The UV spectrum as a signature of the Lambda Bootis character
The spectra of all the stars previously classified as Lambda Bootisstars and observed by the IUE satellite at low resolution, in the shortwavelength range, are analyzed. The usefulness of this spectral rangefor classifying the Lambda Boo stars is shown; the UV criteria used todistinguish the Lambda Boo stars from other metal-deficient stars areselected and applied. The origin of the Lambda Boo phenomenon is not yetclear (Baschek and Slettebak, 1988) and a careful selection of thecandidates is the first step for a clear definition of the theoreticalproblem. From the present study, it turns out that only seven out of the19 candidates can be assigned to the Lambda Boo group, while for theother stars the previous classification must be considered eroneous. Thepeculiarities of the other metal-deficient, but not Lambda Boo, starsare discussed.
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