  We present the near-infrared images and spectra of four silhouette disks in
the Orion Nebula Cluster (ONC; M42) and M43 using the Subaru Adaptive Optics
system. While d053-717 and d141-1952 show no water ice feature at 3.1 micron, a
moderately deep (tau~0.7) water ice absorption is detected toward d132-1832 and
d216-0939. Taking into account the water ice so far detected in the silhouette
disks, the critical inclination angle to produce a water ice absorption feature
is confirmed to be 65-75deg. As for d216-0939, the crystallized water ice
profile is exactly the same as in the previous observations taken 3.63 years
ago. If the water ice material is located at 30AU, then the observations
suggest it is uniform at a scale of about 3.5AU.

Earth and Planetary Astrophysics;Solar and Stellar Astrophysics