冬夜迎狮王——北京天文同好会观测狮子座流星雨纪实

１９９８年狮子座流星雨期间,北京天文同好会有组织地进行了观测,取得了有价值的数据,并拍摄了大量的摄影作品。１１月２２日国际流星组织目视观测委员会主席给同好会发来贺信,感谢这来自中国的数据记录。同好会取得的成绩不断地得到专家和社会的肯定。     

偶见天龙座流星雨

我曾经作多次流星雨的观测,可一直没见过令人兴奋的场面。１９６５年我就曾观测过狮子座流星雨,可就只见到几颗流星。去年的狮子座流星雨,我们在严寒难耐的冬夜坚守观测了４个小时,也只见到１７颗流星。１９９８年６月２７日夜晚,我们偶然和天龙座流星雨相遇,一颗接...     

1998—1999年国际狮子座流星雨观测研究评述

1998－1999年的狮子座流星雨观测研究取得了十分丰富的成果，概要介绍了在此期间目视观测，雷达观测，航空观测，气球观测，卫星安全检测星撞击月球和月球钠尾观测方面取得的成果和进展。     

流星雨的照相观测

美丽壮观的流星雨,一直是备受大家关注的精彩天象。近些年,稳定的英仙座流星雨和双子座流星雨,以及偶有爆发的狮子座流星雨,不仅为我们带来了视觉上的震撼,也令越来越多的人从此爱上了天文,并且开始尝试进行流星雨的目视和照相观测。     

举办2001年狮子座流星雨摄影赛通知

鉴于2001年11月19日前后,在中国东部、中部,有可能观测到每小时标准天顶计数峰值达到一万颗以上流星的狮子座流星暴雨。为促进这一可能的、罕见的流星雨观测和保留珍贵的流星雨资料,我们决定举办《2001狮子座流星雨摄影赛》。我们在全国范围内(包括港、澳、台)征集狮子座流星雨的观测照片。来稿要求为: 1.提供拍摄有狮子座流星的5对以上     

1998～2000年狮子座流星雨的预报和观测

"1998年狮子座流星雨可能是暴雨,最佳观测地在东亚"的预报,客观上加速了中国对流星雨的现代研究。几年来,对狮子座流星雨的观测和研究,是在全国狮子座流星雨联测小组的组织和领导下发展起来的。这包括使用目视方法、照相方法和无线电方法的观测,以及组织广大天文爱好者在全国范围内的观测。我们的确也观测到了很多重要的现象,如流星雨的纤维结构、尺度分布和质量密度分布的变化等等。我们发展了数据处理方法,将处理其它天文观测数据的"时间窗"方法移植到了流星雨的数据处理中。这一方法如今在流星雨研究中已经在世界上普遍使用了。我们还提出了流星雨的质量流参量ZHMR,它对于今后流星雨的观测比较和预报可能更加有用。在雷达观测方面,我们观测到了1998年所期待的流星雨强度主峰。在此主峰过了大约18h之后,又观测到了地球电离层的反常爆发。从1998年连续两天狮子座流星雨不同的表现,以及从全国不同地区的观测得到的流星质量分布系数的差异,我们提出了大、小2种不同粒子的混合流模型,很好地解释了观测到的现象。从天体力学的基本公式出发,我们发现流星群轨道升交点和其母彗星轨道升交点之差,不仅与当时的抛射速度,而且与彗星抛出这些尘埃粒子时在轨道上的位置有关。对于1998年的观测,最可能的是这些粒子是     

1998～2000年狮子座流星雨的预报和观测

“1998年狮子座流星雨可能是暴雨，最佳观测地在东亚”的预报，客观上加速了中国对流星雨的现代研究。几年来，对狮子座流星雨的观测和研究，是在全国狮子座流星雨联测小组的组织和领导下发展起来的。这包括使用目视方法、照相方法和无线电方法的观测，以及组织广大天文爱好者在全国范围内的观测。我们的确也观测到了很多重要的现象，如流星雨的纤维结构、尺度分布和质量密度分布的变化等等。我们发展了数据处理方法，将处理其它天文观测数据的“时间窗”方法移植到了流星雨的数据处理中。这一方法如今在流星雨研究中已经在世界上普遍使用了。我们还提出了流星雨的质量流参量ZHMR，它对于今后流星雨的观测比较和预报可能更加有用。在雷达观测方面，我们观测到了1998年所期待的流星雨强度主峰。在此主峰过了大约18h之后，又观测到了地球电离层的反常爆发。从1998年连续两天狮子座流星雨不同的表现，以及从全国不同地区的观测得到的流星质量分布系数的差异，我们提出了大、小2种不同粒子的混合流模型，很好地解释了观测到的现象。从天体力学的基本公式出发，我们发现流星群轨道升交点和其母彗星轨道升交点之差，不仅与当时的抛射速度，而且与彗星抛出这些尘埃粒子时在轨道上的位置有关。对于1998年的观测，最可能的是这些粒子是彗星在1933年回归的时候、在距离太阳1．44A．U．距离的时候抛射出来的。按照传统的统计图分析方法，我们还对1999—2001年的狮子座流星雨强度进行了预报。事实证明，我们对1999和2000年的预报的准确性还是很高的。此外，我们还在狮子座流星雨的照相观测、轨道计算以及其它方面做了一些工作，本文仪仅是对我们所做的一些主要工作进行了一个小结。     

