V795 Her的观测特征

简要介绍激变变星及激变变星的测光特征,重点介绍了类新星主为星V795 Her自发现以来的一系列观测,包括测光、分光、X射线、紫外观测等。同时,介绍了V795 Her的双星模型、演化模型及我们的测光结果。     

间隙时间序列谱分析方法的检验及其在激变变星短周期振荡分析中的…

本文对具有或长或短间隙（ｇａｐ）的时间序列的谱分析方法进行研究，给出递推公式，并且用模拟信号进行检验，证实这个方法的可靠性，并把它应用到激变变星Ｖ７９５Ｈｅｒ和激变前景为星ＨＷ，Ｖｉｒ的短周期振荡分析中，结果表明这两颗变星都有明显的闪变，在Ｖ７９５Ｈｅｒ中还存在周期为２６５．９１ｓ和１１６．７０ｓ的振荡。     

短周期激变变星周期分布的新统计

我们对周期小于周期分布空缺段的激变变星(CVs),重新进行了周期分布统计,使用了比Warner等人更多、更新的资料.统计中发现一个AM Her型CVs:GRU V1偏离了Warner等人的统计结果.我们给出了CVs 新的周期分布图和相应于此分布的随机概率.虽然结果与Warner等人的不同,但周期分布同磁场仍呈现一定的相关性,磁激变变星(MCVs)与非磁激变变星(NMCVS)同样显示出成团趋势.     

激变变星中的快速光变

文中综述了激变变星中快速光变的研究进展，讨论了闪变，相干振荡和准周期振荡的观测特征和可能的产生机制。     

20个激变变星或相关天体的分光证认

在２０个研究得很少的激变变星或者曾经被分类为激变变星的相关天体的光谱中,１３个被证实为属于激变变星（６５％）,另外７个似乎应该被排除（表１第８列）,不像其他研究者那样,仅给出非激变变星或热天体,还以更强的证据和更多的光谱特征征认出１个ＤＡ型白矮星,４个双星系统及其子星的光谱型。新的光谱资料不支持ＦＹ Ｐｅｒ的Ｈｅｒｂｉｇ Ａｅ／Ｂｅ分类,它是一个激变变星。对于ＰＧ１７１２＋４９３,不仅给出星和云的     

短周期激变变星周期分布的新统计

我们对周期小于周期分布空缺段的激变变星，重新进行了周期分布统计，使用了比Ｗａｒｎｅｒ等人更多，更新的资料，统计中发现一个ＡＭＨｅｒ型ＣＶｓ：ＧＲＵＶ１偏离了Ｗａｒｎｅｒ等人的统计结果，我们给出了ＣＶＳ新的周期分布图和相应于此分布的随机概率。虽然结果与Ｗａｒｎｅｒ等人的不同，但周期分布同磁场仍呈现一定的相关性，磁激变变星与非磁激变变星同样显示出成团趋势。     

激变变星的长期演化

介绍激变变星长期演化的基本概念和标准模型,及辐照效应对激变变星长期演化的影响。     

激变变星0623＋71的光谱研究

本文提出了激变变星０６２３十７１的４个时间分辨光谱，覆盖轨道周期的７３％．其中的３个谱清楚地显示了各种光谱特征随轨道运动的变化，在流量、能谱以及谱线轮廓方面的这种变化正是对一个倾角不太大的激变变星所期望的．然而另一个曝光对分钟的谱，流量和视向速度与预期的相比都太大，很难加以解释，可能它是一次象ＡＥＡｑｒ中观测到的跃发事件．     

谱分析的CLEAN方法及其在激变变星TT Ari短周期振荡分析中的应用

对适用于非等间隔时间序列的一维ＣＬＥＡＮ谱分析方法进行了研究。用模拟信号进行了检验,证实了它也适用于有噪声的序列,但谱质量和噪声强度密切相关,把这种方法应用到激变变变星ＴＴ Ａｒｉ的测光资料分析中,检测到近２０ｍｉｎ周期的准周期振荡。     

双星统计演化及激变变星的形成

介绍了双得统计演化的方法和手段,并对激变星的形成进行了Monte-Carlo模拟,模拟显示,激变变星的诞生度、白矮子星质量分布、轨道周期分布的理论结果与观测结果保持一致。另外,还研究了激变变星的形成与模型参量之间的关系,这些参量包括公共包层抛射效率、双星初始质量比分布、年龄、金融丰度等。     

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.     

On the possibility of investigation of the magnetic field structure in subphotospheric layers of the Sun according to observations of sunspot torsional oscillations

A method of investigation of the magnetic field structure in subphotospheric layers of the Sun has been developed. The method is based on observations of the torisonal oscillations of single sunspots. Characteristics of the torsional oscillations have been obtained from observations of the longitudinal magnetic field and radial velocities of seven single sunspots in the photospheric line Fe I λ5253 Å. The parameters of the torsional oscillations and magnetic tubes in the deep layers have been determined. The radius of the cross section of a magnetic flux tube forming a sunspot is greatest near the Sun’s surface and is approximately equal to the radius of a sunspot umbra. Down to the deeper layers, it decreases quite quickly. The longitudinal electric current appearing in the magnetic tube changes direction. The typical time of the current changes is determined by the period of the torsional oscillations. The intensity of the longitudinal magnetic field in the tube increases with depth. The Alfven wave velocity averaged over the length of a magnetic tube is tens or hundreds of times less than this velocity in a sunspot umbra. It decreases with an increase in the period of oscillations. A decrease in the Alfven wave velocity leads to an increase in the twisting angle of magnetic field lines.     

