Publication details

New spectroscopic classifications of 35 chemically peculiar candidate stars



Year of publication 2011
Type Article in Periodical
Magazine / Source Astronomische Nachrichten
MU Faculty or unit

Faculty of Science

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

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