2004, Vol.4, No.2 (April 20, 2004)


Contents

Cosmology
  • Mass-Temperature Relation of X-ray Clusters in Triaxial Halo    p.105
    Rong Yang, Jun Yu and Guo-Peng Shen  
    Abstract | | PDF file (267 KB) | PS file *.gz  (248 KB) 
  • The Amplitude of Mass Fluctuations and Mass Density of the Universe Constrained by Strong Gravitational Lensing    p.118
    Da-Ming Chen  
    Abstract | | PDF file (236 KB) | PS file *.gz  (360 KB) 
Extragalactic Astronomy
  • Age and Mass Estimates for 41 Star Clusters in M33    p.125
    Jun Ma, Xu Zhou and Jian-Sheng Chen
    Abstract | | PDF file (209 KB) | PS file *.gz  (231 KB) 
  • Optical Photometric Observations of $\gamma$-Ray Loud Blazars   p.133
    Jun-Hui Fan, O. M. Kurtanidze, M. G. Nikolashvili, A. C. Gupta, Jiang-Shui Zhang 
    and Yu-Hai Yuan

    Abstract | | PDF file (202 KB) | PS file *.gz   (173 KB)  | Table 2
  • Evolution of M81 with Exponentially Decreasing Star Formation Rate of PEGASE    p.143
    Jiu-Li Li, Xu Zhou, Jun Ma and Jian-Sheng Chen 
    Abstract | | PDF file (226 KB) | PS file *.gz  (251 KB) 
Stars
  • Stellar X-ray Sources in the Rosette Nebula   p.153
    Wen Ping Chen, Po-Shih Chiang and Jin-Zeng Li
    Abstract | | PDF file (1116 KB) | PS file *.gz  (6,445 KB)  
The Solar System
  • A Study on the Recovery and Classification of Meteorites from the Mt. Grove Region of Antarctica    p.166
    Jian-Zhong Liu, Yong-Liao Zou, Chun-Lai Li, Lin Xu and Zi-Yuan Ouyang 
    Abstract | | PDF file (220 KB) | PS file *.gz  (332 KB) 
The Sun
  • A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts    p.176
    Qi-Jun Fu, Yi-Hua Yan, Yu-Ying Liu, Min Wang and Shu-Juan Wang
    Abstract | | PDF file (2987 KB) | PS file *.gz  (12,240 KB) 
  • The Effect of Solar Activity on the Annual Precipitation in the Beijing Area    p.189
    Juan Zhao, Yan-Ben Han and Zhi-An Li
    Abstract | | PDF file (285 KB) | PS file *.gz  (332 KB) 
Instruments, observational techniques and data processing
  • A New Method for Optimizing the configuration of the Chinese Square Kilometer Array    p.198
    Yan Su, Ren-Dong Nan and Bo Peng
    Abstract | | PDF file (399 KB) | PS file *.gz  (601 KB) 

 


Abstract

 


Mass-Temperature Relation of X-ray Clusters in Triaxial Halo 

Rong Yang, Jun Yu and Guo-Peng Shen 

Affiliation:  (1) Center for Astrophysics, University of Science and Technology of China, Hefei 230026
                   (2) National Astronomical Observatories, Chinese Academy of Science, Beijing 100012
 
E-mail:   

Abstract

We investigate the mass-temperature relation of clusters for both the spherical NFW halo model and a concentric triaxial halo model. We study the temperature and density distributions of both an isothermal and a polytropic intra-cluster gas in hydrostatic equilibrium. We find that both the uncertainties in the concentration parameter and in the eccentricities (in case of the triaxial halo) lead to a greater scatter in the emission-weighted temperature at a given halo mass for less massive clusters. This may be helpful when determining the intrinsic statistical error of the $\sigma_8$ normalization of the linear power spectrum from cluster abundance.

Key words: cosmology: theory --- galaxy: cluster: general --- large-scale structure of universe

PDF file (267 KB) | gzipped PS file (248 KB) | Back to Contents



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

Da-Ming Chen

Affiliation:   National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

E-mail:    

Abstract

We investigate the linear amplitude of mass fluctuations in the universe, $\sigma_8$, and the present mass density parameter of the Universe, $\Omega_{\rm m}$, from statistical strong gravitational lensing. We use the two population model of lens halos with fixed cooling mass scale $M_{\rm c}=3\times 10^{13}h^{-1}M_{\sun}$ to match the observed lensing probabilities, and leave $\sigma_8$ or $\Omega_{\rm m}$ as a free parameter to be constrained by the data. Another varying parameter, the equation of state of dark energy $\omega$, and its typical values of -1, -2/3, -1/2 and -1/3 are investigated. We find that $\sigma_8$ is degenerate with $\Omega_{\rm m}$ in a way similar to that suggested by present day cluster abundance as well as cosmic shear lensing measurements: $\sigma_8\Omega_{\rm m}^{0.6}\approx 0.33$. However, both $\sigma_8\leq 0.7$ and $\Omega_{\rm m}\leq 0.2$ can be safely ruled out, the best fit is when $\sigma_8$=1.0, $\Omega_{\rm m}$=0.3 and $\omega$= -1. This result is different from that obtained by Bahcall & Bode, who gave $\sigma_8$ =0.98± 0.1 and $\Omega_{\rm m}$ =0.17± 0.05. For $\sigma_8$=1.0, the higher value of $\Omega_{\rm m}$=0.35 requires $\omega$ =-2/3 and $\Omega_{\rm m}$=0.40 requires $\omega$=-1/2.

