Discovery of six high-redshift quasars with the Lijiang 2.4 m telescope and the Multiple Mirror Telescope     

Xue-Bing Wu  Wen-Wen Zuo  Qian Yang  Wei-Min Yi  Chen-Wei Yang  Wen-Juan Liu  Peng Jiang  Xin-Wen Shu  and Hong-Yan Zhou 《天文和天体物理学研究(英文版)》2012,(9):1185-1190

Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.  相似文献   

Environmental dependence of stellar mass,SFR, and SSFR for the Luminous Red Galaxy (LRG) sample of the SDSS DR7     

X.‐F. Deng  B. Yang  Y.‐P. Ding  P. Jiang 《Astronomische Nachrichten》2012,333(7):644-647

Using the Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), we investigate the environmental dependence of stellar mass, star formation rate (SFR) and specific star formation rate (SSFR) of LRGs. It is found that stellar mass of LRGs nearly is independent of local environments, and that the environmental dependence of SFR and SSFR in the LRG sample is much weaker than the one in the Main galaxy sample. One possible explanation is that galaxy color and morphology are a pair of galaxy properties most predictive of local environments, while LRGs are a group of galaxies that are likely to be luminous, red and of early types (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Study on the Stressed Mirror Polishing with a Continuous Polishing Machine for Large Aperture Off-axis Aspheric Mirrors     

Li Xin-nan  Zhang Hai-ying  Cui Xiang-qun  Jiang Zi-bo  Zheng Yi  Liu Xing-tao  Ni Hou-kun 《Chinese Astronomy and Astrophysics》2012

A special stressed annular polishing technique is proposed to mill the off-axis aspheric sub-mirrors of a large segmented mirror with an annular polishing machine. Based on the basic principle of stressed annular polishing technique, a set of special stressing mechanisms are designed to convert milling the aspheric surfaces of sub-mirrors with different off-axis distances into milling the spherical surfaces with identical radii of curvature, so that they can be pol- ished simultaneously on a continuous polishing machine. It took about contin- uous 40 hours to polish a scaled-down mirror of the planning Chinese Future Giant Telescope (CFGT) using this technique. This mirror has the 330 mm di- ameter, 3.6 m off-axis distance, and the 21.6 m radius of curvature, and its max- imum asphericity is 16 micron. The experiment shows that this method has a high effciency, suits batch manufacturing, especially the batch manufacturing of aspheric sub-mirrors of the segmented primary mirror of an extremely large aperture telescope.  相似文献   

The Asymmetrical Eruption of a Quiescent Filament and Associated Halo CME     

J. Yang  Y. Jiang  B. Yang  R. Zheng  D. Yang  J. Hong  H. Li  Y. Bi 《Solar physics》2012,279(1):115-126

We will present detailed observations of the asymmetrical eruption of a large quiescent filament on 24 November 2002, which was followed by a two-ribbon flare, three coronal dimmings, endpoint brightenings, and a very fast halo-type coronal mass ejection (CME). Before the eruption, the filament lay along the main neutral line (MNL) underneath a single-arcade helmet streamer with a simple bipolar configuration. However, photospheric magnetic fields on both sides of the filament showed an asymmetrical distribution, and the filament and MNL were not located just at the center of the streamer base but were closer to the eastern leg of the streamer arcade. Therefore, instead of erupting along the streamer’s symmetrical axis, the filament showed a nonradial and asymmetrical eruption. It lifted from the eastern flank of the streamer arcade to impact the western leg directly, leading to an asymmetrical CME that expanded westward; eventually the streamer was disrupted significantly. Accordingly, the opposite-polarity coronal dimmings at both sides of the filament forming in the eruption also showed an asymmetrical area distribution. We thus assume that the streamer arcade could guide the filament at the early eruption phase but failed to restrain it later. Consistent with previous results, these observations suggest that the global background magnetic field can impose additional action on the initial eruption of the filament and CME, as well as the dimming configuration.  相似文献   

