The double-lined spectroscopic binary HR 6046

HR 6046 has long been known as a single-lined binary system, for which preliminary orbital solutions were given in the 1930s, but the nature of the secondary star in the system has to date appeared puzzling. The rather large masses which the component stars were once believed to possess caused much speculation that the secondary was a 'collapsed star', and the large mass function that was originally published encouraged determined, but unsuccessful, efforts to be made to resolve the system by optical interferometry. We have observed the system as a double-lined binary, and now present the orbit. We are unable to specify the exact nature of the secondary star, whose mass is only slightly less than that of the primary, but comparison with late-type standard spectra suggests that it is an evolved star, while the primary is a giant somewhat cooler than the published spectral type indicates. The Hipparcos parallax is consistent with such a model for the system, but it is possible that it is vitiated by the photocentric motion. Our new orbital elements and their improved level of precision show conclusively that the system is by no means as exotic as was once thought.     

Dynamics and Control for a Small Telescope

Our main goal is to determine the dynamic equations of a certain complex system, as is the case of the mechanical system for a small aperture telescope. Causes of this complexity are: the lack of documents about the operation of the elements belonging to the system, and the variation of dynamics with respect to the time and the position of the telescope. To check that we have obtained a valid set of dynamic equations, we will design a computer control system that will implement a self-guide system for the telescope. This revised version was published online in July 2006 with corrections to the Cover Date.     

一种双向测距与时间同步系统的设计与分析

在研究双向单程伪距测量原理的基础上,设计了双向测距与时间同步（DRTS）终端系统总体构架,阐述了在系统中使用的技术,并搭建了基于DSP＋FPGA的双向测距与时间同步系统软硬件平台。实验结果表明,此系统的码速率为5MHz、中心频率为15MI-Iz时,测距和时间同步的分辨率可达0．15cm和5ps（@1S）,采用不同频率源时测距和时间同步的精度分别为1．038m和3．46ns,采用相同频率源时分别为0．28cm和9．43ps（参考频率稳定度1×10^-10／d量级）。与国外同类产品相比具有测量精度优势,但考虑通用性,此系统的硬件仍需进一步优化,软件上需要做到码速率可调。     

Photometric solution for the eclipsing binary system AO Camelopardalis

UBV light curves of AO Cam were analyzed with Wilson and Devinney's model. The system was found to be a contact configuration with a degree of overcontact of 1.4%. The mass ratio of the system is about 1.30, and the inclination is 75 _. ⁰ 9. The primary eclipse appears to be an occultation. Thus AO Cam has the characteristics of a W-type W UMa system. Its location in a period-spectral type diagram suggests that the system may be a zero-age contact system.     

Non-pulsed Emission from the Binary System B1259-63

PSR B1259-63 is the only known binary system with a radio pulsar from which the non-pulsed radio and X-ray emission was detected. The companion star in this system is a Be star SS 2883. A rapidly rotating radio pulsar is expected to produce a wind of relativistic particles. Be stars are known to produce highly asymmetric mass loss. Due to the interaction of the pulsar wind and the Be star wind the system of two shocks between the pulsar and the Be star forms. In this paper we show that the observed non-pulsed radio emission from the system is a result of the synchrotron emission of the relativistic particles in the outflow beyond the shock wave and that the non-pulsed X-ray emission is due to the inverse Compton scattering of the Be star photons on this particles. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spatial Structure of Regular and Chaotic Orbits in A Self-Consistent Triaxial Stellar System

We created a triaxial stellar system through the cold dissipationless collapse of 100,000 particles whose evolution was followed with a multipolar code. Once an equilibrium system had been obtained, the multipolar expansion was freezed and smoothed in order to get a stationary smooth potential. The resulting model was self-consistent and the orbits and Lyapunov exponents could then be computed for a randomly selected sample of 3472 of the bodies that make up the system. More than half of the orbits (52.7 % ) turned out to be chaotic. Regular orbits were then classified using the frequency analysis automatic code of Carpintero and Aguilar (1998, MNRAS 298(1), 1–21). We present plots of the distributions of the different kinds of orbits projected on the symmetry planes of the system. We distinguish chaotic orbits with only one non-zero Lyapunov exponent from those with two non-zero exponents and show that their spatial distributions differ, that of the former being more similar to the one of the regular orbits. Most of the regular orbits are boxes and boxlets, but the minor axis tubes play an important role filling in the wasp waists of the boxes and helping to give a lentil shape to the system. We see no problem in building stable triaxial models with substantial amounts of chaotic orbits; the difficulties found by other authors may be due not to a physical cause but to a limitation of Schwarzschild’s method.     

Long-Term Study of the Starspot Activity on the Eclipsing Short-Period RS Canum Venaticorum Star UV Piscium

We present optical photometry of the short period eclipsing RS CVn system, UV Piscium for the years 1966–1984. After removing the spot effects from the light curves of Vivekananda Rao and Sarma (1981), we analyzed the cleaned data to obtain system parameters. For each light curve, we model the distortion waves in order to study the behaviour of star spots in this system. This revised version was published online in July 2006 with corrections to the Cover Date.     

