哈雷彗星的彗发光谱

用云南天文台一米望远镜卡焦摄谱仪(f=175mm相机),在哈雷彗星的日心距分别为1.11AU和0.83AU时,作了两次彗发光谱观测,得到了典型的彗发光谱。本文绘出了各带系清晰的分子发射光谱图及认证结果。此外,本文还给出了彗发CN的(0—1)带(λ4216)和C_3的蓝紫发射(λ4052)及C_2的(2—0)带(λ4365)的强度比CN/C_3和CN/C_2,其值分别为CN/C_3=1.03,CN/C_2=1.00。最后,我们还将结果与其他作者在这次回归中所得到的结果进行了比较。     

磁场对辐射及中子星结构的影响

本文是近几年“攀登计划”执行情况的汇报。它概括了同步曲率辐射新机制发现的意义、解决的问题及应用前景。同时它阐明了中子星内部超强磁场存在的影响,以及可与观测相比较的效应。     

用斯托克斯轮廓推导太阳矢量磁场和热力学参量的三维结构

一种根据斯托克斯轮廓分析推导太阳矢量磁场和热力学参量的空间三维结构的新方法在本文中提出．在不考虑散射和原子偏振的假设下，该方法由三个具有不同功能的操作分别作用于太阳大气中一层或二层斯托克斯轮廓组成．这三个操作构成一个运行单元．将此单元运用到从表面到光球底层所划分的大气层格点，然后对扫描区所有的点应用同样的程序便可获得太阳上观察区的矢量磁场和热力学参量的空间三维结构．文中给出了相应的流程图和三个操作的详细描述，并用简化了的程序对理论轮廓进行了拟合．结果表明此方法能较满意地导出矢量磁场尤其是磁场强度的三维空间结构，而热力学参量结构的推导还需进一步改进．     

RECONSTRUCTION OF THE THREE-DIMENSIONAL CORONAL MAGNETIC FIELD

Studies of solar flares indicate that the mechanism of flares is magnetic in character and that the coronal magnetic field is a key to understanding solar high-energy phenomena. In our ongoing research we are conducting a systematic study of a large database of observations which includes both coronal structure (from the Soft X-ray Telescope on the Yohkoh spacecraft) and photospheric vector magnetic fields (from the Haleakala Stokes Polarimeter at Mees Solar Observatory). We compare the three-dimensional nonlinear force-free coronal magnetic field, computed from photospheric boundary data, to images of coronal structure. In this paper we outline our techniques and present results for active region AR 7220/7222. We show that the computed force-free coronal magnetic field agrees well with Yohkoh X-ray coronal loops, and we discuss the properties of the coronal magnetic field and the soft X-ray loops.     

RECONSTRUCTING THE SOLAR CORONAL MAGNETIC FIELD AS A FORCE-FREE MAGNETIC FIELD

We present some preliminary results on different mathematical problems encountered in attempts to reconstruct the coronal magnetic field, assumed to be in a force-free state, from its values in the photosphere. We discuss the formulations associated with these problems, and some new numerical methods that can be used to get their approximate solutions. Both the linear constant- and the nonlinear cases are considered. We also discuss the possible use of dynamical 3D MHD codes to construct approximate solutions of the equilibrium force-free equations, which are needed for testing numerical extrapolation schemes.     

