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1.
A procedure for tidal analysis with a Bayesian information criterion 总被引：16，自引：0，他引：16
2.
<正>A titanosauriform dinosaur:Fukuititan nipponensis gen.et sp.nov.is erected based on the incomplete skeleton.It is characterized by elongated asymmetric tooth crown with a weak or absent labial groove and without lingual concavity;stalk-like epipophysis of cervical vertebra;the transverse width of the proximal end of the humerus approximately 32%of the humerus length;metacarpal longer,approximately 48%of the radius and the distal end of the ischia slightly expanded.It represents the first relatively complete titanosauriform skeleton found from Japan.The discovery of Fukuititan indicates that the diversity and geographical distribution of Titanosauriformes are much higher than the previous thought. 相似文献
3.
Alberto Cellino Fumi Yoshida Philippe Bendjoya Masateru Ishiguro Jun Saito 《Icarus》2005,179(2):297-303
The near-Earth Asteroid 25143 Itokawa, the target of the Japanese space mission Hayabusa, was observed in June, 2004 with the Torino photopolarimeter attached at the 2.15 m telescope of the El Leoncito Observatory (Argentina). The degree of linear polarization in five colors was measured over a wide range of phase angles, between 40° and 80°. The data obtained are sufficient to derive an estimate of the asteroid's albedo of 0.24±0.01, which is in good agreement with the S-type taxonomic classification of this object. The phase-polarization curve has been sampled in UBVRI colors, covering a wide range of phase angles that cannot be reached by Earth-based observations of Main Belt asteroids. 相似文献
4.
A high world demand for crude palm oil has caused a reduction in the area of Indonesia’s tropical rainforests over the past several decades. Our hypothesis is that the expansion of the area devoted to oil palm plantations at the expense of primary and secondary tropical rainforests will increase the local surface temperature. While similar studies of other crops have been reported, this is the first time this particular hypothesis has been investigated and reported using the remote sensing methods described in this paper. In this study, we used remotely sensed data to quantify land use changes from tropical rainforests to oil palm plantations, calculated the surface temperature from thermal infrared data supplied by band 6 of the Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+), examined the correlations of surface temperature to foliage cover, and conducted field work to verify the results obtained using the remotely sensed data. For this study, we used a new spectral index, Principal Polar Spectral Greenness (PPSG), that is potentially more sensitive than other index to small changes in foliage cover at high cover levels. The outcome of satellite image processing is only 0.2 °C different from direct temperature measurement in the field. Our study indicated that less density of the closed-canopy composition of oil palm trees resulted in higher surface temperature. 相似文献
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Tomoyasu Tanigawa Shinsuke Abe Masateru Ishiguro Tadashi Mukai 《Earth, Moon, and Planets》2010,106(1):55-65
We present two scenarios for production of the Quadrantid stream based on two different models for its origin: the extinct
model in which 2003EH1 was an active comet that released the dust particles during past 5000 years, stopping its activity
abruptly in AD 1488; and the split model; in which a catastrophic disruption of an asteroid at AD 1488 released a large number
of dust particles in a single event. We calculate the orbital evolution of test particles released in both cases and derive
the resulting size distribution of surviving meteoroids in the current Quadrantid stream in the form of s
−α
ds, where s denotes the radius of a meteoroid. We find α = 3.1 in the extinct model and 2.0 in the split model. In addition, the radius
of the surviving meteoroids is derived as s >10 μm in the both models. We propose, based on our estimation of the infrared color ratio for the Quadrantid stream derived
from both models, that infrared observations of the Quadrantid stream may determine which origin model is more reasonable. 相似文献
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TheF
N
method is used to solve radiative transfer problems, based on the general anisotropically scattering model, in multi-layer atmospheres. 相似文献
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Masateru Ishiguro Yuki Sarugaku Munetaka Ueno Fumihiko Usui Suk Minn Kwon 《Icarus》2007,189(1):169-183
