The blue stars above the turn-off in M67 - Horizontal branch or blue stragglers.

The nature of the pseudohorizontal branch in the galactic cluster M67 is investigated. A differential technique is used to determine the masses of these stars relative both to the turnoff-point stars and to the zero-age main sequence. The results obtained suggest that the pseudohorizontal-branch stars are analogs of the blue stragglers found in other galactic clusters.