The Silicon Lines in the Far Ultraviolet Spectrum of HD 172883

The comparison of the mean high resolution spectrum of the chemically peculiar star HD 172883 recorded by the SWP camera on board the International Ultraviolet Explorer with the mean spectrum of HD 38899, a normal late B-type star having similar fundamental parameters, reveals the large flux deficiency of HD 172883 shortwards of 1700 Å. This flux deficiency is due to the strong lines, photoionization edges and autoionization transitions of Si II. The three strongest autoionization lines of Si II are present The strong resonance line of Al II conspicuous in HD 38899 is very ewak in HD 172883 highlighting a strong aluminum deficiency in HD 172883. Conversely, the Hg II resonance line at 1649.94 Å is much stronger in HD 172883, confirming the large overabundance of mercury in this star.