A SPECTROSCOPIC SURVEY OF B-SUPERGIANTS IN THE LARGE MAGELLANIC CLOUD

We present the results of a low-dispersion (DELTA-lambda congruent-to 2 angstrom) digital, optical, spectral survey of approximately 100 B-type supergiants in the Large Magellanic Cloud. The MK spectral classification framework for B supergiants has been transferred to the metal-weak LMC stars, and recommended classification standards have been designated. Variations among the metal line strengths are examined. The most extreme variations are found for the nitrogen lines, for which a range of a factor of 3 or more may be seen in the equivalent widths within some spectral subclasses. It is suggested that these variations indicate a range of nitrogen surface abundances among the B supergiants, resulting from contamination of some of the stellar surfaces by processed material from the original H-burning core.