Contamination of ground-based measurements of OI (6300 Å) and NI (5200 Å) airglow by OH emissions

High resolution spectra of the 6300 Å and 5200 Å regions of the night sky have been obtained using a 1 m spectrometer. Typical errors in measurements of $\text{O}\text{(}{}^1\text{D}\text{)}$ 6300 Å and $\text{N}\text{(}{}^2\text{D}\text{)}$ 5200 Å intensities due to contanimation by overlapping OH emissions have been calculated for a fixed-filter photometer, a tilting-filter photometer and a spectrophotometer. The importance of careful selection of certain instrumental parameters in order to minimize measurement errors is emphasized.     

Unidentified molecular features in the red spectrum (5800 to 7300 Å) of PI Gruis

Moderate dispersion (46 Å mm^–1 at H) image-tube spectrum (5800–7300 Å) of the S star ¹ Gru is found to exhibit several unidentified molecular features, in addition to the well-known bands of the oxides ofs-process elements. A list is presented of 28 measured unidentified red-degraded bands, of which six, at 5998, 6128, 6143, 6223, 6257, and 6557 Å, are prominent. Of the reported 28 bands, 22 are observed for the first time. A discussion is included on the expected molecular sources of the unidentified features. The possible presence of two new molecules, Pr O and Nd O, in ¹ Gru is suggested.This paper is dedicated to the memory of Dr. M. K. V. Bappu.     

The EUV continuum emission (1400–1960 Å) in a solar flare observed from Skylab

The total radiative output in the EUV continuum (1400–1960 Å) from the 5 September 1973 flare has been obtained from the EUV spectra of the flare observed with the NRL slit spectrograph (SO82B) on Skylab. The radiative energy in the EUV continuum is of the order of 10²⁹ ergs, which is more than a factor of 2 greater than those radiated in soft X-rays (8–20 Å) and in H for the flare. Thus, the EUV continuum emission is an important radiative energy loss, and should be included in the consideration of the energy balance of the flare.Ball Corporation.Now at the Institute of Theoretical Astrophysics, University of Oslo, Oslo, Norway.     

Stars with discrepant v sin i as derived from Ca II λ 3933 Å and Mg II λ 4481 Å lines. III. Stars with v sin i (λ 3933 Å) < v sin i (λ 4481 Å)

Axial rotation of a star plays an important role in its evolution, physical conditions in its atmosphere and the appearance of its spectrum. We analyzed CCD spectra of nine stars for which the projected rotational velocity derived from the Ca II line at λ 3933 Å was remarkably lower than the one derived from the MgII line at λ 4481 Å. We derived effective temperatures and surface gravities using published uvbyβ photometries, and computed synthetic spectra. Comparing the observed line profiles of the two lines with the computed ones, we estimated the values of v sin i. One of the stars, HD44783, is a Be-star which, besides the narrow absorptions in the spectrum originating in its circumstellar envelope, also has lines of interstellar origin. We also found indications of circumstellar matter in the spectrum of HD25152. In the spectra of the remaining seven stars the narrow components in the Ca II λ 3933 Å line as well as narrow absorptions in the Na I λ 5889.951 Å (D1) and λ 5895.924 Å (D2) lines are of interstellar origin. In HD114376 there are two systems of interstellar components, thus disclosing two different interstellar clouds in the direction of the star. In the spectrum of HD138527 signs of a possible companion were detected, the emission of which contributes 15% to the total light of the system.     

Spectral observations using a BTA telescope of chemically peculiar stars in the spectral region near the Li I (6708 Å) resonance doublet

New spectral observations of chemically peculiar (CP) magnetic stars were obtained using an NES echelle spectrometer with a BTA telescope in the Special Astrophysical Observatory (Russian Academy of Sciences). Several stars were shown to have anomalous Li abundances. Testing and monitoring the stars with Doppler shifts Vsini > 10 km/s indicated that the lithium 6708 Å line was variable in the spectra of some roaAP-CP stars. To distinguish variable features in the spectra, the dispersogram technique was used. The most peculiar among the stars studied is HD 12098. The strong and variable lithium 6708 Å line was detected in the spectrum of this star. The star has been shown to have greatly different lithium abundances in two rotation phases corresponding to opposite surface areas. As mentioned earlier, a similar behavior of the Li blend was found in the spectra of HD 83368 and HD 60435 which have lithium spots on their surface. Spectral observations of slowly rotating CP stars with the Doppler shifts Vsini < 10 km/s revealed the strong and nonvariable lithium 6708 Å line in the spectra of these stars. Quantitative spectral analysis using the Li I 6708 Å resonance doublet and the Li I 6103 Å line shows the lithium abundance, as determined by the 6103 Å line, to be somewhat greater than that determined by the 6708 Å line. A higher ratio of ⁶Li/⁷Li amounting to ～0.3–0.5 was found in these stars. ⁶Li production is assumed to be due to spallation reactions on the surface of magnetic CP stars; this isotope ratio remained in strong magnetic fields.     

