2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12423High-resolution spectra of lambda Bootis stars reveal the presence of circumstellar gas for example in the Ca K line. The example of the normal A star beta Pictoris shows, that the narrow stable absorption component in Ca K can be reproduced using appropriate disk models and a calcium underabundance in the circumstellar gas of a factor of ~30. Similar models are suggested for the group of metal-deficient lambda Bootis stars, but the observational material is still very poor.5 pages, 3 figures, to appear in: Proc. of the 26th workshop of the European Working Group on CP stars, eds. P. North, A. Schnell and J. Ziznovsky, Contrib. Astr. Obs. Skalnate Pleso Vol. 27, No 3Astrophysicstext