The properties of OB supergiants in the Large Magellanic Cloud. I - Energy distributions of 10 B supergiants

It is demonstrated here that line-blanketed, LTE plane-parallel model atmosphere calculations provide excellent fits to the energy distributions from the ultraviolet through the visual ranges of B supergiants in the LMC. The models are computed using the atmosphere program of Kurucz (1979) but have been constructed with lower gravities than were contained in Kurucz's model grid. The models are also shown to fit the ultraviolet through near-infrared continua of several lightly reddened luminous Milky Way stars. Measurements of effective temperatures and gravities for 10 LMC B supergiants from model fits to the continua are used to obtain estimates of the radii, luminosities, and masses of the stars. For supergiants earlier than type B2, these parameters are reasonable when compared to the results of stellar evolution calculations. The results for the later B types, however, appear incompatible with evolution theory.