关于摄谱仪中畸象系统的若干讨论

本文讨论了摄谱仪中若干畸象系统,它们的作用是缩放入射狭缝的象单在高或宽的方向的尺寸,这等效于在狭缝前、后单在子午面内或弧矢面(色散方向面)内改变光束的孔径角,也等效于准直光束单在子午面或弧矢面内缩放光束宽度,在讨论中指出了准直畸象系统优于非准直畸象系统。 在着重讨论和分析准直畸象系统的不同形式时,我们提出了棱镜系统,它具有许多优点,是最为可行的方案。     

金牛座η星的H_α发射短时标变化

在1990年12月—1991年1月期间,我们用2.16米望远镜卡焦摄谱仪的单光纤系统、红敏CCD探测器,对金牛座η星进行了三个夜晚观测,取得18条H_α波段的光谱.发现其H_α发射成分存在短时标变化.     

一米望远镜象增强摄谱系统试观测报告

一九八三年八月我们把光增益高的三级象增强器引用到天文仪器中。设计了象管导星装置。经过实验证明:它的运用使一米望远镜的导星能力提高了三个星等。一九八四又设计研制了象管摄谱系统,并在一米卡焦摄谱仪上进行了试观测。 经过实验室和试观测证明:使用该系统后使一米望远镜卡焦摄谱能力对不同的波段     

云台一米镜卡焦摄谱仪重力弯沉的谱线位移及展宽效应

本文在理论上着重分析了云台一米镜卡焦摄谱仪中准直镜和照相机的重力弯沉效应。并拍摄了一米镜处于四十五个不同指向时的铁谱,测量重力弯沉效应引起谱线位移的大小。表明,重力弯沉引起谱线位移为μ的数量级,在观测中的连续变化产生特殊的谱线展宽效应。实验与理论分析的拟合基本一致。并讨论了重力弯沉对波长测量、谱线轮廓测量、光谱分辨率测量的影响以及克服的方法。     

在各类反射望远镜系统中设计改正透镜的初步讨论

本文讨论在反射望远镜系统中不限制主镜、副镜的表面形状,加入改正透镜后怎样达到同时消去球差、彗差、象散以及场曲的效果,以提高成象的光学质量.一、改正透镜在主焦点系统中的应用1.改正透镜在经典的抛物面主镜主焦点系统中的应用为了提高抛物面反射镜轴外象点的光学质量,罗斯(F.E.Ross)提出可以在焦面以前     

卡塞格林系统非球面板像场改正器的设计和研究

本文通过口径为1000,主焦比为3,卡氏焦比为8的实例,对四种主要的卡氏系统:1.类R-C、2.R-C、3.抛物面主镜和4.球面主镜的卡氏系统,研究和设计了四种不同的非球面板改正器。对类R-C、R-C和抛物面主镜的卡氏系统,视场直径取为1°.5,在4047—4861波段附近,像的最大弥散小于0″.2。在3650—10140的波段范围,各色光叠加在一起的最大弥散约为0″.5。对于球面主镜的卡氏系统,视场直径取为40′,相应的像斑为0″.8和1″.1。以上这些系统,当取去改正器后,都有一个消球差的焦点。对于其它焦比值的卡氏系统,这些研究和结果,仍具有参考价值。     

离焦量误差对相位差法波前重构的影响

相位差法波前探测是利用焦面和已知像差函数及像差尺度的离焦位置上同时采集的一对短曝光图像,通过最优化方法使代价函数最小化,从而得到目标和波前相位估计值的渡前探测方法.本文通过计算机模拟了像差函数为离焦像差的情况下,经相位差法波前探测成像系统后在焦面和离焦面上采集得到的图像强度分布,采用有限内存拟牛顿法(LFBGS)对模拟图像进行数值求解,实现了渡前相位的重构和对面源目标的重建;由于在实际应用中测量误差和机械加工带来的离焦量偏差是不可避免的,因此在模拟实验中就离焦量尺度不精确的情况进行了分析.     

