利用地球定向参数确定依巴谷输入星表与射电天球参考架之间的旋转

通过比较地球定向参数（ＥＯＰ）序列和对应的地固参考架，本文得到了依巴谷输入星表（ＨＩＣ）和国际地球自转服务（ＩＥＲＳ）基于甚长基线干涉测量（ＶＬＢＩ）建立的河外天球参考架（ＩＣＲＦ）之间的旋转参数，在Ｊ２０００．０历元，前者至后者的旋转参数为［８．４±１．１ｍａｓ，４６．７±１．１ｍａｓ，４５．５±１．５ｍａｓ］，其时间变率为［－０．１４±０．０５ｍａｓ／ａ，３．２２±０．０５ｍａｓ／ａ，５．７０±０．０７ｍａｓ／ａ］。依巴谷输入星表是完全基于ＦＫ５系统的，本文得到的旋转参数与ＩＣＲＦ和ＦＫ５之间的系统差异情况相符     

两个底片天区的依巴谷星自行

利用上海天文台佘山４０ 厘米折射望远镜拍摄的２ 个底片天区１５ 张照相底片上的３１ 次观测,以ＡＣＴ 星表作为初始参考星表,按中心重叠法进行归算处理,得到了１６ 颗依巴谷星和３８ 颗场星的高精度位置和自行结果,其中依巴谷星的赤经和赤纬标准误差的平均值分别为１０ ．５ ｍａｓ 和７ ．５ ｍａｓ,赤经自行和赤纬自行标准误差的平均值分别为０ ．７０ ｍａｓ／ｙｒ 和０ ．５９ ｍａｓ／ｙｒ     

南天区耀变体的VLBI研究

本文报道南天区５ＧＨｚＶＬＢＩ的第二轮观测．第二轮观测是在１９９３年５月期间进行的，共观测了２５个射电源，检测到２４个源，获得了２３个南天区耀变体（Ｂｌａｚａｒ）的ＶＬＢＩ高分辨率的图象，其中１５个是第一次ＶＬＢＩ成图，７个是高能（＞１００ＭｅＶ）γ射电源，１２个源呈现核－喷流结构，其余１１个源是单一的致密核，未发现致密双源．有两个源可能有视超光速现象．     

具有哈勃流的相对论抛射运动学.(Ⅲ)求出超光速源反喷流可观测波长和寻找类星体的蓝移谱线(英文)

在求解类星体的喷流和反喷流的问题时,必须考虑哈勃流所起的作用．超光速反喷流的观测波长应是λｃｊ＝（δ／δ′）λｏｂ,这里δ和δ′分别是正喷流和反喷流的多普勒因子,λｏｂ是正喷流的观测波长．由于多普勒因子的作用,（δ／δ′）值是较大的,对于大多数超光速源可大到两个数量级,远远超出一般ＶＬＢＩ的观测波长范围．不过,也有些超光速的（δ／δ′）值小于１０,足以观测它们的反喷流．因为反喷流的波长值主要由哈勃流常数Ｈ０所决定,一旦测定反喷流观测波长,即可反过来估计Ｈ０的值．本文提出寻找类星体蓝移谱线的方法,这些类星体以高速向视线方向抛射物质而形成吸收线．我们在文献中找到１８条可能的蓝移谱线．     

经典造父变星的银河系运动学研究

利用视向速度资料和依巴谷星表的自行资料,研究了经典造父变星的银河系运动学问题。采用Ｏｇｏｒｏｄｎｉｋｏｖ－Ｍｉｌｎｅ三维运动学模型,获得银河系旋转速度Ｖ０＝２４０．５±１０．２ｋｍ／ｓ（取太阳至银心距离为８．５ｋｐｃ）。同时发现,在太阳附近沿银河系旋转方向存在一种收缩运动,其值（δＶθ／δθ）／Ｒ＝－２．６０±１．０７ｋｍ ｓ＾－１ｋｐｃ＾－１。本分析了产生这种收缩运动的原因。另外,得出太阳运动     

