The resonance lines of aluminium in IUE spectra of B-type chemically peculiar stars

The resonance lines of aluminum in IUE spectra of 22 Hg-Mn stars, five Si-type (magnetic) stars, seven helium-weak stars, and seven normal stars are analyzed. The Al II resonance line at 1670.79 A and the Al III line at 1862.79 A are used to determine the Al Abundances. The Al abundances in normal stars are found to be nearly normal except for Alpha Lyr, in which Al is underabundant by 0.8 dex. The Al II line in the five coolest Hg-Mn stars is slightly weaker than in normal B9 stars. The Al lines are definitely weak in the other 17 Hg-Mn stars, and Al is apparently underabundant by 1.2 dex on average. The Hg-Mn star Kappa Cnc shows the weakest Al lines among observed Bp stars, and Al is about 2.0 dex underabundant in this star. No clear dependence of the Al abundance on the effective temperature is found for Hg-Mn stars except for the five coolest stars. Al is underabundant by about 1.0 dex in Si-type stars and in He-weak stars, except for the hot Si-type star HD 34452, in which Al is nearly normal. Observed abundances of Al in Bp stars do not confirm the suggestion of the diffusion theory that Al may be overabundant.