1975年天鹅座新星

1975年8月30日晚上,我国许多天文爱好者和北京天文台兴隆站独立发现了这颗新星.从8月30日北京天文台所拍底片估计该新星的坐标为赤经21~h10~m,赤纬 48°.0(1950.0).自8月31日起,北京天文台用90厘米折反射式镜的光栅摄谱仪对它进行了系统的光谱观测.8月31日所拍色散50(?)/mm 的光谱中呈现强而宽的氢巴尔末发射线、星际 NaI 的 D 和 CaII 的 H 和 K 的锐吸收线,红区连续谱很强.由 H_β粗略估算壳层膨胀速     

狐狸座PU(PU Vul)的一次小爆发

狐狸座PU是1979年4月8日由日本东京天文台Y.Kuwano等人首先发现的一颗光度变化特殊的类新星天体.1978—79年间,梅苞在用北京天文台40/200双筒天体照相仪对这一天区的其他天体作系统观测时,同时取得了这颗星的一批照相观测资料,在获悉有关这颗星的发现报道之前,他也曾独立地发现了这颗星的光度变化(图版Ⅰ,图2),并随即用北京天文台的60/90/1800施密特望远镜有缝摄谱仪取得了该星的部分光谱资料.此外,还用北京天文台60厘米反射望远镜进行了高速光电观测.从1978年12月到1983年3月,共取得照相观测底片和光谱片200余张以及一些光电测光资料.     

双水平式卫星跟踪望远镜运动控制卡的设计与实现

从硬件和软件的设计角度介绍了双水平式卫星跟踪望远镜运动控制卡的技术实现。其检测运动角的编码器采用BISS传输,能够高速通信(10MHz),比传统的SSI模式传输数据更稳定和安全可靠。望远镜的二个运动轴具有快/慢/微动三档,可以由用户分别设置速率,同时又设置了限位功能。GPS模块则为系统提供了精确的时间,激光发射的设置则满足了用户的特殊需求。通过测试表明该电控卡能够配合CPU的相关软件实现对卫星的精确定位和跟踪,满足了实际的性能要求。     

Morphological and kinematic signatures of a binary central star in the planetary nebula Hu 2-1

We present H α , [N  ii ] and [O  iii ] ground-based and HST archive images, VLA–A 3.6-cm continuum and H92 α emission-line data and high-resolution long-slit [N  ii ] spectra of the planetary nebula Hu 2-1. A large number of structural components are identified in the nebula: an outer bipolar and an inner shell, two pairs of collimated bipolar structures at different directions, monopolar bow-shock-like structures, and an extended equatorial structure within a halo. The formation of Hu 2-1 appears to be dominated by anisotropic mass ejection during the late-AGB stage of the progenitor and by variable, 'precessing' collimated bipolar outflows during the protoplanetary nebula and/or early planetary nebula phases. Different observational results strongly support the existence of a binary central star in Hu 2-1, among them (1) the observed point-symmetry of the bipolar lobes and inner shell, and the departures from axial symmetry of the bipolar lobes, (2) the off-centre position of the central star, (3) the detection of mass ejection towards the equatorial plane, and (4) the presence of 'precessing' collimated outflows. In addition, (5) an analysis of the kinematics shows that the systemic velocity of the bipolar outflows does not coincide with the systemic velocity of the bipolar shell. We propose that this velocity difference is a direct evidence of orbital motion of the ejection source in a binary system. From a deduced orbital velocity of ∼10 km s⁻¹, a semimajor axis of ∼ 9–27 au and period of ∼ 25–80 yr are obtained, assuming a reasonable range of masses. These parameters are used to analyse the formation of Hu 2-1 within current scenarios of planetary nebulae with binary central stars.     

Evidence for ablated flows in the shell of the nova DQ Herculis

High-resolution long-slit Hα spectra of the shell of the old nova DQ Herculis have been obtained with the William Herschel Telescope using the ISIS spectrograph. An equatorial expansion velocity of  370 ± 14   km s⁻¹  is derived from the spectra which, in conjunction with a narrow-band Hα image of the remnant, allows a distance estimate of 525 ± 28 pc. An equatorial ring which exhibits enhanced [N  ii ] emission has also been detected and the inclination angle of the shell is found to be     with respect to the line of sight. The spectra also reveal tails extending from the clumps in the shell, which have a radial velocity increasing along their length. This suggests the presence of a stellar wind, collimated in the polar direction, which ablates fragments of material from the clumps and accelerates them into its stream up to a terminal velocity of the order of 800–900 km s⁻¹.     

