Gasdynamical simulations of the large and little homunculus nebulae of eta carinae

Here we present two-dimensional, time-dependent radiatively cooling hydrodynamical simulations of the large and little Homunculus nebulae around h Carinae. We employ an alternative scenario to previous interacting stellar wind models that is supported by both theoretical and observational evidence, where a nonspherical outburst wind (with a latitudinal velocity dependence that matches the observations of the large Homunculus), which is expelled for 20 years, interacts with a preeruptive slow wind also with a toroidal density distribution but with a much smaller equator-to-polar density contrast than that assumed in previous models. A second eruptive wind with spherical shape is ejected about 50 years after the first outburst and causes the development of the little internal nebula. We find that as a result of an appropriate combination of the parameters that control the degree of asymmetry of the interacting winds, we are able to produce not only the structure and kinematics of both Homunculus but also the high-velocity equatorial ejecta. These arise from the impact between the nonspherical outburst and the preoutburst winds in the equatorial plane.