Galactic halo age estimated from LAMOST DR4 and Gaia DR1

The stellar halo is one of the major components in the Milky Way. Research on its age can provide critical constraints on the origin of the stellar halo and further on the formation of our Galaxy.So far, different approaches and samples have been used to estimate the age of the Galactic halo. In our previous paper, we carefully selected 63 field halo turn-off stars within 1 kpc from the literature using a kinematic approach, then estimated the age of the halo. In this following work, we not only update the data from LAMOST DR4 and Gaia DR1, but also try a different method to select a clean halo sample by combining the metallicity and orbital parameters. Then we compare this halo turn-off sample with the GARSTEC model in the B-V vs. metallicity plane. After Monte Carlo simulations are performed, the age is estimated to be 10.5±1.4 Gyr, highly consistent with our previous result and other studies. However,due to the limited common sources between LAMOST DR4 and Gaia DR1, the final sample in this paper is still quite small. The estimated age will be more robust with the much larger Gaia DR2.     

印尼苏门答腊岛苏利特河铜矿地质特征

印尼苏门答腊岛西部的苏利特河铜矿床代表了侏罗纪-早白垩世岩浆弧相关的铜金成矿期次。为了总结其特征并指导该区找矿实践,本文对其地质背景、岩相学和主量及微量元素特征进行了研究。岩石地球化学特征表明:该矿床矽卡岩主量元素与岩浆岩相比,其Ca O含量增多,Si O2、Al2O3、K2O以及Na2O含量降低;在FAM图解和Fe Ot-Mg O-Al2O3图解中,矿化矽卡岩落在变质闪长斑岩附近,但是二者的REE配分模式不尽相同:闪长斑岩岩体具有更高的Σw(REE)含量和Eu正异常,而矽卡岩普遍表现为Eu负异常。综合主量元素地球化学和年代学的证据,苏利特河矿床时代可能为早侏罗世以后,属于造山后和碰撞后阶段的板内岩浆活动的产物。     

New background quasars in the vicinity of the Andromeda Galaxy discovered with the Guoshoujing Telescope (LAMOST)

Planetary nebulae (PNe) are good tracers of the stellar populations, chem-ical composition and dynamics of their host galaxies. This paper reports the dis-covery of new PNe in the outskirts of the Andromeda Galaxy (M 31) with the Guoshoujing Telescope (GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope-LAMOST) during its early commissioning phase. In total, 36 candidates selected from SDSS photometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previously known emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented.We discuss the potential for detecting more PNe in M 31 with GSJT's multi-object spectroscopy and the related applications in studies of the dynamics and chemistry of M31 and its assemblage history.     

Impacts of Initial Perturbations on 24-h Sea-Level Pressure Predictions Near Typhoon Matsa

This study investigates the impact of uncertainty in initial conditions on 24-h sea-level pressure predictions near 0509 Typhoon Matsa by using conditional nonlinear optimal perturbation (CNOP).The CNOP is calculated by using a newly proposed fast algorithm.The model used is the Global/Regional Assimilation and PrEdiction System (GRAPES).The sensitivity of the 24-h predictions is studied in terms of horizontal and vertical ranges and also in terms of different initial state variables.To study the sensitivity of 24-h sea-level pressure predictions to different initial state variables,four functions are given as metrics to find the sensitive initial locations.The results show that the main prediction errors come from initial uncertainty on the levels below 200 hPa and at the region south of about 37.6°N,with more sensitivity to initial winds than to other initial state variables.     

宁夏近50 a降水集中度和集中期特征分析

 利用宁夏气象台站1961-2010年逐侯降水量序列资料,研究了表征降水量时间分配特征的降水集中度(PCD)和集中期 (PCP)的空间分布与年际变化特征。结果表明：宁夏降水PCP与PCD空间分布特征明显,中北部PCP比南部山区偏早1候,PCD自北向南逐渐减小,北部1年中最大降水出现的时间变率较大,且出现极端降水的可能性比中南部大; 1961-2010年全区PCD与PCP呈微弱的下降趋势,但近20 a PCD明显增大,PCP显著推迟;PCD与PCP显著正相关,PCP出现得越晚,PCD集中度越高;各地的PCD与年降水量、汛期降水量以及年日最大降水量都有非常好的正相关性,正相关中心区位于北部的惠农、陶乐、中卫,中部的盐池、麻黄山和南部山区的大部,上述地区降水越集中,年降水量、汛期降水量以及年日最大降水量越大,导致洪涝灾害发生的可能性将越大;宁夏汛期降水多雨年各地降水更集中,且大降水中北部大部易出现得早,南部出现得晚;中高纬的北极涛动和低纬的南海季风对宁夏降水集中度有着显著的影响,北极涛动偏弱的年份,南海季风爆发偏早的年份,宁夏各地年降水比较集中。     

