What can HST-GHRS FeII observations of alpha Orionis (M2 lab) tell us about short-period heating?

Cuntz (1997) suggested that apparent velocity shifts in Fe II emission line s observed in Betelgeuse (alpha Orionis: M2 Iab) indicate that non-magnetic wave modes are relevant for the heating and dynamics of alpha Ori's chromo sphere. This claim was based on the similarity of computed stochastic veloc ities in 1-D short-period acoustic wave models and velocity shifts in profi le fits to Fe II emission lines (Carpenter & Robinson 1997), which is now i dentified as coincidental. While acoustic waves may indeed be important for the heating and dynamics of alpha Ori's chromosphere, the interpretation o f the Fe II emission line profiles does not provide evidence for this possi bility. The line formation of optically thick scattering lines in an extend ed out ow makes Fe II emission lines poorly suited as a diagnostic for smal l-scale structure in hydrodynamical models. Better diagnostics include elec tron density sensitive, low opacity lines such as C II]. In the view of the se findings, we discuss directions of future research.