海尔—波普彗星的一个可能的巨大等离子体喷流

１９９６年９月１１日，使用上海天台１．５６ｍ望远镜和Ｓｅｒｉｓ２００ＣＣＤ照相机，在Ｂ波段发现海尔－波普彗星有一个巨大的喷流，初步认定为等离子喷流。     

海尔—波普彗星喷流的一次成功检测

上海天文台余山观测站1．56m望远镜于1996年9月23日北京时间19点40分拍摄了海尔-波普彗星的CCD图象。使用的滤光片是R，露光时间为45s。经过偏流（bias）、暗流（dark）以及平场（flat）改正的图象上可以看出彗核附近有5条喷流，但是并不十分清楚（见图1）。这主要是由于喷流叠     

Hale—Bopp彗星喷流结构的周期变化

通过对上海天台佘山观测基地１９９７年３月３至５月 初期间所得到的Ｈale－Ｂｏｐ ｐ彗星喷流观测流观测资料的处理和分析，发现该彗星的喷流结构有周期性变化，其周期为８－９天，这种周期变化可能与彗星的自转轴在空间的进动周期有关。     

1997年3月4日海尔-波普彗星的小规模分裂

１　引言彗核分裂是彗星的最重要特征之一．至１９８２年止文献记录共观测到２２个彗核分裂,３３个次核［１］．１９８６年哈雷彗星回归时观测到彗核的分裂［２］．１９９６年紫金山天文台２００ｍｍ赤道望远镜和青岛观象台同时观测到百武彗星的分裂［３］．海尔波普彗星从１９９５年８月到１０月曾爆发５次［４］．１９９６年３月至１２月不断有喷流射出,彗核活动日趋剧烈［５］．１９９７年３月４日我们观测到彗核的小规模分裂及喷流特征,３月３日我们观测到海尔波普彗星近核照片上有喷流,这可能是３月４日彗核小块分裂的前奏．３…     

Hale-Bopp 彗星喷流结构的周期变化

通过对上海天文台佘山观测基地１９９７年３月至５月初期间所得到的Ｈａｌｅ－Ｂｏｐｐ彗 星喷流观测资料的处理和分析,发现该彗星的喷流结构有周期性变化,其周期为８—９ 天,这种周期变化可能与彗星的自转轴在空间的进动周期有关．     

海尔—波普彗星近核区图像增强方法及比较

用Ｓｅｋａｎｉｎａ 等的方法和小波处理方法分别对１９９７ 年３ 月３ 日至５ 日在紫金山天文台行星室观测得到的海尔－ 波普彗星的近核现象ＣＣＤ 图像加以增强处理和分析比较,明显地从ＣＣＤ 图像还原出壳层（ｓｈｅｌｌ） 和喷流（ｊｅｔ） 结构,结果表明小波处理方法比Ｓｅｋａｎｉｎａ 等的方法在小视场图像处理中效果更佳     

3C390．3的弱秒差距尺度喷流及其变化

通过对射电星系３Ｃ３９０．３在历元１９８９．２９及６ｃｍ波长的ＶＬＢＩ观测数据的多软件包成象，辨认出其弱秒差距尺度喷流中几个分离的节，将它们和以前发表及未发表的同一波长的成象结果比较，显示了该源弱秒差距尺度喷流的弯曲和反喷流，并重新证认了喷流中节的视超光速运动。     

3C390.3的弱秒差距尺度喷流及其变化

通过对射电星系３Ｃ３９０．３在历元１９８９．２９及６ｃｍ波长的ＶＬＢＩ观测数据的多软件包成象，辨认出其弱秒差距尺度喷流中几个分离的节，将它们和以前发表及未发表的同一波长的成象结果比较，显示了该源弱秒差距尺度喷流的弯曲和反喷流，并重新证认了喷流中节的视超光速运动。     

SL9彗星撞击木星时S碎片的CCD观测

用上海天台１．５６ｍ望远镜和ＣＣＤ照相机，观测Ｓ＝５碎片时，发现了类似彗尾的奇异现象。     

SL9彗星撞击木星时S碎片的CCD观测

用上海天文台１．５６ｍ望远镜和ＣＣＤ照相机，观测ｓ＝５碎片时，发现了类似彗尾的奇异现象。     

太阳表面米粒结构观测对比度分析

分析以观测系统焦面上和探测器测到的太阳表面米粒结构的对比度与观测系统口径，大气湍流相干长度以及系统探测灵敏度的关系，给出了不同口径，不同大气湍流相干长度以及不同系统探测灵敏度时的米粒结构对比值计算结果，此外还给出了实验结果。     

