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Determination of atmospheric parameters of the B-supergiant HD 198478

Atmospheric parameters of the early B-supergiant HD198478 were obtained from the IUE UV silicon lines. We used TLUSTY numerical code to model the stellar atmosphere and to determine the temperature, surface gravity, macroturbulent and rotational velocities. HD 198478 shows a significant degeneracy in velocity, which means that the individual contributions of the macroturbulence and rotation in the total velocity broadening cannot be distinguished. Similar results have been obtained by the use of HST STIS spectra, showing that the IUE spectra are reliable enough to determine the B supergiants' photospheric parameters.

atmospheric parameters; supergiants; UV spectroscopy

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