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In this study we test the possibility that the asymmetry in the profiles ofthe H-alpha and Ca II K lines in red giant stars is due to the presence of anactive chromosphere rather than to mass loss. To this end, we compare lineprofiles computed using relevant model chromospheres to profiles of the H-alphaand Ca II K lines observed in five red giant stars of the globular cluster NGC2808. The spectra were taken with FLAMES during Science Verification, using theUVES mode at high resolution (R=43,000) for the H-alpha line, and GIRAFFE inMEDUSA mode (R=20,000) for the Ca II K line. We find that the observed profilesare better described if a negative (outward) velocity field is included in themodel chromospheres. This leads to mass loss rates of a few 10**(-9) solarmasses per year, very close to the requirements of the stellar evolutiontheory.Comment: LaTeX v5.2, 9 pages, 10 Postscript figures, to be published in  Astronomy & Astrophysic

Modelling chromospheric line profiles in NGC 2808: evidence of mass loss from RGB stars