EGS场中高红移极亮红外星系的形态与结构

通过利用CANDELS-EGS(Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey-Extended Groth Strip)场中HST WFC3(Hubble Space Telescope Wide Field Camera 3)F160W高分辨率的观测图像,研究了9个光谱红极亮红外星系的形态结构特征.发现这些星系的形态表现出多样性(从椭圆到多个亮核或弥散的结构),如:双核,气体桥,双不对称体,不规则或椭圆结构.为了定量地研究这些极亮红外星系的形态,测量了它们在静止光学波段的形态参数(基尼系数G和矩指数M20).与近邻极亮红外星系相比,高红移极亮红外星系的G偏小而M20偏大,表明这些星系的星族分布聚集度小且不对称性大.基于对样本中极亮红外星系2维面亮度轮廓的拟合,得到这些星系的有效半径分布在2.4 kpc到5.8 kpc之间,其平均值是(3.9±1.1)kpc.相比较于近邻相似质量的恒星形成星系来说,高红移极亮红外星系的平均大小要小1到2倍.在类似红移和红外光度条件下,得出的这些结果也与其它文献中给出的结论相一致.     

近邻星系恒星形成区光谱观测研究

近年来随着国际8~10 m口径望远镜数目的不断增加,4 m及以下口径望远镜已成为中小型望远镜.如何利用中、小口径望远镜做出有影响的科学成果,须做到"有所为,有所不为".为此,自2013年开始针对国家天文台2.16 m望远镜推出了重点课题支持计划.介绍的"近邻星系恒星形成区光谱观测研究"为2.16 m望远镜支持的3个重点课题之一.它将利用2.16 m望远镜3 yr、每年30个暗夜或灰夜的观测时间,开展20个近邻、大星系中多个恒星形成区、平行星系主轴方向和垂直主轴方向的光谱观测,获得一个有显示度的、科学意义重要的近邻星系恒星形成区和径向分布的光谱样本.同时该课题还利用6.5 m多镜面望远镜(MMT)的观测时间,开展近邻、特大星系的恒星形成区的光谱观测.利用2.16 m望远镜和MMT望远镜观测得到的星系不同区域的光谱数据,结合已有的紫外、光学、红外波段宽带滤光片数据和BATC(Beijing-Arizona-Taiwan-Connecticut)15个中带滤光片数据,可开展星系尘埃消光、恒星形成率、金属丰度和星族特性二维分布等方面的研究;开展星系二维特性和星系形态、星系环境关系的研究.将介绍这个重点课题的科学意义、星系样本的选取、光谱观测策略和星系NGC 2403的光谱观测和初步研究结果.     

利用日晕光度计反演大气水汽含量

大气总水汽含量是天文观测和气象科学领域最为重要的参量之一.介绍云南天文台研制的新一代日晕光度计反演大气水汽含量的原理和方法,分析了新一代日晕光度计在天文选址和气象科学中的应用,给出了其在丽江高美古地区测试的结果,并和其他仪器测试结果进行了对比分析.结果表明:新一代日晕光度计反演大气水汽含量方法直观,性能稳定,能很好地应用于云南天文台的西部太阳望远镜选址及气象科学研究工作.     

The orbital period variations of AH Virginis

We present a study of orbital period changes in AH Virginis. We perform a careful literature search for all available minima times, from which we derived a new linear ephemeris and constructed an O- C curve. We found that the orbital period of AH Virginis shows a long-term increase, d P/dt =(2.1869 ± 0.0161) × 10-7d yr-1,and a small periodic variation with a period of 37.19 yr. Since AH Virginis is an overcontact system and the primary component shows strong Hα and Mg II emission lines,we discuss the possible connection between mass transfer, magnetic activity and orbital period changes.     

Chromospheric activity in several single late-type stars

New high-resolution echelle spectra of six single late-type Pleiades-like stars(V368 Cep, EP Eri, DX Leo, GJ 211, PW And and V383 Lac) were obtained with the 2.16 meter telescope at Xinglong Station in 2008–2010. Using the spectral subtraction technique, we analyzed our spectroscopic data and calculated the equivalent widths of excess emission from several indicators of chromospheric activity(Na I D1, D2, Hα and Ca II infrared triplet lines). All our results using chromospheric activity indicators confirmed the previous findings. In addition, the maximum amplitudes of chromospheric rotational modulation and the ratio of EW8542/EW8498 were found to rise with increasing v sin i velocity.     

A high-contrast coronagraph for direct imaging of Earth-like exoplanets: design and test

A high-contrast coronagraph for direct imaging of an Earth-like exoplanet at the visible band needs a contrast of 10-10 at a small angular separation of 4λ/D or less. Here we report our recent laboratory experiment that approaches these limits. Our test of a high-contrast imaging coronagraph is based on our step-transmission apodized filter. To achieve this goal, we use a liquid crystal array as a phase corrector to create a dark hole based on our dedicated algorithm. We have suppressed the diffraction and speckle noise near the point image of a star to a level of 1.68 × 10-9at4λ/D, which can be used for direct imaging of Jupiter-like exoplanets. This demonstrates that a telescope incorporating a high-contrast coronagraph in space has the potential to detect and characterize Earth-like planets.     

Numerical experiments on the evolution in coronal magnetic configurations including a filament in response to the change in the photosphere

We investigate equilibrium height of a flux rope, and its internal equilibrium in a realistic plasma environment by carrying out numerical simulations of the evolution of systems including a current-carrying flux rope. We find that the equilibrium height of a flux rope is approximately described by a power-law function of the relative strength of the background field. Our simulations indicate that the flux rope can escape more easily from a weaker background field. This further confirms that a catastrophe in the magnetic configuration of interest can be triggered by a decrease in strength of the background field. Our results show that it takes some time to reach internal equilibrium depending on the initial state of the flux rope. The plasma flow inside the flux rope due to the adjustment for the internal equilibrium of the flux rope remains small and does not last very long when the initial state of the flux rope commences from the stable branch of the theoretical equilibrium curve. This work also confirms the influence of the initial radius of the flux rope in its evolution; the results indicate that a flux rope with a larger initial radius erupts more easily. In addition, by using a realistic plasma environment and a much higher resolution in our simulations,we notice some different characteristics compared to previous studies in Forbes.     

今年全国地灾防灾形势依然严峻

<正>2011年2月23日国土资源部环境司主持召开了2011年全国地质灾害趋势会商会。会上根据地质环境背景分析、地质灾害发育规律、汛期气候趋势展望和多年灾情统计预测,预计2011年全国地质灾害防灾形势依然严峻。预测结果显示:3～5月黄土地区     

国土资源系统抗旱找水工作进展顺利

<正>截止到3月4日,四川省抗旱打井突击队已在山东临沂、济宁、泰安等3市12县(市、区)开孔钻进抗旱水井111口,总进尺12 755.38m,目前共有57口抗旱水井顺利终孔,日总出水量达21 945方以上。山东全省打井累计进尺72 039m,共成井519口,累     

创新能源开发与地质环境关系新认识,研发矿山地质环境保护新技术——评《能源开发与地质环境互馈效应研究》

<正>由中国地质科学院水文地质环境地质研究所研究员张发旺、陈立、张胜等撰写编著的《能源开发与地质环境互馈效应研究》一书,已由地质出版社出版发行。该书不仅是一部针对鄂尔多斯能源基地地质环境问题研究的专著,也是一部集作者多年研究矿山