NWA 13943(CK5型)碳质球粒陨石的矿物岩石学和稳定同位素组成研究

CK型陨石是一类高度氧化的碳质球粒陨石, 金属/磁铁矿的比值接近零. 与其它类型的碳质球粒陨石(岩石类型: 1-3)不同, 大多数CK型陨石在母体上经历了强烈的热变质过程(550--1270K), 以4-6型为主. 多项证据表明, CK和CV3型陨石具有成因联系. 但是, 两者在岩相结构和化学组成方面仍存在微小差异. 因此, 精细地区分和比较两者的地球化学特征对于验证CK-CV单一母体假说非常重要. Northwest Africa (NWA) 13943是一块新发现的陨石, 经历过较强烈的热变质作用. 利用扫描电子显微镜和电子探针, 确定了NWA 13943的岩石类型. 并运用质谱分析技术, 重点测定了NWA 13943陨石的全岩氧同位素和铬同位素组成. 综合岩石结构、矿物化学成分、氧同位素异常(△¹⁷O,△代表同位素分馏值)和铬同位素异常(ε⁵⁴Cr, ε表示样品中的同位素比值与标样中的同位素比值的相对偏差的10⁴倍),CK和CV型陨石的母体可能形成于原行星盘中两个相似但不同的化学源区.     

昭平、惜福和哈密铁陨石的矿物岩石学研究和化学群分类

详细分析了中国新近发现的3块铁陨石即：昭平、惜福和哈密的矿物组成和化学成分，并根据它们的化学元素（Ga、Ge、Ni和Ir等）含量进行了分群；昭平和惜福铁陨石分别属于IAB的低Ni低Au亚群和ⅢCD铁陨石群，哈密铁陨石因为其本身的Ga和Ge的含量很低以及实验仪器的精度限制，只能得知该陨石的Ga含量小于2ppm、Ge含量小于10ppm，根据其化学元素含量、结构特征和矿物组成，初步判断哈密铁陨石应属于未分群铁陨石．     

云南西双版纳(曼桂)目击陨石的热变质和冲击变质研究

曼桂陨石是新近(2018年6月1日)陨落在云南西双版纳地区的目击球粒陨石,其中的主要矿物为橄榄石(Fa_(24.3±0.6))、斜方辉石(Fs_(20.6±0.5)Wo_(0.4±0.2))、长石(An_(11-12)Or_(2-4))、铁镍金属和陨硫铁,次要矿物为铬铁矿、白磷钙矿等.橄榄石和辉石的化学成分表明曼桂陨石属于L型普通球粒陨石.陨石中球粒很少且轮廓不清晰,基质矿物普遍经历过重结晶,重结晶矿物颗粒粒径较大,高钙辉石粒径25–30μm,长石颗粒大多超过50μm,说明该陨石属于6型岩石类型.橄榄石和辉石颗粒中发育有波状消光、嵌晶块状消光现象、平面裂隙和面状变形构造,长石熔长石化并不完全,陨石中观察到宽度不等且纵横交错的冲击熔融脉,表明曼桂普通球粒陨石受到的冲击变质作用可以达到S5级以上.通过熔融脉中的矿物组合推断出熔融脉中矿物经历的压力在15–16 GPa左右.     

球粒陨石难熔包体中贵金属的矿物岩石学分析:对太阳星云演化的启示

球粒陨石中的富钙富铝难熔包体(Ca,Al-rich Inclusion,CAI)是太阳系最早形成的物体,保留了太阳星云早期的原始信息,但深入研究发现许多难熔包体具有复杂的演化历史,包括部分熔融和后期变质作用等.针对难熔包体中更为难熔、化学性质更为稳定的贵金属颗粒进行天体化学研究,选取CV群碳质球粒陨石NWA 2140,对其CAI中的贵金属颗粒进行岩石学观察及化学成分测定.根据得到的成分分析结果,能大致推出包体经历过的热力学历程,辨识出两类贵金属合金颗粒,这两类贵金属分别为早期冷凝产物和原生金属的后期蚀变产物.     

