  RW Aur is a young binary system showing strong signatures of a recent tidal
encounter between the circumprimary disk and the secondary star. The primary
star has recently undergone two major dimming events ($\Delta$mag $\approx$ 2
in V-band), whose origin is still under debate. To shed light on the mechanism
leading to the dimming events, we study the extinction properties, accretion
variability, and gas kinematics using absorption lines from the material
obscuring star RW Aur A. We compare our moderate resolution X-Shooter spectra
of the dim state of RW Aur A with other spectral observations. In particular,
we analyse archival high resolution UVES spectra obtained during the bright
state of the system, in order to track the evolution of the spectral properties
across the second dimming event. The spectrum obtained during the dim state
shows narrow absorption lines in the Na and K optical doublets, where the
former is saturated. With a velocity of -60 km/s these lines indicate that
during the dim state the disk wind is either enhanced, or significantly
displaced into the line of sight. The photometric evolution across the dimming
event shows a gray extinction, and is correlated with a significant reduction
of the EW of all photospheric lines. Emission lines tracing accretion do not
vary significantly across the dimming. We conclude that the dimming event is
related to a major perturbation on the inner disk. We suggest that the inner
disk is occulting (most of) the star, and thus its photosphere, but is not
occulting the accretion regions within a few stellar radii. Since observations
of the outer disk indicate that the disk is modestly inclined (45 - 60 deg), we
propose that the inner disk might be warped by a yet unseen (sub-)stellar
companion, which may also explain the 2.77 day periodic variability of the
spectral lines.
