1997A&A...324.1145H

We present the results of observations of the λ3130.4Å interstellar absorption line of ⁹BeII in the direction of ζ Per. The data were obtained at the Canada-France-Hawaii 3.6m Telescope using the Coude f/4 Gecko spectrograph at a resolving power λ/{DELTA}λ≃1.1x10⁵, and a signal-to-noise ratio S/N≃2000. The ⁹Be II line is not detected, and we obtain an upper limit on the equivalent width W_3130.4≤30µÅ. This upper limit is 7 times below the lowest upper limit ever reported hitherto. The derived interstellar abundance is (⁹Be/H)≤7x10^–13, not corrected for the depletion of ⁹Be onto interstellar grains; it corresponds to an upper limit δ_Be≤-1.5dex on the depletion factor of ⁹Be. As such, it argues in favour of models of formation of dust grains in stellar atmospheres.