MAGNETO-ATMOSPHERIC OSCILLATIONS IN A MODEL UMBRA

The behaviour of magneto-acoustic-gravity oscillations in a model umbra is investigated by means of a normal mode analysis. The normal modes are evaluated for different types of boundary conditions holding at various levels in the model atmosphere and for a range of magnetic field strengths and horizontal wave numbers. For certain boundary conditions complex eigenfrequencies are present. For atmospheric cavities whose lower boundary is located at the bottom of the photosphere or in the upper convective region, the coupling between horizontal and vertical motions leads to spectra which are sensitive to the value of the horizontal wave number, k, and the strength of the vertical magnetic field, B0. For cavities located above the temperature minimum, the eigenfrequencies are independent of both k and B0, supporting the conclusions of ugda, Locns, and Staude (1987) that the motion is longitudinal along the magnetic field lines. The frequencies evaluated from the normal mode analysis correspond closely to the observed 2–3-minute band found in sunspot umbrae.     

EQUILIBRIUM CONDENSATION IN A SOLAR NEBULA

In attempts to reconstruct the environment of condensation of solar system materials, particularly exemplified by certain meteorite components, the relative temperatures of the gas and the solid are of critical importance. The relationships that determine the heat balance in a circumsolar grain-gas system are examined. Fundamental considerations show that regardless of opacity or gas density, the gas will always be at a higher temperature than the solid in such regions of the system where condensation is possible. Implications of the characteristic temperature differential between the gas and the condensing solid are discussed.     

导致太阳耀斑爆发的暗条扭绞

本文主要根据Ｈａ线心和不同偏带的观测资料，结合紫外ＣＩＶ１５４８谱线的测量结果，分析研究了１９８０年６月２５日ＡＲ２５２２活动区中一段暗条在耀斑爆发前１５分钟所经历的三次逐渐增强的间歇式扭绞，最终导致暗条破裂和耀斑爆发的物理过程，并且用无力场磁绳近似模拟时间条的扭绞运动，估算了暗条扭绞引直怕无力因子ａ的变化，轴向电流增大和守能，讨论了暗条的稳定性，试图对暗条的瓦解和耀斑爆发予以理论解释。     

THE RELATIONSHIP BETWEEN SOLAR FLARE GAMMA-RAY EMISSION AND NEUTRON PRODUCTION

We have examined six solar neutron events measured by satellite instruments and/or neutron monitors (NM) to understand the relationship between the intensity–time profiles of the -ray lines, the pion-related -rays, and the neutron production. In all six events the solar neutron production was clearly time-extended. We find that neutron emission as detected by NMs most closely follows the emission of pion-related -rays, whereas lower energy neutron production may follow that of nuclear -ray line emissions. Although this distinction is not unexpected, it is safe to say that the 2.223 MeV -ray line from neutron capture on hydrogen is a poor measure of the neutron production at energies >200 MeV. During the three events on 1982, June 3, 1990, May 24 and 1991, June 4 solar neutrons with energies greater than 200 MeV were recorded by NMs. The NM increases on 1982, June 3 and 1990, May 24 can be modeled using the time profile of the pion-related -rays. For the 1991, June 4 event the NM signal was small but lasted for 60 min and the high-energy -ray data available to us are insufficient to conclude unambiguously that the high-energy neutron production followed the pion-related -rays. In the other three events on 1991, June 9, 11, and 15 solar neutrons with energies 10–100 MeV were observed by the COMPTEL -ray instrument on the Compton Gamma Ray Observatory. The duration of the low-energy neutron production on 1991, June 9 corresponded clearly to the high-energy and not to the low-energy -ray emission.     

OSCILLATIONS IN THERMALLY-CONDUCTING POLYTROPIC ATMOSPHERES IN THE PRESENCE OF A VERTICAL MAGNETIC FIELD

We have investigated the normal modes of subadiabatic and superadiabatic polytropic atmospheres with constant vertical magnetic field and constant thermal conductivity. In the subadiabatic case, we found the lowest, third and fifth modes were always damped, however overstability was detected in the second and fourth modes at low values of the background magnetic field. In the superadiabatic case, instability was detected in several modes, however the effect of the change from sub to superadiabatic had little effect on the frequencies of the modes. The introduction of a variety of boundary conditions varying the degree of thermal and mechanical isolation altered the decay rates of the modes from moderately damped with rigid boundary conditions toward zero decay with the less restrictive conditions, again with essentially no effect on the oscillation frequencies. In both types of atmosphere, modes with periods in the 3-min and 5-min bands were present with magnetic fields around 3000 G, whereas only the 5-min modes were present at 2000 G.     