Key words: cosmology: theory --- cosmological parameters --- gravitational lensing

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Age and Mass Estimates for 41 Star Clusters in M33

Jun Ma, Xu Zhou and Jian-Sheng Chen

Affiliation:   National Astronomical Observatories, CAS (NAOC), Beijing 100012, China
              
E-mail:   majun@vega.bac.pku.edu.cn   

Abstract

In this second paper of our series, we estimate the age of 41 star clusters, which were detected by Melnick & D'odorico in the nearby spiral galaxy M33, by comparing the integrated photometric measurements with theoretical stellar population synthesis models of Bruzual & Charlot. Also, we calculate the mass of these star clusters using the theoretical M/LV ratio. The results show that, these star clusters formed continuously in M33 from $\sim$ 7× 106 -- 1010 years and have masses between $\sim$ 103 and 2 ×106$M_{\odot}$. M33 frames were observed as a part of the BATC Multicolor Survey of the sky in 13 intermediate-band filters from 3800 to 10 000Å. The relation between age and mass confirms that the sample star cluster masses systematically decrease from the oldest to the youngest.

Key words: galaxies: individual (M33) --- galaxies: evolution --- galaxies: star clusters

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Optical Photometric Observations of $\gamma$-Ray Loud Blazars

Jun-Hui Fan
(1), O. M. Kurtanidze (2, 3, 4), M. G. Nikolashvili (2), A. C. Gupta (5), Jiang-Shui Zhang (1) and Yu-Hai Yuan (1)

Affiliation:  (1) Center for Astrophysics, Guangzhou University, Guangzhou 510400
                   (2) Abstumani Observatory, 383762 Abstumani, Republic of Georgia      
                   (3) Landessternwarte Heidelberg-Koenigshtuhl, D-69117, Heidelberg, Germany
                   (4) Astrophysikalisches Institute Potsdam, An der Sternwarte 16, D-14482, Germany
                   (5) Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad -- 211019, India

E-mail:   fjh@gzhu.edu.cn      

Abstract

We report results of our optical photometric observations of ten gamma-ray loud blazers, namely: 0219+428 (3C66A), PKS 0420--014 (OA 129), S5 0716+714, 0754+100 (OI 090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTA 102), 2251+158 (3C 454.3) and 2344+514. The observations were carried out in September--October, 2000 using the 70 cm optical telescope at Abstumani Observatory, Georgia. We found intra-day variations in 0420--014, S5 0716+714, BL Lacertae and CTA 102. A variation of 0.3 magnitude over a time scale of about 3 hours was observed in the R passband in BL Lacertae on JD 2451827. We did not detect any variation in 3C 66A, Mrk 501, or 3C 454.3 during our observations. Nor did we detect any clear evidence of variation in 1ES 2344+514 during our two weeks' observing run of the TeV gamma-ray source.

Key words: galaxies: active --- Blazars: individual: PKS 0219+428 (3C 66A), PKS 0420--014 (OAl29), S5 0716+714, 0754+100 (OI090.4), 0827+243 (OJ248), 1652+398 (Mrk 501), 2200+420 (BL Lacertae), 2230+114 (CTAl02), 2251+158 (3C 454.3), and 1ES 2344+514 --- galaxies: photometry

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Evolution of M81 with Exponentially Decreasing Star Formation Rate of PEGASE

Jiu-Li Li, Xu Zhou, Jun Ma and Jian-Sheng Chen

Affiliation:   National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012

E-mail:   ljl@vega.bac.pku.edu.cn     (corresponding author)
  
Abstract

Based on the large field multicolor observations of Beijing-Arizona-Taiwan-Connecticut (BATC) program, we obtain the spectral energy distribution (SED) for individual regions of M81. We study the structure and evolution of M81 with an evolutionary population synthesis (EPS) model, PEGASE. We find that the exponentially deceasing star formation rate (SFR) with star formation scale 3 Gyr (hereafter Exp, $\tau$=3 Gyr) gives the best agreement between the model predictions and the observed SEDs. We then obtain the structure, age distribution and evolutionary history of M81. There is a clear age gradient between the central and outer regions. The populations in the central regions are older than 7 Gyr, those in the outer regions are younger, at about 4.5 Gyr. The youngest components in the spiral arms have ages of about 2.5 Gyr or less.

