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There is an ongoing debate regarding the onset luminosity of dusty mass lossin population-II red giant stars. In this paper we present VISIR@VLT MIR 8.6micron imaging of 47Tuc, centre of attention of a number of space-based Spitzerobservations and studies. The VISIR high resolution (diffraction limited)observations allow excellent matching to existing optical Hubble spacetelescope catalogues. The optical-MIR coverage of the inner 1.15 arcmin of thecluster provide the cleanest possible, blending-free, sampling of the upper 3magnitudes of the giant branch. Our diagrams show no evidence of faint giantswith MIR-excess. A combined NIR-MIR diagram further confirms the near absenceof dusty red giants. Dusty red giants and asymptotic giant stars are confinedto the 47Tuc long period variables population. In particular, dusty red giantsare limited to the upper one 8.6 micron magnitude below the giant branch tip.This particular luminosity level corresponds to ~1000 solar luminosity,suggested in previous determinations to mark the onset of dusty mass-loss.Interestingly, at this luminosity level, we detect a small deviation betweenthe colours of red giants and the theoretical isochrones.

The VISIR@VLT Mid-IR view of 47Tuc: A further step in solving the puzzle of RGB mass loss