活动星系致密核的研究

本文对几个大样本ＶＬＢＩ观测的致密核（ｃｏｒｅ） 进行了统计研究,包括核的谱指数, 核的角大小随ＶＬＢＩ观测频率的变化,核角大小与致密喷流角大小的关系以及核角大小随红移的变化,并在非均匀喷流模型下估算了喷流中磁场和相对论性电子密度的分布。     

大型太阳活动区磁场的一个模型

用时间缓变的非线性无力场模拟超级活动区（弧岛式大型δ黑子）的磁场位形。这个复杂磁场包含了向量磁场的主要观测特征：正负磁流极端不平衡性（正负磁流之比为１：６）,Ｕ形磁反变线,局域磁场的二极子、四极子差异性。模拟结果厅用来解释一些观测结果：（１）大耀斑主要产生在Ｕ形中性线的磁性混杂区或四极子区（２）Ｕ形反变线的准双极性区几乎没有大耀斑很小。（３）活动区内部的大型旋转运动和磁沲运动会导致四极子场磁拓扑分     

MINERALOGICAL RELATIONSHIPS IN SEYMOUR,A COARSE OCTAHEDRITE

Seymour is a coarse octahedrite weighing 24.5 kg. It contains two types of troilite-graphite nodules (massive graphite nodules with irregular troilite rims, and troilite nodules with irregular, partial or total, rims of graphite); four morphologically distinct types of phosphide (lamellar, swathing, grain boundary, and rhabdite); and three types of cohenite (lamellar, swathing, and inclusions in kamacite). It is believed that lamellar and swathing schreibersite crystallized from taenite at approximately 900°C. This was followed by the crystallization of kamacite, then the development of cohenite, and finally a second period of phosphide nucleation giving rise to grain boundary schreibersite and rhabdite. Compositional data indicates that grain boundary schreibersite and rhabdite grew simultaneously.     

A REFRACTORY GLASS CHONDRULE IN THE VIGARANO CHONDRITE

Vigarano, a type 3 carbonaceous chondrite, contains a chondrule composed of highly refractory Ca and Al rich glass with minor spinel. The chondrule formed from material similar to the Ca, Al, Ti-rich aggregates that are common in Vigarano and other type 3 chondrites and formation of these refractory aggregates must predate formation of some Vigarano chondrules. Experiments with synthetic analogues and a comparison with studies in the system CaO-MgO-Al₂O₃-SiO₂ indicate a temperature for formation of the chondrule at or above 1700 °C followed by very rapid cooling.     

A POSSIBLE SOURCE IN CAMBODIA FOR AUSTRALASIAN TEKTITES

A possible crater representing the source of Australasian tektites is identified in northeastern Cambodia at longitude, 106° 34′E., and latitude, 13° 55′N. The crater is an incomplete oval ring of hills 10 km long and 6 km wide located near the center of the Muong Nong-type tektite strewnfield. The morphology of the structure may have been significantly changed by relatively recent erosion and deposition processes. The types of rocks in the area of the crater are consistent with the compositional requirements for the tektite source rocks. Collection of impactite material from the vicinity of the structure will be required to confirm its association with Australasian tektites.     

A TRANSITION IN THE ACCRETION PROPERTIES OF AGN

This contribution focuses on the evidence for a bimodality in the luminosity believed to be associated with the accretion process in AGN. In particular, it will be stressed that this behavior does seem to be present in an analogous way both in radio-loud and radio-quiet AGN, as inferred from samples selected in an independent way. The found bimodality can be naturally – although not uniquely – interpreted in the frame of the ADIOS solution for radiative inefficient accretion flows. The (so far) qualitative analogy with the behavior of XRB provides an interesting perspective to find a unique framework for the accretion and jet production in accreting black hole systems.     

