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Journal of Applied Mathematics and Physics 2015年第11期3卷 1431-1442页

作者： Manesh Michael Sreekala Gopinathan Sijo Sebastian Neethu T. Willington Anu Varghese Renuka Gangadharan Chandu Venugopal School of Pure & Applied Physics Mahatma Gandhi University Priyadarshini Hills Kottayam Kerala India Department of Physics C. M. S. College Kottayam India Kerala State Council for Science Technology & Environment Sasthra Bhavan Pattom Thiruvananthapuram India

We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold electrons. The KPB equation is derived for the system;its solution is plotted for different kappa values, as well as for the temperature ratios of ions. It is found that the amplitude of solitary structure increases with increasing kappa values and negatively charged oxygen ion densities. As the temperature of the positively charged oxygen ions increases, the amplitude of solitary wave also increases. We have also studied the dependence of coefficients of the KPB equation on physical parameters relevant to comet Halley.

关键词： cometary Multi-Ion Plasma Ion-Acoustic Solitary Wave Shock Wave KPB Equation

SOME PHENOMENA NEAR THE NUCLEUS OF THE COMET HALE-BOPP

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中国科学院上海天文台年刊 2000年 92-100页

作者： Wu Guangjie Chen Peisheng (Yunnan Observatory and United Laboratory of Optical Astronomy, the Chinese Academy of Sciences, Kunming 650011, China)

An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.

关键词： Comets - cometary nucleus - cometary dust - Periods - Solar wind

ION-PICKUP MECHANISM AND TWO-STREAM INSTABILITY IN COMET

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中国科学院上海天文台年刊 2000年 194-200页

作者： Pang Yongjiang Li Zhongyuan Liu Yuan (University of Science and Technology of China Anhui, Hefei 230026) (Advanced Center for Earth Science and Astronomy, Third World Academy of Science)

In this paper, we adopted a reasonable particle distribution function and used a simplified judgement to analyze the possibility of the ion-pickup caused by two-stream instibility in cometary tail. On calculation, we get an energy limitation(ΔE 1, ΔE 2) between the solar wind particles and the cometary particles .When the energy diffference is between ΔE 1 and ΔE 2, the pickup of ions in the cometary tail is more effective.

关键词： comet - cometary tail - instability of plasmas - ion acceleration

EFFECT OF DUST CHARGE FLUCTUATIONS ON KELVIN-HELMHOLTZ INSTABILITY IN A COLD DUST PLASMA

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中国科学院上海天文台年刊 2000年 206-211页

作者： Lu Li 1 Li Zhongyuan 1 Liu Zhenxing 2 (1. Department of Earth and Space Science, University of Science and Technology of China, Hefei 230026) (2. Center for Space Science and Applied Research, Academia Sinica, P. O. Box 8701, Beijing, 100080)

Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.

关键词： dust-charge fluctuation - dust plasma - comet - cometary tail

VELOCITY SHEAR INSTABILITY IN DUSTY PLASMAS OF COMET

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中国科学院上海天文台年刊 2000年 201-205页

作者： Lu Li Li Zhongyuan (Department of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026)

The velocity shear instability in a magnetized, three-component dusty plasma is investigated for both positively and negatively charged dust particles. The critical shears as a function of the relative charge of dust grains for both positively and negatively charged dust grains are in the same form. The instability excitation is easier in colder proton’s environment for positively charged dust, and so also in colder electron’s environment for negatively charged dust. For a certain flow pattern, the instability excites in different direction for different sign of charged dust grains. This conclusion may be helpful in interpreting the helical structures and streamer splitted phenomena in a cometary tail.

关键词： velocity shear instability - dusty plasma - cometary tail - comet plasma

THE CCD PHOTOMETRIC OBSERVATIONS OF COMET C/1995 O1 (HALE-BOPP)

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中国科学院上海天文台年刊 2000年 51-54页

作者： Zhou Hongnan 1 Huang Keliang 2 Wang Yu 1 Zhou Qinglin 1 (1. Department of Astronomy, Nanjing University, Nanjing 210093) (2. Department of Physics, Nanjing Normal University, Nanjing 210097)

The CCD photometric observation of secular periodic comet C/1995 O1 (Hale-Bopp) was carried out at the Sheshan Station of Shanghai Observatory of China. We obtained 23 CCD images on 1996 March 11, April 22 and May 22. We derived the magnitude of the cometary nucleus in V, R bands, and estimated the lower limits of cometary mass and size. The results show that the diameter of nucleus ≈ 5 ～ 10km, which corresponds to a mass of 2 × 10 12～ 3 × 10 13 kg for different parameters when the bulk density is assumed to 1000 kg·m -3.

关键词： Comet: C/ 1995 O1 (Hale-Bopp) - CCD Photometry - Mass and size of cometary nucleus