寺巷口普通球粒陨石的热变质和冲击变质历史研究

寺巷口陨石是一块经历强冲击变质的普通球粒陨石.系统研究陨石主体和冲击熔融脉的岩相学和矿物学.该陨石中球粒较少且轮廓和内部结构均模糊不清,基质重结晶程度高,橄榄石和辉石的成分非常均一.单斜辉石-斜方辉石矿物对计算得到的平衡温度峰值为891 4-36°C.说明寺巷口陨石的热变质程度与6型一致.陨石主体中的橄榄石具有明显的波状消光和面状变形裂隙,熔长石广泛存在,在冲击熔融脉中含有粗粒的林伍德石和镁铁榴石以及细粒的高压矿物组合,这些特征预示了寺巷口陨石经历了S6级的冲击变质作用且形成冲击脉的峰期压力可能在20 GPa-24 GPa左右,而温度可能高于2000°C.冲击熔融脉中自磷钙矿和铬铁矿的存在可能是因为经历了较长的退火时间,导致其高压矿物的回退.     

火星陨石NWA 8716的岩矿学特征及粗粒橄榄石斑晶的来源

火星陨石可以为研究火星岩浆演化过程提供直接证据并限制其源区特征.通常认为含粗粒橄榄石斑晶辉玻无球粒陨石携带有火星原始地幔的信息,因此选取该类样品Northwest Africa (NWA) 8716为研究对象,进行岩相结构及矿物成分分析. NWA8716由橄榄石、辉石、填隙状熔长石以及其他次要矿物组成.其中橄榄石颗粒有两种级别的粒径,长轴分别约为0.5–1.8 mm和50–400μm.较小橄榄石斑晶内部的熔体包裹体和NWA 8716全岩成分(计算值)均显示明显的轻稀土元素亏损([La/Yb]CI值为0.06–0.1),说明NWA 8716源于一个亏损的火星岩浆池.粗粒橄榄石斑晶的来源对衡量该样品是否能够代表原始熔体成分非常重要.对橄榄石晶体的粒径统计分析发现,粗粒橄榄石斑晶应为堆晶.进一步对铁-镁以及稀土元素分配特征的计算表明NWA 8716并非形成于一个封闭系统,但是计算所得原始熔体成分与全岩成分差异不大,因此粗粒橄榄石斑晶应当来源于与母岩浆成分相似的熔体.总的看来, NWA 8716应当来源于亏损型火星幔源区且演化程度较低.     

A New Analysis of Fireball Data from the Meteorite Observation and Recovery Project (MORP)

Sixty fireball cameras operated in Western Canada from 1971 to 1985. Over one thousand (1016) fireballs were recorded at more than one station, but only 367 were reduced, of which 285 have been published, including that of the Innisfree meteorite. Digitization of all the data is underway, and procedures are being developed which will allow the automatic reduction of events not previously examined. The results of the analysis of 80 fireballs reduced but not previously published are presented. When the new analysis is complete, the MORP archive will be a valuable source of information on meteoroid orbits.     

SWAN: A study of Solar Wind Anisotropies on SOHO with Lyman alpha sky mapping

On board the SOHO spacecraft poised at L1 Lagrange point, the SWAN instrument is mainly devoted to the measurement of large scale structures of the solar wind, and in particular the distribution with heliographic latitude of the solar wind mass flux. This is obtained from an intensity map of the sky Lyman emission, which reflects the shape of the ionization cavity carved in the flow of interstellar H atoms by the solar wind. The methodology, inversion procedure and related complications are described. The subject of latitude variation of the solar wind is shortly reviewed: earlier Lyman results from Prognoz in 1976 are confirmed by Ulysses. The importance of the actual value of the solar wind mass flux for the equation of dynamics in a polar coronal hole is stressed. The instrument is composed of one electronic unit commanding two identical Sensor Units, each of them allowing to map a full hemisphere with a resolution of 1°, thanks to a two-mirrors periscope system. The design is described in some details, and the rationale for choice between several variants are discussed. A hydrogen absorption cell is used to measure the shape of the interplanetary Lyman line and other Lyman emissions. Other types of observations are also discussed : the geocorona, comets (old and new), the solar corona, and a possible signature of the heliopause. The connexion with some other SOHO instruments, in particular LASCO, UVCS, SUMER, is briefly discussed.     

