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Astron. Astrophys. 355, 308-314 (2000)

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1. Introduction

Adelman et al. (1995) (hereafter Paper 1) found effective temperatures and surface gravities for five magnetic Chemically Peculiar (mCP) stars by matching the predictions of ATLAS9 metal-rich model atmospheres (Kurucz 1993) with optical region spectrophotometry and H[FORMULA] profiles. For four stars the theoretical continua were also able to match their [FORMULA]5200 broad, continuum features (depressions). These model atmospheres contain much improved representations of the line opacities compared with previous models. Adelman & Pyper (1993 and references therein) used this feature in particular to differentiate the mCP from normal stars as did Maitzen (1976), for example, using photometry. Longward of H[FORMULA] the spectrophotometric data systematically began to be brighter than the models, a systematic also seen in some normal stars. The derived temperatures showed considerable differences compared with values in literature based upon using uvby[FORMULA] photometry (Napiwotzki et al. 1993) and other methods (see, e.g, Gerbaldi et al. 1989). The current algorithms based on photometry for the mCP stars are somewhat questionable since the flux distributions and colors of mCP stars can be quite different from those of the normal stars. Further the [FORMULA]5200 broad, continuum, which was shown to be at least in part produced by differential line blanketing and thus is in part an indicator of metallicity, is not directly considered. Unfortunately the model predictions were not able to reproduce the [FORMULA]4200 and [FORMULA]6300 broad, continuum features.

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© European Southern Observatory (ESO) 2000

Online publication: March 17, 2000