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1. chinaXiv:201708.00221 [pdf]

Quiescent photometric modulations of two low-inclination cataclysmic variables KZ Gem and TW Vir

Dai, Zhibin ; Szkody, Paula ; Taani, Ali; Garnavich, Peter M.; Kennedy, Mark
Comment:29 pages, 12 figures, accepted by A&A Journal
分类: 天文学 >> 恒星和银河系

Aims. The quiescent periodic photometric modulations of two low-inclination cataclysmic variables observed in Kepler K2 Campaigns 0 and 1, KZ Gem and TW Vir, are investigated. Methods. A phase-correcting method was successfully used to detect the orbital modulations of KZ Gem and TW Vir and improve their orbital periods. The light curve morphologies of both CVs were further analyzed by defining flux ratios and creating colormaps. Results. KZ Gem shows ellipsoidal modulations with an orbital period of 0.22242(1) day, twice the period listed in the updated RK catalogue (Edition 7.24). With this newly determined period, KZ Gem is no longer a CV in the period gap, but a long-period CV. A part of the quiescent light curve of TW Vir that had the highest stability was used to deduce its improved orbital period of 0.182682(3) day. The flat patterns shown in the colormaps of the flux ratios for KZ Gem demonstrate the stability of their orbital modulations, while TW Vir show variable orbital modulations during the K2 datasets. In TW Vir, the single versus double-peaked nature of the quiescent orbital variations before and after superoutburst may be related to the effect of the superoutburst on the accretion disk.

提交时间: 2017-08-17 点击量48, 下载量34

2. chinaXiv:201707.00113 [pdf]

A New Measurement of the Spectral Lag of Gamma-Ray Bursts and its Implications for Spectral Evolution Behaviors

Shao, Lang; Zhang, Bin-Bin ; Wang, Fu-Ri; Wu, Xue-Feng; Cheng, Ye-Hao; Zhang, Xi; Yu, Bang-Yao; Xi, Bao-Jia; Wang, Xue; Feng, Huan-Xue; Zhang, Meng; Xu, Dong
分类: 天文学 >> 天体物理学

We carry out a systematical study of the spectral lag properties of 50 single-pulsed Gamma-Ray Bursts (GRBs) detected by Fermi/GBM. By dividing the light curves into multiple consecutive energy channels we provide a new measurement of the spectral lag which is independent on energy channel selections. We perform a detailed statistical study of our new measurements. We find two similar power-law energy dependencies of both the pulse arrival time and pulse width. Our new results on the power-law indices would favor the relativistic geometric effects for the origin of spectral lag. However, a complete theoretical framework that can fully account for the diverse energy dependencies of both arrival time and pulse width revealed in this work is still missing. We also study the spectral evolution behaviors of the GRB pulses. We find that the GRB pulse with negligible spectral lag would usually have a shorter pulse duration and would appear to have a ``hardness-intensity tracking'' (HIT) behavior and the GRB pulse with a significant spectral lag would usually have a longer pulse duration and would appear to have a ``hard-to-soft'' (HTS) behavior.

提交时间: 2017-07-13 点击量78, 下载量49

3. chinaXiv:201705.00742 [pdf]

冰巨星大气研究进展

王聪
分类: 天文学 >> 天体物理学

摘要:与类木行星等气态巨行星相比,冰巨星是由大量比氢氦重的气体成分(水、氨、摘要:与类木行星等气态巨行星相比,冰巨星是由大量比氢氦重的气体成分(水、氨、甲烷等)组成的气体行星,天天星和海王星便是典型的冰巨星。天王星和海王星的大气中保存着太阳系形成初期的气体,对研究太阳系和行星的形成演化有很大帮助;对其大气的动力学研究可以了解到大气内部的结构、热源驱动机制和对流机制;随着证认的系外行星数量逐渐增加,发现类海王星型系外行星是普遍存在的。梳理了天王星和海王星的大气结构和大气成分以及太阳系外类海王星的研究进展,并对未来冰巨星的探测和研究做了展望。 关 键 词:行星;冰巨星;大气;成分;系外行星 1 引 言 冰巨星是指内部结构中有大量“冰”存在的巨行星,这种“冰”是由原始行星盘中低折射率的物质(比如H2O, CH4, NH3等)冷凝而成[1],其外围仍存在有大量的氢和氦。天王星和海王星是典型的冰巨星。天王星和海王星的成分和内部结构反映出了不同于气态巨行星(木星和土星)的形成环境和演化过程[2],同时二者在表面温度,有效温度,磁场结构、大气纬向环流等物理特征方面都十分的类似 [3]。天王星和海王星的质量分别为14.5M?和17.1M?(M?为地球质量),由于冰巨星的引力势能较大,对于太阳系的形成起到了重要的作用,它们保留了大量太阳系形成初期的气体[1],包含着原恒星云的状态条件和行星形成的位置信息[2],因此研究冰巨星的大气成分和大气结构不仅有助于研究其内部热源的驱动机制和对流机制,也有助于研究太阳系和行星的形成及演化历史。 在太阳系内的冰巨星(天王星、海王星)由于距离比较远,目前只有 1977 年美国发射的“旅行者 2 号”飞行器对其进行过飞掠探测[4-6],此后便没有飞行器对其进行过近距离考察。根据“旅行者 2 号”飞行器的射电掩星观测[7, 8],木星和土星的大气温度分别为165 ± 5K和134 ± 4K(1bar处),而天王星和海王星的大气温度分别为76 ± 2K和72 ± 2K(1bar处),可见冰巨星的大气温度是远远低于气态巨行星的。 气态巨行星有大体积的气态

提交时间: 2017-05-12 点击量969, 下载量292

4. chinaXiv:201611.00882 [pdf]

