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Effect of Conversion Efficiency on Gamma-Ray Burst Energy

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Chinese Journal of astronomy and Astrophysics 2004年第3期4卷 267-274页

作者： Lei Xu Zi-Gao Dai department of astronomy nanjing university {3. 210093 department of astronomy Nanjing University Nanjing 210093

Beaming effect makes it possible that gamma-ray bursts have a standardenergy, but the gamma-ray energy release is sensitive to some parameters. Our attention is focusedon the effect of the gamma ray conversion efficiency (η_γ), which may range between 0.01 and 0.9,and which probably has a random value for different GRBs under certain conditions. Making use of theafterglow data from the literature, we carried out a complete correction to the conical openingangle formula. Within the framework of the conical jet model, we ran a simple Monte Carlo simulationfor random values of η_γ, and found that the gamma-ray energy release is narrowly clustered,whether we use a constant value of η_γ or random values for different gamma-ray bursts.

关键词： gamma rays: bursts ISM: jets

Precession of the Orbital Plane of Binary Pulsars and Significant Variabilities

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Chinese Journal of astronomy and Astrophysics 2005年第4期5卷 379-398页

作者： Bi-Ping Gong department of astronomy, nanjing university, {3. 210093.bpgong@*** department of astronomy Nanjing University Nanjing 210093

There are two ways of expressing the precession of orbital plane of a binary pulsar system, given by Barker ＆ O＇Connell, Apostolatos et al. and Kidder, respectively. We point out that these two ways actually come from the same Lagrangian under different degrees of freedom. Damour ＆ Schaefer and Wex Kopeikin applied Barker ＆ O＇Connell＇s orbital precession velocity in pulsar timing measurement. This paper applies Apostolatos et al.＇s and Kidder＇s orbital precession velocity. We show that Damour ＆ Schaefer＇s treatment corresponds to negligible Spin-Orbit induced precession of periastron, while Wex ＆ Kopeikin and this paper both found significant （but not equivalent） effects. The observational data of two typical binary pulsars, PSR J2051-0827 and PSR J1713.0747, apparently support a significant Spin-Orbit coupling effect. Specific binary pulsars with orbital plane nearly edge on could discriminate between Wex ＆ Kopeikin and this paper： if the orbital period derivative of the double-pulsar system PSRs J073.-3.3. A and B, with orbital inclination angle i=87.7-29^＋17 deg, is much larger than that of the gravitational radiation induced one, then the expression in this paper is supported, otherwise Wex ＆= Kopeikin＇s is supported.

关键词： pulsars: binary pulsars - geodetic precession: individual (PSR J2051-0827 PSR J1713.0747 PSRs J073.-3.3. A and B)

On critical values concerning the evolution of the long period families

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Chinese Journal of astronomy and Astrophysics 2009年第4期9卷 494-500页

作者： Xi-Yun Hou1,21 astronomy department, nanjing university,{3. 2 Institute of Space Environment and Astronautics, nanjing university,{3. astronomy department Nanjing University Nanjing 210093 China Institute of Space Environment and Astronautics Nanjing University Nanjing 210093 China

In a previous paper, we proposed another special critical value concerning the evolution of the long period family around the equilateral equilibrium points, besides the two values given by Henrard. Are there any other special critical values？ After studying the stability curves of the long period family carefully, we gave a negative answer. During the study, we found an interesting family of periodic orbits which we called the homo family. We studied the evolution of this family following the increase of μ. With these findings, we were able to explain the origin of the four branches of periodic families emanating from L4 and the stability results of the equilateral equilibrium points.

关键词： celestial mechanics

(1.2)INVERSES OF OPERATORS BETWEEN BANACH SPACES AND LOCAL CONJUGACY THEOREM

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Chinese Annals of Mathematics,Series B 1999年第1期20卷 57-62页

作者： MA JIPU(department of Mathematics,nanjing university,nanjing 210093.china) department of Mathematics Nanjing University Nanjing 210093 China

Let E and F be Banach spaces and f non-linear C1 map from E into F. The main result isTheorem 2.2, in which a connection between local conjugacy problem of f at x0E and a localfine property of f'(x) at x0(see the Definition 1.1 in this paper) are obtained. This theoremincludes as special cases the two known theorems: the finite rank theorem and Berger's Theoremfor non-linear Fredholm operators. Moreover, the thcorem gives rise the further results for somenon-linear semi-Fredholm maps and for all non-linear semi-Wedholm maps when E and F areHilbert spaces. Thus Theorem 2.2 not only just unifies the above known theorems but alsoreally generalizes them.

