行星天文学的重要地位及其热点

对1995年至2001年《Natue》和《Science》上发表的天文学论文的统计表明，行星天文学领域的论文数量明显超过天文学的其它分支学科，占天文学总论文数的1/3左右。从这个角度来看，行星天文学是天文学最活跃和重要的分支学科之一。对这些论文具体内容的分析可以给出当前行星天文学领域的若干热点问题。相比之下，我国对这一重要领域的关注和投入还远远不够。     

疏散星团M11的研究——相对自行和成员概率

本给出了疏散星团M11中心25′×25′天区内872颗恒星的相对自行、自行测定误差以及团中心距r≤25′范围内785颗恒星的成员概率，并对有关问题作了简单的讨论。     

小行星动态(2001.04～2001.05)

年 月 获永久编号小行星数 小行星命名数 2001 4 1200(17 1) 0 2001 5 0(0) 206(0) (括号内数字分别指国家天文台施密特CCD小行星项目组和紫金山天文台的发现数) 小行星命名:和平号空间站与美国宇航局 宇航事业与天文研究关系密切。很多小行星发现者都倾向于以宇航方面的事物命名小行星。在2001年5月新命名的小行星中,(11365)号小行星被命名为NASA,这是美国宇航局的缩写。美国宇航局成立于1958年,主要进行宇宙探测和研究。1969年首次将人类送上月球,创造了人类历史上的伟绩。(11881)号小行星被命名为Mirstation(和平号空间站)。它是俄罗斯最早     

Ellerman Bombs,Type Ⅱ White—light Flares and Magnetic Reconnection in the Solar Lower Atmosphere

Ellerman bombs and type Ⅱ white-light flares share many common features despite the large energy gap between them.Both are considered to result from local heation in the solar lower atmosphere.This paper presents numerical simulations of magnetic reconnection occurring in such a deep atmosphere,with the aim to account for the common features of the two phenomena.Our numerical results manifest the following two typical characteristics of the assumed reconnection process:(1)magnetic reconnection saturates in-600-900s,which is just the lifetime of the two phenomens;(2)ionization in the upper chromosphere consumes quite a large part of the energy released through reconnection,making the heation effect most significant in the lower chromosphere.The applicationof the reconnection model to the two phenomena is discussed in detail.     

广州白云山常绿阔叶林的结构特征

在线路调查和样方调查的基础上分析了广州白云山常绿阔叶林的结构特征，群落主要由亚热带科属组成，优势科为芸香科，五加科，茜草科，山茶科，壳斗科，鼠刺科，樟科等。优势树种也以相应的优势科属树种为主，群落中胸径≥3cm的个体密度较小，只有1964株/hm^2；群落较为低矮，平均高度只有6m；乔木垂直分化不明显，树种水平分布不均，白云山的植被是次生植被和人工造林改造的结果，只在山谷少数植被没受人类干扰，其现状植被是天然次生植被和人工植被的混合体，在一些由马尾松发展起来的群落，天然侵入的阔叶树种已在主要层中居优势；群落中可见马尾松衰退的痕迹。     

致密碎屑岩储层裂缝和产能预测的单井建模——以新场气田沙溪庙组为例

近年来，利用三维地震资料进行致密碎屑岩储层裂缝和产能的识别预测取得了一些进展，而这之中最重要也最基础的是单井裂缝和产能的建模工作。本以新场气田沙溪庙组致密储层为例，详细介绍了综合运用岩芯资料、测井资料和录井资料进行裂缝和产能单井建模的方法，为利用三维地震资料建立裂缝和产能的灰色遗传过程识别模式打下了良好的基础。     

MERLIN Images of Five Compact Symmetric Object Candidates at 1.6 GHz

1 INTRODUCTIONCompact Symmetric Objects (CSOs) are powerful and compact sources (overall size <1 bpc) with lobe emission on both sides of the central engine. The small size of these sourcesis almost certainly to be attributed to the youth of the sources themselves (ages < 104 yr) andnot due to a dense coallning medium (Readhead 1996). The unification scenario assumes thatCSOs evolve into compact steep spectrum (CSS) sotirces and then into Fanaroff-Riley type 11objects (Fanti 1995). …     

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggest that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photospheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field.