title: Water ice at the surface of HD 100546 disk

authors: M. Honda, T. Kudo, S. Takatsuki, A.K. Inoue, T. Nakamoto

abstract: We made near infrared multicolor imaging observations of a disk around Herbig Be star HD100546 using Gemini/NICI.
K (2.2 micron), H2O ice (3.06 micron), and L'(3.8 micron) disk images were obtained and we found the 3.1 micron absorption feature in the scattered light spectrum probably due to water ice grains at the disk surface.
We compared the observed depth of the absorption feature with the Oka et al. 2012 disk model including water ice photodesorption by UV photons.
The observed absorption depth can be explained with the water ice grain size larger than 0.3 micron, and smaller grain size is ruled out.