A bimodal model of the solar wind speed

Until the ULYSSES spacecraft reached high latitude, the only means for measuring the solar wind velocity in the polar regions was from radio scattering observations (IPS), and these remain the only way to measure the velocity near the sun. However, IPS, like many remote sensing observations, is a line-of-sight integrated measurement. This integration is particularly troublesome when the line-of-sight passes through a fast stream but that stream does not occupy the entire scattering region. Observations from the HELIOS spacecraft have shown that the solar wind has a bimodal character which becomes more pronounced near the sun. Recent observations from ULYSSES have confirmed that this structure is clear at high latitudes even at relatively large solar distances. We have developed a method of separating the fast and slow contributions to an IPS observation which takes advantage of this bimodal structure. In this paper I will describe the technique and its application to IPS observations made using the receiving antennas of the EISCAT incoherent backscatter radar observatory in northern Scandinavia.     

A model for the tail region of the heliospheric interface

The physical processes in the tail of the region where the solar wind interacts with a partially ionized local interstellar medium are investigated in terms of a self-consistent kinetic-gas-dynamical model. Resonant charge exchange between hydrogen atoms and plasma protons is shown to cause the contact discontinuity to disappear far from the Sun. The solar wind plasma cools down and, as a result, the parameters of the plasma and hydrogen atoms approach the corresponding parameters of the unperturbed interstellar medium at large heliocentric distances.     

Observations of interplanetary scintillation with a single-station mode at Urumqi

The Sun affects physical phenomena on Earth in multiple ways.In particular,the material in interplanetary space comes from coronal expansion in the form of inhomogeneous plasma flow (solar wind),which is the primary source of the interplanetary medium.Ground-based Interplanetary Scintillation (IPS) observations are an important and effective method for measuring solar wind speed and the structures of small diameter radio sources.We discuss one mode of ground-based single-station observations: Single-Station Single-Frequency (SSSF) mode.To study the SSSF mode,a new system has been established at Urumqi Astronomical Observatory (UAO),China,and a series of experimental observations were successfully carried out from May to December,2008.     

用太阳系主要天体的位置建立特大地震的时间预测模型

根据某类事件发生时太阳系主要运动天体的位置，通过对其历史资料的归算，尝试并设计出一种具有普适性的事件时间预测模型．以1900-1980年间全球所有8级及以上的99次地震为例，定义与天体特征位置(视黄经)相关的发震率，初步建立预测发震时刻的概率曲线．指出这可能成为研究地震预报问题的新途径．     

New high resolution observations of the solar diameter from space and ground with the microsatellite program PICARD

The PICARD microsatellite mission will provide 2 to 6 years simultaneous measurements of the solar diameter, differential rotation and solar constant to investigate the nature of their relations and variabilities. The 100 kg satellite has a 40 kg payload consisting of 3 instruments which will provide an absolute measure (better than 10 milliarcsec) of the diameter and the solar shape, a measure of total solar irradiance, and UV and visible flux in selected wavelength bands. Now in Phase B, PICARD is expected to be launched before mid-2003. The engineering model of the diameter telescope will be used on ground simultaneously with the satellite to investigate the atmospheric bias and state on the possible accuracy of the ground measurements carried up to now. We review the scientific goals linked to the diameter measurement, present the payload, and give a brief overview of the program aspects.     

A New Protocol for the Astrometric Follow-up of Near Earth Asteroids

A new protocol was devised to improve the efficiency of astrometric follow-up observations of Near Earth Asteroids for the accurate determination of their orbits. It was implemented in the activities of the Spaceguard Central Node (SCN, a facility of the Spaceguard Foundation, established with the support of the European Space Agency) in the form of a Priority List. Here we describe this protocol and results obtained during five years of activity (2000–2004).     

1m望远镜夜间观测概况

本文主要介绍1m望远镜夜间观测情况，并对夜间观测时段(有效观测时间)进行统计、分析，并给出其结果。