虚拟天文台

赵永恒
分类: 天文学 >> 天文学

四百年前伽利略发明了天文望远镜,使人类首次摆脱了用肉眼直接观测天空的历史,为从哥白尼开始的天文学革命提供了大量的科学证据。历史悠久的天文学经过哥白尼、伽利略、开普勒和牛顿等人的发展,演变成了一门崭新的科学,同时也催生了现代科学技术。

提交时间: 2016-11-16 点击量492, 下载量189

5. chinaXiv:201611.00880 [pdf]

中国虚拟天文台

赵永恒; 崔辰州
分类: 天文学 >> 天文学

目前,虚拟天文台已经成为世界天文学界乃至 IT 界的热门话题。美国、欧盟、英国的虚拟天文台计划已经进入实施阶段,更多国家的类似计划正在酝酿之中,国际虚拟天文台联盟初现端倪。如此形势之下,中国为什么有必要建立自己的虚拟天文台?中国虚拟天文台将有何特色,对国际虚拟天文台会有怎样的贡献?中国虚拟天文台将采用何种体系结构,何时能实现?本文就这些问题进行了探讨。

提交时间: 2016-11-16 点击量449, 下载量168

6. chinaXiv:201611.00879 [pdf]

VOFilter, Bridging Virtual Observatory and Industrial Office Applications

Chen-zhou Cui; Markus Dolensky; Peter Quinn; Yong-heng Zhao; Fran鏾ise Genova
分类: 天文学 >> 天文学

VOFilter is an XML based filter developed by the Chinese Virtual Observatory project to transform tabular data files from VOTable format into OpenDocument format. VOTable is an XML format defined for the exchange of tabular data in the context of the Virtual Observatory (VO). It is the first Proposed Recommendation defined by International Virtual Observatory Alliance, and has obtained wide support from both the VO community and many Astronomy projects. OpenOffice.org is a mature, open source, front office applications suite with the advantage of native support of industrial standard OpenDocument XML file format. Using the VOFilter, VOTable files can be loaded in OpenOffice.org Calc, a spreadsheet application, and then displayed and analyzed as other spreadsheet files. Here, the VOFilter acts as a connector, bridging the coming VO with current industrial office applications. Virtual Observatory and technical background of the VOFilter are introduced. Its workflow, installation and usage are presented. Existing problems and limitations are also discussed together with the future development plans.

提交时间: 2016-11-16 点击量337, 下载量201

7. chinaXiv:201611.00877 [pdf]

互动式数字天象厅的研究与集成设计

徐鹏飞
分类: 天文学 >> 天文学

本文提出了一种天象厅环境下的座席区设计方法,该方法将天象厅中的观众体验感分为五类,将感官体验量化,分别进行数学建模,然后将五个模型根据比重综合,得到天象厅中体验感的数学模型,对其进行分析得出较优的座席区范围,并引入偏转角变量设计了固定座席区与旋转座席区。并针对天象厅超大垂直面视野设计了一种座椅,该座椅能舒适地为观众提供较大的仰角观看节目

提交时间: 2016-11-16 点击量726, 下载量473

8. chinaXiv:201611.00866 [pdf]

Update of the China-VO AstroCloud

Chenzhou Cui; Ce Yu; Jian Xiao; Boliang He; Changhua Li; Dongwei Fan; Chuanjun Wang; Zhi Hong; Shanshan Li; Linying Mi; Wanghui Wan1; Zihuang Cao; Jiawei Wang; Shucheng Yin; Yufeng Fan; Jianguo Wang; Sisi Yang; Yin Ling; Hailong Zhang; Junyi Chen
分类: 天文学 >> 天文学

As the cyber-infrastructure for Astronomical research from Chinese Virtual Observatory (China-VO) project, AstroCloud has been archived solid progresses during the last one year. Proposal management system and data access system are redesigned. Several new sub-systems are developed, including China-VO PaperData, AstroCloud Statics and Public channel. More data sets and application environments are integrated into the platform. LAMOST DR1, the largest astronomical spectrum archive was released to the public using the platform. The latest progresses will be introduced.

提交时间: 2016-11-16 点击量320, 下载量128

9. chinaXiv:201611.00865 [pdf]

The LAMOST Data Archive and Data Release

Boliang He; Dongwei Fan; Chenzhou Cui; Shanshan Li; Changhua Li; Linying Mi
分类: 天文学 >> 天文学

The Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is the largest optical telescope in China. In last four years, the LAMOST telescope has published four editions data (pilot data release, data release 1, data release 2 and data release 3). To archive and release these data (raw data, catalog, spectrum etc),we have set up a data cycle management system, including the transfer of data, archiving,backup. And through the evolution of four software versions, mature established data release system.

提交时间: 2016-11-16 点击量266, 下载量120

10. chinaXiv:201611.00860 [pdf]

Efficient Catalog Matching with Dropout Detection

Dongwei Fan; Tam碼s Budav碼ri; Alexander S. Szalay; Chenzhou Cui; Yongheng Zhao
分类: 天文学 >> 天文学

Not only source catalogs are extracted from astronomy observations. Their sky coverage is always carefully recorded and used in statistical analyses, such as correlation and luminosity function studies. Here we present a novel method for catalog matching, which inherently builds on the coverage information for better performance and completeness. A modified version of the Zones Algorithm is in-troduced for matching partially overlapping observations, where irrelevant parts of the data are excluded up front for efficiency. Our design enables searches to focus on specific areas on the sky to further speed up the process. Another im-portant advantage of the new method over traditional techniques is its ability to quickly detect dropouts, i.e., the missing components that are in the observed regions of the celestial sphere but did not reach the detection limit in some observations. These often provide invaluable insight into the spectral energy dis-tribution of the matched sources but rarely available in traditional associations.

提交时间: 2016-11-15 点击量335, 下载量171

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