<正>Ship waves in shallow water are greatly different from those in deep water. In the present paper, the numerical method of ship waves by Tanimoto et al. was applied to open sea with a constant water depth and a c...
<正>Ship waves in shallow water are greatly different from those in deep water. In the present paper, the numerical method of ship waves by Tanimoto et al. was applied to open sea with a constant water depth and a coast with straight, parallel depth contours in order to investigate characteristics of propagation and transformation of ship waves. The ship length is 82m, the breadth is 14.6m and the draft is 5.88m. The ship sails on a straight course of a constant water depth from 6.5m to 18m. The wave pattern changes by the depth Froude number as pointed out by Havelock. When the ship speed is critical or super-critical, bow waves ahead of the ship are split to several isolated waves as they propagate. Transformations due to shoaling and refraction occur when ship waves propagate on the sloping coast. When the ship sails on the straight course of 15m deep and the speed is critical, the maximum wave height exceeds to 2m at the water depth of 1.5m.
A high angular resolution near-infrared image that shows the intensity of polarization for the GG Tau A binary system was obtained with the Subaru Telescope. The image shows a circumbinary disk scattering the light fr...
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A high angular resolution near-infrared image that shows the intensity of polarization for the GG Tau A binary system was obtained with the Subaru Telescope. The image shows a circumbinary disk scattering the light from the central binary. The azimuthal profile of the intensity of polarization for the circumbinary disk is roughly reproduced by a simple disk model with the Henyey-Greenstein phase function and the Rayleigh function, indicating there are small dust grains at the surface of the disk. Combined with a previous observation of the circumbinary disk, our image indicates that the gap structure in the circumbinary disk orbits counterclockwise, but material in the disk orbits clockwise. We propose that there is a shadow caused by material located between the central binary and the circumbinary disk. The separations and position angles of the stellar components of the binary in the past 20 yr are consistent with the binary orbit with a = 33.4 AU and e = 0.34.
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