再发新星天箭WZ(WZSge)1978年的爆发

本文给出了再发新星天箭WZ1978年爆发期间,应用北京天文台兴隆站的40/200厘米双筒天体照相仪于1978年12月6日到25日对其所做的照相观测结果。同时对再发新星WZ Sge爆发期间的光度变化情况进行了讨论。并计算了其在1978年爆发时所释放出的总辐射能量约为1.07×10~(40)尔格。估计了WZ Sge下次可能爆发的时间以及它在爆发时的极大光度情况。     

The Low Inclination Dwarf Nova UY PUP

A spectroscopic study of the frequently outbursting dwarf nova UY Pup has been undertaken whilst the system was in outburst. The Hα andHβ line profiles in UY Pup are typical of low inclination dwarf novae after outburst maximum. No evidence for two components is seen in the emission lines. Using radial velocity measurements of Hα, we find the best fit orbital period for the system to be 10.22 ± 0.19 h(although we cannot with certainty rule out a period of 7.13 ± 0.14 h).We place limits on the system parameters. We also present multicolour photometry of UY Pup in quiescence. This revised version was published online in July 2006 with corrections to the Cover Date.     

1RXS J232953.9＋062814： a New SU UMa Dwarf Nova below the Period Minimum

1 INTRODUCTION1RXS J232953.9 062814 was identilied as a cataclysndc variable (CV) by Wei et al. (1999)when they selected a brW AGN sample from the optical ideottheations of the Bright SourceCatalog of ROSAT All Sky Survey (RASS-BSC) (Voges et al. 1999). It was classthed as adwarf nova by Hu et al. (1998). The CCD photometric observaioas by Uemura et al. (20()1)on 2001 Nov. 4.47--6.17 revealed superhuIns with amplitudes of 0.2Al.3mag and a periodof 0.046311(12) days, indicati…     

Outburst Cycle of the Dwarf Nova SS Cygni

Extensive observational data obtained to date is analyzed with special attention given to space observations. The spectral type of the white dwarf is estimated and it is concluded that accretion of matter on it is the only source of the x-ray flux in the system. The rotation of the secondary is shown to be synchronous and therefore its illumination by hard x-rays results in the formation of stellar wind. This is the main mechanism of mass transfer onto the white dwarf. The geometry of the system prevents the formation of the disk by stellar wind. Instead, stellar wind forms a quasispherical envelope whose variability influences the outburst process. Based on these conclusions, the properties of the system are interpreted, which so far have remained unexplained: short-term appearance of peculiar spectrum during the rising phase of the outburst, rather constant width of absorption lines during the outburst, decrease of the width of emission lines during the outburst, variation of the x-ray and ultraviolet fluxes during ordinary and low-amplitude anomalous outbursts, and, finally, the quasiperiodicity of the outbursts.     

Observations of the Deeply Eclipsing Dwarf Nova Gy Cnc

We present photometric measurements of the eclipsing dwarf nova and X-ray source GY Cnc. The observations were collected during outbursts and in quiescence. The investigation of plates from the Sonneberg archive showed that the mean outburst interval is about 210–270 days, that the outburst is very fast, and lasts for about 5 days.     

The Long-Period Dwarf Nova V2466 Cyg: The 2003 and 2019 Superoutbursts

Astronomy Letters - Results of the first multicolor photometric observations of the unusual dwarf nova V2466 Cygni during its 2003 and 2019 superoutbursts are presented. The total amplitude of the...     

A Spectroscopic Study of the SU Uma-type Dwarf Nova YZ Cnc during its 2002 Superoutburst

We report on time-resolved spectroscopic observations of the SU Ursae Majoris dwarf nova, YZ Cnc for over 11 h on two nights during its 2002 January superoutburst. The spectra on the first day only showed absorption-line profiles, while on the second day the lines showed "W" profiles with blue and red troughs. The radial velocity curve of the absorption troughs and emission peaks of Hβ has an amplitude of 49±10 km s-1 and a phase offset of -0.07±0.04, which are very similar to those measured in quiescence. However, the γ velocity deviates strongly from the systemic velocity measured in quiescence, by some ±60 km s-1. Large shifts of -70 km s-1 in the orbital-averaged velocity and -0.09 in the phase are also found in our observations. All these features can be well explained by a precessing, eccentric disk.     

FG Sge: New Multicolor Photometry and Short-Term Dust Shell Clearing in 2019

Astronomy Letters - We present the results of a new stage of the long-term photometric study of FG Sge which is a quickly evolving central star of the planetary nebula Hen 1-5. Our new observations...     

