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Vertical Scale Parameter Estimates for 48 Non-edge-on Spiral Galaxies

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Chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 499-504页

作者： Jun MaNational astronomical observatories, Chinese Academy of Sciences, beijing 100012 National astronomical observatories CAS NAOC Beijing 100012 China

In the first paper of this series, we directly studied the mathematicalforms, symmetry of spiral structure, and the projection of galactic discs on the images, andmeasured the pitch angles of the spiral arms and inclination angles of the galactic discs for 60spiral galaxies. In this second paper, we estimate the vertical scale parameters of 48 non-edge-onspiral galaxies based on the method proposed by Peng et al. and on the results given in Paper I. Aswe know, for edge-on disc galaxies we can obtain the vertical scale parameter from the photometry,once a mathematical form is specified for the vertical light distribution. For non-edge-on galaxies,some other methods have to be used. The statistical result was that the vertical scale parameter iscomparable for edge-on and non-edge-on galaxies, although it is obtained from two very differentmethods.

关键词： galaxies: spiral galaxies galaxies: vertical scale parameter

The Amplitude of Mass Fluctuations and Mass Density of the Universe Constrained by Strong Gravitational Lensing

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Chinese Journal of Astronomy and Astrophysics 2004年第2期4卷 118-124页

作者： Da-Ming ChenNational astronomical observatories, Chinese Academy of Sciences, beijing 100012 cdm@*** National astronomical observatories Chinese Academy of Sciences Beijing 100012

We investigate the linear amplitude of mass fluctuations in the universe, σ8, and the present mass density parameter of the Universe, Ωm, from statistical strong gravitational lensing. We use the two population model of lens halos with fixed cooling mass scale Mc = 3.1013.-1M⊙ to match the observed lensing probabilities, and leave σ8 orΩm as a free parameter to be constrained by the data. Another varying parameter, the equation of state of dark energy ω, and its typical values of -1, -2/3. -1/2 and -1/3.are investigated. We find that σ8 is degenerate with Ωm in a way similar to that suggested by present day cluster abundance as well as cosmic shear lensing measurements: σ8Ω0.6m≈0.3.. However, both σ8≤0.7 and Ωm≤0.2 can be safely ruled out, the best fit is when σ8 = 1.0, Ωm = 0.3.and ω= - 1. This result is different from that obtained by Bahcall & Bode, who gave σ8 = 0.98±0.1 and Ωm = 0.17 ±0.05. For σ8 = 1.0, the higher value ofΩm = 0.3. requires ω = -2/3.and Ωm = 0.40 requires ω= -1/2.

关键词： cosmology: theory - cosmological parameters - gravitational lensing

Testing the Universality of the TIS Model on Cluster Scales from the X-ray Surface Brightness Profiles

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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 29-38页

作者： Yu-Ying Zhang (beijing astronomical Observatory and National astronomical{3., Chinese Academy of Sciences, beijing 100012) beijing astronomical Observatory and National astronomical{3. Chinese Academy of Sciences Beijing 100012

The truncated isothermal sphere (TIS) model has been recently suggested as an alternative for virialized dark halos (Shapiro et al. 1999). Both its profound theoretical motivation and its successful explanations for the galactic rotation curves and the gravitational scaling laws of clusters indicate that the TIS model is a promising candidate among other prevailing models such as the NFW profile and the Burkert profile. This promotes us to re-examine the universality of the TIS model on cluster scales from a different angle. Using an ensemble of X-ray surface brightness profiles of 45 clusters, we test the goodness of fit of the TIS predicted gas distributions to the X-ray data under the assumption of isothermal, hydrostatic equilibrium. Unlike the conventional B model or the NFW/Burkert profile, for which about half of the clusters have the reduced X2 values smaller than 2, the TIS model fails in the fitting of the X-ray surface brightness profiles of clusters in the sense that 3. out of the 45 clusters show X2 > 2. This may constitute a challenge for the universality of the TIS model unless the present analysis is seriously contaminated by other uncertainties including the negligence of non-gravitational heating processes and the unconventional sampling of the X-ray data.

关键词： cosmology: theory -dark matter - galaxies: clusters: general- X-rays: galaxies

Expected Number Counts of Radio Galaxy Clusters

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Chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 106-111页

作者： Wei Zhou National astronomical observatories, Chinese Academy of Sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

Clusters of galaxies may contain radio sources if they still experience successive mergers at present. This has been confirmed by radio observations that about 3.% of nearby clusters possess radio halos. We present a theoretical pre- diction of radio cluster counts using a semi-analytic approach which incorporates the empirical correlation between radio power and dynamical mass of clusters, and the cluster mass function described by the Press-Schechter formalism. The total population of radio clusters over the whole sky and their redshift distribution are given.

