Title: Attempts to Explore the Formation and Evolution Processes of Circumstellar Dust
Author(s): Itsuki Sakon, Takashi Onaka, Yasuhiro Takahashi (University of Tokyo), 
Hidehiro Kaneda (Nagoya University), Yoshiko K. Okamoto(Ibaraki University), 
Hirokazu Kataza(ISAS/JAXA), Yuki Kimura (Hokkaido University), Midori Saito 
(Institute for Molecular Science), In-Ok Song (Seoul National University), 
Takuya Fujiyoshi (NAOJ)

Abstract: Based on Recent mid-infrared spectroscopic observations with 
Subaru/COMICS and other mid-infrared instruments on-board large ground-based 
facilities, various dust features that have different spectral characteristics
from those in the general ISM have been found in various circumstellar 
environment. For example, observational evidence for the increasing UIR 
7.7/11.2um band ratio with the decreasing distance of the heating source have 
has been reported in reflection nebulae. Moreover, new 8.2um feature in place 
of usual UIR 7.7 and 8.6um features has been reported for sources with soft 
radiation environment and, on the other hand, new broad 8-10um feature has 
been detected for several massive star-forming region with harsh environment. 
In addition, recent near- to mid-infrared observations of supernovas with 
AKARI satellite have suggested the evidence for significant amount of dust 
formation in the mass-loss wind associated with Wolf-Rayet activity and, 
therefore, mid-infrared observation, especially, of massive Wolf-Rayet binary 
systems are greatly important to explore the formation process of dust. In this 
presentation, I will introduce our recent attempts to explore the formation 
and evolution scenario of circumstellar dust focusing on the scientific topics 
that will be achieved by mid-infrared observations with Subaru and Gemini.