Key words: galaxies: individual (M81) --- galaxies: evolution --- galaxies: star general

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Stellar X-ray Sources in the Rosette Nebula

W. P. Chen (1), P. S. Chiang (1) and J. Z. Li (2)

Affiliation:   (1) Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
                    (2) National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012
                         
E-mail:      wchen@astro.ncu.edu.tw   (corresponding author)

Abstract

We present optical photometric and spectroscopic studies of ROSAT X-ray stellar sources in the Rosette Nebula star-forming region. The brightest X-ray sources are either massive stars or active T Tauri stars associated with the open cluster NGC 2244, or are foreground stars. Some of the spectra of the young stars newly identified in the region are presented.

Key words: stars: early-type --- stars: pre-main sequence --- stars: formation --- HII regions

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A Study on the Recovery and Classification of Meteorites from the Mt. Grove Region of Antarctica

Jian-Zhong Liu (1), Yong-Liao Zou (1), Chun-Lai Li (1), Lin Xu (1, 2) and Zi-Yuan Ouyang (1,2)

Affiliation:    (1) National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012  
                    (2) Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002

E-mail:    jzliu007@bao.ac.cn    (corresponding author)

Abstract

The Antarctic Continent has become the largest natural preservatory of meteorites in the world because of its unique geographical position and climatic conditions. Mt. Grove is located in the inland area of the Antarctic Continent where the conditions are favorable for the preservation of meteorites. During China's 15th, 16th and 19th Antarctic Scientific Explorations a large number of meteorites were recovered in the Mt. Grove region. Especially during the 19th Exploration in 2002/03 a total of 4448 meteorites were recovered, which at one stroke put China among countries that have recovered most numbers of meteorites. Here, we report mainly the results of microscope and electron microprobe studies of 28 meteorites recovered during the 16th Exploration. The meteorites are chemically classified based on their mean Fa contents of olivine, mean Fs contents of low-Ca pyroxene and abundances of Fe-Ni metal. We also give a brief account of the meteorite recovery during the three Explorations and of some preliminary classification results of the Antarctic meteorites.

Key words: Earth --- meteorites

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A New Catalogue of Fine Structures Superimposed on Solar Microwave Bursts

Qi-Jun Fu, Yi-Hua Yan, Yu-Ying Liu, Min Wang and Shu-Juan Wang

Affiliation:   National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012
                    
E-mail:    fuqijun2002@sohu.com     (corresponding author)

Abstract

The 2.6--3.8 GHz, 4.5--7.5 GHz, 5.2--7.6 GHz and 0.7--1.5 GHz component spectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations, respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed to catch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst data with high temporal and high spectral resolution and high sensitivity were obtained. A variety of fine structures (FS) superimposed on microwave bursts have been found. Some of them are known, such as microwave type III bursts, microwave spike emission, but these were observed with more detail; some are new. Reported for the first time here are microwave type U bursts with similar spectral morphology to those in decimetric and metric wavelengths, and with outstanding characteristics such as very short durations (tens to hundreds ms), narrow bandwidths, higher frequency drift rates and higher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra pattern and fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomena closely associated with CME are considered to manifest the initial phase of the CME, and quasi-periodic pulsation with periods of tens ms have been recorded. Microwave ``patches", unlike those reported previously, were observed with very short durations (about 300 ms), very high flux densities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths (about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotron process. A superfine structure in the form of microwave FS (ZPS, type U), consisting of microwave millisecond spike emission (MMS), was also found. 

Key words: Sun: flares --- Sun: radio radiation --- instrumentation: spectrographs

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The Effect of Solar Activity on the Annual Precipitation in the Beijing Area

Juan Zhao (1, 2), Yan-Ben Han (2) and Zhi-An Li (1,2)

Affiliation:  (1) Department of Astronomy, Beijing Normal University Beijing 100875
                   (2)  National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012
                    
E-mail:   zj@bnu.edu.cn     (corresponding author)

Abstract

Using continuous wavelet transform, we examine the relationship between solar activity and the annual precipitation in the Beijing area. The results indicate that the annual precipitation is closely related to the variation of sunspot numbers, and that solar activity probably plays an important role in influencing the precipitation on land.

Key words: Sun: activity --- sunspots --- solar-terrestrial relation

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A New Method for Optimizing the Configuration of the Chinese Square Kilometer Array

Yan Su, Ren-Dong Nan and Bo Peng

Affiliation:  National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012
                    
E-mail:   suyan@bao.ac.cn       (corresponding author)

Abstract

KARST, the Chinese SKA concept, consists of some 30 individual FAST-type elements to be set up in a karst region of Guizhou Province. A crucial question is how to select 30 optimized sites from hundreds of candidates. Here we introduce a uniform weight method, which can pick out suitable sites on the basis of uniformity and completeness of the u-v coverage. In order to meet some special scientific goals, such as imaging extended sources, a modification of this method is also discussed. Although the method is specially designed for the KARST array, it could be useful for more general types of arrays.

Key words: techniques: interferometric --- instrumentation: interferometers

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ChJAA, 2004, Vol.4, No.2

Chinese Journal of Astronomy and Astrophysics: Online Edition

http://www.chjaa.org 

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