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The LAMOST spectroscopic survey of globular clusters in M31and *** and new identifications

research in astronomy and Astrophysics 2015年第8期15卷 1392-1413页

作者： Bing-Qiu Chen Xiao-Wei Liu Mao-Sheng Xiang Hai-Bo Yuan Yang Huang Zhi-Ying Huo Ning-Chen Sun Chun Wang Juan-Juan Ren Hua-Wei Zhang Alberto Rebassa-Mansergas Ming Yang Yong Zhang Yong-Hui Hou Yue-Fei Wang Department of astronomy Peking University Kavli institute for astronomy and Astrophysics Peking University national Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Optical astronomy National Astronomical ObservatoriesChinese Academy of Sciences Nanjing institute of Astronomical Optics & Technology National Astronomical ObservatoriesChinese Academy of Sciences

We present a catalog of 908 objects observed with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope（LAMOST） in fields in the vicinity of M31 and M33, targeted as globular clusters（GCs） and candidates. The targets include known GCs and candidates selected from the literature, as well as new candidates selected from the Sloan Digital Sky Survey（SDSS）. Analysis shows that 356 of them are likely GCs with various confidence levels, while the remaining ones turn out to be background galaxies and quasars, stars and H II regions in M31 or foreground Galactic stars. The 356 likely GCs include 298 bona fide GCs and 26 candidates known in the literature. Three candidates, selected from the Revised Bologna Catalog of M31 GCs and candidates（RBC） and one possible cluster from Johnson et al., are confirmed to be bona fide clusters. We search for new GCs in the halo of the M31 among the new candidates selected from the SDSS photometry. Based on radial velocities yielded by LAMOST spectra and visual examination of the SDSS images, we find 28 objects, 5bona fide and 23 likely GCs. Among the five bona fide GCs, three have been recently discovered independently by others, and the remaining 25 are our new identifications,including two bona fide ones. The newly identified objects fall at projected distances ranging from 13 to 265 kpc from M31. Of the two newly discovered bona fide GCs,one is located near M33, probably a GC belonging to M33. The other bona fide GC falls on the Giant Stream with a projected distance of 78 kpc from M31. Of the 23 newly identified likely GCs, one has a projected distance of about 265 kpc from M31 and could be an intergalactic cluster.

关键词： galaxies: individual: M31 M33—galaxies: star clusters—galaxies: Local Group

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Source mechanism of small-moderate earthquakes and tectonic stress field in Yunnan Province

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Acta Seismologica Sinica(English Edition) 2004年第5期17卷 509-517页

作者： WU Jian-ping(吴建平) MING Yue-hong(明跃红) WANG Chun-yong(王椿镛) institute of geophysics China Earthquake AdministrationBeijing100081China Institute of GeophysicsChina Earthquake AdministrationBeijing100081China Institute of GeophysicsChina Earthquake AdministrationBeijing100081China

In the paper, source mechanisms of 33 small-moderate earthquakes occurred in Yunnan are determined by modeling of regional waveforms from Yunnan digital seismic network. The result shows that most earthquakes occurred within or near the Chuandian rhombic block have strike-slip mechanism. The orientations of maximum compressive stresses obtained from source mechanism are changed from NNW-SSN to NS in the areas from north to south of the block, and tensile stresses are mainly in ENE-WSW or NE-SE. In the eastern Tibetan Plateau, the orientations of maximum compressive stress radiate toward outside from the plateau, and the tensile stress orientations mostly parallel to arc structures. Near 28N the orientations of both maximum compressive stress and tensile stress changed greatly, and the boundary seems to correspond to the southwestern extended line of Longmenshan fault. Outside of the Chuandian rhombic block, the orientations of P and T axes are some different from those within the block. The comparison shows that the source mechanism of small-moderate events presented in the paper is consistence with that of moderate-strong earthquakes determined by Harvard University, which means the source mechanism of small-moderate events can be used to study the tectonic stress field in this region.

关键词： source mechanism small-moderate earthquakes stress field Yunnan

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Modeling the global ionospheric total electron content with empirical orthogonal function analysis

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Science China(Technological Sciences) 2012年第5期55卷 1161-1168页

作者： WAN WeiXing DING Feng REN ZhiPeng ZHANG ManLian LIU LiBo NING BaiQi Beijing national Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

In the present work we model the global ionospheric total electron content (TEC) with the analysis of empirical orthogonal functions (EOF). The obtained statistical eigen modes, which makeup the modeled TEC, consist of two factors: the eigen vectors mapping TEC patterns at latitude and longitude (or local time LT), and the corresponding coefficients displaying the TEC variations in different time scales, i.e., the solar cycle, the yearly (annual and semiannual) and the diurnal universal time variations. It is found that the EOF analysis can separate the TEC variations into chief processes and the first two modes illustrate the most of the ionospheric climate properties. The first mode contains both the semiannual component which shows the semiannual ionospheric anomaly and the annual component which shows the annual or non-seasonal ionospheric anomaly. The second mode contains mainly the annual component and shows the normal seasonal ionospheric variation at most latitudes and local time sectors. The annual component in the second mode also manifests seasonal anomaly of the ionosphere at higher mid-latitudes around noontime. It is concluded that the EOF analysis, as a statistical eigen mode method, is resultful in analyzing the ionospheric climatology hence can be used to construct the empirical model for the ionospheric climatology.

