Photometric observations of 107P/Wilson-Harrington     

Seitaro Urakawa  Shin-ichiro Okumura  Tsuyoshi Sakamoto  Shinsuke Abe  Kohei Kitazato  Sunao Hasegawa  Nobuyuki Kawai  Shogo Nagayama  Michitoshi Yoshida 《Icarus》2011,215(1):17-26

We present lightcurve observations and multiband photometry for 107P/Wilson-Harrington using five small- and medium-sized telescopes. The lightcurve has shown a periodicity of 0.2979 day (7.15 h) and 0.0993 day (2.38 h), which has a commensurability of 3:1. The physical properties of the lightcurve indicate two models: (1) 107P/Wilson-Harrington is a tumbling object with a sidereal rotation period of 0.2979 day and a precession period of 0.0993 day. The shape has a long axis mode (LAM) of L₁:L₂:L₃ = 1.0:1.0:1.6. The direction of the total rotational angular momentum is around λ = 310°, β = −10°, or λ = 132°, β = −17°. The nutation angle is approximately constant at 65°. (2) 107P/Wilson-Harrington is not a tumbler. The sidereal rotation period is 0.2979 day. The shape is nearly spherical but slightly hexagonal with a short axis mode (SAM) of L₁:L₂:L₃ = 1.5:1.5:1.0. The pole orientation is around λ = 330°, β = −27°. In addition, the model includes the possibility of binary hosting. For both models, the sense of rotation is retrograde. Furthermore, multiband photometry indicates that the taxonomy class of 107P/Wilson-Harrington is C-type. No clear rotational color variations are confirmed on the surface.  相似文献   

Simultaneous MITSuME g'R_CI_C monitoring of S5 0716+714     

C. S. Stalin  Koji. S. Kawabata  Makoto Uemura  Michitoshi Yoshida  Nobuyuki Kawai  Kenshi Yanagisawa  Yasuhiro Shimizu  Daisuke Kuroda  Shogo Nagayama  Hiroyuki Toda 《Monthly notices of the Royal Astronomical Society》2009,399(3):1357-1366

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Real-time geophysical measurements on the deep seafloor usingsubmarine cable in the southern Kurile subduction zone     

Hirata  K. Aoyagi  M. Mikada  H. Kawaguchi  K. Kaiho  Y. Iwase  R. Morita  S. Fujisawa  I. Sugioka  H. Mitsuzawa  K. Suyehiro  K. Kinoshita  H. Fujiwara  N. 《Oceanic Engineering, IEEE Journal of》2002,27(2):170-181

A permanent real-time geophysical observatory using a submarine cable was developed and deployed to monitor seismicity, tsunamis, and other geophysical phenomena in the southern Kurile subduction zone. The geophysical observatory comprises six bottom sensor units, two branching units, a main electro-optical cable with a length of 240 km and two land stations. The bottom sensor units are: 1) three ocean bottom broadband seismometers with hydrophone; 2) two pressure gauges (PGs); 3) a cable end station with environmental measurement sensors. Real-time data from all the undersea sensors are transmitted through the main electro-optical cable to the land station. The geophysical observatory was installed on the continental slope of the southern Kurile trench, southeast Hokkaido, Japan in July 1999. Examples of observed data are presented. Sensor noises and resolution are mentioned for the ocean bottom broadband seismometers and the PGs, respectively. An adaptable observation system including very broadband seismometers is scheduled to be connected to the branching unit in late 2001. The real-time geophysical observatory is expected to greatly advance the understanding of geophysical phenomena in the southern Kurile subduction zone  相似文献   

IV-4 On absorbed power from irregular waves by wave power devices     

Hisaaki Maeda  Takeshi Kinoshita 《Ocean Engineering》1985,12(6):578

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V-2 Study on the system simulation for an O.W.C. type wave energy absorber     

Takeshi Kinoshita  Koichi Masuda  Shogo Miyajima  Wataru Kato 《Ocean Engineering》1985,12(6):580-581

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Acute toxicity of tributyltin to the Caprellidea (Crustacea: Amphipoda)     

Ohji M  Arai T  Miyazaki N 《Marine environmental research》2005,59(3):197-201

In order to compare the acute toxicity of tributyltin (TBT) between sexes, five species of caprellid amphipods were exposed to seven levels (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg l(-1)) of TBT for 48 h at 20 degrees C. The 48-h LC50 values in male and female were 1.3-6.4 microg TBTCl l(-1) and 1.2-8.6 microg TBTCl l(-1), respectively. No sex-specific differences of the acute toxicity of TBT were observed in the caprellids. These findings suggest that the risk of survival in response to exposure to TBT between sexes is similar in the caprellids.  相似文献   

