从ROSAT数据中寻找河内X射线暂现源     

卢方军  孙学军 《中国天文和天体物理学报》1997,(3)

从ＲＯＳＡＴ巡天和定点观测结果的对比出发，发现了几个低银纬的巡天源表中的Ｘ射线源在定点观测中没有出现．本文计算了在这些位置的定点观测中出现点源的流强上限，发现比巡天源表中这些源的流强值低很多，这表明它们的流强变化很大，可能是Ｘ射线双星系统中的一类———Ｘ射线暂现源．  相似文献   

Optical Flash of GRB 990123: Constraints on the Physical Parameters of the Reverse Shock     

Yi-Zhong Fan  Zi-Gao Dai  Yong-Feng Huang  Tan Lu Department of Astronomy  Nanjing University  Nanjing 《中国天文和天体物理学报》2002,2(5):449-453

The optical flash accompanying GRB 990123 is believed to be powered by the reverse shock of a thin shell. With the best-fit physical parameters for GRB 990123 and the assumption that the parameters in the optical flash are the same as in the afterglow, we show that: 1) the shell is thick rather than thin, and we have provided the light curve for the thick shell case which coincides with the observation; 2) the theoretical peak flux of the optical flash accounts for only 3×10~-4 of the observed. In order to remove this discrepancy, the physical parameters, the electron energy and magnetic ratios, εe and εB, should be 0.61 and 0.39, which are very different from their values for the late afterglow.  相似文献   

基于Chandra的活动星系核观测     

李丹丹  王竞  陈阳  何香涛 《天文学进展》2005,23(3):239-247

活动星系核（AGN）是宇宙中最奇特的天体之一。它是真正意义上的全波天体，其中X射线波段的发射功率占到全波段功率的50％左右。AGN的X射线辐射研究涉及天体物理中的最基本问题，例如能量产生、辐射机制和宇宙论等，而Chandra X射线卫星的高分辨率图像和光谱对这一研究有着重要作用。以Chandra卫星的部分观测结果为例，简要介绍了几类不同类型AGN的X射线辐射研究进展：（1）宽吸收线类星体APM08279＋5255（z=3．91）的X射线谱分析，以及高红移类星体的观测概况；（2）Seyfert星系NGC 4151延展X射线发射问题的解决，及NGC 1068X射线辐射与光学波段的高激发态发射线（[OⅢ]λ5007）有很强相关性的发现；（3）6个BLLac天体样本的X射线环境分析；（4）射电星系X射线喷流的观测等。  相似文献   

Sequences in the Hardness Ratio-Peak Energy Plane of Gamma-Ray Bursts     

Xiao-Hong Cui  En-Wei Liang  Rui-Jing Lu National Astronomical Observatories/Yunnan Observatory  Chinese Academy of Sciences  Kunming  ciwei@.com Department of Physics  Guangxi University  Nanning Department of Astronomy  Nanjing University  Nanjing Graduate School of the Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2005,5(2):151-158

The narrowness of the distribution of the peak energy of the vFv spectrum of gamma-ray bursts (GRBs) and the unification of GRB populations are great puzzles yet to be solved. We investigate the two puzzles based on the global spectral behaviors of different GRB populations, the long GRBs, the short GRBs, and the X-ray flashes (XRFs), in the HR - Ep plane (HR the spectral hardness ratio) with BATSE and HETE-2 observations. It is found that the long GRBs and the XRFs observed by HETE-2 seem to follow the same sequence in the HR-Ep plane, with the XRFs at the low end of this sequence. We fit the sequence by a universal Band function, and find that this sequence is mainly defined by the low energy index α, and is insensitive to the high energy index,β. With fixed β=-5, a best fit is given by α=-1.00 with X^2min/dof=2.2. The long and short GRBs observed by BATSE follow significantly different sequences in the HR-Ep plane, with most of the short GRBs having a larger hardness ratio than the long GRBs at a given Ep. For the long GRBs a best-fit yields α=-0.30 and β=-2.05. For the short GRBs, a best fit gives α=-0.60 with x^2min=1.1 (withβfixed at-2.0 because it is numerically unstable). The α value for the short GRBs is significantly greater than that for the long GRBs. These results indicate that the global spectral behaviors of the long GRB sample and the XRF sample are similar, while that of the short GRBs is different. The short GRBs seem to be a unique subclass of GRBs, and they are not the higher energy extension of the long GRBs.  相似文献   

Is the Variable X—ray Source in M82 due to Gravitational Lensing？     

Da-Ming Chen 《中国天文和天体物理学报》2001,1(4):287-290

1 INTRODUCTIONObservations of the most famous starburst galaxy M82 with the High-Resolution Cameraon board the Chandra X-Ray Observatory, showed that there are nine sources in the celltral11 x 11 region, but no son-roe was detected at the galactic center (Matsumoto et al. 2001).Comparing the observations on 1999 October 28 and those on 2000 January 20, the authorsfound an extremely large time variability of the source CXO M82 J095550.2 694047, which islocated gll away from the galact…  相似文献   

1m望远镜夜间观测概况     

胡汉明  张文元 《云南天文台台刊》2001,(1):54-57

本文主要介绍1m望远镜夜间观测情况，并对夜间观测时段（有效观测时间）进行统计、分析，并给出其结果。  相似文献   

加像场改正透镜的1.56米天体测量望远镜的天体测量检验     

毛亚庆  陈进 《天文学报》1993,34(2):173-180

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丽江高美古的二期选址——望远镜地面高度的确定     

钱铜铃汪从云  岑学奋王建成 《云南天文台台刊》2003,(2):75-81

在丽江高美古前期选址工作的基础上^[1-2]，二期选址的望远镜地面高度的确定工作于2000年11月3日至2000年12月16日进行，采用30m铁塔的温度脉动测量装置，对6#选址观测点的近地面大气湍流进行反复多次测量，得到近地面不同高度(4-30m和8-22m)上每夜温度结构系数CT^2的平均值，对观测取得的资料作进一步处理和分析，得到高美古6#观测点的望远镜地面高度为13～15m。  相似文献   

不同速度模型条件下地震波走时的射线追踪计算     

嘉世旭 《物探化探计算技术》1993,15(3):218-225

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我国近年来天文的新发现     

胡景耀 《天文学进展》2001,19(2):92-93

这里叙述的新发现仅指某一特殊类型的发现（如新星，超新星和小行星等）及某一特殊类型天体的认证（如X射线源证认为类星体等），而不包括某一类天体的某种天象及未知性质源的列表（如深度成像观测得到的前人没有纪录过的一般天体，如恒星，但一些特殊天体亦列入），由于收集不全面和所谓“发现”定义的困难，向有发向而未列入者先歉意。从80年代后期开始，我国的观测设备有了很大垢发展，所以有一批重的的天文发现，为天文提供了很好的机会，它包括下面几方面，层系层次天体：（1）用X射线源和射电源证认了一批包括类星体，BL Lac天体，赛弗特天体在内的活动星系核；（2）用IRAS源证认了一批W－R星系；（3）BATC巡天在一个星系周围发现了一个“环”。恒星层次天体：（1）河外星系中发现了一批超新星的一个新星，（2）发现了和用ROSAT源证认了一批激变变星，（4）BATC和超新星巡天发现了一批变星，（4）发现了若干新的δSct变星，（5）发现了一批Herbig-Haro天体，（6）发现了一批水脉泽。行星层次天体：（1）发现了大批小行星，特别是有些是近地不行星，（20发现若干彗星。  相似文献