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Diagnostics of magnetic field strength for gyrosynchrotron radiation regions of the lower harmonics

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chinese Science Bulletin 1998年第14期43卷 1183-1187页

作者： ZHOU Aihua Purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china Purple mountain observatory Chinese Academy of Sciences Nanjing China

A diagnostic formula of magnetic field strength of gyrosynchrotron radiation regions of the lower harmonics (5 ≤S≤10 ) is presented based on their emissivity η νBN , absorptivity κ νBN , and the turnover frequency of radio spectra ν P. Their diagnostic error is estimated. And an accurate relation between electron energy spectral index δ and brightness temperature spectral index β is also given.

关键词： lower harmonic radio emission magnetic field.

Effects of various solar indices on accuracy of Earth’s thermospheric neutral density models

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Science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 1120-1128页

作者： WANG HongBo1,2 & ZHAO ChangYin1 1 Purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2 Graduate University of chinese academy of sciences, Beijing 100049, china Purple mountain observatory Chinese Academy of Sciences Nanjing China Graduate University of chinese academy of sciences Beijing China

Four kinds of solar indices F10.7, E10.7, S10, Mg10 and four thermospheric neutral density models, i.e., CIRA72, DTM94, NRLMSISE00 and JB2006, are discussed. The CHAMP accelerometer data are used to calculate thermospheric total mass density. Based on the comparison of the model densities with CHAMP observations, the effects of various indices on the model accuracy are detected. It is found that under quiet and moderate solar conditions (F10.7200) the error’s standard deviation using E10.7 increases quickly and causes the models’ accuracy to fall down. With regard to S10, Mg10, their effects under quiet solar conditions are inconspicuous. If under active solar conditions, they can reduce the model error’s standard deviation by 5%-10%, implying that S10, Mg10 make the model error more stable. The JB2006 model, which was constructed by multi-solar-index (F10.7, S10, Mg10), is compared with DTM94 and NRLMSISE00 based on single-solar-index. It is found that JB2006’s accuracy is better than DTM94’s, and is close to NRLMSISE00 under the quiet solar condition. During the solar burst occurring on October 26, 2003, JB2006 has been in best agreement with CHAMP observations. All in all, the new indices may improve thermospheric density models’ accuracy under some special conditions. Concretely, E10.7 may reduce the average error of models and S10, Mg10 may prevent the error’s divergence.

关键词： solar radiation index CHAMP accelerometer data neutrals density model

A new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem

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Science china(Physics,Mechanics & Astronomy) 2009年第9期52卷 1404-1413页

作者： XU XingBo1,2 & FU YanNing1 1 Purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2 Graduate University of chinese academy of sciences, Beijing 100039, china Purple mountain observatory Chinese Academy of Sciences Nanjing China Graduate University of chinese academy of sciences Beijing China

We show that there exists a new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem. In such a solution, the infinitesimal body is confined to the vicinity of a primary and moves on a nearly circular orbit. This orbit is almost perpendicular to the orbital plane of the primaries, where the line of symmetry of the orbit lies. The existence is shown by applying a corollary of Arenstorf's fixed point theorem to a periodicity equation system of the problem. And this existence doesn't require any restriction on the mass ratio of the primaries, nor on the eccentricity of their relative elliptic orbit. Potential relevance of this new class of periodic solutions to real celestial body systems and the follow-up studies in this respect are also discussed.

关键词： periodic orbits spatial restricted three-body problem symmetric orbits averaging

Recent study of emission line star 3G71

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chinese Science Bulletin 1998年第6期43卷 470-473页

作者： HANG Hengrong 1,2 and XIA Jianping+1 1. Purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2. Joint Laboratory for Optical Astronomy, chinese academy of sciences, nanjing 2.0008, china Purple mountain observatory Chinese Academy of Sciences Nanjing China Joint Laboratory for Optical Astronomy Chinese Academy of Sciences Nanjing China

New spectral observations of 3G71 are presented. The main features of optical spectra which exhibit a lot of forbidden lines and unusual strong H-Balmer emission lines are discussed. Our data, together with its large IRAS infrared color excess and other characteristics, show evidence that the star may be a Herbig Ae/Be star rather than the optical counterpart of Be/X-ray source of 1H2214+589.

关键词： Be/X-ray binary emission line IRAS identification Herbig Ae/Be star.

An Alternative Explanation for a Screw-like Meteoric Train Photographed by Double-Station Observations

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chinese Journal of Astronomy and Astrophysics 2007年第6期7卷 814-822页

作者： Guang-Jie Wu1,2 1 National Astronomical Observatories/Yunnan observatory,chinese academy of sciences,Kunming 650011 2 Purple mountain observatory,chinese academy of sciences,nanjing 2.0008 National Astronomical Observatories / Yunnan observatory Chinese Academy of Sciences Kunming 650011 Purple mountain observatory Chinese Academy of Sciences Nanjing 210008

Two-station observation of meteors, especially a meteor trains, provides an effective approach to the measurement of the physical parameters. We have collected four special groups of photographs of meteoric trains taken at two stations during Leonids 2001. One representative group has been measured and analyzed in detail. An analysis has been reported in our first paper. In this paper, an alternative explanation for the screw-like meteoric train is suggested based on some physical calculations. The results reveal that this train has a screw-like structure and, apparently, spoke beams. The mother meteor of this train may be negatively charged and moves forward along a left-hand screw trajectory under the effect of the geomagnetic field. The spoke beams might be the visual effect of the long time exposure of many particles released from the disintegrated meteoroid.

