2006BaltA..15..123P

The use of Balmer line profiles to determine atmospheric parameters of subdwarf B stars is a well-established method that relies on a comparison of spectroscopic observations with synthetic spectra generated from model atmospheres. This method allows us to determine parameters such as the effective temperature, surface gravity and photospheric helium abundance. The self-consistency of these parameters can be investigated by examining the Lyman lines covered by current far-ultraviolet observations. We discuss the results of a preliminary analysis of a sample of ten subdwarf B stars for which both optical and far-ultraviolet spectra were secured. At temperatures below 30000 K we find good consistency between optical and ultraviolet spectra when some allowance is made for the metal-line blanketing present in the ultraviolet region. At higher effective temperatures, however, the consistency is not as satisfactory. Possible solutions to this puzzle are considered.