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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 210008, 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

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,210008,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

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 210008,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

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

On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

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chinese Physics C 2018年第7期42卷 113-122页

作者： Yi-Qing Guo1 2 Qiang Yuan1 3 1. Key Laboratory of Dark Matter and Space Astronomy purple mountain observatory chinese academy of sciences nanjing 210008 china 2. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of Sciences School of Astronomy and Space Science University of Science and Technology of China

More than fifty years after the discovery of the knee in the cosmic ray （CR） spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectra of individual components. Recently, direct measurements from several space experiments found significant spectral hardenings of CR nuclei at ~200 GV. A joint modeling of the direct and indirect measurements may help to understand the experimental systematics and the physics of the knee. In this work, we update the phenomenological ＂poly-gonato＂ model to include the spectral hardenings, with a changing spectral index of γ ＋ β·logE. This modification gives a reasonable description of the CR spectra in a wide energy range. However, the fits to different data sets give different results. We find that the fit to the AMS-02 and CREAM data slightly favors a relatively low energy knee of the light components. In such a case, the expected all-particle spectra under-shoot the data, which may require an extra component of CRs. The fits to AMS-02 data and the light component （H＋He） data from the Tibet ASγ/ARGO-YBJ/WFCTA and KASCADE experiments give consistent results with the all-particle spectra. We further propose a possible physical realization of such a ＂modified poly-gonato＂ model of spectral hardenings by means of spatially-dependent diffusion of CRs. We find reasonably good agreement between the model predictions and the data for CR spectra, the secondary-to-primary ratios, and the amplitude of anisotropies.

关键词： cosmic ray knee spectrum propagation

THEORETICA　LCALCULATION　OF　ATOMIC　AND　MOLECULAR　DATA

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原子与分子物理学报 1997年第2期 35-37页

作者： Pei Chunchuan purple mountain observatory Academia Sinica nanjing 210008

ＴＨＥＯＲＥＴＩＣＡＬＣＡＬＣＵＬＡＴＩＯＮＯＦＡＴＯＭＩＣＡＮＤＭＯＬＥＣＵＬＡＲＤＡＴＡＰｅｉＣｈｕｎｃｈｕａｎＰｕｒｐｌｅＭｏｕｎｔａｉｎＯｂｓｅｒｖａｔｏｒｙＡｃａｄｅｍｉａＳｉｎｉｃａＮａｎｊｉｎｇ２１０... 详细信息

ＴＨＥＯＲＥＴＩＣＡＬＣＡＬＣＵＬＡＴＩＯＮＯＦＡＴＯＭＩＣＡＮＤＭＯＬＥＣＵＬＡＲＤＡＴＡＰｅｉＣｈｕｎｃｈｕａｎＰｕｒｐｌｅＭｏｕｎｔａｉｎＯｂｓｅｒｖａｔｏｒｙＡｃａｄｅｍｉａＳｉｎｉｃａＮａｎｊｉｎｇ２１０００８ＡＢＳＴＲＡＣＴＢｙｕｓｉｎ...

关键词： Atomic and molecular data Interstellar molecules Equation of state Molecular lines observation

Electron surfing acceleration in a current sheet of flares

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Science china(Physics,Mechanics & Astronomy) 2009年第11期52卷 1810-1812页

作者： WANG DeYu1 & LU QuanMing2 1 purple mountain observatory, nanjing 210008, china 2 School of Earth and Space sciences, University of Science and Technology of china, Hefei 230026, china purple mountain observatory Nanjing 210008 China School of Earth and Space sciences University of Science and Technology of China Hefei 230026 China

A model of electron acceleration in a current sheet of flares is studied by the analytical approximation solution and the test particle simulation. The electron can be trapped in a potential of propagating electrostatic wave. The trapped electron moving with the phase velocity v p of wave may be effectively accelerated by ev p/c × B z force along the outflow direction in the current sheet, if a criterion condition K > 0 for electron surfing acceleration is satisfied. The electron will be accelerated continuously until the electron de-trap from the wave potential at the turning point S.

关键词： electron acceleration electrostatic wave current sheet

On the Evolution of the Lower Energy Cutoff of Nonthermal Electrons in Solar Flares

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chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 103-105页

作者： Wei－QunGan You－PingLi 等 purplemountainobservatory ChineseAcademyofSciencesNanjing210008 NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012

Using the method recently developed by Can et al. (2001a, 2002), We investigate the time variation of the lower energy cutoff (Ec) of nonthermal electrons for three BATSE/CGRO hard X-ray events. The result shows that Ec changes with time, from smaller before the peak flux, to larger at the peak, and then back to smaller after the peak. Such a variation of Ec, being a preliminary conclusion for the first time, should be checked in the future by using data with a higher energy resolution.

关键词： Sun: hard X-rays─Sun: gamma-rays─Sun: flares─Sun: particles

Unusually Broadened Spectral Profiles Observed in Solar Prominences

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chinese Journal of Astronomy and Astrophysics 2004年第4期4卷 377-389页

作者： HuiLi Jian-QiYou EijiroHiei purplemountainobservatory ChineseAcademyofSciencesNanjing210008 NationalAstronomicalobservatoryofJapan MitakaTokyo181-8588Japan

After surveying the spectra of 39 prominences observed by the Multi-channel Infrared Solar Spectrograph at purple mountain observatory and the 25 cm coronagraph at the Norikura Solar observatory, we found that about 28% of them show small spatial scale (6''–8'') and short time scale (tens of seconds to a few minutes), unusual large broadening and large shift velocities in spectral lines including Hα, Hβ, H, Ca II H, Ca II K, Ca II 8542?, He I D3 and He I 10830?. We present in detail two typical events observed respectively on 2002 May 27 and 1981 August 2. The full-width at half maximum of the widest profile of the 2001 prominence is 1.8? for Hα and 2.9 ? for He I 10830?, while that of the 1981 prominence is 5.3 ? for Hβ, 3.6 ? for Ca II K, 4.0 ? for Ca II H and 2.8 ? for He I D3. Such broadenings generally occur at a level of several-thousand kilometres above the chromosphere. Further, most of these prominences manifest a rotation of (0.4–1.35)×10-2 rads s?1 pointing to the Sun and large line-of-sight velocities of 20–200 km s?1. Some of these events correspond in time to an enhancement or a small peak in the GOES X-ray flux, indicating the existence of high energy process at work. These prominences generally display discernible changes in the Hα morphology around the time of large broadening, but do not show Hα brightening or overall eruption except for a few small surge-like events, hence, they are hardly observed in daily Hα patrols. According to the characteristics of their Hα structures and spectral properties, we infer these events are small-scale eruptions similar to nano-flares, which may contribute to the mass and energy transported into the corona. Large turbulent velocities of 25–120 km s?1 are responsible for the observed broadenings.

关键词： sun: prominences line: profiles turbulence