GC星表的系统差研究

本文介绍GC星表相对于FKS星表的系统差及其计算方法,对星表系统差中存在的差异进行了分析研究．主要内容包括以下几个方面．（1）在FK5系统内建立一个新的暗星系统（RFK5ex）．（2）GC星表中的暗星相对于RFK5ex的系统差．（3）GC星表中的亮星相对于FK5bas的系统差．（4）GC星表中的暗星系统与亮星系统的差别,以及GC星表系统差改正中的一些有关问题．     

黑洞周围一般轨道发光环的坐标系拖曳(FD)特征

根据Ｋｅｒｒ度规下粒子运动的一般方程,计算黑洞周围一般轨道单色发光环的谱线轮廓,获得了坐标系曳（ＦＤ）的特征。结果表明,原谱线发生分裂,呈现具有伴峰的双主峰轮廓,且随参数变化峰型差异明显;谱线全部发生谱移,计算参数下谱移量为负０．５到１．５;并且应用上述ＦＤ的证据,结合ＭＣＧ－６－３０－１５实际观测结果,讨论了利用发射谱线获得黑洞相关信息的可行性。     

HALF-WIDTH OF A SOLAR DYNAMO WAVE IN PARKER'S MIGRATORY DYNAMO

A kinematic -dynamo model of magnetic field generation in a thin convection shell with nonuniform helicity for large dynamo numbers is considered in the framework of Parker's migratory dynamo. The asymptotic solution obtained of equations governing the magnetic field has the form of an anharmonic travelling dynamo wave. This wave propagates over most latitudes of the solar hemisphere from high latitudes to the equator, and the amplitude of the magnetic field first increases and then decreases with propagation. Over the subpolar latitudes, the dynamo wave reverses; there the dynamo wave propagates polewards and decays with latitude. The half-width of the maximum of the magnetic field localisation and the phase velocity of the dynamo wave are calculated. Butterfly diagrams are plotted and analysed and these show that even a simple model may reveal some properties of the solar magnetic fields.     

EVOLUTION OF A DELTA GROUP IN THE PHOTOSPHERE AND CORONA

We present a study of the evolution of NOAA AR 7205 in the photosphere and corona, including an analysis of sunspot motions, and show the evolutionary aspects of flare activity using full-disc white-light observations from Debrecen, vector magnetograms from Mees Observatory, Hawaii, and Yohkoh soft X-ray observations. NOAA AR 7205 was born on the disc on 18 June, 1992. During the first 3 days it consisted of intermittent minor spots. A vigorous evolution started on 21 June when, through the emergence and merging (v 100–150 m s^-1) of several bipoles, a major bipolar sunspot group was formed. Transverse magnetic fields and currents indicated the presence of shear (clockwise twist) already on 21 June (with 0.015 Mm^-1). On 23 June, new flux emerged in the trailing part of the region with the new negative polarity spot situated very close to the big positive polarity trailing spot of the main bipole. The secondary bipole seemed to emerge with high non-potentality (currents). From that time the AR became the site of recurrent flare activity. We find that all 14 flares observed with the Yohkoh satellite occurred between the highly sheared new bipole and the double-headed principal bipole. Currents observed in the active region became stronger and more extended with time. We propose that the currents have been (i) induced by sunspot motions and (ii) increased by non-potential flux emergence leading to the occurrence of energetic flares (X1.8 and X3.9). This observation underlines the importance of flare analysis in the context of active region evolution.     

一种基于CCD的白天激光光束的监视方法

介绍了采用曝光时间小于 10的高速CCD以及相应的图像卡成功实现白天强背景光下实时显示激光束的方法 ,该方法可以有效提高卫星激光测距的白天测距能力。     

PROCESSES AND SUBDIVISIONS IN DIOGENITES,A MULTIVARIATE STATISTICAL ANALYSIS

Multivariate statistical techniques used on diogenite orthopyroxene analyses show the relationships that occur within diogenites and the two orthopyroxenite components (class I and II) in the polymict diogenite Garland. Cluster analysis shows that only Peckelsheim is similar to Garland class I (Fe-rich) and the other diogenites resemble Garland class II. The unique diogenite Y 75032 may be related to type I by fractionation. Factor analysis confirms the subdivision and shows that Fe does not correlate with the weakly incompatible elements across the entire pyroxene composition range, indicating that igneous fractionation is not the process controlling total diogenite composition variation. The occurrence of two groups of diogenites is interpreted as the result of sampling or mixing of two main sequences of orthopyroxene cumulates with slightly different compositions.     

窄吸积环动力学不稳定性的数值解

本文在细环近似和共转半么位移不为零的条件下，考虑吸积环中非轴对称动力学不稳定性的线性扰动过程，采用数值计算方法求得不稳定性的线性增长率和共转半径位移随波数的变化关系，发现线性增长率受共转半径不为零的影响较小，而共转半径位移项随波数的色散关系与线性Ｋｄｖ方程的色散关系相同，说明窄吸收环在动力学不稳定性数值模拟中出现的“行星状解”很可能是类似于Ｋｄｖ方程中的孤子解。