川滇地区电离层多参量异常监测系统的设计与实现          下载免费PDF全文

刘江  徐锐  陈聪  饶太国  李兴泉 《地震学报》2021,43(5):605-614

介绍了川滇地区电离层多参量异常监测系统的设计思路与功能实现,并将该系统应用于2019年6月17日四川长宁M_S6.0地震的监测试验。结果表明:该系统实现了全球和中国区域垂直总电子含量VTEC、站点VTEC和F₂层临界频率f_oF₂异常变化的实时监测,有助于开展示范性地震电离层异常监测工作,其图形及数据结果可为地震-电离层异常扰动判识提供佐证,为川滇地区地震监测预报提供电离层前兆信息支持。   相似文献   

考虑卸荷变形模量的坑底回弹变形计算方法          下载免费PDF全文

陈晓  董建华  董和平  汤小林  田文通 《地震工程学报》2021,43(5):1134-1141

针对基坑开挖卸荷导致坑底土体回弹变形问题,考虑开挖卸荷过程中土体弹性模量随着卸荷应力路径变化的特征,推导在卸荷应力路径作用下土体变形模量的计算公式,考虑基坑的开挖为地表以下基坑开挖面处应力的变化,基于Mindlin应力解计算矩形基坑开挖卸荷引起的坑底土体附加应力,采用分层总和法计算基坑开挖引起的坑底土体的回弹变形,结合已有文献中的工程实例,采用该方法计算开挖引起的坑底隆起变形,并与实际监测数据对比分析表明,该方法能够有效预测基坑开挖引起的坑底隆起变形,能够作为基坑开挖坑底隆起变形的一种有效预测方法。  相似文献   

地震地球物理数据监控软件设计与实现     

陈凯  易江  孙国栋  于天航  汪建 《地震地磁观测与研究》2021,42(3):291-297

台站设备故障响应和风险排除是地震监测工作的基本内容,针对其便捷性和高时效性要求,采用Java语言,开发基于Android平台的地震地球物理数据监控软件。该软件整合重庆市地震局监测工作中的各项业务需求,采用云服务、Tomcat服务器及百度地图等技术,实现了数据实时查看及历史数据波形浏览等功能,及时获取仪器设备工作状态,及时发现设备故障并进行维护,工作效率得以提高。  相似文献   

基于1973年炉霍MS7.6地震震后跨断层变形的地震轮回特征     

杜方  吴江  梁明剑 《地震地磁观测与研究》2021,42(z1):131-135

1 研究背景 地震活动断层不同区段和时段均具有不同的力学特性,主要是表现在活动断层上发生地震的断层段所呈现的震前、同震、震后和震间4个时域范围内的滑动行为.换言之,地震活动断层的滑动行为分为震前、同震、震后和震间4个滑动阶段.通过研究活动断层地震破裂段震前、同震、震后和震间滑动,可深入破解沿活动断层破裂段的应力、应变的积累和释放的时空信息变化(Reilinger et al,1999;Yagi et al,2001;Ozawa et al,2004).  相似文献   

关于促进国内气象企业健康发展的思考     

王柏林  姜长波  刘欣  刘新伟  黄秋菊 《气象科学进展》2022,(1):37-43

经济全球化和服务贸易市场化趋势的加快,特别是新媒体技术和信息技术的快速发展,为我国气象服务发展带来了良好机遇和严峻挑战.进入新时代,我国气象企业迈入快速发展的重要机遇期.2015—2016年,中国气象局适应气象服务体制改革,逐步开放气象信息服务市场、鼓励社会企业参与气象仪器研发生产、规范防雷检测资质管理,培育气象服务市...  相似文献   

物质点强度折减法边坡失稳判据选择方法     

蒋先平  张鹏  卢艺伟  刘磊磊  张明辉 《地质科技情报》2022,41(2):113-122

用物质点强度折减法求解边坡安全系数时,需要选择一定的失稳判据,而采用不同的失稳判据获得的安全系数通常存在一定差异.为此,采用物质点强度折减法对两个边坡算例进行了稳定性分析,对比研究了文献中常用的4种边坡失稳判据(计算不收敛、特征点位移突变、塑性应变贯通及界限值判据)在计算边坡安全系数时的合理性及适用性.同时,将Spen...  相似文献