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GRB Energies and Eγ-Epeak Correlation with the Jet Expanding Laterally at the Sound Speed 伽马射线暴能量和e - γ-峰值与喷流在声速下横向膨胀的关系
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/05
Xiao-Hong Zhao, J. Bai
{"title":"GRB Energies and Eγ-Epeak Correlation with the Jet Expanding Laterally at the Sound Speed","authors":"Xiao-Hong Zhao, J. Bai","doi":"10.1088/1009-9271/7/4/05","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/05","url":null,"abstract":"A Gamma-ray burst (GRB) is generally believed to be a jet with a small opening angle, this opening angle is usually derived with the afterglow light curve break time using an analytical method. Here we show that the method is not accurate. Using the set of equations of hydrodynamic evolution with the sideways expansion at the local sound speed derived by previous authors and the observed light curve break times, we numerically derive the initial opening angles. Then the collimation-corrected energies (E-gamma) for a sample of GRBs are calculated. They are found to show a wide spread, suggesting that the previously declared clustering by some authors may not exist. Also, the E-peak - E-gamma relation, claimed by some other authors (E-peak is the spectral peak energy), is found still to hold, with a slightly stronger correlation.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"166 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114430915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Velocity Distance of the Open Cluster M11 疏散星团M11的速度距离
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/14
Jun-liang Zhao, Li Chen
{"title":"Velocity Distance of the Open Cluster M11","authors":"Jun-liang Zhao, Li Chen","doi":"10.1088/1009-9271/7/4/14","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/14","url":null,"abstract":"On the reasonable hypothesis that the internal motions of member stars of a cluster are random and isotropic, a method which can be used to estimate the velocity distance of the cluster and its uncertainty is developed. The velocity distance so determined is an absolute distance estimate, and is completely independent of the (widely used) luminosity distance, which is a relative distance estimate. Using the published high-accuracy observational data of radial velocities and proper motions of the stars in the open cluster M11 region, we have determined the distance of M11 to be 1.89±0.52 kpc. This is in quite good agreement with the published luminosity distances of the cluster. We briefly discuss the problems concerned, including the sources of errors in the method and its applicable range.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"419 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126703595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Model for Contact Binary Systems 接触二元系统的一个模型
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/10
Hanfeng Song, Run-qian Huang, S. Bi
{"title":"A Model for Contact Binary Systems","authors":"Hanfeng Song, Run-qian Huang, S. Bi","doi":"10.1088/1009-9271/7/4/10","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/10","url":null,"abstract":"A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understanding that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rotation and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M(circle dot) and one 5M(circle dot) star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133324487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
The multi-wavelength quasar survey - IV. Quasars in the Leo cluster 多波长类星体巡天——四。狮子座星团中的类星体
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/17
Yang Chen, Y. Bai, Xiangtao He, Jianghua Wu, Jing Wang, Qing-Kang Li, Yanchun Sun, R. Green, W. Voges
{"title":"The multi-wavelength quasar survey - IV. Quasars in the Leo cluster","authors":"Yang Chen, Y. Bai, Xiangtao He, Jianghua Wu, Jing Wang, Qing-Kang Li, Yanchun Sun, R. Green, W. Voges","doi":"10.1088/1009-9271/7/4/17","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/17","url":null,"abstract":"We aim to provide a quasar sample that is more complete than any previous surveys by using a combined selection technique to reduce the selection effects. Here we present the observational results for the X-ray candidates in the field of the Leo Cluster. We found 33 X-ray AGNs in this field of which 10 are new discoveries. The X-ray data and optical spectra of these AGNs are given. We also study the near-IR properties of the X-ray-selected AGNs by using the data from 2MASS. Most of the AGNs in our sample span the color range 0.0 <  B − J  < 2.5, 1.0 <  J − K s  < 2.0 and 0.5 <  H − K s  < 1.2.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116669076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Velocity Curve Analysis of Spectroscopic Binary Stars AI Phe, GM Dra, HD 93917 and V502 Oph by Nonlinear Regression 光谱双星AI Phe、GM Dra、HD 93917和V502 Oph速度曲线的非线性回归分析
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/12
K. Karami, R. Mohebi
{"title":"Velocity Curve Analysis of Spectroscopic Binary Stars AI Phe, GM Dra, HD 93917 and V502 Oph by Nonlinear Regression","authors":"K. Karami, R. Mohebi","doi":"10.1088/1009-9271/7/4/12","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/12","url":null,"abstract":"We introduce a new method to derive the orbital parameters of spectroscopic binary stars by nonlinear least squares of (o−c). Using the measured radial velocity data of the four double lined spectroscopic binary systems, AI Phe, GM Dra, HD 93917 and V502 Oph, we derived both the orbital and combined spectroscopic elements of these systems. Our numerical results are in good agreement with the those obtained using the method of Lehmann-Filhes.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121687215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 11
Disk Thicknesses and Some Parameters of 108 Non-Edge-On Spiral Galaxies 108个非边缘螺旋星系的盘厚及一些参数
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/15
T. Hu, Q. Peng, H. Zong
{"title":"Disk Thicknesses and Some Parameters of 108 Non-Edge-On Spiral Galaxies","authors":"T. Hu, Q. Peng, H. Zong","doi":"10.1088/1009-9271/7/4/15","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/15","url":null,"abstract":"We present disk thicknesses, some other parameters and their statistics of 108 non-edge-on spiral galaxies. The method for determining the disk thickness is based on solving Poisson's equation for a disturbance of matter density in three-dimensional spiral galaxies. From the spiral arms found we could obtain the pitch angles, the inclination of the galactic disk, and the position of the innermost point (the forbidden region with radius r 0 to the galactic center) of the spiral arm, and finally the thickness.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133642645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Observational Features of Large-Scale Structures as Revealed by the Catastrophe Model of Solar Eruptions 太阳爆发突变模型揭示的大尺度结构观测特征
