Properties of cluster satellites in hydrodynamical simulations     

Giuseppe Tormen  Lauro Moscardini  Naoki Yoshida † 《Monthly notices of the Royal Astronomical Society》2004,350(4):1397-1408

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Detection of high concentrations of 137Cs in Walleye pollock collected in the Sea of Japan     

Morita T  Fujimoto K  Minamisako Y  Yoshida K 《Marine pollution bulletin》2007,54(8):1293-1300

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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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A type of second order linear ordinary differential equations with periodic coefficients for which the characteristic exponents have exact expressions     

Haruo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1984,32(1):73-86

It is shown that the characteristic exponents can be exactly expressed for a type of second order linear ordinary differential equations with periodic coefficients (Hill's equation) which appear as the variational equations of certain periodic solutions of dynamical systems. Key points are the transformation of the equation to the Gauss' hypergeometric differential equation, and evaluation of the trace of monodormy matrix in the complex plane of the independent variable. Two simple examples are given for which the stability of periodic solutions is rigorously analyzed.  相似文献   

Superclusters with thermal Sunyaev–Zel'dovich effect surveys     

Antonaldo Diaferio  Adi Nusser  Naoki Yoshida  Rashid A. Sunyaev 《Monthly notices of the Royal Astronomical Society》2003,338(2):433-442

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Hill stability of the planar three-body problem: General and restricted cases     

Takeshi Nakamura  Junzo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1992,54(1-3):255-260

The equations of motion of the planar three-body problem split into two parts, called an external part and an internal part. When the third mass approaches zero, the first part tends to the equations of the Kepler motion of the primaries and the second part to the equations of motion of the restricted problem.We discuss the Hill stability from these equations of motion and the energy integral. In particular, the Jacobi integral for the circular restricted problem is seen as an infinitesimal-mass-order term of the Sundman function in this context.  相似文献   

TeV γ-rays from old supernova remnants     

Ryo Yamazaki  Kazunori Kohri  Aya Bamba  Tatsuo Yoshida  Toru Tsuribe  Fumio Takahara 《Monthly notices of the Royal Astronomical Society》2006,371(4):1975-1982

We study the emission from an old supernova remnant (SNR) with an age of around 10⁵ yr and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 10⁵ yr, proton acceleration is efficient enough to emit TeV γ-rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV γ-rays and X-rays are dominated by hadronic processes,  π⁰  -decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 10⁵ yr, there are few high-energy particles emitting TeV γ-rays because of the energy-loss effect and/or the wave-damping effect occurring at low-velocity isothermal shocks. For old SNRs or SNR–GMC interacting systems capable of generating TeV γ-ray emitting particles, we calculated the ratio of TeV γ-ray (1–10 TeV) to X-ray (2–10 keV) energy flux and found that it can be more than  ∼10²  . Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.  相似文献   

Splitting of the subtropical gyre in the western North Pacific     

Keiichi Hasunuma  Kozo Yoshida 《Journal of Oceanography》1978,34(4):160-172

Examined here is a hypothetical idea of the splitting of the subtropical gyre in the western North Pacific on the basis of two independent sources of data,i.e., the long-term mean geopotential-anomaly data compiled by the Japanese Oceanographic Data Center and the synoptic hydrographic (STD) data taken by the Hakuho Maru in the source region of the Kuroshio and the Subtropical Countercurrent in the period February and March 1974. Both of the synoptic and the long-term mean dynamic-topographic maps reveal three major ridges, which indicate that the western subtropical gyre is split into three subgyres. Each subgyre is made up of the pair of currents, the Kuroshio and the Kuroshio Countercurrent, the Subtropical Countercurrent and a westward flow lying just south of the Countercurrent (18°N–21°N), and the northern part of the North Fquatorial Current and an eastward flow at around 18°N. The subgyres are more or less composed of a train of anticyclonic eddies with meridional scales of between 300 and 600 km, so that the volume transport of the subgyres varies by a factor of two or more from section to section. The upper-water characteristics also support the splitting of the subtropical gyre; the water characteristics are fairly uniform within each subgyre, but markedly different between them. The northern rim of each subgyre appears as a sharp density front accompanied by an eastward flow. The bifurcations of the sharp density fronts across the western boundary current indicate that the major part of the surface waters in the North Equatorial Countercurrent is not brought into the Kuroshio. The western boundary current appears as a continuous feature of high speed, but the waters transported change discontinuously at some places.  相似文献   

The coastal undercurrent— A role of longshore scales in coastal upwelling dynamics     

Kozo Yoshida 《Progress in Oceanography》1980,9(2):83-131

A simple three-dimensional model of a time-dependent coastal upwelling is discussed for time scales of several days to a week, with the linear, two-layer, flat-bottom and $\text{?-}\text{plane}$ approximation. Emphasis is placed on the effects of longshore scales determined by the longshore variabilities in the wind stress distributions. The responses of the inshore motions are shown to depend critically on the longshore scales. For a certain wide range of the scales, the system reveals dominantly baroclinic responses and a full development of the poleward coastal undercurrent without β effect. Somewhat detailed discussions are given on the coastal upwelling, the coastal jet and the poleward undercurrent, which are interpreted simply as the orbital velocities of the forced Kelvin-type waves.  相似文献