流星的摄影观测技巧

一、流星摄影观测的意义１９９８年１１月狮子座流星雨已经过去,但是随着坦普尔－塔特尔彗星的回归,１９９９年的１１月我们还可能看到狮子座流星雨的再现,这无疑又给天文爱好者们一线希望。许多人都想用相机记录下那一令人兴奋的场面,留作永久的纪念。然而,流星的摄...     

1998年德令哈狮子座流星雨目视观测及初步分析

根据中国－荷兰狮子座流星雨合观测1998年11月13日至18是日在紫金山天文台德令哈观测站观测所得的数据，以及同期中国其他地方的观测数据，分析了1998年狮子座流星雨的分布特征，提出此次地球所遭遇的流星群带呈3层结构。     

强流星雨及其灾害性空间天气事件的观测与研究

在首届狮子座强流星雨国际联测期间,开展了多学科、多手段的狮子座和天龙座强流星雨及其灾害性空间天气事件的综合观测,并结合近半个世纪的(1957-2003年)狮子座、英仙座和天龙座强流星雨及其相关资料的综合分析,充分证实了非偶现的周期性强流星雨可导致灾害性空间天气事件的形成.下述结论亦得到初步证认:强流星雨形成机制;f_bE_s异常峰出现规律;对宇航安全的严重危害.文中还对彗星尘演化过程、宇宙尘暴出现和丢失规律及中纬区E_s层宇宙尘维持机制作了讨论.     

The empirical mass-luminosity relation

On the basis of the most recent data for visual and spectrophotometric binaries, the empirical mass-luminosity relation has been investigated. It is shown that, for the sample collected, the relation may be divided into three parts, for which numerical relations are given. A table summarizing the observational results on the fractional mass of the secondary component in visual systems is given.     

Mixed Particle Stream Model Of The Main Peak Of 1998 Leonids

On the basis of the radar observational data of the Leonids obtained in China in November of 1998, we found that the characteristics of the meteor population index γ during the main peak could not be explained well with a one-component magnitude distribution. Moreover, according the visual observational data obtained in China and other districts of Asia, γ also presents the property of non-uniformity. In this paper, we set forth a mathematical model of mixed particle streams. From this, the observed phenomenon of rarity of visual meteors and abundance of radar meteors during the main peak is interpreted. This revised version was published online in July 2006 with corrections to the Cover Date.     

Johnson Space Center's Leonids optical observations

Abstract— The 1998 Leonid meteor shower was videotaped by NASA Johnson Space Center (JSC) personnel, Jim Pawlowski and Jerry Winkler, at Houston, Texas, and Anna Scott at Cloudcroft, New Mexico. The videotapes were screened and the Leonid meteors in the videotapes were analyzed. The outcome of this effort was tables of counts per hour over the viewing period and a comparison to the Leonids meteors mass distribution model (Matney, 1998, unpubl. data) used for risk assessment calculations associated with space shuttle missions. The comparison exhibited a difference between the observed data and the model. Perhaps this difference can be resolved when observations from other parts of the Earth are assimilated with JSC observations.     

SHORT vs LONG TIME SERIES : EXAMPLE OF THE SOLAR DIAMETER

The significance of a time series obviously changes with its length and accuracy; data about the Sun are no exception. In this short paper, we compare the 23-year long series of visual observations of the solar semi-diameter at Calern Observatory with the activity cycle to find an apparent opposing phase. The comparison of the sub-series of the same, carried out during 26-month long measurements of SOHO/MDI (April 1996, June 1998), reveals an apparent phase with the same activity cycle, in line with most of the recent results. Consequently, the importance of long and coherent ground measurements of the solar diameter has to be stressed.     

