Explaining the Praesepe blue straggler HD 73666

Abstract

Aims. The blue straggler phenomenon is not yet well explained by current theory, although evolutionary models of star clusters require a good knowledge of it. We attempt to develop a formation scenario for HD 73666, a blue straggler member of the Praesepe cluster. Methods. We compile the known physical properties of HD 73666 found in the literature, focusing in particular on possible binarity and the abundance pattern. Results. HD 73666 appears to be slowly rotating, have no detectable magnetic field, and have normal abundances, thereby excluding close binary evolution and mass transfer processes. There is no evidence of a hot radiation source. Conclusions. With the use of theoretical results on blue straggler formation present in literature, we are able to conclude that HD 73666 was probably formed by physical collision involving at least one binary system, between 5 and 350 Myr (50 Myr if the star is an intrinsic slow rotator) ago. © ESO, 2010.