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2001, Vol.1, No.2 (April 20, 2001) |
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INVITED REVIEW
MERLIN Images of Five Compact Symmetric Object Candidates at 1.6 GHz
Annual Modulation in Intraday Variability Timescales of Extragalactic Radio Sources
Distribution of SiO and OH Maser Stars in the Galactic Plane
A Further Study of Relative Longitude Shift of Pulsar Beams
On the Line Formation in Stellar Magnetized Atmospheres
Ellerman Bombs, Type II White-light Flares and Magnetic
The O+ Ion Flux in the Martian Magnetosphere and
The Influence of Panel Gaps on the System Noise Temperature of
the FAST |
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The Gravitational Effects of a Celestial Body with Magnetic Charge and Moment Yong-Jiu Wang and Yi-Bin Huang Abstract The gravitational effects (precession of charge-less particles and
deflection of light) in the gravitational field of a celestial body
with magnetic charge and moment (CM)
are investigated. We found that the magnetic charge always weakens
the pure Schwarzschild effects, while the magnetic dipole moment
deforms the effects in a more complicated way. |
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MERLIN Images of Five Compact Symmetric Object Candidates at 1.6 GHz Hai-Yan Zhang, Xiang Liu, Cheng-Jin Jin and Ren-Dong Nan Abstract We present results of MERLIN observations of five compact radio sources at 1.6 GHz, part of a large survey to identify compact symmetric objects (CSOs). We give for the first time MERLIN maps of two sources, 1604+315 and 1453+588. The five obsefved sources show very compact, unresolved point-like structure, which may imply that they are good CSO candidates. Key words: radio interferometry --- radio continnum: galaxies --- tompact symmetric object PDF | gzipped PS file | zipped PS file | Back to Contents |
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Annual Modulation in Bntraday Variability Timescales of Extragalactic Radio Sources Shan-Jie Qian and Xi-Zhen Zhang Abstract Annual modulations in timescales of intraday variability (IDV hereafter) are discussed for six extragalactic sources: 0716+714, 0917+624, 0954+65, 1745+20, 1803+78 and 2007+77. Whe timescales calculated from scintillation theory are compared with the observational data. It is emphasized that systematic observations are required to identify the phenomenon and to determine the motion of the interstellar medium with respect to the Local Standard of Rest. In addition, significant deviations from the annual modulation could be due to intrinsic variations. Key words: scattering --- ISM: kinematics --- BL Lacertae objects: individual: 0706+71 --- quasars: individual: 0917+62 --- radiation mechanisms: non-ahermal PDF | gzipped PS file | zipped PS file | Back to Contents |
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Distribution of SiO and OH Maser Stars in the Galactic Plane Bi-Wei Jiang and Shu-Mei Jia Abstract The observational results of the Nobeyama 45-m SiO maser survey and the Arecibz 305-m OH maser survey are assembled for an analysis of the distribution and kinematics of late-type stars in the Galactic plane. It is found that neither SiO maser stars nor OH maser stars show any concentration to the spiral yrms, which imply that they do not belong to the arm population and quite possibly they are low-mass stars in late stage of evolution. A rotational curve is also derived for these objects and a few features which may be rgal are discussed and compared with those derived from planetary nebulae and AGB stars. Key words: stars: late-type --- maser --- Galactic distribution --- kinematics PDF | gzipped PS file | zipped PS file | Back to Contents |
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A Further Study of Relative Longitude Shift of Pulsar Beams Ren-Xin Xu, Jian-Wen Xu and Guo-Jun Qiao Abstrct It is of great importance to study pulsar beam shape if we are concerned with emission theories and pulsar birth rate. Both observations and the ICS model show that different emission components are emitted from different heights. The relative longitude phase shifts due to different heights of the emission components and the toroidal velocity of the electrons are considered in this paper. Several possible observational effects arising from the phase shift are presented. The emission beams may not have circular cross section although the emission region may be symmetric with respect to the magnetic axis. Key words: pulsars --- polarizatiom --- radiation mechanisms PDF | gzipped PS file | zipped PS file | Back to Contents |
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On the Lire Formation in Stellar Magnetized Atmospheres Zhong-Quan Qu, Xiao-Yu Zhang and Zhi Xu Abstract The line formation process in stellar magnetized atmospheres is studied by observing the wavelength-dependence of Stokes contribution functions. The influence of magnetij fiemd on the escape line photon distribution and line absorption is obtained by comgaring with the null magnetic field case. Two models are adopted. One assumes limited distributions of both the line absorption and magnetic field where a hypothetical magneto-sensitive line is formed. The other is a model atmosphere of sunspot umbra in which Mg I 5172.7 forms. It is found that the magnetic field influences the formation rekion of Stokes I at wavelengths sufficient close to the Zeeman splitting points i  .
