Crystalline Silicate Grains Of Comet 17P/Holmes Ejected At Its Outburst Observed With Subaru/COMICS
Abstract
Comets had formed from dust and icy materials in the solar nebula 4.6 Gyrs ago. The cometary materials are considered as the most pristine in the solar system and both dust grains and icy materials in comets have been used to investigate the formation conditions of the solar system. Furthermore, it is considered that the existence of crystalline silicate in comets indicates the radial mixing of materials in the early solar nebula.
Crystalline silicate is formed in high temperature environment. Then, it is clue to understand the difference between thermal and dynamical evolution of dust in proto-solar nebula. A large outburst of comet 17P/Holmes has occurred in late October 2007. Just after the outburst began, we carried out low-dispersion spectroscopic observation in mid-infrared region (8 -13 µm) with COMICS mounted on the 8.2-m Subaru Telescope on October 25th-28 th, 2007 UT, when the comet was at a heliocentric distance of 2.44 -2.45 AU. We detected an isolated dust cloud that moved toward the south-west direction from the nucleus by imaging observations in mid-infrared region. The 11.2 µm peak of a crystalline silicate feature onto a broad amorphous silicate feature was detected both in the central condensation of the nucleus and an isolated dust cloud. We will present the time variation of the spectra at different positions in the coma of comet 17P/Holmes at the outburst.- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #42
- Pub Date:
- October 2010
- Bibcode:
- 2010DPS....42.2813Y