关键词： meteors meteoroids -- magnetic fields

The red damping wing of Gunn-Peterson trough in the high redshift GRBs

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Science china(Physics,Mechanics & Astronomy) 2009年第9期52卷 1428-1433页

作者： XU Zhou1,2 & WEI DaMing1,3 1 Purple mountain observatory, chinese academy of sciences, nanjing 2.0008, china 2 Graduate University of chinese academy of sciences, Beijing 100012, china 3 Joint Center for Particle Nuclear Physics and Cosmology of Purple mountain observatory-nanjing University, nanjing 2.0008, china Purple mountain observatory Chinese Academy of Sciences Nanjing China Graduate University of chinese academy of sciences Beijing China Joint Center for Particle Nuclear Physics and Cosmology of Purple mountain observatory-nanjing University Nanjing China

We calculate the red damping wing of Gunn-Peterson trough taking the evolution of the neutral fraction into consideration and take a clear look at the ionized region around the ionizing sources. We get the result that the damping wing flux feature is mainly determined by the neutral hydrogen outside the ionized bubble and the cut off in the damping wing would be useful to get the size of the ionized bubble. We also fit the red damping wing of the recently discovered high redshift GRB080913 and find that the ionized bubble is too small to create apparent cut off in the spectrum of this burst.

关键词： cosmology theory intergalactic medium gamma ray burst

Development of superconducting mixers for THz astronomy

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Science china(Information sciences) 2012年第1期55卷 120-126页

作者： SHI ShengCai1,2 1Purple mountain observatory,chinese academy of sciences,nanjing 2.0008,china 2Key Laboratory of Radio Astronomy,chinese academy of sciences,nanjing 2.0008,china Purple mountain observatory Chinese Academy of Sciences Nanjing China Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing China

The terahertz(THz)regime,loosely defined as 0.1-10 THz,is the last frequency window to be fully explored in *** particular,it is a regime in which there are rich molecular rotation lines and atomic fine structure *** are very important tracers for studying the dynamics of astronomical objects such as stars and planetary *** those spectral lines usually makes use of coherent detectors(i.e.,heterodyne mixers).With sensitivity approaching the quantum limit,superconducting mixers have become the coherent detector of choice in THz *** this paper we mainly introduce the superconducting mixers developed at Purple mountain observatory and those for international collaborative projects.

关键词： terahertz detection superconducting mixer quantum limit

Molecular Gas and Dust in the Massive Star Forming Region S 233 IR

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chinese Journal of Astronomy and Astrophysics 2004年第5期4卷 440-454页

作者： Rui-Qing Mao and Qin Zeng1 Purple mountain observatory, chinese academy of sciences, nanjing 2.0008 2 National Astronomical Observatories, chinese academy of sciences, Beijing 100012 Purple mountain observatory Chinese Academy of Sciences Nanjing 210008 National Astronomical Observatories CAS NAOC Beijing 100012 China

The massive star forming region S 233 IR is observed in the molecular lines CO J = 2–1, 3–2, NH3 (1,1), (2,2) and the 870 um dust continuum. Four submillimeter continuum sources, labelled SMM 1–4, are revealed in the 870 um dust emission. The main core, SMM1, is found to be associated with a deeply embedded near infrared cluster in the northeast; while the weaker source SMM2 coincides with a more evolved cluster in the southwest. The best fit spectral energy distribution of SMM1 gives an emissivity of β = 1.6, and temperatures of 32 K and 92 K for the cold- and hot-dust components. An SMM1 core mass of 246 M☉, and a total mass of 445 M☉ are estimated from the 870 um dust continuum emission. SMM1 is found to have a temperature gradient decreasing from inside out, indicative of the presence of interior heating sources. The total outflow gas mass as traced by the CO J = 3–2 emission is estimated to be 35 M☉. Low velocity outflows are also found in the NH3 (1,1) emission. The non-thermal dominant NH3 line width as well as the substantial core mass suggest that the SMM1 core is a ``turbulent, massive dense core', in the process of forming a group or a cluster of stars. The much higher star formation efficiency found in the southwest cluster supports the suggestion that this cluster is more evolved than the northeast one. Large near infrared photometric variations found in the source PCS-IR93, a previously found highly polarized nebulosity, indicate an underlying star showing the FU Orionis type of behavior.

关键词： ISM: jets and outflows ISM: molecules ISM: dust, extinction stars:formation ISM: individual

Projection Effects on Physical Parameters Obtained from Solar Vector Magnetograms

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chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 174-182页

作者： Hui Li Purple mountain observatory, chinese academy of sciences, nanjing 2.0008 National Astronomical Observatories, chinese academy of sciences, Beijing 100012 Purple mountain observatory Chinese Academy of Sciences Nanjing 210008 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Projection effects in Huairou solar vector magnetograms are corrected by transferring or mapping the observed vector magnetogram in the image plane to the heliographic plane (planar correction) and to the heliospheric coordinate system (spherical correction). The magnetograms after the correction are considerably dif- ferent. The planar correction and the spherical correction lead to slightly different magnetic configurations, especially when the active region involved is far from the disk center. We also discuss the effects of the corrections on magnetic activity pa- rameters, such as magnetic shear, current helicity, etc. It is shown that the neutral line is obviously distorted after the mapping. The mapping generally decreases the average shear angle on the neutral line by several degrees when the active region is in the eastern hemisphere, and increases it when in the western hemisphere. In most of the cases studied, the correction reduces the current helicity imbalance, and sometimes even changes its sign. It is found that the current helicity imbalance may change its sign in its evolution when there are apparent fluxes emerging from the lower photosphere. The corrections increase the noise level of Bz greatly, and decrease the noise level of B~ slightly. The accuracy of the magnetic field measure- ment at Huairou is estimated to be better than 20 G and 150 G for the longitudinal and the transverse component, respectively.

关键词： Sun: magnetic fields ─Sun: activity ─Sun: photosphere