球状星团NGC4147基于依巴谷系统的自行和空间运动

王家骥等［１］曾得到球状星团ＮＧＣ４１４７的绝对自行为（－２．８２±０．４９,２．３７±０．４３）ｍａｓ／ｙｒ．但是,其中所用的参考星表是Ｂｒｏｓｃｈｅ等［２］１９８５年发表的结果,含有ＡＧＫ３星表的系统误差．在Ｄａｕｐｈｏｌｅ等［３］给出的２６个球状星团轨道远银心距（ａｐｏｇａｌａｃｔｉｃｄｉｓｔａｎｃｅ）与金属度［Ｆｅ／Ｈ］的关系图上,ＮＧＣ４１４７处于一个特殊的位置,即按照它的远银距（５２ｋｐｃ）,它的金属度［Ｆｅ／Ｈ］应该大于－２．０,但实际上只有－１．８３［４］．类似的问题在文［１］的…     

南天区耀变体的VLBI研究

本报道南天区５ＧＨｚＶＬＢＩ的第二轮观测，第二轮观测是在１９９３年５月期间进行的，共观测２５个射电源，检测到２４个源，获得了２３个南天区耀变体的ＶＬＢＩ高分辨率的图象，其中１５个是第一次ＶＬＢＩ成图，７个高能γ射电源，１２个泊呈现核－喷流结构，其余１１个源是单一的致密核，未发现致密双源。有两个源可能有视超光速现象。     

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。     

南天区20个河外射电源的VLBI研究

本报道南天区５ＧＨｚ普查式观测结果，首次观测是在１９９２年１１月期间进行的，共观测２３个河外射电源，获得了２０个河外射电源的ＶＬＢＩ高分辨率的射电图象，有１５个射电源呈现核喷流结构，１个有双向喷流，３个未分解，未发现有致密双源，在１６个核喷流（包括一个双向喷流源）源中有１１个呈现弯曲喷流现象。此外还首次发现了３个源中可能有超光速运动现象。     

Multiple relativistic outbursts of GRS 1915+105: radio emission and internal shocks

We present 5-GHz Multi-Element Radio-Linked Interferometer Network (MERLIN) radio images of the microquasar GRS 1915+105 during two separate outbursts in 2001 March and July, following the evolution of the jet components as they move outwards from the core of the system. Proper motions constrain the intrinsic jet speed to be  >0.57 c   , but the uncertainty in the source distance prevents an accurate determination of the jet speed. No deceleration is observed in the jet components out to an angular separation of ∼300 mas. Linear polarization is observed in the approaching jet component, with a gradual rotation in position angle and a decreasing fractional polarization with time. Our data lend support to the internal shock model whereby the jet velocity increases leading to internal shocks in the pre-existing outflow before the jet switches off. The compact nuclear jet is seen to reestablish itself within 2 d, and is visible as core emission at all epochs. The energetics of the source are calculated for the possible range of distances; a minimum power of 1–10 per cent of the Eddington luminosity ( L _Edd) is required to launch the jet.     

Multi-band polarimetric and total intensity imaging of 3C 345

We monitored the superluminal QSO 3C 345 at three epochs during a one-year period in 1995–1996, observing with the VLBA at 22, 15, 8.4, and 5 GHz. We imaged the radio source both in total and in polarised intensity. In the images at 5 and 8.4 GHz, the jet emission is traced up to 20 milliarcseconds (mas) from the jet core. In the 15 and 22 GHz images, we identify several enhanced emission regions moving at apparent speeds of 5c. Images of the linear polarised emission show predominantly an alignment of the electric vector with the extremely curved jet along the inner part of the high frequency jet. At 5 GHz, the jet shows remarkably strong fractional polarisation (m∼15%) with the electric vector perpendicular to the jet orientation.     

