Using high resolution 3D hydrodynamical simulations we quantify the amount of mass accreted onto the secondary star of the binary system η Carinae during periastron passage on its highly eccentric orbit. The accreted mass is responsible for the spectroscopic event occurring every orbit close to periastron passage, during which many lines vary and the x-ray emission associated with the destruction wind collision structure declines. The system is mainly known for its giant eruptions that occurred in the nineteenth century. The high mass model of the system, M1=170M⊙ and M2=80M⊙, gives Macc≍ 3×10−6M⊙ compatible with the amount required for explaining the reduction in secondary ionization photons during the spectroscopic event, and also matches its observed duration. As accretion occurs now, it surely occurred during the giant eruptions. This implies that mass transfer can have a huge influence on the evolution of massive stars.