Time Analysis of the CO+ COMA OF COMET P/HALLEY BY IMAGE PROCESSING TECHNIQUES

Photographic and photoelectric observations of comet P/Halley's ion gas coma from CO⁺ at 4250 ? were part of the Bochum Halley Monitoring Program, conducted from 1986 February 17, to April 17 at the European Southern Observatory on La Silla (Chile). In this spectral range it is possible to watch the continuous formation, motion and expansion of plasma structures. To observe the morphology of these structures 32CO⁺ photos (glass plates) from P/Halley's comet have been analysed. They have a field of view of 28°.6× 28°.6 and were obtained from 1986 March 29, to April 17 with exposure times between 20 and120 minutes. All photos were digitized with a PDS 2020 GM (Photometric Data System) microdensitometer at the Astronomisches Institut derWestf?lischen Wilhelms-Universit?t in Münster (one pixel= 25 μm × 25 μm ≈ 46′.88×46′.88). After digitization the data were reduced to relative intensities, and the part with proper calibrations were also converted to absolute intensities, expressed in terms of column densities using the image data systems MIDAS (Munich Image Data Analysis System; ESO – Image Processing Group, 1988) and IHAP (Image Handling And Processing; Middleburg, 1983). With the help of the Stellingwerf-Theta-Minimum-Method (Stellingwerf, 1978) a period of (2.22 ± 0.09) days results from analysis of structures in the plasma-coma by subtracting subsequent images. This method is also compared with the Fourier method. There may be a second cycle with a period of about 3.6 days. The idea behind subtracting subsequent images is that rotation effects are only 10% phenomena on gas distribution. Difference images are than used to suppress the static component of the gas cloud. This revised version was published online in July 2006 with corrections to the Cover Date.     

CONFIGURATION OF THE MAGNETIC FIELD IN SOLAR ACTIVE REGIONS

In this paper we present the observational results of chromospheric and photospheric magnetograms in active regions obtained at the Huairou Solar Observing Station of the Beijing Astronomical Observatory. Simultaneous observations of the chromospheric and photospheric magnetic fields enable us to construct a possible configuration of the magnetic field in the solar atmosphere. The chromospheric magnetic field shows more diffusion than the photospheric magnetic field and consists of fibril-like features. We also discuss the possible configuration of the magnetic shear in highly sheared active regions.     

太阳黑子半影的形成和返回磁通量的来源

本文从无半影的黑子成长为带半影的黑子伴随着磁场强度增强和延伸运动这个观测事实出发，通过MHD数值模拟，证明了：（1）对流层内黑子中涡旋流动的自然形成；（2）仅在黑子表面附近磁矢才急速向外移动，最终形成我们观测到的半影磁场位形；（3）光球之上由于β迅速减少，这么小的延伸速度（0.2公里／秒）仅在β～1的光球区200公里厚的层里使磁矢有效地旋转，在约几小时至一天量级时间内将近似垂直的本影磁场向水平方向旋转，形成Osherovich所期的ReturnFlux磁位形，将注入日冕空间的本影主磁流同在色球和光球内就返回的半影磁流自然地划分开来．     

从微波爆和X射线爆联合估算日冕磁场

本文假定Ｘ射线爆和微波爆有共同的起源，用它们的爆发流量资料联合估算源中的磁场强度Ｂ、离子数密度ｎｉ和视线方向深度Ｌ．以１９８１年４月２７日０８００ＵＴ的由五个峰组成的延伸爆为例进行了计算。计算结果为：从厚靶模型和热模型得到的五个峰的磁场Ｂ分别为１８６５─６５９Ｇ和７７６─２３４Ｇ；而从薄靶模型算得的Ｂ为３５─１５３Ｇ，ｎｉ为１０８─６×１０９／ｃｍ３，最大的Ｌ为３．３×１０９ｃｍ．这个爆发的Ｘ射线主源的高度在光球上１．４×１０４ｋｍ，因此从薄靶模型得到的结果较为合理，这也与五个峰的“微波富有指数”随时增加相一致的。这似乎表明，五个峰的源位于同一冕环中，能量释放从环顶沿着磁力线向色球方向传播。传播的速度可能是离子声速，因为用上述数据得到的最小的阿尔芬速度超过１０４ｋｍ／ｓ。     

太阳磁场和速度场的研究

本文介绍了怀柔太阳学术集团于２２ 太阳周期间在太阳磁场和速度场研究方面的部分成果及对２３ 太阳活动周工作的展望     

强磁场下逆康普顿散射的偏振特性

本文在Herold和我们前一工作的基础上,讨论了强磁场中不同情况(相对论情况和非相对论情况)下的逆Compton散射的偏振特性,并与无磁场情况进行了比较,得出一些有益的结果。在研究气体,尤其是具有强磁场天体的高能X射线和γ射线,甚至光学辐射机制时,这些偏振特性必须给予充分注意。     

THE SOLAR MAGNETIC FIELD IN THREE DIMENSIONS

Historically, our understanding of the solar magnetic field has been shaped by an interplay between theoretical ideas about the subsurface dynamo and precise measurements of magnetic flux at the level of the photosphere. Today we have an unprecedented ability to measure, or to infer from measurements, properties of the magnetic field at every level from the solar interior to interplanetary space, although photospheric observations still lead the way in completeness and precision. I review the state of our capabilities to measure or calculate the magnetic field and suggest that the next major goal should be to follow specific magnetic structures in space and time from before they emerge until they can no longer be detected at any level.     