The galactic infrared/submillimeter dust radiation

Summary The unprecedented quality of the IRAS data prompted a series of papers reinvestigating the origin of the galactic infrared/submillimeter radiation and the nature of the heating sources of the interstellar dust. The scope of this paper is to review the main results of these new studies. Sect. 1 contains a general introduction to the subject and an overview of the earlier work. In Sect. 2 and 3, we summarize our current knowledge on dust properties and on the interstellar radiation field. Then, we present the recent interpretations of the infrared emission of our Galaxy, which are based on the IRAS data: in Sect. 4 we present the results from the galactic disk; Sect. 5 covers the question of the contribution from small dust particles, and in Sect. 6 we describe the infrared radiation from the galactic center. The nature of the heating sources and the origin of the galactic infrared radiation is then discussed in Sect. 7. Finally, Sect. 8 presents a comparison of our Galaxy with external galaxies     

The interaction and eruption of two adjacent filaments

We present a case study of two successive filament eruptions at the southeast limb of the Sun observed by Solar Dynamics Observatory (SDO) on 2012 April 19. At the initial stage of the first filament (F1) eruption, one leg of the F1 moved toward the second filament (F2) and swept the F2. The interaction between two filaments occurred. After the leg of the F1 swept the F2, it returned from northeast to southwest following the F1 expansion. During the F1 eruption, the middle of the F1 exhibited an obvious twisted structure. The rising speed of the F1 was 85.6 km/s. The partial material of the F1 fell back to the surface along the other leg of the F1 after the F1 eruption and the falling speed was 311.6 km/s. A CME was observed by SOHO/LASCO after the F1 eruption. One of the bright flare ribbons and the dimming regions formed after the F1 eruption were found to move toward the F2. The propagation speeds of the flare ribbons were 4.7 km/s and 4.1 km/s and the propagation speeds of the dimmings were 3 km/s and 6.3 km/s. The small active region was emerging in the northern flank of the F2. The ejection and the falling plasma in the small active region produced the disturbance to the right part of the F2. When the F1 erupted, the large-scale overlying coronal loops of the F1 were pushed out toward the southeast of the Sun by its expanding. During the F1 eruption, the large-scale overlying coronal loops of the F2 began to open toward the southeast. Following the opening of the large-scale overlying coronal loops, the F2 became instable and began to erupt. The rising speed of the F2 was 300.1 km/s. A two-ribbon flare and a weak CME were formed after the F2 eruption. These observations evidenced that the interaction of two filaments and the opening of the large-scale overlying coronal loops caused by the F1 eruption are the most important reason that led to the F2 eruption. Our observations also support the standard solar flare model.     

Corrections stemming from the non-osculating character of the Andoyer variables used in the description of rotation of the elastic Earth