Intermediate Circulation in the Northwestern North Pacific Derived from Subsurface Floats     

Takanori Iwao  Masahiro Endoh  Nobuyuki Shikama  Toshiya Nakano 《Journal of Oceanography》2003,59(6):893-904

In order to examine the formation, distribution and synoptic scale circulation structure of North Pacific Intermediate Water (NPIW), 21 subsurface floats were deployed in the sea east of Japan. A Eulerian image of the intermediate layer (density range: 26.6–27.0σ_θ) circulation in the northwestern North Pacific was obtained by the combined analysis of the movements of the subsurface floats in the period from May 1998 to November 2002 and historical hydrographic observations. The intermediate flow field derived from the floats showed stronger flow speeds in general than that of geostrophic flow field calculated from historical hydrographic observations. In the intermediate layer, 8 Sv (1 Sv ≡ 10⁶ m³s⁻¹) Oyashio and Kuroshio waters are found flowing into the sea east of Japan. Three strong eastward flows are seen in the region from 150°E to 170°E, the first two flows are considered as the Subarctic Current and the Kuroshio Extension or the North Pacific Current. Both volume transports are estimated as 5.5 Sv. The third one flows along the Subarctic Boundary with a volume transport of 5 Sv. Water mass analysis indicates that the intermediate flow of the Subarctic Current consists of 4 Sv Oyashio water and 1.5 Sv Kuroshio water. The intermediate North Pacific Current consists of 2 Sv Oyashio water and 3.5 Sv Kuroshio water. The intermediate flow along the Subarctic Boundary contains 2 Sv Oyashio water and 3 Sv Kuroshio water. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Long-term behavior of the motion of Pluto over 5.5 billion years     

Hiroshi Kinoshita  Hiroshi Nakai 《Earth, Moon, and Planets》1995,71(3):165-173

The motion of Pluto is said to be chaotic in the sense that the maximum Lyapunov exponent is positive: the Lyapunov time (the inverse of the Lyapunov exponent) is about 20 million years. So far the longest integration up to now, over 845 million years (42 Lyapunov times), does not show any indication of a gross instability in the motion of Pluto. We carried out the numerical integration of Pluto over the age of the solar system (5.5 billion years 280 Lyapunov times). This integration also did not give any indication of chaotic evolution of Pluto. The divergences of Keplerian elements of a nearby trajectory at first grow linearly with the time and then start to increase exponentially. The exponential divergences stop at about 420 million years. The divergences in the semi-major axis and the mean anomaly ( equivalently the longitude and the distance) saturate. The divergences of the other four elements, the eccentricity, the inclination, the argument of perihelion, and the longitude of node still grow slowly after the stop of the exponential increase and finally saturate.  相似文献   

Comparison of new nutation series with numerical integration     

J. Souchay  H. Kinoshita 《Celestial Mechanics and Dynamical Astronomy》1991,52(1):45-55

To check the results given by the new tables of the nutation for the rigid Earth model in (Kinoshita and Souchay, 1990), we perform a calculation of this nutation by numerical integration, using the basic equations of Kinoshita (1977). Results show very small long period residuals, with a discrepancy of 0.06 mas sin in longitude, -0.04 mas cos in obliquity, without out-of-phase components. Moreover, the total residuals of short period do not exceed 0.1 mas in longitude, 0.06 mas in obliquity. All these results are considerably better than those found by previous numerical integrations, thus confirming the validity of the new tables.  相似文献   

The runaway instability of self-gravitating tori with non-constant specific angular momentum around black holes     

Nobuyuki Masuda  Shogo Nishida  & Yoshiharu Eriguchi 《Monthly notices of the Royal Astronomical Society》1998,297(4):1139-1144

We discuss the runaway instability of axisymmetric tori with non-constant specific angular momentum around black holes, taking into account self-gravity of the tori. The distribution of specific angular momentum of the tori is assumed to be a positive power law with respect to the distance from the rotational axis. By employing the pseudo-Newtonian potential for the gravity of the spherical black hole, we have found that self-gravity of the tori causes a runaway instability if the amount of the mass which is transferred from the torus to the black hole exceeds a critical value, i.e. 3 per cent of the mass of the torus. This has been shown by two different approaches: (1) by using equilibrium models and (2) by dynamical simulations. In particular, dynamical simulations using an SPH code have been carried out for both self-gravitating and non-self-gravitating tori. For non-self-gravitating models, all tori are runaway stable. Therefore we come to the conclusion that self-gravity of the tori has a stronger destabilizing effect than the stabilizing effect of the positive power-law distribution of the angular momentum.  相似文献