Aperture-synthesis images of η Car observed in February 2020 at orbital phase ϕ ~14.0022. Top: continuum-normalized Brα 4.052 μm flux (heliocentric vacuum wavelength; the small correction due to the system velocity of − 8 km s⁻¹ (Smith 2004) has been neglected). Bottom: aperture-synthesis iso-velocity images of η Car’s compact continuum stellar wind of the primary star (central circular, compact region in mainly white, red, and yellow) and the much more extended emission line stellar wind of the primary star in several spectral channels distributed across the Brα 4.052 μm line (extended, irregular region in green and blue). The average LOS velocities of the spectral channels of the images are indicated in the images. The FOV of the images is 60 × 60 mas or 138 × 138 au for the adopted distance of 2.3 kpc (N is up, and E is to the left). The 6.0 mas diameter of the resolution beam is inserted in the 863 km s⁻¹ image. The images show that the radius of the faintest visible primary stellar wind regions is ~26 mas (~60 au). Bottom right: comparison of the extension of the primary stellar wind (at an LOS velocity of − 324 km s⁻¹) with a sketch of the orbit (white) of the secondary star relative to the primary star on the sky (e.g., the outer − 8 km s⁻¹ Brα stellar wind radius is larger than the major axis of the binary orbit). The black dot indicates the position of the primary star. The major axis of the orbit is 30.9 au (Madura et al. 2012; orbit sketch adapted from Teodoro et al. 2016).