关键词： cosmology: theory-galaxies: cluster: general-radio sources:extended

“Small Equipment Strategy” in the Development of Astronomy

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Chinese Journal of Astronomy and Astrophysics 2003年第1期3卷 1-11页

作者： Shou-Guan WangNational astronomical observatories, Chinese Academy of Sciences, beijing 100012 shouguanwang@*** National astronomical observatories CAS NAOC Beijing 100012 China

Astronomy is an observational science. This paper points out that in the development of astronomy, the means of observation at every stage has as its main body the large equipment of the time, but equally important is the simultaneous development of small equipment as strategic complement. A number of historical examples are cited. The recently suggested 'Special Radio Telescope Dedicated to Pulsar Research' originates in the small equipment strategy, and a brief introduction to this instrument is included here.

关键词： instrumentation telescopes

A Date Recovery System launched for chronological studies in ancient China

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Science China(Physics,Mechanics & Astronomy) 2008年第1期51卷 105-110页

作者： LI Yong National astronomical observatories,Chinese Academy of Sciences,beijing{3.,China 1. National astronomical observatories Chinese Academy of Sciences Beijing 100012 China

Benefited from the performance of the Xia-Shang-Zhou Chronology Project(XSZP) in China and our new astronomical chronology method designed and processed for Chinese particular 60-day-cycle Ganzhi(the heavenly stems and earthly branches)date records,we launch a Date Recovery System(DRS)for ancient China. Of high analysis function,this software can recover and convert the complete or incomplete date information originally from Ganzhi style in the historical period of China to the Gregorian Calendar System,which may have wide applications in the area of literary history,archaeology and cultural relic,etc.,and solve the Goldbach Puzzles of Chinese *** an example,we give the detailed process for the sculptures on four bronze wares with the Ganzhi data and afterwards employ this software and provide their possible dates corresponding to Gregorian system.

关键词： chronology date ephemeris software

Discovery of an Optical Jet in the Rosette Nebula: Rosette HH2

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Chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 495-498页

作者： Jin-Zeng LiNational astronomical observatories, Chinese Academy of Sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

We report on the discovery of an optical jet - Rosette HH2 - in the RosetteNebula. The jet system bears unique features for residing at the center of a giant HII region, andits energy source is visible with apparently very low extinction along the line of sight. Unlikemost other Herbig-Haro jets, this jet indicates a high-excitation origin, and its extended portionshows a seemingly intact structure, instead of normally a shocked working surface, which isattributed to photoablation.

关键词： stars: formation stars: pre-main sequence herbig-haro objects ISM: jetsand outflows

Modeling earthquake indexes derived from the earthquake warning system upon the planet earth

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Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2293-2299页

作者： LI Yong National astronomical observatories, Chinese Academy of Sciences, beijing 100012, China 1. National astronomical observatories Chinese Academy of Sciences Beijing 100012 China

By studying the correlation between historical earthquake data and the distributional characteristics of parameters of solid earth tides in the earthquake epicenter, we are able to design a forecasting function of earthquake probability. We put forward a design method for the Earthquake Warning System. The model could theoretically simulate and be used to predict the probability of strong earthquakes that could occur anywhere at any time. In addition, the system could also conveniently obtain global or partial Modeling Earthquake Indexes to finally combine the precise pointing prediction and forecast of partial indexes. The literature quotes global data values, provided by NEIC, of 1544 M ≥ 6.5 earthquakes. It also gives examples of instantaneous earthquake indexes of the whole world and Taiwan Region on 1st January 2010, UT=0:00 and the average earthquake index near the Taiwan Region. According to the 10-year pointing prediction of strong earthquakes in San Francisco, the literature provides the average earthquake index on 24th June 2015 (± 15 days), in its neighborhood.

关键词： earthquake earthquake warning system astrogeodynamics index

IRAS 01005+7910:a High Galactic Latitude Post-AGB Star

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Chinese Journal of Astronomy and Astrophysics 2002年第3期2卷 193-196页

作者： Jing-Yao HuNational astronomical observatories, Chinese Academy of Sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

IRAS 01005+7910 is a cold IRAS source. We present its optical identification, photometric and spectroscopic observation results. Its optical counterpart is classified as a B2Ie star with V magnitude 10.85. Its Hα line shows the P Cygni profile. According to its location in the Galaxy (b = 16.6), we consider it to be a post-AGB star or a proto-planetary nebula.

关键词： stars: post-AGB - infrared: stars - stars: evolution