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Chemical abundance studies of CP stars in open clusters

In stellar astrophysics, the study of the atmospheres of early-type stars plays a very special role. The atmospheres of these stars display a variety of different phenomena, such as the presence of large magnetic fields, strong surface convection, pulsation, diffusion of chemical elements. In particular, about 10% of early F-, A- and late B-type stars present chemical peculiarities, which rise as a result of diffusion. A detailed study of the evolution of the chemical peculiarities as traces of diffusion processes requires the precise knowledge of stellar ages and initial chemical composition. Open clusters provide these information: 1) it is possible to assume that all cluster members have approximately the same original chemical composition and age; 2) the age of stars belonging to open clusters can be determined with much higher accuracy than for field stars. For this reason chemically peculiar stars member of open clusters have been targeted to study the evolution of the chemical peculiarities primarily to provide constraints to diffusion models. We review the abundance studies of chemically peculiar stars in open clusters performed until now, putting their results into the broader context of stellar evolution.