2004/08/31 by R. F. Gonzalez, R. F. González, E. M. de Gouveia Dal Pino +3 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Circular symmetry #Classical mechanics #Ejecta #Event (particle physics) #Geometry #Optics #Physics #Radiative transfer #Stellar, planetary, and galactic studies #Supernova #Symmetry (geometry) #astro-ph
paper · pdf · doi:10.1086/425112
published as Astrophys.J. 616 (2004) 976-987 · 33 pages, 9 figures, accepted by the Astrophysical Journal
arxiv created 2004/08/31 · openalex publication_date 2004/12/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In this paper, we present two-dimensional gasdynamic simulations of the formation and evolution of the η Car bipolar outflows. Adopting the interacting nonspherical winds model, we have carried out high-resolution numerical simulations, which include explicitly computed time-dependent radiative cooling, for different possible scenarios of the colliding winds. In our simulations, we consider different degrees of nonspherical symmetry for the preoutburst wind and the great eruption of the 1840s produced by the η Car wind. Different models show important differences in the shape and kinematical properties of the Homunculus structure. In particular, we search for the appropriate combination of wind parameters (which control the degree of nonspherical symmetry) to obtain the numerical results that best match both the observed morphology and the expansion velocity of the η Car bipolar shell. In addition, our numerical simulations show the formation of a bipolar nebula embedded within the Homunculus (the little Homunculus) that developed from a secondary eruptive event suffered by the star in the 1890s, and also the development of tenuous, high-velocity ejections in the equatorial region that resulted from the impact of the eruptive wind of the 1840s with the preoutburst wind; these ejections could explain some of the high-speed features observed in the equatorial ejecta. The models were, however, unable to produce the equatorial ejections associated with the second eruptive event.