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tokens: forbidden line emission such as [O i ] lines (Appenzeller, Oestreicher Jankovics 1984 ; Hartigan, Edwards Ghandour 1995 ). Our spectra show that the EW of the [O I] (6300 Å) line increases by a factor of 10 after the eclipse (Figs 6 and 7 ). The observed EW increase is in agreement with measurements by Petrov et al. ( 2015 ) and Takami et al. ( 2016 ). Petrov et al. ( 2015 ) attribute the change in the forbidden line's EW to a drop in the photospheric continuum, as reported by the resolved photometry of RW Aur A by Antipin et al. ( 2015 ). Petrov et al. ( 2015 ) further imply that the obscuring body must be blocking the inner parts of the system while the outflow remains visible. The He i (6678 Å) and Hα emission lines remain clearly visible in our spectra after RW Aur enters the eclipse. This again indicates that at least part of the accretion flow is still visible. The He i EW remains constant (Fig. 8 ), implying the He-emitting regions are obscured in the same way as the photosphere. The Hα EW decreases after the eclipse (Fig. 7 ). Our EW measurements show lower values for the line during the dimming compared to the values reported by both Petrov et al. ( 2015 ) and Takami et al. ( 2016 ). We attribute this to the fact that our spectroscopy does not resolve the A and B components, hence we get an additional flux in the continuum from RW Aur B, resulting in a lower EW value. The Hα line profiles show a suppressed blueshifted peak after the start of the dimming (Fig. 5 ). This can also be seen in the Hα profiles from Takami et al. ( 2016 ) from both the 2010 and 2014 dimmings. This blueshifted absorption can be interpreted as the presence of an absorbing material moving towards the observer's line of sight, i.e. an outflow. 4.3 Origin of the eclipse In Section 1 , we introduce two possible explanations for the long dimming event observed in RW Aur. The obscuring screen could either be a tidal arm in the outer disc, as suggested by Rodriguez et al. ( 2013 , 2016 ), or a wind emanating in the inner disc, suggested by Petrov et al. ( 2015 ). Our observations provide new evidence to support the occultation by a wind. In particular, we show that the blueshifted portion of the Hα line is suppressed since the beginning of the eclipse, indicating the presence of outflowing and thus blueshifted gas with velocities of 100–200 km s −1 in the occulting screen. This scenario is further supported by the increase in the mid-IR fluxes of the system in eclipse, reported by Shenavrin et al. ( 2015 ) and visible in archive NEOWISE data in the W 2 band (Fig. 4 ). Shenavrin et al. ( 2015 ) fit a blackbody to the spectral energy distribution of RW Aur in its faint state and find that the excess IR emission is plausibly explained by the presence of hot dust with temperature around 1000 K along the line of sight. Thus, the occulting body is outflowing and contains hot dust, which fits with a scenario where a wind emanating from the inner disc eclipses the