We study the sub-AU-scale circumstellar environment of the Herbig Ae star
HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the
structure of its inner dust disk. The interferometric observations were carried
out with the AMBER instrument in the H and K band. We interpret the measured H-
and K-band visibilities, the near- and mid-infrared visibilities from the
literature, and the SED of HD144432 by using geometric ring models and
ring-shaped temperature-gradient disk models with power-law temperature
distributions. We derived a K-band ring-fit radius of 0.17 \pm 0.01 AU and an
H-band radius of 0.18 \pm 0.01 AU (for a distance of 145 pc). This measured
K-band radius of \sim0.17 AU lies in the range between the dust sublimation
radius of \sim0.13 AU (predicted for a dust sublimation temperature of 1500 K
and gray dust) and the prediction of models including backwarming (\sim0.27
AU). We found that an additional extended halo component is required in both
the geometric and temperature-gradient modeling. In the best temperature-
gradient model, the disk consists of two components. The inner part of the disk
is a thin ring with an inner radius of \sim0.21 AU, a temperature of \sim1600
K, and a ring thickness \sim0.02 AU. The outer part extends from \sim1 AU to
\sim10 AU with an inner temperature of \sim400 K. We find that the disk is
nearly face-on with an inclination angle of < 28 degree. Our
temperature-gradient modeling suggests that the NIR excess is dominated by
emission from a narrow, bright rim located at the dust sublimation radius,
while an extended halo component contributes \sim6% to the total flux at 2
{\mu}m. The MIR model emission has a two-component structure with \sim20% flux
from the inner ring and the rest from the outer part. This two-component
structure suggests a disk gap, which is possibly caused by the shadow of a
puffed-up inner rim.Comment: 7 pages, 5 figures, accepted by A&