Abstract:
It is shown that if a thin, isolated and untwisted magnetic flux tube, consisting of a current-free core bounded by a thin current sheath, is in an ‘overall’ equilibrium in a stratified atmosphere, then there is, in general, a net upward force on the current sheath and a net downward force on the core or vice-versa. It is suggested that this effect may be used to model the Evershed flows in sunspots and other longitudinal flows in solar and stellar magnetic flux tubes.