POSITION OBSERVATIONS OF THE COMET HYAKUTAKE

1. Introduction When astronomers all over the world observed this particular large and bright Comet Hale-Bopp, that was still outside orbit of the jupiter, another japanese amateur astronomer, Yuji Hyakutake, discovered a new unknown comet on 31 January 1996, which appeared quite near the Earth and was very bright. At Yunnan Observatory, we planned to take pictures of Comet Hale Bopp. We were also interested in Comet Hyakutake. At midnight of 16 March 1996, before we conducted the     

Hale-Bopp彗星自转轴指向的确定

根据上海天文台1．56米望远镜提供的Hale-Bopp彗星近核观测资料,利用两种不同的方法对该彗星的自转轴指向进行了测定．两种方法求出的自转轴指向结果非常接近,Hale-Bopp彗星自转轴指向点的赤经为0h14m32s,赤纬为-49°09′35″(2000年历元)．     

RELEVANCE OF CME TO THE STRUCTURE OF LARGE-SCALE SOLAR MAGNETIC FIELDS

The relevance of the occurrence rate and location of CME events to two main systems (giant and supergiant) of the large-scale solar magnetic field structure has been investigated. The clustering of CME events and solar flares toward the neutral line of the global field system (neutral line of the source surface field) corroborates the finding by Hundhausen that CME locations track the heliomagnetic equator. A good correlation has been revealed between the CME occurrence rate and variations of the index of the effective solar multipole, that characterizes the typical scale of the global solar magnetic field. The CME rate exhibits sharp jumps/decreases when the index of the effective solar multipole passes through n=4. The observations of X-ray 'blow-out' effects have been analyzed as probable manifestations of CMEs on the disk and have been compared with the large-scale magnetic field structure. As shown by the analysis, the X-ray arcades straddle the neutral line and occur, or at least tend to occur, where the neutral line exhibits a sharp bend. A conclusion is made that CME events are caused by interaction of two large-scale field systems, one of them (the global field system) determining the location of CMEs and another (the system of closed magnetic fields) their occurrence rate.     

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.     

海尔—波普彗星自转周期的测定

采用小波方法对海尔波普彗星的近核ＣＣＤ图像进行处理,并进一步分析了彗核的亮度中心周围的特征结构,从而提出了一种直观而有效的方法来测定海尔波普彗星投射在观测平面上的平均自转周期,结果为２４．４１±０．９６小时     

THE INFLUENCE OF SOLAR PHOTOGRAVITATION ON THE MOTION OF COMET TAIL

On the basis of photogravitational theory, the influence of solar photogravitation on the motion of comet tail is discussed in this paper. It is shown that for plasma tail and some of the dust tail, there are two coplaner libration points L6, L7, and three collinear points L21, L22,L3 at most. The regions in which the dust grain of comet tail can move are also obtained.     

海尔—波普彗星1996年春观测

1996年2月底至3月初，海尔-波普彗星在清晨前重新出现，地平高度较低．本文使用云南天文台1米望远镜加新研制的1024×1024CCD照像机，对该彗星进行了照像观测，精密测定了其位置及光度．结果表明，即使与最新的预报比较起来，仍旧存在着明显的系统偏差．因此，海尔一波普彗星的轨道根数仍需修正．其亮度也比最新的预报稍亮．     

THE FRAGMENTS OF COMET HYAKUTAKE (C/1996 B2)

Several fragments of Comet Hyakutake were observed in March and April of 1996. This leads to the impression that the splitting of Comet Hyakutake on a small scale occurred frequently. Data analysis points to a rotation period of about 6.18hr if the fragments of Apr. 11 are the condensations within a jet.