On the connection between radial systems of dark globules and stellar associations

We study the connection between radial systems of dark globules and stellar associations. It is shown that of the 17 systems of type 1 in Table 1 of [1] 16 radial systems are connected with known associations. A new association is found (missing from the catalogs) connected with the remaining system (System No. 2). Four systems of the six systems of type 2 (Table 2 of [1]) are connected with known associations. A new method of determining the distance to associations is proposed, using the mean linear thickness of dark globules of radial systems connected with these associations as the criterion for distance. Using this method we make the distance to the association Cyg OB 9 more precise and answer the question whether several radial systems belong to the corresponding stellar associations.Translated fromAstrofizika, Vol. 37, No. 4, 1994.The authors are grateful to Academician V. A. Ambartsumyan for constant attention to this work.     

Precessing collimated outflows in the planetary nebula IC 4846

We present [N  ii ] and H α images and high-resolution long-slit spectra of the planetary nebula IC 4846, which reveal, for the first time, its complex structure and the existence of collimated outflows. The object consists of a moderately elongated shell, two (and probably three) pairs of collimated bipolar outflows at different orientations, and an attached circular shell. One of the collimated pairs is constituted by two curved, extended filaments the properties of which indicate a high-velocity, bipolar precessing jet. A difference of ≃10 km s⁻¹ is found between the systemic velocity of the precessing jets and the centroid velocity of the nebula, as recently reported for Hu 2-1. We propose that this difference is as a result of orbital motion of the ejection source in a binary central star. The orbital separation of 30 au and period 100 yr estimated for the binary are similar to those in Hu 2-1, linking the central stars of both planetary nebulae to interacting binaries. Extraordinary similarities also exist between IC 4846 and the bewildering planetary nebula NGC 6543, suggesting a similar formation history for both objects.     

The chemical compositions of 10 new sub-DLAs and strong Lyman-limit systems at z≲ 1.5

We present chemical abundance measurements from medium-resolution observations of eight subdamped Lyα (sub-DLA) absorber and two strong Lyman-limit systems at   z ≲ 1.5  observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5-m Magellan II Clay telescope. These observations were taken as part of an ongoing project to determine abundances in   z _abs≲ 1.5  quasar absorption line systems focusing on sub-DLA systems. These observations increase the sample of Zn measurements in   z _abs≲ 1.5  sub-DLAs by ∼50 per cent. Lines of Mg  i , Mg  ii , Al  ii , Al  iii , Ca  ii , Mn  ii , Fe  ii and Zn  ii were detected and column densities were determined. Zn  ii , a relatively undepleted element and tracer of the gas-phase metallicity is detected in two of these systems, with  [Zn/H]=−0.05 ± 0.12  and  [Zn/H] > +0.86  . The latter one is however a weak system with   N _{H  I} < 18.8  , and therefore may need significant ionization corrections to the abundances. Fe  ii lines were detected in all systems, with an average Fe abundance of  〈[Fe/H]〉=−0.68  , higher than typical Fe abundances for DLA systems at these redshifts. This high mean [Fe/H] could be due to less depletion of Fe on to dust grains, or to higher abundances in these systems. We also discuss the relative abundances in these absorbers. The systems with high metallicity show high ratios of [Mn/Fe] and [Zn/Fe], as seen previously in another sub-DLA. These higher values of [Mn/Fe] could be a result of heavy depletion of Fe on to grains, unmixed gas, or an intrinsically non-solar abundance pattern. Based on cloudy modelling, we do not expect ionization effects to cause this phenomenon.     

The nature and structure of the emission line nebula K 3-35: a very young planetary nebula with precessing bipolar jet-like outflows?

