B[e] stars. III. MWC 645 ^*

¹ Observatoire de Strasbourg, URA 1280, CNRS, 11 rue de l'Université, 67000 Strasbourg, France
² Laboratoire d'Astronomie Université de Montpellier 2, URA 1280 and 1981, CNRS, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France

Send offprint request to: Y. Andrillat

Received: February 1996
Accepted: 26 March 1996

Abstract

We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide identifications and equivalent width measurements in the wavelength region 3740-8790. About 350 emissions lines were measured and about 88 of them were identified. A comparison of our results with those of other authors is provided, as well as a table of elements identified in the spectrum of this star. The pattern of elements present is analogous to that of a late B-type star, but some exceptions are noted, such as the absence of Ne and Mg lines and the presence of K, Cu and Zr lines which appear usually in later type stars. We review the little which is known concerning this object and we also present a quantitative account of the variations in equivalent widths. The observations indicate that the spectrum is highly variable, so that in two different years only half of the lines appear on both spectra. Furthermore variations by at least a factor of two in the equivalent widths are present in many lines. The radial velocity derived from the emission lines (-76 km/s) corresponds to that of the shell which probably has a velocity of about 50 km/s with respect to the underlying star.