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Suprathermal particle events observed by WIND spacecraft in interplanetary space during 1995―1999 and their classification

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Science china(Technological sciences) 2008年第9期51卷 1542-1553页

作者： SUN LingPeng1,2, WU DeJin1 & WANG DeYu1 1 purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2 Graduate School of chinese academy of sciences, Beijing 100049, china purple mountain observatory Chinese Academy of Sciences Nanjing 210008 China Graduate School of chinese academy of sciences Beijing 100049 China

Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999. Based on systematic analysis on the observational characteristics of these events a two-parameter (the rising time and the flux ratio of electrons to protons in each event) classification method was proposed to classify these events. The three clas-sified classes are (1) impulsive electron events with the flux ratio of electrons to protons being bigger than 1 and rising time being shorter than 200 min, (2) impulsive proton events with the flux ratio being smaller than 1 and rising time being shorter than 200 min, and (3) gradual proton events with the flux ratio being smaller than 1 and the rising time being longer than 200 min. In the past, "impulsive solar electron events" were under in-tense research. However, because the selection standards of their velocity dispersions or pitch-angle distributions were inadequate, statistical surveys of selected events were dif-ferent from each other and even some conclusions were not consistent with the theory, for example, the relation of type-III solar radio bursts to the "impulsive solar electron events". The first class of impulsive electron events are associated with type-III radio bursts and with clear velocity dispersions; therefore they ought to originate from the Sun. The second class of the events, which have short continuance time and usually are not associated with type-III radio bursts and without velocity dispersion, are still far away from inter-planetary shocks and most of them do not one-to-one correspond to corrotating interact-ing regions (CIRs); such events are possible results of local interplanetary magnetic field reconnection or electromagnetic disturbances. Finally, about 2/3 gradual proton events of the third class occur with interplanetary shocks, the delay times of which are almost equal to the rising time. Some of these events can be understood as particle accelerations by shocks.

关键词： suprathermal particles solar wind plasma solar eruptive activity interplanetary active regions

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Time Evolution of the Turnover Frequency for Diagnosis of the Coronal Magnetic Field

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chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 113-119页

作者： Guang-Li Huang purple mountain observatory Chinese Academy of Sciences Nanjing 210008

Two impulsive microwave bursts observed by Owens-Valley Solar Arrays （OVSA） are studied. The fast time variation of the turnover frequency in these bursts is quite different from the constant value in the earlier conclusion. The observational turnover frequencies are consistent with the calculations using the non-thermal gyrosynchrotron radiation model. We find the turnover frequency may play an important role for calculating the coronal magnetic field on the basis of Dulk and Marsh＇s approximations.

关键词： Sun: radio radiation -- Sun: corona- Sun: magnetic fields

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The Gyrosynchrotron Radiation Spectrum in a Nonuniform Source

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chinese Journal of Astronomy and Astrophysics 2006年第2期6卷 260-264页

作者： Ai-Hua Zhou purple mountain observatory Chinese Academy of Sciences Nanjing 210008

Effects of the energy spectral index δ, low energy cutoff E0 and number density N of energetic electrons on gyrosynchrotron spectrum are investigated for a model source with a nonuniform magnetic field. It is found that the flux density SVT of the x-mode and o-mode systematically increase with increasing E0, N and with decreasing δ. The peak frequency of the spectrum, vp, also systematically increases as increasing E0 and N, but it may not depend on δ. The gyrosynchrotron radiation in the nonuniform case is polarized predominately in the x-mode at v ≥ 3 GHz. A sense reversal of circular polarization also occurs but at much lower frequencies （v ≤ 3 GHz）. The reversal frequency also increases with increasing E0 and N, but it perhaps is independent of δ.

关键词： Sun: flares - Sun: radio radiation

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Discrepancy between infrared and optical emission in some Be stars

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chinese Science Bulletin 2002年第18期47卷 1511-1513页

作者： LIU Qingzhong & WEI Jianyanpurple mountain observatory, chinese academy of sciences, nanjing2.0008, china National Astronomical Observatories, chinese academy of sciences, Beijing 100012, china purple mountain observatory Chinese Academy of Sciences Nanjing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

An expanding ring model is put forward to investigate the original regions of Ha line emission and infrared excess emission in Be stars, by taking optical depth into account. We find that the two regions depend strongly on the physical properties of the envelope of Be stars such as the initial density and density structure. This model can be used to qualitatively interpret the disagreement between the near infrared excess and the equivalent width (EW) of Ha emission line, as observed in some Be stars.

关键词： Be star emission line near infrared excess.

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Statistical study of EUV and X-ray transient brightenings

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Research in Astronomy and Astrophysics 2010年第7期10卷 696-706页

作者： Jing-Wei Li Hui Li purple mountain observatory Chinese Academy of Sciences Nanjing 210008 China

Using the visual inspection and base difference method and data from the X-ray Telescope （XRT） onboard Hinode and TRACE with improved spatial and temporal resolution, we selected 48 X-ray transient brightenings （XTBs） and 237 EUV transient brightenings （ETBs） to study the connection between these two types of transient brightenings （TBs）. These ETBs and XTBs have smaller areas （8.42 Mm^2 and 36.3 Mm^2, respectively, on average） and shorter durations （9.0 min and 6.9 min, respectively, on average） than previous studies. These XTBs show three types of morphological structure： point-like, single-loop and multiple-loop. We find only 20% of the ETBs have corresponding XTBs while the other 80% have no X-ray signatures at all. This is presumably due to the small amount of released energy, which is not enough to heat the plasma to coronal temperatures which produce X-ray emission rather than being due to the limitation of spatial resolution and temperature sensitivity of the X-ray instrument. These small ETBs may significantly contribute to the coronal heating.