We present Hα, [N  II ]6583 and 6-cm continuum images of the emission line nebula K 3-35. The optical images reveal an extended nebula (size ≃ 11 × 9 arcsec² in [N  II ]) in which most of the emission originates in a very narrow (width 0.7–1.3 arcsec) S-shaped region which extends almost all along the nebula (≃ 7 arcsec). The 6-cm continuum emission also arises in this narrow region, which is characterized by an exceedingly high point-symmetry and systematic and continuous changes of the orientation with respect to the nebular centre. The properties of the narrow region suggest that it represents a system of precessing bipolar jet-like components. Two low-excitation, compact bipolar knots near the tips of the jet-like components are observed in the deduced [N  II ]/Hα image ratio. These knots may be generated by the interaction of the collimated outflows with surrounding material. A comparison of the optical and radio images shows the existence of differential extinction within the nebula. Maximum extinction is observed in a disc-like region which traces the equator of the elliptical shell previously observed at 20-cm continuum. All available data strongly suggest that K 3-35 is a very young planetary nebula in which we could be observing the first stages of the formation of collimated outflows and point-symmetric structures typically observed in planetary nebulae. The properties of the jet-like components in K 3-35 are in good agreement with models of binary central stars in which highly collimated outflows originate either from a precessing accretion disc or via magnetic collimation in a precessing star.     

Spectrophotometric observations of a peculiar nitrogen-rich planetary nebula NGC 2440

By using the Boller and Chivens spectrograph with a moderate dispersion (59 å mm^-1) in the red spectral region, we obtained 65 spectra covering the whole surface of the planetary nebula NGC 2440. Intensities of Hα, [N II] λλ 6548–6584 and [S II] λλ 6717–6731 lines are derived using the IDS system available at the ESO in La Silva (Chile). The nebula is known to be a nitrogen-rich nebula (Peimbert 1978) surrounded by secondary structures (Minkowski 1964). The unusual high value of the [N II]/Hα in the central core (~ 30) is certainly due to the nitrogen overabundance occurring in that part of the nebula. Its variations from scale ionization structure (Capriotti, Cromwell and Williams 1971). The observations show clearly an outward increase of both [NII]/Hα andI(6717)/I(6713) ratios.     

Spectroscopic Studies of the Herbig-Haro Objects Hh84 and Hh85

Spectroscopic studies have been made of the two Herbig-Haro objects HH84 and HH85. Isocontours of the [SII] emission lines, the radial velocities, and the relative line intensities and electron densities are given for the A, B, C, E clusters of HH84 and the A, B1, and B2 clusters of HH85. Comparisons with earlier results are made. Significant variations in the radial velocities and line widths are observed within the confines of HH84. It is concluded that HH84 may actually be a shock wave at the termination of a collimated outflow, but it is still not known whether this flow is coupled to HH83. HH85 is definitely a part of the HH34 giant outflow.     

The phenomenon of the galaxy NGC 6286: A forming polar ring or a superwind?

We present our observations of the pair of interacting galaxies NGC 6285/86 carried out with the 6-m Special Astrophysical Observatory (SAO) telescope using 1D and 2D spectroscopy. The observations of NGC 6286 with a long-slit spectrograph (UAGS) near the Hα line revealed the rotation of the gaseous disk around an axis offset by 5″–7″ from the photometric center and a luminous gas at a distance up to 9 kpc in a direction perpendicular to the galactic plane. Using a multipupil fiber spectrograph (MPFS), we constructed the velocity fields of the stellar and gaseous components in the central region of this galaxy, which proved to be similar. The close radial velocities of the pair and the wide (5′×5′) field of view of the scanning Fabry-Perot interferometer (IFP) allowed us to simultaneously obtain images in the Hα and [N II]λ6583 lines and in the continuum, as well as to construct the radial velocity fields and to map the distribution of the [N II]λ6583/Hα ratio for both galaxies. Based on all these data, we studied the gas kinematics in the galaxies, constructed their rotation curves, and estimated their masses (2 × 10¹¹M_⊙ for NGC 6286 and 1.2 × 10¹⁰M_⊙ for NGC 6285). We found no evidence of gas rotation around the major axis of NGC 6286, which argues against the assumption that this galaxy has a forming polar ring. The IFP observations revealed an emission nebula around this galaxy with a structure characteristic of superwind galaxies. The large [N II]λ6583/Hα ratio, which suggests the collisional excitation of its emission, and the high infrared luminosity are additional arguments for the hypothesis of a superwind in the galaxy NGC 6286. A close encounter between the two galaxies was probably responsible for the starburst and the bipolar outflow of hot gas from the central region of the disk.