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$\eta$~Car is one of the most massive stars in the Galaxy. It underwent amassive eruption in the 19th century, which produced the impressive bipolarHomunculus nebula now surrounding it. The central star is an eccentric binarywith a period of 5.54\,years. Although the companion has not been detecteddirectly, it causes time-variable ionization and colliding-wind X-ray emission.By characterizing the complex structure and kinematics of the ejecta close tothe star, we aim to constrain past and present mass loss of $\eta$~Car.$\eta$~Car is observed with the extreme adaptive optics instrument SPHERE atthe Very Large Telescope, using its polarimetric mode in the optical with theZIMPOL camera. A spatial resolution of 20\,mas was achieved, i.e. very close tothe presumed 13 mas apastron separation of the companion star. We detect newstructures within the inner arcsecond to the star (2\,300\,au at a 2.3\,kpcdistance). We can relate these structures to the eruption near 1890 by trackingtheir proper motions derived from our new images and historical images over a30\,years time span. Besides, we find a fan-shaped structure in the inner200~au to the star in the H$\alpha$ line, that could potentially be associatedwith the wind collision zone of the two stars.

Imaging the expanding knotty structure in the close environment of the LBV star $\eta$ Carinae