Blue-straggler stars
Blue stragglers
Any of stars, often found in globular clusters and old open clusters, that lie on the blueward extension of the main sequence beyond the turnoff point. Blue stragglers have an anomalously blue color and high luminosity in comparison with other cluster members. The most probable ways in which they could form are: mass transfer or coalescence in close binary systems, encounters or collisions in overcrowded cores of globular clusters.
Blue straggler stars
Yellow straggler stars
Stellar evolutionary types