关键词： ionospheric modeling total electron content empirical orthogonal functions

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Stellar X-ray Sources in the Rosette Nebula

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Chinese Journal of astronomy and Astrophysics 2004年第2期4卷 153-165页

作者： W.P.Chen P.S.Chiang J.Z.Li institute of astronomy National Central UniversityChung-Li 32054Taiwan national Astronomical Observatories Chinese Academy of SciencesBeijing 100012

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.

关键词： stars: early-type stars: pre-main sequence stars: formation HII regions

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Lithospheric strength of the Anatolian plateau and implications for strong earthquake activity in Turkey

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Geodesy and Geodynamics 2024年第3期15卷 209-218页

作者： Yuhang Pan Shi Chen Wen Shi institute of geophysics China Earthquake AdministrationBeijing 100081China Beijing Baijiatuan Earth Science national Observation and research Station Beijing 100095China

On February 6, 2023, the doublet earthquake including two main shocks with magnitudes M_(W)7.8 and M_(W)7.5, occurred near the western side of the East Anatolian Fault at the southeast boundary of the Anatolian Plateau in Turkey. Based on the WGM2012 Bouguer gravity anomaly data and the Etopo1topography data, this study first introduced a joint inversion of admittance and coherence functions and used the Bayesian optimal parameter estimation method to obtain the effective elastic thickness Teand loading ratio F of the lithosphere for various tectonic units in the Anatolian Plateau. Secondly, we discussed the characteristics and influencing factors of the lithospheric mechanical strength and analyzed its relationship with seismic activity. The lithospheric mechanical strength of the Anatolian Plateau showed clear lateral heterogeneity and a "weak-strong-weak" spatial pattern from east to west,reflecting various tectonic processes. At last, the strong seismic activity was found where the lithospheric strength was low in the Anatolian Plate. We also incorporated GPS strain rate and other results to investigate the tectonic background and primary causes of the M_(W)7.8 and M_(W)7.5 doublet earthquakes in Turkey. The results have a good insight into urban safety design in the Turkish region, including postdisaster rehabilitation, earthquake hazard assessment, and loss reduction.

关键词： Effective elastic thickness Anatolian plateau Turkey doublet earthquakes Bayesian optimization

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Comparing the diurnal variations in the SuperMAG auroral electrojet indices SML and SMU

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Chinese Science Bulletin 2014年第29期59卷 3877-3883页

作者： Yuan Wang Aimin Du Gengxiong Chen Xin Cao Ying Zhang Min Li Xiaocan Liu Jianpeng Guo Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing national Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences University of Chinese Academy of Sciences institute of geophysics China Earthquake Administration State Key Laboratory of Space Weather Center for Space Science and Applied ResearchChinese Academy of Sciences

Diurnal variations of the SuperMAG auroral electrojet indices(SML and SMU)were examined for the period of 1980–2010,and the differences between SML and SMU were especially *** diurnal variation of SML with a maximum at around 1100 UT has a prenoonpostnoon *** solstices,the diurnal variation of SML is much stronger than that at *** the SMU,two maxima are recorded in the diurnal variation with the bigger one at 1700 UT and the smaller one at 0400 *** seasonal variations are not obvious in the UT variation characteristics of SMU although the intensity of SMU is changed remarkably season by *** both SML and SMU,the contributing stations are located at higher geomagnetic latitude around 1600 UT and at lower geomagnetic latitude around 0400 *** results indicate that:(1)the SML is mostly controlled by the convection electric *** diurnal variation is mainly correlated with the equinoctial and R-M hypothesis;(2)the SMU is largely controlled by the ionospheric *** diurnal variation is tightly correlated with the solar radiation.

