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Kawakita Hideyo Watanabe Jun-Ichi FUSE Tetsuharu Furusho Reiko Abe Shinsuke 《Earth, Moon, and Planets》2002,90(1-4):371-379
The ortho-to-para ratio (OPR) of a cometary molecule is one of primordial character in comets. The OPR which is characterized
by a spin temperature, is thought to reflect the formation conditions of the molecule. In this paper we show the high-dispersion
spectrum of cometary NH2 in Comet C/2001 A2 (LINEAR), from which the OPR of NH2 is determined based on the fluorescence excitation model. Since the NH2 is a photodissociation product of cometary ammonia, we applied the permutation group theory to the whole reaction system
(i.e. the photodissociation reaction of ammonia to NH2 and H) in order to derive the OPR of ammonia from that of NH2.
The derived OPR of ammonia is 1.12 ± 0.03 in Comet C/2001 A2 (LINEAR). This value corresponds to a spin temperature of 30+3
-2 K. If this reflects the temperature where the comet formed in the protosolar nebula, our result indicates that thiscomet
was formed in the region of the giant planets between Jupiter and Neptune. 相似文献
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Takato Naruhisa Fuse Tetsuharu Gaessler Wolfgang Goto Miwa Kanzawa Tomio Kobayashi Naoto Minowa Yosuke Oya Shin Pyo Tae-Soo Saint-Jacque D. Takami Hideki Terada Hiroshi Hayano Yutaka Iye Masanori Kamata Yukiko Tokunaga A. T. 《Earth, Moon, and Planets》2003,92(1-4):183-191
We have measured near-infrared colorsof the binary Kuiper Belt object (KBO)1998 WW31 using the Subaru Telescope withadaptive optics. The satellite was detectednear its perigee and apogee(0.18“ and 1.2” apart from the primary).The primary and the satellite have similar H–Kcolors, while the satellite is redder thanthe primary in J–H. Combined with the Rband magnitude previously published byVeillet et al., 2002, the color of the primaryis consistent with that of optically red KBOs. Thesatellite's R-, J-, H-colors suggest thepresence of ~1 μm absorption band dueto rock-forming minerals. If the surface of thesatellite is mainly composed by olivine, thesatellite's albedo is higher value than the canonicallyassumed value of 4%. 相似文献
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Peng K. Hong Seiji Sugita Yasuhito Sekine Naruhisa Takatoh Tetsuharu Fuse Hideyo Kawakita Eliot F. Young Kosuke Kurosawa Junichi Haruyama Toshihiko Kadono Shunichi Kamata Tomohiko Sekiguchi Hirotomo Noda 《Icarus》2011,214(1):21-29
The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was an impact exploration searching for a volatile deposit in a permanently shadowed region (PSR) by excavating near-surface material. We conducted infrared spectral and imaging observations of the LCROSS impacts from 15 min before the first collision through 2 min after the second collision using the Subaru Telescope in order to measure ejecta dust and water. Such a ground-based observation is important because the viewing geometry and wavelength coverage are very different from the LCROSS spacecraft. We used the Echelle spectrograph with spectral resolution λ/Δλ ∼ 10,000 to observe the non-resonant H2O rotational emission lines near 2.9 μm and the slit viewer with a K′ filter for imaging observation of ejecta plumes. Pre-impact calculations using a homogeneous projectile predicted that 2000 kg of ejecta and 10 kg of H2O were excavated and thrown into the analyzed area immediately above the slit within the field of view (FOV) of the K′ imager and the FOV of spectrometer slit, respectively. However, no unambiguous emission line of H2O or dust was detected. The estimated upper limits of the amount of dust and H2O from the main Centaur impact were 800 kg and 40 kg for the 3σ of noise in the analyzed area within the imager FOV and in the slit FOV, respectively. If we take 1σ as detection limit, the upper limits are 300 kg and 14 kg, respectively. Although the upper limit for water mass is comparable to a prediction by a standard theoretical prediction, that for dust mass is significantly smaller than that predicted by a standard impact theory. This discrepancy in ejecta dust mass between a theoretical prediction and our observation result suggests that the cratering process induced by the LCROSS impacts may have been substantially different from the standard cratering theory, possibly because of its hollow projectile structure. 相似文献
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