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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, {3. academy of Sciences, nanjing 210008, china 2 Graduate University of {3. academy of Sciences, Beijing 100012, china 3.Joint Center for Particle Nuclear Physics and Cosmology of purple mountain observatory-{13. University, nanjing 210008, 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-{3. 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

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, {3. academy of Sciences, nanjing 210008, 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.

Simulations for terrestrial planets formation

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Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 794-803页

作者： ZHANG Niu 1,2 &JI JiangHui 2,3.1Graduate University of chinese academy of Sciences,Beijing 100049,china {3.,chinese academy of Sciences,nanjing 210008,china 3.National Astronomical Observatories,chinese academy of Sciences,Beijing 100012,china Graduate University of chinese academy of Sciences Beijing China purple mountain observatory Chinese Academy of Sciences Nanjing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

In this paper,the formation of terrestrial planets in the late stage of planetary formation is investigated using the two-planet *** that time,the protostar formed for about 3.Ma and the gas disk *** the model,the perturbations from Jupiter and Saturn are *** of the mass of outer planet,and the initial eccentricities and inclinations of embryos and planetesimals are also *** results show that,terrestrial planets are formed in 50 Ma,and the accretion rate is about 60%-80%.In each simulation,3.4 terrestrial planets are formed inside"Jupiter"with masses of 0.15 -3.6M⊕.In the 0.5-4 AU,when the eccentricities of planetesimals are excited,planetesimals are able to accrete material from wide radial *** plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this *** could also happen a few times between two major planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 10 8 *** one of our simulations,commensurability of the orbital periods of planets is very ***,a librating-circulating 3.2 configuration of mean motion resonance is found.

关键词： astrophysics exoplanet planetary formation n-body simulation

Near-Infrared Observations of the Massive Star Forming Region IRAS 23.51+5912

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chinese Journal of Astronomy and Astrophysics 2004年第3期4卷 284-298页

作者： Xue-Peng Chen Yong-Qiang Yao purple mountain observatory {3. academy of Sciences, nanjing 210008 purple mountain observatory Chinese Academy of Sciences Nanjing 210008

Near-infrared images and K-band spectroscopy of the massive star-formingregion IRAS 23.51+5912 are presented. The JHK′ images reveal an embedded infrared clusterassociated with infrared nebula, and the H_2 (2.12 μm) narrowband image provides for the first timeevidence of outflow activity associated with the cluster. That the cluster is young can be shown bythe high percentage of infrared excess sources and the outflow activity. We suggest an age of thecluster of ～ 10~6 yr. Eight young stars are found in the bright nebular core around IRAS23.51+5912. By the color-magnitude diagrams of the cluster, we found five high-mass YSOs and fourintermediate-mass YSOs in the cluster. Eight H_2 emission features are discovered in the region witha scattered and non-axisymmetric distribution, indicating the existence of multiple outflows drivenby the cluster. Diffuse H_2 emission detected to the north and to the west of the cluster mayresult from UV leakage of the cluster. Brγ, H_2, and CIV emission lines are found in the K-bandspectrum of the brightest source, NIRS 19, indicating the presence of envelope, stellar wind, andshock in the circumstellar environment. We have estimated an O7-O9 spectral type for the centralmassive YSO (20 ～ 3. solar mass), with an age of less than 1 x 10~6 yr.

关键词： infrared radiation stars: formation ISM: individual: IRAS 23.51 + 5912 ISM: jets and outflows

Multiwavelength study of low-luminosity 6.7-GHz methanol masers

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Research in Astronomy and Astrophysics 2011年第2期11卷 137-155页

作者： Yuan-Wei Wu,Ye Xu and Ji Yang purple mountain observatory,{3. academy of Sciences,nanjing 210008,china purple mountain observatory Chinese Academy of Sciences Nanjing 210008 China

We present results of 13.O（1-0）,C18O（1-0）,and HCO＋（1-0） map observations and N2H＋（1-0） single point observations directed towards a sample of nine low-luminosity 6.7-GHz masers.N2H ＋ line emission has been detected from six out of nine sources,C18O line emission has been detected from eight out of nine sources,and HCO ＋ and 13.O emission has been detected in all *** particular,a ＂blue profile＂ of the HCO ＋ spectrum,a signature of inflow,is found towards one *** integrated intensity emission maps,we identified 17 cores in the *** them,nine cores are closely associated with low-luminosity methanol *** these cores,we derive the column densities,core sizes,masses and molecular *** of our results with similar molecular line surveys towards the southern sky methanol masers indicates that linewidths of our sample,including only the low-luminosity masers,are smaller than the sample that includes both lowand high-luminosity *** the maser associated cores,their gas masses have the same order of magnitude as their virial masses,indicating that these cores are gravitationally bound *** addition,we have found from our observations that the low-luminosity methanol masers tend to coexist with H2O masers and outflows rather than with OH masers.

关键词： masers -- ISM: abundances -- ISM: molecules -- stars: formation

The investigation of the Neupert effect in two solar flares

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Science china(Physics,Mechanics & Astronomy) 2009年第11期52卷 1686-1690页

作者： NING ZongJun purple mountain observatory, {3., china purple mountain observatory Nanjing China

The Neupert effect suggests a flare model in which the nonthermal emissions are produced by energetic electrons which heat lower corona and chromosphere to produce the thermal emissions. Based on this concept, we investigate the Neupert effect to test the correlation between the hard X-ray spectral index and the time rate of the UV flare area at 1600 or 171 . Using the T RACE and RHESSI observations, we explore these quantities for two solar flares, one on March 14, 2002 and the other on November 1, 2003. The negative dependence between the spectral index and the time rate of the UV flare area is found, especially during the hard X-ray sub-peaks. This finding indicates that the electron-beam-driven heating plays a prominent role in the UV emission of these two flares.

关键词： solar flares UV radiation X-rays

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, {3. academy of Sciences, nanjing 210008 National Astronomical Observatories, {3. 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

Recent study of emission line star 3.71

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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, {3. academy of Sciences, nanjing 210008, china 2. Joint Laboratory for Optical Astronomy, {3. academy of Sciences, nanjing 210008, 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 3.71 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.

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,{3. academy of Sciences,nanjing 210008,china 2Key Laboratory of Radio Astronomy,{3. academy of Sciences,nanjing 210008,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