DETECTION OF SHORT-PERIOD CORONAL OSCILLATIONS DURING THE TOTAL SOLAR ECLIPSE OF 24 OCTOBER, 1995

An experiment to search for short-period oscillations in the solar corona was conducted during the total solar eclipse of 1995 October 24 at Kalpi, India. The intensity in the continuum, centred around 5500 Å and with a passband having a half-width of 240 Å, was recorded at a counting rate of 20 Hz using a thermoelectric-liquid cooled photomultiplier. The power-spectrum analysis of the data reveals that most of the power is contained in 6 frequencies below 0.2 Hz. A least-square analysis gives the periods of the 6 frequency components to be 56.5, 19.5, 13.5, 8.0, 6.1, and 5.3 s. These oscillations are found to be sinusoidal, and their amplitudes are found to lie in the rangeinebreak 0.2–1.3% of the coronal brightness. Assuming these oscillations to be fast magnetosonic modes, the calculations indicate the availability of enough flux for the heating of the active regions in the solar corona.     

V348 Puppis: a new SW Sex star in the period gap

We present time-resolved optical spectroscopy and photometry of the nova-like cataclysmic variable V348 Puppis. The system displays the same spectroscopic behaviour as SW Sex stars, so we classify V348 Pup as a new member of the class. V348 Pup is the second SW Sex system (the first is V795 Herculis) which lies in the period gap. The spectra exhibit enhanced He  ii λ 4686 emission, reminiscent of magnetic cataclysmic variables. The study of this emission line gives a primary velocity semi-amplitude of     . We have also derived the system parameters, obtaining:     ,         ,     and     . The spectroscopic behaviour of V348 Pup is very similar to that of V795 Her, with the exception that V348 Pup shows deep eclipses. We have computed the '0.5-absorption' spectrum of both systems, obtaining spectra that resemble the absorption spectrum of a B0 V star. We propose that absorption in SW Sex systems can be produced by a vertically extended atmosphere which forms where the gas stream re-impacts the system, either at the accretion disc or at the magnetosphere of the white dwarf (assuming a magnetic scenario).     

具局部各向同性速度分布的旋转椭球星系的长期演化

Chandrasekhar等和Sunder等讨论了具有局部各向同性速度分布的旋转椭球星系的短期（远小于哈勃时间）演化,本文运用Laskar的频率分析方法研究这种星系的长期（大于哈勃时间）演化．得到的新结论主要有：（1）这种星系存在唯一的平衡态（球对称平衡态）,它是临界线性稳定的;（2）其半轴一般在平衡态的半径邻近作拟周期或近拟周期（这种近似在远大于哈勃时间后仍可行）振动,从而是长期稳定的;（3）存在一个半轴趋于零,另一个半轴趋于有限值的情形,且一般趋于零的是对称轴的轴长（从而星系趋于扁平）,这意味着某些盘星系可能来源于具旋转棉球构形的星系前物质．     

OBSERVATIONS OF SUNSPOT UMBRAL OSCILLATIONS

The solar vacuum telescopes VTT and GCT at Tenerife have been used to obtain high-resolution two-dimensional spectro-polarimetric observations of oscillations in the photospheric layers of sunspots. At the GCT the area of the sunspot has been scanned by shifting the spectrograph slit; at the VTT a Fabry–Pérot interferometer has been applied to get narrow-band filtergrams directly and to scan through the line profile.The spectra of velocity oscillations show the known features of closely packed power peaks in bands of periods around 3 min (strengthened) and 5 min (weakened with respect to the quiet Sun). In the same frequency bands the more reliable VTT data show significant oscillations of the magnetic field strength as well, which could not be attributed to disturbing influences. Maximum power of both velocity and magnetic oscillations and a strong correlation between them, in the 3-min band in particular, is found to occur in those parts of the umbra where the magnetic lines of force are parallel to the line of sight. The oscillations are characterized by a marked spatial fine structure and a non-stationary behaviour.     

Velocity oscillations in the solar atmosphere

From a series of long duration continuous Doppler records of selected spectral lines, characteristics of solar velocity oscillations have been studied. Statistical distribution of the durations of the bursts of oscillations has been estimated. From the nature of distortion of the waveforms of the oscillation, the presence of disturbing impulses has been speculated. Constancy and homogeneity of the oscillations have been examined from detailed spectral density plots. Duration indices for the oscillations at different heights in the solar atmosphere have been derived by estimating mean spectral densities of characteristic oscillation amplitudes during several individual bursts and comparing them with corresponding spectral densities from long records. The variation among experimental results has been explained as due to the limitations of the power spectral analysis method on short records.     

一种改进的恒星辐射流体动力学方程

本文将本文作者发展的辐流体动力学方程精细化了，在新的理论公式中，描述物质与辐射场的热力学变量被彻底分开了，这不仅使得理论自身内部更为一致，也给变星脉动理论计算带来方便，本文亦证明了新老理论是相容的。     

星表系统差及其计算方法

本文对星表系统差的性质进行了讨论，并分析和评估了目前常用的星表系统差计算方法的优、缺点，从而提出了一个新的星表系统差计算方法．同时也提出了星表系统差计算精度的检验标准．最后对用不同方法计算的系统差进行了分析比较．结果表明，新方法的系统差计算精度好于目前常用的解析方法．