The effect of long-lived vortical circulation on the dynamics of dust particles in the mid-plane of a protoplanetary disc   总被引：1，自引：0，他引：1  

C. de la Fuente Marcos  P. Barge 《Monthly notices of the Royal Astronomical Society》2001,323(3):601-614

We investigate the response of dust particles in the mid-plane of a protoplanetary disc to the turbulent velocity field of long-lived, large-scale vortical circulation. The dynamical problem is studied through numerical integrations of the equations of motion for individual particles (the sizes of which range from centimetres to metres) subject to the solar gravity and the friction drag of the nebular gas. It is found, neglecting the thickness of the disc, that the particles do not drift inwards to the central star as occurs in a standard symmetrical nebula. Vortices tend to capture a large number of the particles. The effectiveness of this size-selective concentration mechanism depends not only on the value of the drag and the distance from the Sun, but also on the elongation of the vortex and its characteristic lifetime. Typical anticyclonic vortices with exponential decay times of 30 orbital periods and semi-axis ratios of 4 can increase the local surface density by a factor of 4 in a lifetime and accumulate 0.03–0.3 Earth masses. If the elongation is significant (>7), the vortex cannot concentrate any significant amount of solid material. Vortices with an elongation of about 2 are the most effective as regards trapping of dust. We have also found analytical expressions for the capture time as well as capture constraints as a function of the friction parameter, the elongation of the vortex and the impact parameter. By increasing the lifetime and the surface density of the solid particles, this confining mechanism can make the agglomeration of the solid material of the nebula (through collisional aggregation or gravitational instabilities) much more efficient than previously believed. This offers new possibilities for the formation of the planetesimals and the giant planet cores, and may explain the rapid formation of extrasolar giant planets.  相似文献   

Interstellar transfer of planetary microbiota   总被引：2，自引：0，他引：2  

Max K. Wallis  N. C. Wickramasinghe 《Monthly notices of the Royal Astronomical Society》2004,348(1):52-61

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A decentralized parallel one-pass fixed-interval deconvolution algorithm for multisensor systems with multiplicative noises     

Chu Dongsheng  Liu Bin  Liang Meng  Zhang Ling 《中国海洋大学学报(英文版)》2002,1(2):206-210

A decentralized parallel one-pass deconvolution algorithm for multisensor systems with multiplicative noises is proposed. Comparing with the conventional deconvolution algorithm, it avoids the computational overload and the high storage requirement. The algorithm is optimal in the sense of linear minimum-variance. The simulation results illustrate the validity of the proposed algorithm.  相似文献   

On the Chermnykh-Like Problems: II. The Equilibrium Points     

Li-Chin Yeh  Ing-Guey Jiang 《Astrophysics and Space Science》2006,306(4):189-200

Motivated by Papadakis (2005a, b), we study a Chermnykh-like problem, in which an additional gravitational potential from the belt is included. In addition to the usual five equilibrium points (three collinear and two triangular points), there are some new equilibrium points for this system. We studied the conditions for the existence of these new equilibrium points both analytically and numerically.  相似文献   

泉州市地下管线探测经验探讨   总被引：1，自引：0，他引：1  

陈南阳 《测绘与空间地理信息》2006,29(5):121-122

系统介绍泉州市地下管线探测成功经验,为我国低纬度地区城市地下管线探测提供参考。  相似文献   

Destruction of protoplanetary discs in the Orion Nebula Cluster     

Aylwyn Scally  Cathie Clarke 《Monthly notices of the Royal Astronomical Society》2001,325(2):449-456

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The nearest extreme starburst: bubbles, young star clusters and outflow in the merger NGC 3256     

S. L. Lípari  R. J. Díaz  J. C. Forte  R. Terlevich  Y. Taniguchi  M. P. Aguero  A. Alonso-Herrero  E. Mediavilla  S. Zepf 《Monthly notices of the Royal Astronomical Society》2004,354(1):L1-L6

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Observational manifestations of the change in the tilt of the accretion disk to the orbital plane in her X-1/HZ her with phase of its 35-day period     

D. K. Klochkov  N. I. Shakura  K. A. Postnov  R. Staubert  J. Wilms  N. A. Ketsaris 《Astronomy Letters》2006,32(12):804-815

We analyze and interpret the RXTE/ASM X-ray light curves for the close binary system Her X-1/HZ Her obtained from February 1996 to September 2004. Some of the features found previously in the averaged X-ray light curves are confirmed by the new RXTE/ASM data. In particular, the anomalous dips and post-eclipse recoveries in two successive orbits in the short-on state are clearly distinguishable and are stable features of the X-ray light curves. We argue that to account for these features, the tilt of the accretion disk to the orbital plane must be assumed to change with phase of the 35-day period. We present a numerical model that can reproduce the observed features of the light curves.  相似文献   

Results from the Wide-Angle Search for Planets prototype (WASP0) – I. Analysis of the Pegasus field     

Stephen R. Kane  rew Collier Cameron  Keith Horne  David James  Tim A. Lister  Don L. Pollacco  Rachel A. Street  Yiannis Tsapras 《Monthly notices of the Royal Astronomical Society》2004,353(2):689-696

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Practical planet prospecting     

S. Aigrain  M. Irwin 《Monthly notices of the Royal Astronomical Society》2004,350(1):331-345

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