Studies of the fine structure of the object 1803+784

We have investigated the fine structure of the object 1803+784 at a wavelength of 18 cm with an angular resolution of ～0.5 mas. The structure consists of a core (injector) and a jet. The angle of the relativistic plasma outflow is equal to the angle of a conical diverging helix—the trajectory of compact components, suggesting a similar shape of the jet. The helical structure and the curvature of the jet axis are assumed to be determined by rapid and long-period precession of the rotation axis. The core radio emission at 18 cm is attenuated by absorption in the ambient ionized medium (cocoon wall) by >25 db. The bright compact component is the nearby part of the jet extending outside the dense part of the screen. Ionization variations in the medium cause low-frequency radio variability. Screen parameters are estimated.     

Bending of Jets in the QSO NRAO 530

We present radio images of NRAO 530 on scales ranging from pc to kpc. The observations include the EVN at 5 GHz, the VLBA at 1.6, 8.6 and 15 GHz, the MERLIN at 1.6 and 5 GHz, and the VLA at 5, 8.4, 15, 22, and 43 GHz. The VLBI images show a core-jet structure with an oscillating trajectory on a scale of about 30 mas north of the strongest compact component (core). Superluminal motions are detected in five of the jet compo-nents with apparent velocities in the range of 13.6 to 25.2c. A new component is detected at 15 GHz with the VLBA observations, which appears to be associated with the outburst in 2002. Significant polarized emission is detected around the core with the VLBA observationsat 15 GHz. Rapid variations of the polarization intensity and angle are found between the epochs in 2002 and 2004. On the kpc-scale, a distant component (labelled as WL) located 11 arcsec west (PA=-86°) of the core is detected beyond the core-jet structure which ex-tended to several hundreds of mas in the north-west direction (-50°). A significant emission between the core-jet structure and the WL is revealed. A clump of diffuse emission (labelled EL, 12 arcsec long) at PA 70° to the core, is also detected in the VLA observations, suggest-ing the presence of double lobes in the source. The core component shows a flat spectrum,while the distant components WL and EL have steep spectra. The steep spectra of the distantcomponents and the detection of the arched emission suggest that the distant components are lobes or hot-spots powered by the core of NRAO 530. The morphologies from pc-to kpc- scales and the bending of jets are investigated. The observed radio morphology from pc to kcp appears to favor the model in which precession or wobbling of the nuclear disk drives the helical motion of the radio plasma and produces the S-shaped structure on kpc scale.     

Is the jet of AO 0235+164 rotating?

We present the VLBI map of a superluminal radio source AO 0235+164 at 5 GHz. This shows that the object's radio structure is dominated by a strong, nearly unresolved core with two extended asymmetric weak jet components. Based on the variation of its flux density with time at 5 GHz, we suggest that the flux density of AO 0235+164 exhibits two periodic variations: a shorter-period variation of 1.81±0.06 yr and a longer-period one of 3.64±0.08 yr. These two periodic variations could be the result of the joint action of jet outbursts and jet rotation.     

Two jets from the Orion nebula (M42) 'proplyds': kinematics, morphologies and origins

A spatially unresolved velocity feature, with an approaching radial velocity of  ≈100 km s⁻¹  with respect to the systemic radial velocity, in a position–velocity array of [O  iii ] 5007-Å line profiles is identified as the kinematical counterpart of a jet from the proplyd LV 5 (158–323) in the core of the Orion nebula. The only candidate in Hubble Space Telescope ( HST ) imagery for this jet appears to be a displaced, ionized knot. Also an elongated jet projects from the proplyd GMR 15 (161–307). Its receding radial velocity difference appears at  ≈80 km s⁻¹  in the same position–velocity array.
A 'standard' model for jets from young, low-mass stars invokes an accelerating, continuous flow outwards with an opening angle of a few degrees. Here an alternative explanation is suggested which may apply to some, if not all, of the proplyd jets. In this, a 'bullet' of dense material is ejected which ploughs through dense circumstellar ambient gas. The decelerating tail of material ablated from the surface of the bullet would be indistinguishable from a continuously emitted jet in current observations.     

Studies of the quasar OH 471

Based on the 1964–1996 observations in the frequency range 0.325–90 GHz, we study peculiarities of the variability of the quasar OH 471 (z=3.4). The double-humped spectrum had peaks at frequencies near 1 and 20 GHz. The flux density of the low-frequency component first decreased and then began to increase. The high-frequency component rose to 2.5 Jy in the late 1970s. The peak frequencies were virtually constant. VLBI observations at 1.6 GHz revealed a core-jet structure with the jet extended eastward to 5 mas. The object is a powerful quasar.     

