“行星地球”一章教材分析

1．本章教材在必修一中的地位和作用 人类生活在地球上,必然离不开地理环境,人类生产、生活都要受地理环境的影响和制约。同时,地球作为宇宙中一颗普通的天体,同样也要受到其他天体的影响,地球也同样离不开自身所处的宇宙环境。不少事实已经证明,地球上发生的许多地理现象都与地球的宇宙环境有关,     

天文观测攻略系列之九：常见星图使用指南

经过近一年的讲述,相信许多初学者已经认识了四季星空的主要星座,并且开始使用望远镜进一步探索星空中隐藏在肉眼视线之外的更有趣的天体了。何谓“更有趣的天体”呢？就是星云、星团和星系,它们通称为“深空天体”。恒星由于离我们极其遥远,看上去只是一个点光源,即使用极大的望远镜去看也只是一个点,因此对于普通业余观测而言没什么意思。而深空天体则不然,由于它们本身的个头非常巨大,虽然离得同样极其遥远,我们看上去也是有视面的、能看出形状和细节的天体。     

一句话新闻

2008年9月27日夜,LAMOST在调试中一次观测得到1000余条天体的光谱开始,到至今的调试观测中,LAMOST都不断地获得每次约2000多天体的光谱。用于调试观测的天体一般是亮于17等,光谱是在无云观测夜曝光至少5分钟后获得的。与国际上迄今最多一次观测只能得到600多条天体的光谱相比,LAMOST已经成为世界上光谱观测获取率最高的望远镜。     

天文观测攻略系列之十三金星观测

随着12月的来临,北半球逐渐进入了隆冬时节。此时在我国中高纬度地区。夜间气温已经很低,如果再遇到刮风,给人的感觉将会非常寒冷。因此,夜间观测一定要特别注意保暖。不光要穿够衣服鞋补,还应该戴上帖子和手套,围上围巾。不过,在这个冬季里,有一个天体不用大家熬夜挨冻就能很好地观测,它就是夜空中的亮星之王——金星。     

射电天文学的功勋及宇宙生命探索（上）

自20世纪30年代接收到银河中心方向的无线电波以来,迅速发展起来一门崭新的学科——射电天文学。迄今射电天文学已经成为天文学的一个重要的分支学科,并且获得了许多激动人心的重要天文发现。射电天文学开创了研究天体物理、天体测量、宇宙的起源与演化和宇宙的大尺度结构的新途径,它正在现代天文研究中发挥着越来越大的作用。     

“心事浩茫连广宇”——功勋卓著的大天区巡天

在天文学飞速发展的20世纪里,天文学家在每一个可能的电磁波段都进行了多次巡天。这些巡天引领了无数个激动人心的伟大发现,并为许多研究课题,例如描绘银河系结构乃至宇宙大尺度结构以及搜寻极端天体等等方面,提供了海量的基础性数据。本文是对各种巡天的综合“巡视”,对近年来比较著名的大天区巡天——2MASS、SDSS、2dfGRS、UKIDSS等进行了简单介绍,列举了它们作出的部分重要科学发现,并对未来的巡天工作进行了展望,希望能有助于大家更深入地认识巡天。     

近三年来我国天体测量的研究工作(英文)

该文简述近三年(2005年7月1日～2008年6月30日)我国天体测量研究工作的情况,其中包括我国天体测量工作者在仪器和归算方法、河外参考架、特别的天文研究项目,如位置、自行、三角视差和近距小质量星、太阳系、疏散星团和银河系,以及天体测量教育等方面取得的研究成果。特别描述了2007年10月在上海天文台召开的国际天文学联合会第248次讨论会的意义和作用。     

Revisiting the Local Kinematics of the Milky Way using the New Hipparcos Data

With the new Hipparcos data recently released, we reexamine the kinematics in the solar neighborhood. Two different populations of objects, namely the thin-disk O-B5 stars and the thick-disk K-M giants, are selected for tracing the kinematical parameters of the Galaxy. Using a 3-D kinematical model, the components of the solar motion and the Oort constants are derived. The solutions and the kinematics inferred from both types of stars are analyzed. The results obtained with the new data are compared with those from the old Hipparcos data. We conclude that the present solution provides a more reliable estimation of the Oort constants, thanks to the new reduction of the Hipparcos data that provides even more accurate astrometric measurements of stars.     

The Vignetting Effect of a LAMOST-Type Schmidt Telescope

Optical vignetting of a Schmidt reflector is caused mainly by the spherical primary mirror not being big enough and by the effective light-collecting area of the corrector,which depends on the direction of the star light.Calculations of the vignetting of LAMOST,a special reflecting Schmidt telescope,are made by ray-tracing methods.The results show various features due to LAMOST's structure and observing modes.The un-vignetted field is small compared with its field of view.In the outmost portions of the field vignetting increases rapidly with the distance to the field center.The vignetting at a general position within the field of view is a function of both its distance to the field center and its position angle.Vignetting varies when the telescope points at different declinations and during observations.There is difference in vignetting between direct imaging and multi-fiber spectroscopy.Vignetting distorts the relative intensity of celestial objects at different positions in a field and also affects accurate sky-estimation and sky-subtraction.The determined vignetting functions may be used to correct the vignetting effect; alternatively flat-fielding may be adopted for the calibration.The effective apertures,which affect the signal-to-noise ratio of the observations,depend on the different declinations the telescope is pointing at and also different positions within a field due to vignetting.     

Hyperaccretion after the Blandford-Znajek Process： A New Model for GRBs with X-Ray Flares Observed in Early Afterglows

We propose a three-stage model with Blandford-Znajek (BZ) and hyperaccretion process to interpret the recent observations of early afterglows of Gamma-Ray Bursts (GRBs). In the first stage, the prompt GRB is powered by a rotating black hole (BH) invoking the BZ process. The second stage is a quiet stage, in which the BZ process is shut off, and the accretion onto the BH is depressed by the torque exerted by the magnetic coupling (MC) process. Part of the rotational energy transported by the MC process from the BH is stored in the disk as magnetic energy. In the third stage, the MC process is shut off when the magnetic energy in the disk accumulates and triggers magnetic instability. At this moment, the hyperaccretion process may set in, and the jet launched in this restarted central engine generates the observed X-ray flares. This model can account for the energies and timescales of GRBs with X-ray flares observed in early afterglows.