O VI (λ = 1032 Å) profiles in and above an active region prominence,compared to quiet Sun center and limb profiles

O vi ( = 1032 Å) profiles have been measured in and above a filament at the limb, previously analyzed in H i, Mg ii, Ca ii resonance lines (Vial et al., 1979). They are compared to profiles measured at the quiet Sun center and at the quiet Sun limb.Absolute intensities are found to be about 1.55 times larger than above the quiet limb at the same height (3); at the top of the prominence (15 above the limb) one finds a maximum blue shift and a minimum line width. The inferred non-thermal velocity (29 km s^–1) is about the same as in cooler lines while the approaching line-of-sight velocity (8 km s^–1) is lower than in Ca ii lines.The O vi profile recorded 30 above the limb outside the filament is wider (FWHM = 0.33 Å). It can be interpreted as a coronal emission of O vi ions with a temperature of about 10⁶ K, and a non-thermal velocity (NTV) of 49 km s^–1. This NTV is twice the NTV of quiet Sun center O vi profiles. Lower NTV require higher temperatures and densities (as suggested by K-coronameter measurements). Computed emission measures for this high temperature regime agree with determinations from disk intensities of euv lines.     

小行星(215)、(323)、(416)和(432)的轨道改进

这四颗小行星的历元很早,都是在二、三十年以前.由于多年未算摄动,轨道逐渐偏离,观测与计算间差值。O—C 已增大到一度以上.鉴于改进轨道、计算准确冲日星历表的迫切需要,1962年冬季在已利用电子计算机算得木星、土星精确摄动的基础上,我们搜集了近几年的观测资料,对此四颗星作了轨道改进.轨道改进的计算系根据爱克尔和勃劳威尔(Eckert and Brouwer)的直角座标的方法.为避免小偏心率和大倾角情况对精确度的影响,使能比较确定地求得方程式的解,我们采用下列方程系统:     

从零开始(六)

这次让我们来制作一件能更加形象化展示天象的天文小制作——星座图转盘。一般星图上的星座图基本上都是点与连线的组合,而我们这次要做的星座图转盘上面的每一个星座,全部都是一个个具体的星座想象图。它们是一年四季最主要的星座:有春夜的狮子     

从零开始(一)

这是今年《天文爱好者》专为初学天文的读者开辟的一个栏目,名字叫“从零开始”。有许多小朋友,当然也有不少大朋友,特别是那些教小朋友的老师们,说不定还有许多年纪大的老人家,很想了解一些关于星星和星座、昼夜和四季的天文知识,想听听关于星星的神话传说。本栏目就是要满足这些读者的要求,给大家介绍怎样在密密麻麻的繁星中将一个个星座、一颗颗行星辨认出来,给大家讲讲星星的天文知识、星座的神话传说。不同季节天上的星座和亮星。怎样看星星辨方向。特别还要介绍几种看星测时的方法。“从零开始”还要教给大家几种天文爱好者特别感兴趣的技法,譬如在短短的30秒钟内通过心算,告诉人们天上有什么星座:用不着计算就可以预报大行星在黄道星座之间的位置和运行动态。当然,要进行这项工作,首先得亲手制作一件预报行星动态的天文仪器纸上小制作,本栏目以后会刊登它的制作图纸的。像这样的小天文仪器还有南北星斗仪等多件。此外,还有演示天体运动,如地球运动、月亮圆缺的小仪器和节气日晷等。这里要说明的是,该栏目更注重用肉眼目视观测星空。因为人眼视野辽阔,望远镜视场再大。也容不下最小的星座所包含的那一片星空。     

从零开始(五)

现在让我们制作一件专门为初学天文的爱好者设计的天文小仪器——南北星斗仪。它包括一年四季所有主要星座,可以用来演示一年中任意日期,任何时刻天上有哪些星座,还可以用来直观地看星测时。南北星斗仪的制作方法1.剪下6个零件,刻出零件 N1上的大圆孔和 N2上的小圆孔。2.将 N3与 N4背靠背粘合起来,粘合时注意将二者的圆周边缘和定位小缺口准确对齐。     

The comparison of H_2CO(1_(10)–1_(11)),C~(18)O(1–0) and the continuum towards molecular clouds

