The oscillating blue stragglers in the open cluster M67

Results from high-precision, time-resolved CCD photometry of two oscillating blue stragglers in M67 are presented. By comparing similar observations obtained two years apart, ten independent modes in one of these Delta Scuti stars, and five modes in the other have been detected. Results from stellar evolution computations and theoretical eigenfrequency analyses are discussed in attempts to make definitive mode identifications. For both oscillating blue stragglers, nonradial p modes are present that carry information on internal structure, rotation, and inclination of the stars. The implications of oscillation frequency analyses for theories of the origin of blue stragglers are discussed.