关键词： Nonlinear semi-Fredholm maps Conjugacy problem Banach space

Galactic kinematics and structure defined by open clusters

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Research in astronomy and Astrophysics 2009年第12期9卷 1285-1302页

作者： Zi Zhu department of astronomy Nanjing University Nanjing 210093 China

On the basis of recently published astrophysical parameters of the open clusters, we have selected 3.1 clusters with measurements of their kinematical parameters to trace the local structure and kinematics of the Galactic disk. The present sample covers a range of over 3.0 kpc from the Sun and gives significant estimates of the disk structure and kinematical parameters of the Galaxy. We derive the disk scale height, vertical displacement of the Sun to the Galactic plane, solar motion with respect to the local standard of rest, circular speed of the Galactic rotation, Galactocentric distance from the Sun, etc. We found that the average scale height of the disk defined by the open clusters is Zh = 58 ± 4pc, with a vertical displacement of the Sun below the Galactic plane of z0 -= - 16±4 pc. Clusters with ages older than 50 Myr are less concentrated in the average plane （Zh=67 ±6pc） than the younger clusters （Zh = 51±5pc）. Using the approximation of axisymmetric circular rotation, we have derived the distance to the Galactic center from the Sun R0 = 8.03.±0.70 kpc, which is in excellent agreement with the best estimate of the Galactocentric distance. From a kinematical analysis, we found an agedependent rotation of the Galaxy. The older clusters exhibit a lower velocity of vorticity, but have the same shear as the younger clusters. The mean rotation velocity of the Galaxy was obtained as 23. ± 10 km s-1.

关键词： Galaxy: disk -- Galaxy: kinematics and dynamics -- Galaxy: open clustersand associations: general -- Galaxy: structure

Existence of Invariant Tori for Certain Weakly Reversible Mappings

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Acta Mathematica Sinica,English Series 2002年第4期18卷 701-718页

作者： Bao She WEI department of Mathematics, nanjing university. nanjing {3. P. R. china department of Mathematics Nanjing University Nanjing P. R. China

In this paper, we consider certain mappings. M, sufficiently close to an integrable one, which is weakly reversible with respect to the mappings G sufficiently close to an involution of type (m.n). where m, n∈Z_+ are arbitrary. Under some weak non-degeneracy condition, we construct a uniform KAM iteration for proving the existence of a Cantor family of m-tori invariant under the reversible mappings M and the reversing mapping G.

关键词： Weakly reversible mappings Weakly undegenerate condition Invariant tori

The Origin of Infrared Emission from the Infrared Luminous Galaxy NGC 4418

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Chinese Journal of astronomy and Astrophysics 2005年第2期5卷 117-125页

作者： Lei Shi and Qiu-Sheng Gu department of astronomy, nanjing university, {3. 210093.qsgu@*** department of astronomy Nanjing University Nanjing 210093

We present a study of the origin of infrared (IR) emission in the opticallynormal, infrared luminous galaxy NGC 4418. By decomposing the stellar absorption features andcontinua in the range of 3.00-8000 A from the Sloan Digital Sky Survey into a set of simple stellarpopulations, we derive the stellar properties for the nuclear region of NGC 4418. We compare theobserved infrared luminosity with the one derived from the starburst model, and find thatstar-forming activity contributes only 7% to the total IR emission, that as the IR emission regionis spatially very compact, the most possible source for the greater part of the IR emission is adeeply embedded AGN, though an AGN component is found to be unnecessary for fitting the opticalspectrum.

关键词： galaxies: general galaxies: active galaxies: stellar content galaxies:individual (NGC 4418)

Formation and evolution of X-ray binaries

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Science china(Physics,Mechanics & astronomy) 2010年第S1期53卷 9-13页

作者： LI XiangDong department of astronomy,nanjing {3.,nanjing 210093.china department of astronomy Nanjing University Nanjing China

We review recent progress in theoretical understanding of X-ray binaries,which has largely been driven by new *** select several topics including formation of compact low-mass X-ray binaries,the evolutionary connection between low-mass X-ray binaries and binary and millisecond radio pulsars,and ultraluminous X-ray sources,to illustrate the interplay between theories and observations.

关键词： X-ray binaries pulsars mass transfer stellar evolution

Measures and dimensions of fractal sets in local fields

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Progress in Natural Science:Materials International 2006年第12期16卷 1260-1268页

作者： QIU Hua** and SU Weiyi(department of Mathematics, nanjing university, nanjing 210093. china) department of Mathematics Nanjing University Nanjing 210093 China

The study of fractal analysis over the local fields as underline spaces is very important since it can motivate new approaches and new ideas, and discover new techniques in the study of fractals. To study fractal sets in a local field K, in this paper, we define several kinds of fractal measures and dimensions of subsets in K. Some typical fractal sets in K are constructed. We also give out the Hausdorff dimensions and measures, Box-counting dimensions and Packing dimensions, and stress that there exist differences between fractal analysis on local fields and Euclidean spaces. Consequently, the theoretical foundation of fractal analysis on local fields is established.

关键词： local field p-series field Hausdorff measure and dimension Boxcounting dimension Packing measure and dimension Cantor type set.