Letter to the Editor Simulations of an alpha-effect due to magnetic buoyancy

Three-dimensional simulations of a thermally stably stratified gas with a localized layer of toroidal magnetic field are carried out. The magnetic field gives rise to a magnetic buoyancy instability. Due to the presence of rotation the resulting fluid motions are helical and lead to an α-effect, i.e. to a component of the electromotive force in the direction of the mean magnetic field. The value of α is estimated during the exponential growth phase of the instability. The mean vertical transport velocity of the magnetic field is also calculated. It is found that α varies with latitude and its value is positive in the northern hemisphere.