We explore the evolution of the angular velocity of an elastic Earth model, within the Hamiltonian formalism. The evolution of the rotation state of the Earth is caused by the tidal deformation exerted by the Moon and the Sun. It can be demonstrated that the tidal perturbation to spin depends not only upon the instantaneous orientation of the Earth, but also upon its instantaneous angular velocity. Parameterizing the orientation of the Earth figure axis with the three Euler angles, and introducing the canonical momenta conjugated to these, one can then show that the tidal perturbation depends both upon the angles and the momenta. This circumstance complicates the integration of the rotational motion. Specifically, when the integration is carried out in terms of the canonical Andoyer variables (which are the rotational analogues to the orbital Delaunay variables), one should keep in mind the following subtlety: under the said kind of perturbations, the functional dependence of the angular velocity upon the Andoyer elements differs from the unperturbed dependence (Efroimsky in Proceedings of Journées 2004: Systèmes de référence spatio-temporels. l’Observatoire de Paris, pp 74–81, 2005; Efroimsky and Escapa in Celest. Mech. Dyn. Astron. 98:251–283, 2007). This happens because, under angular velocity dependent perturbations, the requirement for the Andoyer elements to be canonical comes into a contradiction with the requirement for these elements to be osculating, a situation that parallels a similar antinomy in orbital dynamics. Under the said perturbations, the expression for the angular velocity acquires an additional contribution, the so called convective term. Hence, the time variation induced on the angular velocity by the tidal deformation contains two parts. The first one comes from the direct terms, caused by the action of the elastic perturbation on the torque-free expressions of the angular velocity. The second one arises from the convective terms. We compute the variations of the angular velocity through the approach developed in Getino and Ferrándiz (Celest. Mech. Dyn. Astron. 61:117–180, 1995), but considering the contribution of the convective terms. Specifically, we derive analytical formulas that determine the elastic perturbations of the directional angles of the angular velocity with respect to a non-rotating reference system, and also of its Cartesian components relative to the Tisserand reference system of the Earth. The perturbation of the directional angles of the angular velocity turns out to be different from the evolution law found in Kubo (Celest. Mech. Dyn. Astron. 105:261–274, 2009), where it was stated that the evolution of the angular velocity vector mimics that of the figure axis. We investigate comprehensively the source of this discrepancy, concluding that the difference between our results and those obtained in Ibid. stems from an oversimplification made by Kubo when computing the direct terms. Namely, in his computations Kubo disregarded the motion of the tide raising bodies with respect to a non-rotating reference system when compared with the Earth rotational motion. We demonstrate that, from a numerical perspective, the convective part provides the principal contribution to the variation of the directional angles and of length of day. In the case of the x and y components in the Tisserand system, the convective contribution is of the same order of magnitude as the direct one. Finally, we show that the approximation employed in Kubo (Ibid.) leads to significant numerical differences at the level of a hundred micro-arcsecond.     

Numerical simulation of seasonal dynamics of water vapor in the Martian atmosphere

The seasonal evolution of the H₂O snow in the Martian polar caps and the dynamics of water vapor in the Martian atmosphere are studied. It is concluded that the variations of the H₂O mass in the polar caps of Mars are determined by the soil thermal regime in the polar regions of the planet. The atmosphere affects water condensation and evaporation in the polar caps mainly by transferring water between the polar caps. The stability of the system implies the presence of a source of water vapor that compensates for the removal of water from the atmosphere due to permanent vapor condensation in the polar residual caps. The evaporation of the water ice that is present in the surface soil layers in the polar regions of the planet is considered as such a source. The annual growth of the water-ice mass in the residual polar caps is estimated. The latitudinal pattern of the seasonal distribution of water vapor in the atmosphere is obtained for the stable regime.Translated from Astronomicheskii Vestnik, Vol. 38, No. 6, 2004, pp. 497–503.Original Russian Text Copyright © 2004 by Aleshin.     

磁场中p模/s模的转换及黑子对声波的吸收

在柱坐标下将黑子周围的环形区域（黑子除外）内的振荡分解为朝向黑子传播的（入射的）波和离开黑子传播的（出射的）波。对无黑子的环形区域内的振荡也进行了同样的分解。将黑子周围的入射波看成是被黑子磁流管磁化了的介质（介质内的磁场基本是水平的）中的波。而无黑子区的入射波看成是非磁化介质中的波。比较这两种波在固定波数下功率随频率的分布发现，在磁化介质中不同径向除ｎ的声波（ｐ模）频率系统降低，同时功率也降低，降低的功率最高达非磁化介质中波的功率的３０％。而比较在固定频率下功率随波数的分布发现，磁场中ｆ模及ｎ＝１，２，３的ｐ模的脊向高波数方向位移，功率的降低受频率调制，即声波在某些有限的频带中被吸收。这些观测表明，在磁场中ｐ模与磁声重力波（ＭＡＧ）产生了模式混合或耦合。模式混合的存在支持了模式转换作为ｐ模式被黑子吸收的机制的解释。此外，本文还分析了转换的ＭＡＧ波进入黑子磁流管（其中的磁场基本上是垂直的）后进一步被吸收，吸收的功率最高达ＭＡＧ波的２０％。在磁流管内没有进一步观测到模式的转换     

On the propagation of chromospheric condensations in solar flares (II)

We study the evolution of the mass motion velocity in the chromospheric condensation, when it propagates into the deeper atmosphere. The condensation is represented by a shock-like structure. Its momentum equation can be solved after some approximations. The computations are carried out for two cases, i.e., the case that the gas pressure just behind the condensation front is constant and the case that the pressure increase at the top of the condensation is constant. The results show that the duration of the condensation in the second case is considerably longer than that in the first case. The most evident difference of the velocity evolution between the two cases appears in their later phase. A comparison of the results in this paper with the dynamic simulations indicates that the second case may be closer to the real situation.     