关键词： SMU SML 日变化电喷极光昼夜变化 UT变化季节变化

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Constraints on holographic QCD phase transitions from PTA observations

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Science China(Physics,Mechanics & astronomy) 2025年第1期Mechanics & Astronomy) .卷 71-78页

作者： Song He Li Li Sai Wang Shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin University School of Physical Science and Technology Ningbo University Max Planck institute for Gravitational Physics (Albert Einstein institute) CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences (UCAS) School of Physical Sciences University of Chinese Academy of Sciences (UCAS) Theoretical Physics Division Institute of High Energy Physics Chinese Academy of Sciences

The underlying physics of QCD phase transition in the early Universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT) left undetermined. At specific baryon chemical potential, the first-order QCD phase transition agrees with the observational constraint of baryon asymmetry. It, therefore, provides a scenario for phase transition gravitational waves(GWs) within the standard model of particle physics. If these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA) observations, the duration of this FoPT can be well constrained, and the associated primordial black holes are still allowed by current observations.

关键词： pulsar timing array QCD phase transition gravitational waves primordial black holes

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A proper motion study of the globular cluster M12(NGC 6218)

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research in astronomy and Astrophysics 2018年第10期18卷 97-108页

作者： Devesh P.Sariya Ing-Guey Jiang R.K.S.Yadav Department of Physics and institute of astronomy National Tsing Hua UniversityHsin-Chu Aryabhatta research institute of observational sciencES(ARIES) Manora PeakNainital 263 002India

Using astrometric techniques developed by Anderson et al., we determine proper motions （PMs） in the ~ 14.60 × 16.53 arcmin^2 area of the kinematically ＂thick-disk＂ globular cluster M 12. The cluster＇s proximity and sparse nature makes it a suitable target for ground-based telescopes. Archive images with time gap of ~ 11.1 years were observed with the wide-field imager （WFI） mosaic cam-era mounted on the ESO 2.2m telescope. The median value of PM error in both components is 0.7masyr^-1 for the stars having V ≤ 20mag. PMs are used to determine membership probabil-ities and to separate field stars from the cluster sample. In electronic form, a membership catalog of 3725 stars with precise coordinates, PMs and BVRI photometry is being provided. One of the possible applications of the catalog is demonstrated by gathering the membership information of the variable stars, blue stragglers and X-ray sources reported earlier in the cluster＇s region.

关键词： Galaxy globular clusters - astrometry - catalogs - individual M12

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Ion dynamics associated with substorm dipolarization fronts

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Science China Earth Sciences 2014年第10期57卷 2543-2551页

作者： FU Song Maha ASHOUR-ABDALLA DENG XiaoHua Mostafa EL-ALAOUI ZHOU Meng Robert L RICHARD Raymond J WALKER YUAN ZhiGang School of Electronic and Information Wuhan University institute of geophysics and Planetary Physics University of California Department of Physics and astronomy University of California institute of Space Science and Technology Nanchang University Department of Earth Planetary and Space Sciences University of California national Science Foundation

We report where and how ions are accelerated in the proximity of earthward propagating dipolarization fronts （DFs） in the magnetotail during a magnetospheric substorm on February 15, 2008. Two DFs were observed by multiple THEMIS space- craft in the near-Earth magnetotail （-10 Re）. We studied the ion dynamics associated with these DFs by comparing observed results with large scale kinetic （LSK） simulation results. The LSK simulation reproduced the sudden ion energy flux enhance- ment concurrent with the arrival of the DF at the satellite locations. We found that ions can be accelerated to more than 100 keV energy at the DF. These ions were initially non-adiabatically accelerated near magnetic reconnection site and then still non-adiabatically accelerated at the DF structure.

关键词： dipolarization front particle simulation ion acceleration

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Study of the relationship between fractures and highly productive shale gas zones, Longmaxi Formation, Jiaoshiba area in eastern Sichuan

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Petroleum Science 2018年第3期15卷 498-509页

作者： Yu-Feng Li Wei Sun Xi-Wu Liu Dian-Wei Zhang Yan-Chun Wang Zhi-Yuan Liu School of geophysics and Information Technology China University of Geoscience research institute of Petroleum Exploration and Development Sinopec

Shale fractures are an important factor controlling shale gas enrichment and high-productivity zones in the Longmaxi Formation, Jiaoshiba area in eastern Sichuan. Drilling results have, however, shown that the shale fracture density does not have a straightforward correlation with shale gas productivity. Based on logging data, drilling and seismic data, the relationship between shale fracture and shale gas accumulation is investigated by integrating the results of experiments and geophysical methods. The following conclusions have been drawn：（1） Tracer diffusion tests indicate that zones of fracture act as favorable channels for shale gas migration and high-angle fractures promote gas accumulation.（2） Based on the result of azimuthal anisotropy prediction, a fracture system with anisotropy strength values between 1 and 1.15 represents a moderate development of high-angle fractures, which is considered to be favorable for shale gas accumulation and high productivity, while fracture systems with anisotropy strength values larger than 1.15 indicate over-development of shale fracture, which may result in the destruction of the shale reservoir preservation conditions.

关键词： Azimuthal anisotropy Fracture prediction Shale Shale gas Shale reservoir preservation conditions

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