Hydrodynamical models of the Outer Ejecta of η Carinae: Shock dynamics and X-ray emission

Abstract In this work, we present an analytical study and two-dimensional axisymmetric hydrodynamical simulations of the Outer Ejecta surrounding η Carinae. This extended elliptical structure, considerably larger than the well-known Homunculus produced during the 1890s eruption, provides evidence for multiple mass-ejection episodes between the 13th and 17th centuries. We explore the hypothesis that a major eruption in the 1500s led to the formation of the observed elliptical layer extending up to ~0.7 pc along the symmetry axis of the Homunculus. We modelled this structure as the result of shocks driven by this eruptive event into the ambient stellar wind. After 520 yr of evolution, our models predict a projected size of ~0.73 pc and an expansion velocity of ≃ 1400 km s−1, in good agreement with observations of the Outer Ejecta. In addition, we modelled the expected X-ray emission and obtained results consistent with recent X-ray observations of this astrophysical object.