Hypersonic beam driven by high-energy particles in extragalactic radio sources

A mechanism is proposed for the formation of collimated beams in radio galaxies. The collimated flows which are non-thermally driven by high energy particles and magneto-hydrodynamic (MHD) waves are presented. The galactic nucleus surrounded by a cool gas is investigated. The cool gas accretes onto the nucleus and the accretion matter can confine the wave zone around the nucleus in which the high energy particles are completely locked to the MHD waves. When a quasi-radial magnetic field is embedded in the accretion flow, the MHD wave packets are collimated into the direction of symmetry axis of the galactic nuclear disc. The fluid around the nucleus is considered to be accelerated and heated by the MHD waves and ejected along the axis.A complete set of hydrodynamic equations which contain the energy transfers of high energy particles and MHD waves is presented. One-dimensional flows which are in pressure equilibrium with the surrounding accretion matter are calculated. When the energy density of the MHD waves is higher than that of the thermal energy, the fluid flow is strongly collimated in a narrow beam. When the MHD waves are strongly damped by the resistivity of the fluid at the great distance from the galactic centre, the collimated beam broadly reexpands. On the basis of the collimated beams driven by high energy particles, the radio morphology of the double radio sources is discussed.     

用SAVQ技术实现太阳射电频谱的数据压缩

对自适应矢量量化（SAVQ）技术在太阳射电频谱数据压缩中的应用进行了有意义的讨论．给出一种压缩比和失真可调的SAVQ压缩方法,指出提高数据压缩比的有效方法之一为样本集成,同时介绍了用该技术对北京天文台太阳射电频谱仪上的两个波段（1．0GHz－2．0GHz和2．6GHz－3．8GHz）的观测数据进行压缩的实用效果,并与国际同行所用的ICON方式进行性能比较．最后展示了数据压缩技术及其在天文上的应用．     

Retrieving volume FeO and TiO_2 abundances of lunar regolith with CE-2 CELMS data using BPNN method

The volume FeO and TiO_2 abundances(FTAs) of lunar regolith can be more important for understanding the geological evolution of the Moon compared to the optical and gamma-ray results. In this paper, the volume FTAs are retrieved with microwave sounder(CELMS) data from the Chang'E-2 satellite using the back propagation neural network(BPNN) method. Firstly, a three-layered BPNN network with five-dimensional input is constructed by taking nonlinearity into account. Then, the brightness temperature(TB) and surface slope are set as the inputs and the volume FTAs are set as the outputs of the BPNN network.Thereafter, the BPNN network is trained with the corresponding parameters collected from Apollo, Luna,and Surveyor missions. Finally, the volume FTAs are retrieved with the trained BPNN network using the four-channel TBderived from the CELMS data and the surface slope estimated from Lunar Orbiter Laser Altimeter(LOLA) data. The rationality of the retrieved FTAs is verified by comparing with the Clementine UV-VIS results and Lunar Prospector(LP) GRS results. The retrieved volume FTAs enable us to re-evaluate the geological features of the lunar surface. Several important results are as follows. Firstly, very-low-Ti(1.5 wt.%) basalts are the most spatially abundant, and the surfaces with TiO_2 5 wt.% constitute less than 10% of the maria. Also, two linear relationships occur between the FeO abundance(FA) and the TiO_2 abundance before and after the threshold, 16 wt.% for FA. Secondly, a new perspective on mare volcanism is derived with the volume FTAs in several important mare basins, although this conclusion should be verified with more sources of data. Thirdly, FTAs in the lunar regolith change with depth to the uppermost surface,and the change is complex over the lunar surface. Finally, the distribution of volume FTAs hints that the highlands crust is probably homogeneous, at least in terms of the microwave thermophysical parameters.