A very reduced upper limit on the interstellar abundance of beryllium
Guillaume Hébrard, Martin Lemoine, Roger Ferlet, Alfred Vidal-Madjar
Abstract
We present the results of observations of the
λ3130.4
Å interstellar absorption line of Be II in the direction of zeta Per. The data were obtained at the Canada-France-Hawaii 3.6m Telescope using the Coudé f/4 Gecko spectrograph at a resolving power
≃1.1×
10
5
, and a signal-to-noise ratio S/N
≃
2000. The Be II line is not detected, and we obtain an upper limit on the equivalent width
W
3130.4
≤30
μ
Å. This upper limit is 7 times below the lowest upper limit ever reported hitherto. The derived interstellar abundance is (
9
Be/H)
≤7×
10
−13
, not corrected for the depletion of Be onto interstellar grains; it corresponds to an upper limit
δ
Be
≤−1.5
dex on the depletion factor of Be. As such, it argues in favour of models of formation of dust grains in stellar atmospheres.