We present observations of the extended dust structures near the orbits of three short-period comets: 2P/Encke, 22P/Kopff, and 65P/Gunn. The dust trails were originally discovered by the Infrared Astronomical Satellite (IRAS). Our observations were made using wide-field optical CCD cameras on the University of Hawaii 2.24-m telescope, the Canada-France-Hawaii 3.6-m telescope, and the Kiso 1.05-m Schmidt telescope. We compared the observed images with models and found that the extended structures seen around 2P/Encke and 22P/Kopff before perihelion passage were most likely “dust trails,” whereas images taken after perihelion passage show a high contamination by recently released particles (i.e., particles in Neck-Line structures are visible). We could not confirm the existence of a dust trail from 65P/Gunn within the field of view of the camera used. The effective sizes of the particles responsible for the scattered light were estimated at 1-100 mm (2P/Encke), 1-10 mm (22P/Kopff), and 100 μm-1 mm (65P/Gunn), respectively, which is consistent with previous studies of dust trails made with infrared space telescopes and optical telescopes. We evaluated the mass loss rates of these comets, averaged over their orbits, as reaching (2P/Encke), (22P/Kopff), and (65P/Gunn). These values are consistent with previous work. Therefore, the total amount of material ejected from these three comets is , which would contribute a considerable fraction of the lost within 1 AU that needs to be replaced if the zodiacal cloud is to be maintained in a steady state. We also found that the particles in the dust structures are significantly redder than the Sun and the zodiacal light, and might be redder than the average short-period comet nuclei. Specifically, the reflectivity gradients of 2P/Encke, 22P/Kopff, and 65P/Gunn are 13±7 (% 103 Å−1), 20±5 (% 103 Å−1), and 15±4 (% 103 Å−1), respectively. We examined the change in color with distance from the nucleus. No clear correlation was detected for 2P/Encke or 22P/Kopff to an accuracy of 3-11%, while the 65P/Gunn tail did show color variation, becoming redder with increasing distance from the nucleus. This dark red material, consisting of particles of sand-cobble size, has marginally escaped from the nuclei and will evolve into finer-grained interplanetary dust particles after subsequent collisions. 相似文献
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High spatial resolution observations (approximately 5") were made for the 3 mm transitions of methanol (CH3OH), methyl formate (HCOOCH3), and dimethyl ether [(CH3)2O] toward Orion-KL using the Nobeyama Millimeter Array. The 15(3)-14(4) A- CH3OH emission appears to be elongated along the line connecting IRc2 and "the southern condensation (SC)", which may suggest a relation between methanol and the outflow from IRc2. The HCOOCH3 (7(1,6)-6(1,5)) and (CH3)2O (15(2,13)-15(1,14)) emissions appear to be well concentrated toward SC with an angular size of approximately 6".5 (at the 2 sigma level). There also exists another oxygen-rich condensation to the west of IRc2 (angular size approximately 4".5) having column densities of HCOOCH3 and (CH3)2O comparable to those of SC. We derive the total column densities 6.8 x 10(16) cm-2, 1.4 x 10(16) cm-2 and 2.7 x 10(16) cm-2 for CH3OH, HCOOCH3, and (CH3)2O, respectively, at the core of SC. 相似文献
10.
Nagayoshi Ohashi Ryohei Kawabe Masato Ishiguro Masahiko Hayashi 《Astrophysics and Space Science》1994,212(1-2):239-250
The Nobeyama Millimeter Array Survey for protoplanetary disks has been made for 19 protostellar IRAS sources in Taurus; 13 of them were optically invisible protostars and 6 were young T Tauri stars. We observed 98-GHz continuum and CS(J = 2 – 1) line emissions simultaneously with spatial resolutions of 2
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8-8
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8 (360-1,200 AU). The continuum emission was detected from 5 out of 6 T Tauri stars and 2 out of 13 protostar candidates: the emission was not spatially resolved and was consistent with being originated from compact circumstellar disks. Extended CS emission was detected around 2 T Tauri stars and 11 protostar candidates. There is a remarkable tendency for the detectability of the 98-GHz continuum emission to be small for protostar candidates. This tendency is explained if the mass of protoplanetary disks around protostars is not as large as that around T Tauri stars; the disk mass may increase with the increase of central stellar mass by dynamical accretion in the course of evolution from protostars to T Tauri stars.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A. 相似文献