Detailed visual observations and modelling of the 1998 Leonid shower

We present a detailed activity profile for the 1998 Leonid shower from visual observations. The shower displayed at least two distinct components – a broad component peaking between 2344 and 2350, and two narrower filaments near 23521 and 23533 probably of younger origin based on modelling results. This dual-peaked structure in the flux profile has peak fluxes to a limiting magnitude of +6.5 of 0.03 Leonid km⁻² h⁻¹. The distribution of particles also changes dramatically across the stream in 1998, with large meteoroids dominating the early peak and smaller meteoroids relatively more abundant near the time of the nodal passage of the comet. Detailed comparison of the observed activity with models in 1998 shows that the early component comes from material ejected between 500 and 1000 yr ago. Our modelling results suggest that the later dual peaks are caused by high- β meteoroids with large ejection velocities released during the 1932 and 1965 passages of Comet 55P/Tempel–Tuttle.     

Pulsations of the B[e]-type component in the CI camelopardalis system

CI Cam is a well-known B[e]-type star and an X-ray transient, which underwent a powerful outburst in all parts of electromagnetic spectrum in 1998. An extensive V-band photometric monitoring revealed that rapid variability of CI Cam on the time scale of several hours is due to the pulsations of the B4 III–V type component. High-precision CCD photometry of the star was performed with the 50-cm Maksutov (meniscus) telescope of the Crimean station of the Sternberg Astronomical Institute of Moscow State University in December 2006 during the quiescent state of the star. The data are analyzed using the methods of discrete Fourier transform and by modeling of the light curve. The amplitude spectrum of the star is dominated by two peaks corresponding to the periods of 0.41521 and 0.26647 days with the period ratio close to 3:2. At least two pulsation modes are excited and the star exhibits signs of the resonance between modes.     

The 1998 outburst and history of the June Boötid meteor shower

The June Boötid meteor shower (sometimes referred to as the Draconids) surprised a number of regular and casual observers by an outburst with maximum zenithal hourly rates (ZHRs) near 100 on 1998 June 27 after a quiescent period of several decades. A total of 1217 June Boötid meteors were recorded during regular visual meteor observations throughout this outburst. An average population index of r =2.2±0.10 was derived from 1054 shower magnitude estimates. The broad activity profile with ZHR>40 lasting more than 12 h and the large spread of apparent radiants in 1998 resemble the 1916 and 1927 outbursts. The peak time is found to be at about λ _⊙=95°.7 (2000.0); peak ZHRs are of the order of 200, whereas reliable averages reach only 81±7. The period of high ZHRs covered by a single observer implies a full width at half-maximum of 3–4 h. The resulting maximum flux of particles causing meteors brighter than +6.5 mag is between 0.04 and 0.06 km⁻² h⁻¹. The average radiant from photographic, radar and visual records is α =224°.12, δ =+47°.77. The observed activity outbursts in 1916, 1927 and 1998 are not related to the orbital period or the perihelion passages of the parent comet 7P/Pons–Winnecke. These are probably a consequence of the effects of the 2:1 resonance with Jupiter.     

Taurid resonant-swarm encounters from two decades of visual observations

Enhanced Taurid activity in terms of visual meteor and fireball rates has been found in 1988, 1991, 1995, 1998 and 2005 data. The years of heightened activity are shown to be unequivocally linked to the encounters of swarms of resonantly trapped particles in the Taurid meteoroid stream according to the model proposed by Asher & Clube. While the annual activity level of the Taurid meteor shower in terms of zenithal hourly rate  (ZHR) is 7.8 ± 1.2  , swarm year activity typically reaches ZHRs of 12–17. The annual fraction of fireballs is below 1 per cent; in swarm years, this fraction is as high as 2.4–4.6 per cent near the maximum of the Taurid activity period.     

A model of the chromosphere and transition zone. Radio and UV emission of these layers

A model of the chromosphere and transition zone for quiet regions of the Sun is given.The height dependence of temperature and density are different for the borders of the supergranules and for their inner parts. The difference is caused by the enhanced mechanical energy flux at the places of strengthened magnetic field.The average dependence of density on height is given by eclipse data, the corresponding values for temperatures are obtained by a trial and error method using calculation of solar radio emission for different wavelengths and comparison with observations.The adopted model is consistent with observational data on the solar visual, radio and UV emission. This model also accounts for the brightness distribution on spectroheliograms taken in H wings, K₂₃₂ Caii and in several UV spectral lines.