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The shape of Carinae and LBV nebulae

(Received 19 December 2000 / Accepted 11 April 2001 )

Abstract
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 ("-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 Carinae and LBV nebulae are accounted for by the anisotropic ejection from rotating stars.