We present large scale observations of C18O(1–0) towards four massive star forming regions: MON R2,S156,DR17/L906 and M17/M18. The transitions of H2CO(110–111),C18O(1–0) and the 6 cm continuum are compared in these four regions. Our analysis of the observations and the results of the Non–LTE model shows that the brightness temperature of the formaldehyde absorption line is strongest in a background continuum temperature range of about 3 – 8 K. The excitation of the H2 CO absorption line is affected by strong background continuum emission. From a comparison of H2 CO and C18 O maps,we found that the extent of H2 CO absorption is broader than that of C18 O emission in the four regions. Except for the DR17 region,the maximum in H2 CO absorption is located at the same position as the C18 O peak. A good correlation between intensities and widths of H2 CO absorption and C18 O emission lines indicates that the H2 CO absorption line can trace the dense,warm regions of a molecular cloud. We find that N(H2CO) is well correlated with N(C18O) in the four regions and that the average ratio of column densities is N(H2CO)/N(C18O) ～ 0.03.     

太阳日冕环的运动(Ⅰ)、(Ⅱ)

几年以前天空实验室的观测发现太阳日冕中多数瞬变过程是以环状形式发生质量喷射,并且测得环状瞬变过程前导边缘是加速运动或者是等速运动。这些日冕环是细长的环。环中的磁能密度大约是热能密度的十倍。观测表明:磁场是控制日冕环的主要因素。     

行星环(Ⅱ)

本文评述了有关土星环的七个方面的理论研究:(1)东-西不对称性;(2)粒子大小分布;(3)环的稳定性;(4)环缝的共振起源;(5)密度波和挠曲波;(6)轮辐结构;(7)F环。 还评述了天王星环以及行星环中的碰撞、光度理论和起源等问题的研究。     

探秘火星(三)

Q1哪个探测器将深入到火星地下探测?几十年来,人类一直对火星进行探索,之前登陆火星的探测器,如勇气号、机遇号、好奇号等,都是探测火星表面上的火山、峡谷、岩石、土壤的演变历史。只探测地表特征,是无法了解火星早期的演化情况的,因为包含此种信息的样品都深埋于火星地表之下。     

行星环(Ⅰ)

本文是关于行星环的现有观测资料的总结。     

流星观测(一)

记得F4有一首歌叫“流星雨”,歌词很煽情:“温柔的天空,应该让你感动,我在你身后,为你布置一片天空……陪你去看流星雨落在这地球上,让你的泪落在我肩膀……”如果在一个晴朗的夜晚,约上两三好友,或聚屋顶,或聚球场,更为潇洒一点,或去郊外空旷的草地、山顶,在这首缠绵悱恻的“流星雨”的浅吟低唱中,各自凝视一方的天空,守侯一闪即逝的流星的出现,岂不是一件很惬意的事民间一直有这样一个说法,如果你在流星还没有消失之前许下一个心愿,这个心愿就一定能够实现。当然,这只是一种美好的愿望,但作为一种生活的点缀,也可以为守望星空的我们增添几分浪漫的情趣。流星是飘浮在宇宙空间的尘粒,受到地球引力的影响,飞向地球,与地球大气摩擦燃烧的现象。流星的高度通常以     

星系传奇(二)

你来我往:为方便大家阅读英文资料并逐步熟悉科研前沿,我将尽可能把涉及到的基本专业术语以及关键词汇的英文标注在括号里,如果大家对此有不同意见,欢迎您与我联系:dnchen@bjp.org.cn     

追逐类星体(27) 黑洞——类星体的发电机(5)

黑洞也可以蒸发天文学的发展遵循着一条规律:观测、理论、再观测、再理论……这大概也是任何一门自然科学的发展规律,只不过天文学表现得更为突出,而在漫长的发展过程中,观测又始终是天文科学的真谛。因此,天文学又被称为是一门观测的科学。黑洞的观测证据越来越丰富,黑洞对宇宙的威胁也越来越严重。理论天文学家必须出来释疑,让黑洞不仅能吃进去,还要吐出来。吐出来的困难在于黑洞的引力太强,在黑洞的视     

射电选BLLac天体(RBLs)的观测性质(Ⅱ)

收集了ＢＬＬａｃ天体的有关信息作为前文（Ｆａｎ＆Ｌｉｎ１９９６）的补充,并在文中加入了具有喷流、具有超光速子元和具有高能射线辐射的ＢＬＬａｃ天体表。同时在表１ｃ中列出了ＢＬＬａｃ天体的发射线,对偏振度与大幅光变的统计相关在相对论成束框架下给予了解释。