(Proposal ID) S14B-153

(PI) Ootsubo Takafumi

(Proposal Title)
 Cometary crystalline silicate before and after perihelion passage II

(Abstract)
Crystalline silicate is often observed in comets as an 11.3-micron resonant 
emission feature, and may be used for probing the early solar nebula. Because 
the formation of the crystalline silicate requires high temperature, they are 
thought to have been born from amorphous silicate at the inner region, and 
then transported toward the outer regions where comets were born. This 
transportation can produce the difference in the crystalline fraction in the 
cometary silicate dust between two dynamical types of comets, Oort-cloud 
comets (OCs) and Ecliptic comets (ECs), due to the different heliocentric 
distances of their birth places. The study of peak wavelengths in crystalline 
features is important to investigate the conditions of the crystalline 
silicate formation as well. Thus far, we don't have enough observational 
samples of OCs. Fortunately, we can observe comet C/2012 K1 (PanSTARRS) 
along with C/2013 A1 (Siding Spring) in this semester. In particular, the 
comet C/2012 K1 (PanSTARRS) is a bright and good target for this silicate 
peak feature study. Observations at pre- and post-perihelion provide us 
precious information on the dust evolution of the comet.