华北地区Lg尾波衰减研究--Lg尾波Q的测量

利用1989～1998年间发生在中国华北地区ML≥3.0级的地震事件,华北遥测台网以及数字化台网记录到的信噪比较高的Lg尾波时间序列,经过滤波、消除背景噪声等预处理,采用单台记录叠加频谱比法,得到传播路径上Lg尾波Q0（Q=Q0fη, Q0是1Hz的Q值,η是Q值与频率相关系数）,进而获得该地区Q0和η的空间分布. 测量结果表明,华北地区地壳Lg尾波Q0值分布存在显著的横向不均匀性,这种不均匀性与该地区地壳的速度分布基本一致,表现为与该地区地表地质特征明显的一致性,即传播路径位于太行山隆起和燕山隆起区为高Q0值分布;传播路径位于冀中坳陷和黄骅坳陷等平原区表现为低Q0值;传播路径位于隆起区和坳陷区二者之间,其Q0值也介于二者之间,说明华北地区的地壳结构没有很大的阶跃式变化而使波导遭到破坏,Lg尾波Q0值基本上反映了地壳内介质滞弹性的固有衰减.     

华北地区Lg尾波衰减研究--Lg尾波Q0地震成像

利用单台记录叠加频谱比法测量出的华北地区560余条单台传播路径上平均Lg尾波Q0值数据（Q0是1Hz的Q值）,采用随机褶积模型和奇异值分解法,重建该地区地壳中Q0的横向变化.结果表明,华北地区地壳中Lg尾波Q0值分布具有显著的横向不均匀性,这种不均匀性与地质构造明显相关,块隆区具有较高的Q0值,例如,燕山造山带、太行山块隆、鲁西隆起;华北平原区表现为低Q0值分布,例如冀中坳陷、黄骅坳陷、济阳坳陷,二者界限分明.结合研究区内的大地热值分布研究表明,低Q0值区大都处于高热流区,这可能是地壳内热物质的活动有关.虽然华北地区Lg尾波Q0值高、低分区明显,但是,从总体上应该属于低Q0值异常区,也就是说,该区的地壳是高地震波衰减区,这可能是该地区受太平洋板块和欧亚板块的相互作用而使地壳减薄,热物质上升造成的结果.     

Indirect carbon emissions from household consumption between China and the USA: based on an input–output model

Based on an input–output model, this paper calculates carbon emissions from household energy consumption in 2002, 2005, 2007, and 2010 between China and the USA. By a comparative analysis of the two countries, the results indicate the following: (1) In terms of the total household indirect carbon emissions, the USA has always been at a higher level than China. However, in recent years, China has presented a rapidly rising trend. In contrast, the USA appears to be experiencing a downward trend. (2) Indirect carbon emissions from USA household consumption mainly focus on Residence; Education, Culture, and Recreation; and Transport and Communications. By comparison, residence accounts for 50 % of China’s household indirect carbon emissions, and seven other sectors are much less than the USA (3) Although the number of China’s household facilities is growing rapidly, the carbon emissions remain at a relatively steady level. (4) In terms of the absolute value of the indirect carbon emissions from housing, the USA maintains a steady 400 million ton, while China increased from 150 to 500 million ton over 2002–2010.

     

Astrometric calibration of the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anti-center （XSTPS-GAC）

We present astrometric calibration of the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anti-center(XSTPS-GAC). XSTPS-GAC is the photometric part of the Digital Sky Survey of the Galactic Anti-center(DSS-GAC),which is a photometric and spectroscopic sky survey, in combination with LAMOST.In order to select an astrometric reference catalog, we made comparisons between the four widely used astrometric catalogs, GSC2.3, USNO-B1.0, UCAC3 and PPMXL.PPMXL shows relatively small systematic errors in positions and more homogeneous proper motion distributions toward the Galactic Anti-center(GAC), and was selected as the reference catalog. Based on the high quality and bright reference stars that were picked out from PPMXL, we performed a 4th-order polynomial fitting in image units,to construct the transformation relation between coordinates used by XSTPS-GAC and standard coordinates, and to simultaneously correct the image distortions in the CCD. Then we applied the derived relation to all sources to obtain their mean celestial coordinates based on the International Celestial Reference System. For bright point sources with r 17.0 mag, the accuracy of astrometric calibration could reach about80 mas for each of the g, r, i bands, with systematic errors being less than 10 mas. But for the faint sources at the brightness limit of the survey, which was r ～ 19.0 mag, the accuracy can still reach 200 mas. After combining all observations, the final weighted average coordinates could reach an accuracy of less than 70 mas for bright stars. For faint stars, the rms residuals of weighted coordinates decrease to ～ 110 mas. The final combined XSTPS-GAC coordinates show a good consistency with the Sloan Digital Sky Survey.