UBV Photometric Study of the Eclipsing Binary DM Delphini

The near-contact system DM Del with an A2V primary and a G8 secondary was observed in U, B and V wavelengths in July 1998. A new seasonal light curve is presented and a new observed time of minimum is given. The unperturbed part of the light curve was used to determine some basic parameters of the system with the Wilson-Devinney code, some of which were kept fixed for spot modelling of the light curves. A simple spot distribution was determined, based on a model with two cool spots on the surface of the secondary. Absolute elements were calculated and the evolutionary status was determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Regular and chaotic orbits in a self-consistent triaxial stellar system with slow figure rotation

We created a self-consistent triaxial stellar system through the cold disipationless collapse of 100,000 particles whose evolution was followed with a multipolar code. The resulting system rotates slowly even though its total angular momentum is zero, i.e., it offers an example of figure rotation. The potential of the system was subsequently approximated with interpolating formulae yielding a smooth potential stationary in the rotating frame. The Lyapunov exponents could then be computed for a randomly selected sample of 3,472 of the bodies that make up the system, allowing the recognition of regular and partially and fully chaotic orbits. The regular orbits were Fourier analyzed and classified using their locations on the frequency map. A comparison with a similar non-rotating model showed that the fraction of chaotic orbits is slightly but significantly enhanced in the rotating model; alternatively, there are no significant differences between the corresponding fractions neither of partially and fully chaotic orbits nor of long axis tubes, short axis tubes, boxes and boxlets among the regular orbits. This is a reasonable result because the rotation causes a breaking of the symmetry that may increase chaotic effects, but the rotation velocity is probably too small to produce any other significant differences. The increase in the fraction of chaotic orbits in the rotating system seems to be due mainly to the effect of the Coriolis force, rather than the centrifugal force, in good agreement with the results of other investigations.     

Analysis of the photoelectric light curve and the orbital period variations of the binary system UU Andromedae

In this work, the analysis of the photoelectric light curve (LC) in the broad‐band filter (400–700 nm) for the UU And system was carried out using the PHOEBE program (vers. 0.31a). The absolute dimensions of the system are determined and its evolution is discussed. Moreover, the period changes of the system are studied using updated O – C data, which shows a cyclic change with a period of P_mod = 18 yr. This was attributed to a magnetic activity cycle operating in this system. In addition to the cyclic change, a long‐term secular variation due to mass transfer from the secondary to the primary component with a rate of 6.17×10^–9 M_⊙ yr^–1 was also detected. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Starburst Galaxies in Clusters

The nature of the starburst phenomenon in galaxies is investigated using a narrow-band colour system designed to study colour evolution in distant clusters. Work on zero redshift, luminous far-IR galaxies, calibrated by starburst models, demonstrates the usefulness of this colour system in isolating starburst from normal star-forming colours, and also demonstrates a strong correlation with far-IR colours despite reddening effects. The same colour system applied to distant clusters finds that a majority of the faint blue cluster population are starburst dwarf galaxies, probably the progenitors of the current population of dwarf ellipticals in nearby clusters. This revised version was published online in July 2006 with corrections to the Cover Date.     

VLA and MERLIN observations of RZ Cassiopeiae

We present radio interferometric observations of the Algol-type binary system RZ Cassiopeiae made with the VLA and MERLIN arrays at 6 cm over an incomplete orbital cycle of the system (1.195 d). We detected RZ Cas with both instruments. The images were unresolved in both cases, with angular extents comparable to the synthesized beams. The peak flux density in the VLA image was 1.14 mJy beam⁻¹ and in the MERLIN image it was 0.93 mJy beam⁻¹. The derived brightness temperatures are  4.02 × 10⁸  and  4.35 × 10⁸ K  and the effective electron energies are 0.347 and 0.346 MeV for the MERLIN and VLA data respectively. The radio light curve shows an interesting modulation centred close to the primary eclipse which seems to correlate with ASCA SIS observations of the system. The results can be interpreted as an emitting region on the outer hemisphere of the cool component aligned along the centroid axis of the binary system.     

Updated UBV Light-Curve and Period Analysis of Eclipsing Binary HS Herculis

UBV light-curves of the eclipsing binary HS Herculis, obtained in 2002–2003 observational seasons, were analysed with Wilson-Devinney computer code. New absolute dimensions of the system were calculated using the results of the light-curve analysis. Period variation of the system was also investigated. Several new times of minima have been secured for this problematic system. An apsidal motion with a period of 80.7 years was confirmed and a third body in a pretty eccentric orbit (e ₃ = 0.90 ± 0.08) with a period of 85.4 years was found. The corresponding internal structure constants of the binary system, log k ₂, and the mass of the third body were derived.     