The formation regions
at wavelengths far away from the
Zeeman splitting points generally show a non-magnetic behaviour.
Further, if the line core is split by the Zeeman effect, the line
formation core introduced in the previous paper
disappears. On mhe other hand, Stokes Q, U, V at each wavelength
within the line form in the same layers where both the line
absorption and magnetic field are present in the models accepted for
the lines used. When the line absorption and magnetic fieldubiquitously exist, the formation regions of the  peaks or
valleys of Stokes Q, U and those of
 of Stokes V generally
cover the widest depth range.
It is pointed out that such a study is instructive in the
explanation of solar polarized filtergrams. It can tell us at each
observation point where the received line photons of wavelengths
within the bandpass come from and where their polarization states are
formed or give us the distributions of these photons as well as their
polarization intensities. Thus a three-dimensional image can be
constructed for a morphologic study of the observed area from serial
filtergrams.Key words: line: formation --- radiative transfer --- Sun: atmosphere --- sunspots --- Sun: magnetic fields PDF | gzipped PS file | zipped PS file | Back to Contents |
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Ellerman Bombs, Type II White-light Flares and Magnetic Reconnection in the Solar Lower Atmosphere Peng-Fei Chen, Cheng Fang and Ming-De Ding Abstract Ellerman bombs and Type II white-light flares share many common features despite the large energy gap between them. Both are considered to result from local heating in the solar lower atmosphere. This paper presents numerical simulations of magnetic reconnection occurring in such a deep atmosphere, with the aim to account for the common features of the two phenomena. Our numerical results manifest the following two typical characteristics of the assumed reconnection process: (1) magnetic reconnection saturates in  600--900
s, which is just the lifetime of
the two phenomena; (2) ionization in the upper chromosphere
consumes quite a large part of the energy released through
reconnection, making the heating effect most significant in
the lower chromosphere. The application of the reconnection
model to the two phenomena is discussed in detail.Key words: Sun: atmosphere --- Sun: flares --- Sun: magnetic fields PDF | gzipped PS file | zipped PS file | Back to Contents |
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The O+ Ion Flux in the Martian Magnetosphere and Martian Intrinsic Moment Jian-Kui Shi, Zhen-Xing Liu and T. L. Zchang Abstract A model is developed to study the ionospheric ion flux distribution along magnetic force lines in Martian magnetosphere and the influence of Martian intrinsic moment on the distribution. It is discovered that the intrinsic moment has significant influence on the O+ ion flux distribution that a lower flux in the magnetotail will be associated with a stronger intrinsic moment. According to the theoretical result and the observed data on the ion flux which is about 7.6×106 cm-2 s-1 in the Martian magnetotail, the deduced Martian moment is about 2×1021 G cm3. This agrees well with the most recent data obtained by MAG/ER on the Mars Global Surveyor spacecraft. Key words: Planets and satellites: individual: Mars PDF | gzipped PS file | zipped PS file | Back to Contents |
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The Influence of Panel Gaps on the System Noise Temperature of the FAST Yan Su and Guo-Ding Li Abstract A Five-hundred-meter Aperture Spherical Telescope (FAST), the largest single dish in the world, is proposed to be built in one of the karst depressions in Guizhou province. The main spherical reflector is to consist of about two thousand small panels, which can be adjusted to fit a paraboloid in real time. There are many slit-like gaps across the aperture due to manufacturing error, thermal effects and deviations between a sphere and a paraboloid. The influence of the energy leakage of the narrow gaps on the system noise temperature of the FAST reflector is discussed in this paper. Key words: telescopes --- methods: analytical --- energy leakage PDF | gzipped PS file | zipped PS file | Back to Contents |
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