A search for rapid oscillations in FG Sge

It has recently been noted that the spectrum of the peculiar variable star FG Sge is beginning to resemble that of HD 101065 (Przybylski's star). Since Przybylski's star is known to show light variations of 0.01 mag with a period of 12.14 min, a search for similar rapid oscillations in FG Sge was carried out. This paper presents 25 hr of high-speed photometry of FG Sge which show that it has no variations in the frequency-range 0.5 to 10.0 mHz larger than 1.2 mmag peak-to-peak.Visiting astronomer, The Florence and George Wise Observatory, Tel Aviv University, Israel.     

Composite spectra: XX. 45 Cancri

From accurate radial‐velocity measurements covering 11 circuits of the orbit of the composite‐spectrum binary 45 Cnc, together with high‐resolution spectroscopy spanning nearly 3 circuits, we have (i) isolated cleanly the spectrum of the early‐type secondary, (ii) classified the component spectra as G8 III and A3 III, (iii) derived the first double‐lined orbit for the system and a mass ratio (M₁/M₂) of 1.035 ± 0.01, and (iv) extracted physical parameters for the component stars, deriving the masses and (log) luminosities of the G star and A star as 3.11 and 3.00 M_⊙, and 2.34 and 2.28 L_⊙, respectively, with corresponding uncertainties of ±0.10 M_⊙ and ±0.09 L_⊙. Since the mass ratio is close to unity, we argue that the more evolved component is unlikely to have been a red giant long enough to have made multiple ascents of the RGB, an argument that is supported somewhat by the rather high eccentricity of the orbit (e = 0.46) and the evolutionary time‐scales of the two components, but chiefly by the presence of significant Li I in the spectrum of the cool giant. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Superhumps in a Peculiar SU Ursae Majoris-Type Dwarf Nova, ER Ursae Majoris

We report the photometry of a peculiar SU Ursae Majoris-type dwarf nova, ER Ursae Majoris, for 10 nights during 1998 December and 1999 March, covering a complete rise to the supermaximum and a normal outburst cycle. Superhumps have been found during the rise to the superoutburst. A negative superhump appeared in the December 22 light curve, while the superhump on the next night became positive and had a large-amplitude waveform distinct from that of the previous night. In the normal outbursts we captured, superhumps with larger or smaller amplitudes seem to always exist, although it is not necessarily true for every normal outburst. These results show great resemblance to V1159 Ori. It is more likely that superhumps occasionally exist at essentially all phases of the eruption cycles of ER UMa stars, which should be considered in modeling.     

AD Cancri：A Contact Binary with Components in Poor Thermal Contact

We present the light curve and photometric solutions of the contact binary AD Cnc. The light curve appears to exhibit a typical O'Connell effect, with Maximum I brighter than Maximum II by 0.010 mag. in V. From 1987 to 2000, the light curve showed changes of shape: the depth of the primary eclipse increased by about 0.056m while that of the secondary eclipse decreased by about 0.032m, so the difference between the primary and the secondary eclipses increased by about 0.088m, while there was no obvious variation in the O'Connell effect. Using the present and past times of minimum light, the changes in the orbital period of the system are analyzed. The result reveals that the orbital period of AD Cnc has continuously increased at a rate of dp/dt = 4.4 ×10-7day yr-1. The light curve is analyzed by means of the latest version of the Wilson-Devinney code. The results show that AD Cnc is a W-subtype contact binary with a small mass ratio of 0.267 and the two components are in poor thermal contact. AD Cnc has     

A Time Evolution Study of the Superhumps of the Dwarf Nova 1RXS J232953.9+062814 by Wavelet Transform

The time evolution behaviour of the superhumps of the dwarf nova1RXS J232953.9+ 062814 is investigated with the wavelet analysis method. On the basis of two nights CCD photometry performed during its first superoutburst as well as other published brightness data, we reveal the superhump's time-dependence as a function of periods and time. Our light curves, which phased in the rapid decay ending portion of the superoutburst and in the dawn of a following normal outburst, are important to help trace the superhump evolution for the star. Both the superhump period and the orbital period of the binary system are detected in the present data. We obtain P _sh=0.0458±0.0002d and P _orb=0.0450±0.0002d. They agree with those existing values. The two periods exchanged their roles during the superhump evolution. The general profile of brightness fading over the outbursts roughly followed an exponential decay law or a form of a five-order polynomial. This revised version was published online in July 2006 with corrections to the Cover Date.     

