

Some light may have been shed on the blue straggler problem by recent Hubble observations of a blue straggler in the globular gluster 47 Tucanae shown below.

This star was found to have a very high rotation rate, about 75 times faster than our Sun. This suggests that the blue stragglers are formed by fusion of a rapidly rotating close binary pair of stars (or in some other type of stellar encounter). Since this could take place any time after the globular's formation, the blue stragglers would naturally be younger than the general globular population. Generally, it is believed that blue stragglers are stars whose evolution has been altered by interactions in binary star systems.