The Location of the Nucleus of NGC 1068 from HST Imaging Polarimetry and Absolute Astrometry

We present the results of a program to obtain an accurate (better than 100 mas) astrometry of HST images of NGC 1068 and consequently a direct registration with radio images. The optical peak seen in the HST images is located at α = 02h42m40.711s, δ = -00°00′47.81 (J2000, FK5), with an error of 80 mas. The hidden nucleus, as determined by HST imaging polarimetry, falls at α = 02h42m40.710s, δ = -00°00′48.11. It is offset toward the South, i.e. along the radio axis, with respect to the inverted spectrum radio component, S1, by 170 mas (12 pc). This does not rule out that S1 is indeed associated with the obscuring torus and the central engine, but suggests that the nucleus of NGC 1068 might be radio silent or its emission absorbed also at radio wavelengths. An anti-correlation between radio and optical emission is revealed; the radio jet lies on a region of relatively low optical emission and is surrounded by line-emitting clouds. These results can be understood as due the interaction between the jet and the surrounding medium. The outflowing plasma is sweeping and heating the interstellar gas causing the line-emission to be highly enhanced along the edges of the radio jet. It appears that the morphology of the Narrow Line Region of NGC 1068 is dominated by the presence of a radio outflow, as already revealed by HST observations of several Seyfert galaxies with extended radio emission. This revised version was published online in July 2006 with corrections to the Cover Date.     

EVN+MERLIN observations of BL Lac object 1400+162

We present simultaneous MERLIN and EVN observations at 5 GHz of the BL Lac Object 1400+162. The new images show a knotty jet extending to the east, about 250 mas long, and smoothly bending from p.a. ∼90° to p.a. ∼120°. At the highest resolution, only a compact core has been detected; it accounts for about 30% of the total flux density of the source at this frequency. It is likely that the jet orientation is far away from the line of sight.     

Fine Structure of the Core of the Blazar OJ 287-I

The fine structure of the active region, the bulge, of the blazar OJ 287 has been investigated with a resolution of 20 μas (0.1 pc) at a wavelength of 7 mm, the epochs of 2007–2017. The structure and kinematics correspond to a vortex nature. The surrounding matter, the plasma, is transferred to the center along two arms from opposite directions. The emerging excess angular momentum is carried away along the rotation axis by bipolar outflows, rotating coaxial tubes, in a direction X ≈ ?120? in the plane of the sky as it is accumulated. The central high-velocity bipolar outflow has a helical shape. The diameters of the low-velocity flows are ø1 ≈ 0.3 and ø2 ≈ 0.65 mas, or 1.4 and 3 pc, respectively. Ring currents whose tangential directions are observed as parallel chains of components are excited in the flow walls. The peak brightness temperature of the nozzle reaches Tb ≈ 1012?1013 K. A “disk” with a diameter ø ≈ 0.5 mas (≈2.2 pc) is observed by the absorption of synchrotron radiation. The disk is inclined to the plane of the sky at an angle of 60? in the jet direction. The fragments are seen from a distance of ～0.2 mas outside the absorption zone. The jet sizes exceed considerably the counterjet ones. An enhanced supply of plasma from the northern arm gives rise to an independent vortex 0.2 mas away from the central one in the NW direction. As in the first case, the helical central bipolar outflow is surrounded by a low-velocity component ø ≈ 0.28 mas in diameter with built-in ring currents. The jet is ejected in the direction X = ?50? in the plane of the sky. The jet orientation changes, X = ?130? at a distance of 1 mas. A high activity of the central and two side nozzles spaced 0.22 mas apart in the direction X = ?40? is occasionally observed simultaneously. The active region of the blazar is observed through an ionized medium, a screen, whose influence is significant even at a wavelength of 7 mm. The absorption and refraction of the transmitted emission in the screen affect the apparent brightness relative to the positions of the fragments.