Investigation of the long-periodic orbits of Trojan-type asteroids in the outer solar system

The present paper demonstrates the results of the numerical integration of equations of motion of a infinitesimal mass pleased in the neighborhood of the triangular point of the Sun-planet system. There are presented the results for the outer solar system, i.e. for Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The long-periodic solutions were searched for the distance from the Lagrangian point changing from ±0.01 to ±0.10 in canonical units. The Trojans of those planets have the circle, tadpole, horseshoe and irregular shape of their orbits. Same of those test particles showed a close approach to planet. Other of those collided with planet and then was removed from the solar system. The tadpole, circle and same trajectories surveyed integration for 100,000 years. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bandwidth Effects in the 3G Photometric System

Bandwidth effects in the GAIA photometric system 3G are discussed. It is demonstrated that careful account for the bandwidth effects in any proposed GAIA photometric system has to be made, in order to determine the fundamental parameters of heavily reddened stars. This revised version was published online in July 2006 with corrections to the Cover Date.     

A photometric study of V566 ophiuchi

The A-type W UMa system V566 Oph was observed photoelectrically in two wavebands (B andV) in the years 1988-1989 at the Kryonerion Astronomical Station of the National Observatory of Athens, Greece. The light curves of the system are analyzed using frequency-domain techniques and new geometric and photometric elements are derived. These elements are combined with the more recent spectroscopic data based on Reticon observations to yield the absolute parameters of the system. The evolutionary status of the system is considered and it is found that V566 Oph has started its evolution away from the Main Sequence. The period of the system continues to increase.     

Star formation and extinct radioactivities

A supernova trigger for star formation, such as was discussed by Cameron and Truran a few years ago, lacks observational confirmation, and the nucleosynthesis arguments for suggesting its relevance to the formation of the solar system no longer seem compelling. Observations of star formation currently point toward nearly isolated individual events taking place in the interiors of dense molecular clouds, in which cores are formed in the clouds and collapse to form stars. If the formation of the solar system proceeded in this manner, then a viable theory of cloud core formation must provide circumstances in which it is not uncommon for the cloud cores to be formed with a significant supply of fresh short-lived radioactivities. A review is made of the evidence for the existence of now extinct radioactivities in primitive solar system material and an examination is made of the implications for the early stages of formation of the Sun and solar system. The characteristics of possible disturbances in dense molecular clouds which can initiate the formation of cloud cores is discussed,and in particular those disturbances which can produce fresh radioactivities are considered. A red giant star of roughly one solar mass on the asymptotic giant branch appears to have been the best candidate to account for the short-lived extinct radioactivities in the early solar system. Star formation itself can generate disturbances through the T Tauri stellar winds and bipolar outflows, and it appears likely that several such disturbances in a chain of star-forming events were needed before the radioactive material was diluted enough to be consistent with the abundances seen in early solar system material.     

脉冲星在空间飞行器定位中的应用

利用脉冲星钟模型能高精度地预报脉冲星脉冲到达太阳系质心的时间。基于脉冲星时、空参考架可实现各类空间飞行器的自主导航。讨论了脉冲星钟的模型和脉冲星导航系统的框架结构,描述了脉冲星导航的基本原理和算法。指出脉冲星导航系统对脉冲星脉冲到达探测器时刻的测量精度,是决定空间飞行器位置解算精度的关键因素。脉冲星导航观测采用的原子钟如果足够稳定,则空间飞行器位置的解算方法可以简化。在脉冲星导航系统计时观测精度达到或优于几十微秒量级时,脉冲星视差、相对论效应的影响是不可忽略的。对脉冲星导航系统开发设计中的关键技术和进一步研究的主要问题进行了初步分析和讨论。     

Experimental Research of First Feed-Support System of FAST

First feed support system, which is one of the key technologies of Five hundred meter Aperture Spherical Telescope (FAST) was discussed in this paper. A 1:30 scaled model (20 m × 20 m × 6 m) has been built to make systemic research on the feasibility of the system. The root mean square of pointing error of moving cable car was measured and the displacements of cable car within the wind speed of 8 m/s, which is the maximal wind speed of the place where the FAST will be located, were evaluated. Then the total maximal pointing error of cable car was computed. Experimental results demonstrate that the total pointing error of the cable car is less than 50 cm, the required pointing accuracy error of the system. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bandpass calibration of a wideband spectrometer using coherent pulse injection

We present a relatively simple time domain method for determining the bandpass response of a system by injecting a nanosecond pulse and capturing the system voltage output. A pulse of sub-nanosecond duration contains all frequency components with nearly constant amplitude up to 1 GHz. Hence, this method can accurately determine the system bandpass response to a broadband signal. In a novel variation on this impulse response method, a train of pulses is coherently accumulated providing precision calibration with a simple system. The basic concept is demonstrated using a pulse generator-accumulator setup realised in a Bedlam board which is a high speed digital signal processing unit. The same system was used at the Parkes radio telescope between 2–13 October 2013 and we demonstrate its powerful diagnostic capability. We also present some initial test data from this experiment.