Drag-induced resonant capture in a multiplanet scenario: An application to 55 Cancri A

The binary star 55 Cancri harbors at least five giant planets. The discovery of a possible dust disk around the primary of the system was announced in 1998 although it was later dismissed as an observational artifact induced by the presence of three background galaxies. However, the possible existence of an asteroid belt beyond 6 AU from the primary could not be excluded. The actual properties of a hypothetical outer asteroid belt around 55 Cancri A are likely to be the result of the gravitational influence of the outermost planets and gas drag during the late stages of the formation of the planetary system. Gaseous drag within a protoplanetary disk in a multiplanet context can induce resonant capture of solid material rather easily, triggering the formation of asteroid belts similar to our own transneptunian belt. In this paper we investigate this scenario using numerical simulations within the framework of the planar restricted four-body problem to find possible stable debris locations or additional planets around 55 Cancri A. Our results indicate that, beyond 55 Cancri d, only the 1:2 and 1:3 mean-motion resonances may be possible although the details of gas drag-induced resonant trapping depend strongly on the size of the particles, with larger particles being preferentially trapped farther away from the host star. For a primary of mass 0.94 M and i=53° we find solid particles submitted to confined chaos at 10.14 and 13.22 AU with average eccentricities 0.14 and 0.20, respectively. The argument of pericentre of the trapped particles is found to librate around π/2 with the pericentres of the two resonant structures nearly aligned. The resonance responsible for the inner ring effectively halts the migration of the particles. The outer structure resembles a rosette or separatrix orbit. Our calculations suggest that hypothetical planets or asteroid belts in these locations would be, in principle, dynamically stable.     

New Stars and telescopes: Nova research in the last four centuries

This article gives a brief overview of 400 years of research in the field of novae and related stars. Important objects, first applications of various observing techniques, and early ideas of the interpretation of phenomena are listed. Also, the historical evolution of the classification of novae and related stars (supernovae, dwarf novae), as well as their use as distance indicators is discussed (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

High-resolution spectroscopy of QY Sge: an obscured RV Tauri variable?

We describe and demonstrate a method for increasing the resolution locally in a Smoothed Particle Hydrodynamic (SPH) simulation, by splitting particles. We show that in simulations of self-gravitating collapse (of the sort that are presumed to occur in star formation) the method is stable, and affords great savings in computer time and memory. When applied to the standard Boss & Bodenheimer test – which has been shown to depend critically on fulfilment of the Jeans Condition – the results are comparable both with those obtained using Adaptive Mesh Refinement, and with those obtained using a standard high-resolution SPH simulation, but they are achieved with considerably less computational resource. Further development and testing is required before the method can safely be applied to more general flows.     

Period investigation of two RS CVn-type binary stars: RU Cancri and AW Herculis

Orbital period variations of two RS CVn-type binaries, RU Cnc and AW Her, are presented based on the analysis of all available times of light minima. It is discovered that the orbital period of RU Cnc shows two possible period oscillations with periods of 13.38(±0.23) and 37.6(±3.4) years. The corresponding amplitudes of the oscillations are about 0.0098(±0.0023) and 0.0119(±0.0017) days. For AW Her, it is found that the period shows a cyclic variation with a period of 12.79(±0.34) years and an amplitude of about 0.0327(±0.0063) days. Since RU Cnc and AW Her are two RS CVn-type systems, the cyclic period oscillations are more likely to be caused by the magnetic activity cycles.     

Nova Oph 1994光谱观测研究

用２．１６ｍ望远镜及其卡焦光谱仪对ＮｏｖａＯｐｈ１９９４进行了一系列的光谱观测，其早期光谱中出现的大量ＦｅＩＩ线表明它是一颗ＦｅＩ型新星，而它的发射线的多峰结构在其他ＦｅＩＩ型新星中是不多见的．我们根据得到的光谱和从国际互联网络（Ｉｎｔｅｒｎｅｔ）得到的测光资料，讨论了它的光谱特征和演化．     

Dwarf Spheroidal Galaxies: Dynamical Evolution

We show the results of numerical simulations of dwarf spheroidal galaxies (DSphs), which allow to understand their evolution in the framework of no internal virial equilibrium. Under this hypothesis, we reproduce with a low dark matter (DM) model the high values of the virial M/L ratio measured observationally for these objects. In this work, we present a model of the Sagittarius (Sgr) DSph, with all its observational features. This revised version was published online in July 2006 with corrections to the Cover Date.     

New Dwarf Galaxies in the M81/M82 Group

A survey for dwarf galaxies (Sculptor-type dwarfs) was carried out in the M81/M82 group of galaxies in an area of about 195 sq. degrees by means of Tautenburg 52-in. Schmidt plates. Eight new faint dwarf galaxies were discovered. Coordinates, linear and absolute dimensions as well as finding charts are given. Results of the photometry will be published in a second article.