Rb and Zr abundances in massive Galactic AGB stars revisited

Víctor Pérez Mesa, O. Zamora, D. A. García-Hernández, B. Plez, A. Manchado, A. Karakas & M. Lugaro

Instituto de Astrofísica de Canarias, Spain

By using more realistic dynamical model atmospheres we report new abundances of Rb and Zr in a complete sample of massive Galactic asymptotic giant branch (AGB) stars previously studied with hydrostatic models. We use a modified version of the spectral synthesis code Turbospectrum and consider the presence of a gaseous circumstellar envelope with a radial wind in these Galactic AGB stars. The Rb and Zr abundances are determinated from the 7800 A Rb resonant line and the 6474 A ZrO bandhead, respectively, and they are compared with the AGB nucleosynthesis theoretical predictions. The derived Rb abundances are much lower with the new dynamical models, while the Zr abundances are close to the hydrostatic values. The new model atmospheres can help to resolve the problem of the mismatch between the observations and the nucleosynthesis theoretical predictions of massive AGB stars.

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