  Inner regions of protoplanetary disks host many complex physical processes
such as star-disk interactions, magnetic fields, planet formation, and the
migration of new planets. To directly study this region requires
milli-arcsecond angular resolution, beyond the diffraction limit of the world's
largest optical telescopes and even too small for the mm-wave interferometer
ALMA. However, we can use infrared interferometers to image the inner
astronomical unit. Here, we present new results from the CHARA and VLTI arrays
for the young and luminous Herbig Be star HD 190073. We detect a sub-AU cavity
surrounded by a ring-like structure that we interpret as the dust destruction
front. We model the shape with 6 radial profiles, 3 symmetric and 3 asymmetric,
and present a model-free image reconstruction. All the models are consistent
with a near face-on disk with inclination $\lesssim 20^\circ$, and we measure
an average ring radius of 1.4 $\pm 0.2$ mas (1.14 AU). Around $48\%$ of the
total flux comes from the disk with ~$15\%$ of that emission appearing to
emerge from inside the inner rim. The cause of emission is still unclear,
perhaps due to different dust grain compositions or gas emission. The skewed
models and the imaging point to an off-center star, possibly due to binarity.
Our image shows a sub-AU structure, which seems to move between the two epochs
inconsistently with Keplerian motion and we discuss possible explanations for
this apparent change.
