New spectroscopic classifications of 35 chemically peculiar candidate stars

Abstract

The chemically peculiar (CP) stars of the upper main sequence are perfect tracers for several astrophysical processes.<br />Their study especially in open clusters further helps to establish their evolutionary status. The latter is most important to<br />understand the origin and evolution of the CP phenomenon, i.e. the connection between diffusion and a stellar magnetic<br />field. There are two important topics, we cover with this paper. First of all, we investigate the reliability of the CCD<br />a photometry for fainter objects in open clusters. The latter method is able to detect CP stars very efficiently, but<br />still a spectroscopic verification is needed to verify the photometric candidates. On the other hand, already published<br />spectral classifications on the basis of photographic plates and prismtechnology have to be tested withmodern instruments.<br />Classification resolution spectroscopy is presented for thirty five bona-fide CP candidates. Twenty six of them are located<br />within the boundaries of fourteen open clusters, for which we also investigated their membership probabilities. Apart from<br />five objects, they seem to be members of the respective clusters. The objects were classified in the framework of a refined<br />Morgan-Keenan system with the extension of well established CP star spectra. We confirm the CP nature of all but one<br />target. The results of a photometry and the spectral classifications are in excellent agreement. For the cluster members<br />we find a continuous sequence of CP stars from 10 to 850Myr, the whole range of investigated cluster ages.<br /><br />