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/01
Jun Lin
{"title":"Observational Features of Large-Scale Structures as Revealed by the Catastrophe Model of Solar Eruptions","authors":"Jun Lin","doi":"10.1088/1009-9271/7/4/01","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/01","url":null,"abstract":"Large-scale magnetic structures are the main carrier of major eruptions in the solar atmosphere. These structures are rooted in the photosphere and are driven by the unceasing motion of the photospheric material through a series of equilibrium configurations. The motion brings energy into the coronal magnetic field until the system ceases to be in equilibrium. The catastrophe theory for solar eruptions indicates that loss of mechanical equilibrium constitutes the main trigger mechanism of major eruptions, usually shown up as solar flares, eruptive prominences, and coronal mass ejections (CMEs). Magnetic reconnection which takes place at the very beginning of the eruption as a result of plasma instabilities/turbulence inside the current sheet, converts magnetic energy into heating and kinetic energy that are responsible for solar flares, and for accelerating both plasma ejecta (flows and CMEs) and energetic particles. Various manifestations are thus related to one another, and the physics behind these relationships is catastrophe and magnetic reconnection. This work reports on recent progress in both theoretical research and observations on eruptive phenomena showing the above manifestations. We start by displaying the properties of large-scale structures in the corona and the related magnetic fields prior to an eruption, and show various morphological features of the disrupting magnetic fields. Then, in the framework of the catastrophe theory, we look into the physics behind those features investigated in a succession of previous works, and discuss the approaches they used.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126808339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Linear correlations between peak frequency of gyrosynchrotron spectrum and photosphere magnetic fields 陀螺同步加速器谱峰频率与光球磁场的线性相关关系
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-08-01 DOI: 10.1088/1009-9271/7/4/03
A. Zhou, Hannan Li
{"title":"Linear correlations between peak frequency of gyrosynchrotron spectrum and photosphere magnetic fields","authors":"A. Zhou, Hannan Li","doi":"10.1088/1009-9271/7/4/03","DOIUrl":"https://doi.org/10.1088/1009-9271/7/4/03","url":null,"abstract":"The gyrosynchrotron spectra are computed in a nonuniform magnetic field case, taking into account the self- and gyroresonance absorption. It is found that the peak frequency nu(p) of the gyrosynchrotron spectrum systematically increases with the increasing photosphere magnetic field strength B-0 and increasing viewing angle theta. It is also found for the first time that there are good positive linear correlations between nu(p) and B-0, and between log nu(p) and log theta, with linear correlation coefficient 0.99 between nu(p) and B-0 and 0.95 between log nu(p) and log theta. We apply the correlations to analyze two burst events observed with OVSA and find that the evolution tendencies of the photosphere magnetic field strength B-0 estimated from the above expression are comparable with the observational results of SOHO/MDI. We also give a comparison of the diagnostic results of coronal magnetic field strength in both uniform and nonuniform source models.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131733184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Two Novel Approaches for Photometric Redshift Estimation based on SDSS and 2MASS 基于SDSS和2MASS的两种光度红移估计新方法
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-07-16 DOI: 10.1088/1009-9271/8/1/13
Danial Q. Wang, Yan-Xia Zhang, Chao Liu, Yong-heng Zhao
{"title":"Two Novel Approaches for Photometric Redshift Estimation based on SDSS and 2MASS","authors":"Danial Q. Wang, Yan-Xia Zhang, Chao Liu, Yong-heng Zhao","doi":"10.1088/1009-9271/8/1/13","DOIUrl":"https://doi.org/10.1088/1009-9271/8/1/13","url":null,"abstract":"We investigate two training-set methods: support vector machines (SVMs) and Kernel Regression (KR) for photometric redshift estimation with the data from the databases of Sloan Digital Sky Survey Data Release 5 and Two Micron All Sky Survey. We probe the performances of SVMs and KR for different input patterns. Our experiments show that with more parameters considered, the accuracy does not always increase, and only when appropriate parameters are chosen, the accuracy can improve. For different approaches, the best input pattern is different. With different parameters as input, the optimal bandwidth is dissimilar for KR. The rms errors of photometric redshifts based on SVM and KR methods are less than 0.03 and 0.02, respectively. Strengths and weaknesses of the two approaches are summarized. Compared to other methods of estimating photometric redshifts, they show their superiorities, especially KR, in terms of accuracy.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"433 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116548739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 25
Improbability of DUrca Process Constraints EOS DUrca过程约束的非概率性
Chinese Journal of Astronomy and Astrophysics Pub Date : 2007-06-28 DOI: 10.1088/1009-9271/7/6/08
Hao Tong, Qiu-he Peng
{"title":"Improbability of DUrca Process Constraints EOS","authors":"Hao Tong, Qiu-he Peng","doi":"10.1088/1009-9271/7/6/08","DOIUrl":"https://doi.org/10.1088/1009-9271/7/6/08","url":null,"abstract":"According to recent observational and theoretical progresses, the DUrca process (direct Urca process) may be excluded from the category of neutron star cooling mechanisms. This result, combined with the latest nuclear symmetry energy experiments, will provide us an independent way of testing the EOS (equation of state) for supernuclear density. For example, soft EOSs, such as FPS, will probably be excluded.","PeriodicalId":124495,"journal":{"name":"Chinese Journal of Astronomy and Astrophysics","volume":"250 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123033905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
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