The variable mass-loss in low-mass red giant stars. Chromospheric motion across stellar evolution in 47 Tuc

Mass-loss ( $ ML $ )is a critical process that remains poorly understood despite its broad implications across astrophysics. Our current knowledge of the underlying physics is still insufficient to reproduce $ ML $ consistently across stars, particularly in the cool low-mass giants regime. A major limitation is likely the intrinsically time-variable nature of chromospheres, the region where most of the physical phenomena powering $ ML $ in this specific regime are expected to occur. In this work we focus on the variable nature of $ ML ,$ aiming to characterize the relevant timescales of chromospheric variability in red giants, and the correlations with intrinsic stellar properties. We analyzed the first large temporal spectroscopic monitoring of chromospheric variability using the $ Hα $ line in red giant stars belonging to the globular cluster NGC-104 (47 Tuc). Our dataset consisted of multi-epoch FLAMES/GIRAFFE multi-object spectroscopy spanning one year and covering 115 cluster stars. We found that, for łog(L/L_⊙) on average increase and widen their range of values with increasing luminosity, together with a systematic blueshift of the line core --which is indicative of outflows-- and deeper cores --which are consistent with increased chromospheric optical depth. The characteristic timescale required to observe variations in the variations in $ Hα $ $ Hα $ profile is only about one day, showing a flat trend for all stars with luminosity. While shorter timescale variations remain consistent with the statistical uncertainties of our measurements, we found a possible increase toward dimmer stars. All of these trends appear similarly correlated with luminosity and effective temperature. No further correlations were found with the different cluster populations, nor were significant differences observed between asymptotic giant branch and red giant branch stars. The outflow trends closely match previous observations across a wide metallicity range. We discuss whether the observations reflect changes in $ Hα $ sensitivity to the winds, a genuine atmospheric transition driven by changes in heating efficiency, or continued chromospheric expansion with geometrically dominated $ Hα $ formation.