[PPS09-P03] Formation condition of minerals of comet 17P/Holmes derived from the mid-infrared spectra
Keywords:comet, 17P/Holmes, mid-infrared spectra, mineral abundance
The mass ratio of crystalline silicates of dust grains is determined from by Si-O stretching vibrational bands of silicate grains around 10 μm using the difference of spectral band features between crystalline and amorphous grains. We present the crystalline-to-amorphous mass ratio of silicate grains in the comet 17P/Holmes by using the thermal emission mode of the dust grains (Ootsubo et al. 2007, P&SS, 55, 1044) applied to the mid-infrared spectra of the comet. These spectra were taken by the COMICS mounted on the Subaru Telescope on 2007 October 25, 26, 27 and 28 immediately after the great outburst of the comet (started on October 23). We discuss about formation condition of minerals incorporated into the nucleus of the comet based on the derived mass ratio of silicate grains of the comet.