The effect of rotation on the abundances of the chemical elements of the A-type stars in the Praesepe cluster

Aims. We study how chemical abundances of late B-, A-, and early F-type stars evolve with time, and we search for correlations between the abundance of chemical elements and other stellar parameters, such as effective temperature and upsilon sin i. Methods. We observed a large number of B-, A-, and F-type stars belonging to open clusters of different ages. In this paper we concentrate on the Praesepe cluster (log t = 8.85), for which we have obtained high-resolution, high signal-to-noise ratio spectra of sixteen normal A- and F-type stars and one Am star, using the SOPHIE spectrograph of the Observatoire de Haute-Provence. For all the observed stars, we derived fundamental parameters and chemical abundances. In addition, we discuss another eight Am stars belonging to the same cluster, for which the abundance analysis had been presented in a previous paper. Results. We find a strong correlation between the peculiarity of Am stars and upsilon sin i. The abundance of the elements underabundant in Am stars increases with upsilon sin i, while it decreases for the overabundant elements. Chemical abundances of various elements appear correlated with the iron abundance.