DETECTION OF THE COMPRESSED PRIMARY STELLAR WIND IN η CARINAE
A series of three Hubble Space Telescope/Space Telescope Imaging Spectrograph spectroscopic mappings, spaced approximately one year apart, reveal three partial arcs in [Fe ii] and [Ni ii] emissions moving outward from η Carinae. We identify these arcs with the shell-like structures, seen in the three-dimensional hydrodynamical simulations, formed by compression of the primary wind by the secondary wind during periastron passages.