The shape of η Carinae and LBV Nebulae

Stellar winds emitted by rotating massive stars may show two main components: firstly bipolar lobes with low density and fast wind, produced by the higher T eff and gravity at the poles (" g eff –effect "); secondly, an equatorial disc with a slow dense wind, produced by the stronger opacities at the equator (" κ–effect "). To see the possible role of this anisotropic wind on the shape of LBV nebulae, we calculate the distribution of the ejected matter in 2 simplified cases: 1) A brief shell ejection. We find that prolate and peanut–shaped hollow nebulae naturally form due to the g eff –effect in rotating stars. 2) A constant wind for a long time. This produces prolate filled nebulae, with a possible strong disc when a bi–stability limit is crossed in the equatorial region. Thus, many features of the η Carinae and LBV nebulae are accounted for by the anisotropic ejection from rotating stars.