  Models predict that in the innermost AU of the disk around Herbig Ae/Be star,
the dust disk forms a "puffed-up" inner rim, which should result in a strongly
asymmetric brightness distribution for disks seen under intermediate
inclination. Using the VLTI/AMBER long-baseline interferometer, we obtained 24
near-infrared (H- and K-band) spectro-interferometric observations on the
Herbig Ae star R CrA. In the derived visibility function, we detect the
signatures of an extended (25 mas) and a compact component (5.8 mas), with the
compact component contributing about 2/3 of the total flux. The brightness
distribution is highly asymmetric, as indicated by the strong closure phases
(up to 40 deg) and the detected position angle dependence of the visibilities
and closure phases. To interpret these asymmetries, we employ geometric as well
as physical models, including a binary model, a skewed ring model, and a
puffed-up inner rim model with a vertical or curved rim shape. Our curved
puffed-up rim model can reasonably well reproduce the interferometric
observables and the SED simultaneously and suggests a luminosity of 29 L_sun
and the presence of relatively large (> 1.2 micron) Silicate dust grains.
Perpendicular to the disk, two bow shock-like structures appear in the
associated reflection nebula NGC 6729, suggesting that the resolved sub-AU size
disk is the driving engine of a large-scale outflow. Detecting, for the first
time, strong non-localized asymmetries in the inner regions of a Herbig Ae
disk, our study supports the existence of a puffed-up inner rim in YSO disks.
