WHERE IS THE DOUGHNUT - LUMINOUS BLUE VARIABLE BUBBLES AND ASPHERICALFAST WINDS

In this paper, we address the issue of the origin of luminous blue var iable (LBV) bipolar bubbles. Previous studies have explained the shape s of LBV nebulae, such as eta Car, by invoking the interaction of an i sotropic fast wind with a previously deposited, slow aspherical wind ( a ''slow torus''). In this paper we focus on the opposite scenario in which an aspherical fast wind expands into a previously deposited isot ropic slow wind. Using high-resolution hydrodynamic simulations, which include the effects of radiative cooling, we have completed a series of numerical experiments to test if and how aspherical fast winds effe ct wind-blown bubble morphologies. Our experiments explore a variety o f models for the latitudinal variations of fast wind flow parameters. The simulations demonstrate that aspherical fast winds can produce str ongly bipolar outflows. In addition, the properties of outflows recove r some important aspects of LBV bubbles that the previous slow torus m odels cannot.