关键词： Sun X-rays, gamma rays -- Sun UV radiation -- Sun corona

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Drifting bands of solar radio spikes

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chinese Science Bulletin 2008年第4期53卷 638-640页

作者： XU FuYing1,2& WU HongAo1,2 1 purple mountain observatory,chinese academy of sciences,nanjing 2.0008,china 2 National Astronomical Observatories,chinese academy of sciences,Beijing 100012,china purple mountain observatory Chinese Academy of Sciences Nanjing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

The solar flare(1N/C5.3) occurred in NOAA 8742 on October 27,1999,and the accompanied complex radio burst was observed by the spectrometer with both high temporal(5 ms) and frequency(10 MHz) resolutions at purple mountain observatory(PMO).It started at 04:27:42 UT,peaked at 04:28:42 UT and ended at 04:29:18 *** most significant feature of the event might be the sequential spikes in both time and frequency to form three slow drift bands over the frequency range of ～5 to ≥7.5 GHz with almost the same drift rate about 2.7 GHz/*** relative bandwidth for the individual spikes varied from 1.6% to 4.9%,typically 3.3%.Based on electron cyclotron maser action driven by loss-cone anisotropy,the rare phenomena of slow drift band consisting of spikes were interpreted by spike source moving back and forth along the magnetic ***,the estimations of the narrow bandwidths of spike given by electron cyclotron maser theory coincided well with the observations.

关键词：太阳耀斑微波爆裂太阳活动天文学

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The approximate state transition matrix based on non-orthogonal decomposition and its application in orbit determination

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 555-561页

作者： CHEN WuShen1,2, MA JingYuan2, ZHANG Jing2 & LU BenKui2 1 nanjing University of Technology, nanjing 210009, china 2 purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 1. nanjing University of Technology Nanjing 210009 China2. Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

The Unit Vector Method (UVM) is an orbit determination method extensively applied. In this paper, the UVM and classical Differential Orbit Improvement (DOI) are compared, and a fusion method is given for the orbit determination with different kind data. Based on non-orthogonal decomposition of position and velocity vectors, an approximation scheme is constructed to calculate the state transition matrix. This method simplifies the calculation of the approximate state transition matrix, analyzes the convergence mechanism of the UVM, and makes clear the defect of weight strategy in UVM. Results of orbit the determination with simulating and real data show that this method has good numerical stability and rational weight distribution.

关键词： Unit Vector Method state transition matrix non-orthogonal decomposition

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Numerical simulations of magnetic reconnection in the lower solar atmosphere

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Research in Astronomy and Astrophysics 2011年第2期11卷 225-236页

作者： Xiao-Yan Xu 1,2,Cheng Fang 2,Ming-De Ding 2 and Dan-Hui Gao 2 1 purple mountain observatory,chinese academy of Science,nanjing 2.0008,china 2 Department of Astronomy,nanjing University,nanjing 210093,china purple mountain observatory Chinese Academy of Science Nanjing 210008 China Department of Astronomy Nanjing University Nanjing 210093 China

Observations indicate that Ellerman bombs （EBs） and chromospheric microflares both occur in the lower solar atmosphere,and share many common features,such as temperature enhancements,accompanying jet-like mass motions,short life-time,and so *** strongly suggest that EBs and chromospheric microflares could both probably be induced by magnetic reconnection in the lower solar *** gravity,ionization and radiation considered,we perform two-dimensional numerical simulations of magnetic reconnection in the lower solar *** influence of different parameters,such as intensity of the magnetic field and anomalous resistivity,on the results are *** result demonstrates that the temperature increases are mainly due to the joule dissipation caused by magnetic *** spectral profiles of EBs and chromospheric microflares are calculated with the non-LTE radiative transfer theory and compared with *** is found that the typical features of the two phenomena can be qualitatively reproduced.

关键词： Sun: chromosphere-- Sun: photosphere -- Sun: magnetic reconnection-- Sun: numerical simulation

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An Electron Density Model above the Sunspot from a Mapping of NOAA 7260 at 17 GHz

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chinese Journal of Astronomy and Astrophysics 2002年第3期2卷 287-292页

作者： Xing－FengYu Jin－XingYao NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012 purplemountainobservatory ChineseAcademyofSciencesNanjing210008

The brightness temperature distribution of microwave emission in a solar active region generally shows a ring structure, with a dip at the centre. However, no dip was found in the Nobeyama Radioheliograph left handed circular polarization (LCP) image on 1992 August 18; instead, there was a peak. This is a completely LCP source with zero right-handed circular polarization (RCP). We examine this structure in terms of the joint effect of gyroresonance and bremsstrahlung mechanism with a raised electron density above the central part of the sunspot, and the commonly assumed temperature and vertical dipole magnetic field models. The raised electron density is found to be 1.4 × 1011 cm-3 at the chromosphere base.

关键词： Sun: activity - sunspots - Sun: radio radiation - Sun: chromosphere

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Kinetic Alfven Waves in Aurora

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紫金山天文台台刊 1996年第2期15卷 60-65页

作者： Wang De-yu purple mountain observatory,nanjing,2.0008,china

On the basis of the differences between ideal MHD Alfven waves and kinetic Alfven waves,the nonlinear kinetic Alfven wave with Poison equation correction and the evolution of kinetic wave have been *** results have be... 详细信息

关键词：今音

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