对地方电视台转播CCTV时延的测定

讲述了同步广播卫星电视时间信号的测量方法和测量结果，获得了ＣＣＴＶ、ＣＣＴＶ２通过同一颗卫星（亚太－１Ａ）转播的时延差值为１６３．３３μｓ，测量精度在１０ｎｓ以内；ＣＣＴＶ２、ＣＣＴＶ４分别经两颗卫星（亚太－１Ａ，亚洲－Ⅱ）转播，在陕西天文台卫星地面接收站时延差值为１６４４．２０μｓ，严谨为５０μｓ，并分析了影响时延差值和精度的原因，同时测量了地方电视台转播亚太－１Ａ的ＣＣＴＶ信号与直接接收亚太－     

GPS同步恒星钟

主要叙述了利用ＧＰＳ定时接收机输出的时间信息和一系列电路完成平太阳时－恒星时转换的ＧＰＳ同步恒星钟的工作原理,以及“平化恒”时差改正的实现方法。     

空间日冕观测进展

近年来Ｙｏｈｋｏｎ,ＳＯＨＯ和Ｕｌｙｓｓｅｓ等飞船的上天大大提高了日冕观测的范围和精度。如ＳＯＨＯ上的ＬＡＳＣＯ使日冕可观测范围扩展到１．１－３０Ｒ并有分光能力;Ｕｌｙｓｓｅｓ则可以取得黄道面外各纬度处的太阳风实地观测数据。这些资料为日冕物态研究提供了大量有用信息：Ｙｏｈｋｏｈ的软Ｘ射线观测发现了大尺度冕环重联的证据;     

对LF电磁波传播时延实测值准确度的讨论

关于 LF 电磁波传播时延实测值与计算值不一致性的问题,日本 Shigetaka Hjima 先生从收、发两地坐标改正和分析 LF 定时接收机天线时延的角度作过论述,本文试图从授时控制 LF 定时及接收机设备时延两个方面进行探讨。根据1978～1981年三次搬钟实验结果,上海天文台、陕西天文台利用“交响乐”卫星和巴黎天文台进行时间比对的结果(1979年6月18日～27日)以及 Shigetaka Hjima 先生在《日本的时间与频率》一文中所公布的搬钟实验资料。分析这几次实验所反映的 LF 地波传播时延实测值与理论计算值的一致性(偏差小于1μs)与不一致性(偏差大于1μs)的情况和其中的原因,认为这种不一致性的主要原因是由于 LF 时号的发射天线电流相位超前于主钟秒詹号。本文讨论了 LF 定时接收机时延采用值和实测值问题,及其对授时台控制和时间同步准确度的影响.强调了正确测定 LF 定时接收机系统时延值的重要性。     

利用GPS时间传递数据修正接收机天线坐标

在采用ＧＰＳ进行共视时问比对过程中，当两站位置相隔不大长（小于１０００ｋｍ）时，由于卫星轨道误差、电离层和对流层延迟修正的误差可减少至只有几纳秒，可以主为接收天线位置的误差是其主要误差来源．利用ＧＰＳ本身的时间比对数据，不必增加别的数据来源和设备，采用相对定位的方法可提高定位精度，从而提高时间比对的精度．本文利用日本（ＣＲＬ）和北京天文台（ＢＡＯ）之间五天的共视时间比对数据，对（ＢＡＯ）的天线坐标进行修正．在水平方向和高程方向的修正偏差分别为２．９ｍ和５．６ｍ．如果试验数据足够，修正６４效果会更好．     

强IRAS远红外源的CO谱线观测

用紫金山天文台青海站的１３７ｍ射电望远镜对２７个强ＩＲＡＳ远红外源（流量Ｆ１００μｍ５００Ｊｙ）进行了ＣＯ（１－０）的谱线观测．观测表明,２７个强ＩＲＡＳ源全部与分子云成协,并与大质量星的形成或早期演化有关．其中１３个源是第一次给出ＣＯ（１－０）的谱线测量结果．本文对这一类源ＣＯ发射的性质进行了简单的讨论．     

罗兰-C最新进展及其对我国相关系统改造的启示

介绍了罗兰－Ｃ的最新进展。风险评估表明基系统（ＧＰＳ、ＧＬＯＮＡＳＳ）不能作为唯一的导航、定位、定时手段。现代罗兰－Ｃ系统的性能已得到较大改善,也具有发播关分ＧＰＳ、ＤＧＬＯＮＡＳＳ等数据的通信能力。它与星基系统能以多种方式组合,可以获得比单独一个系统更好的民航、定位、授时性能。最后讨论了我国相关系统发展的一些体会和设想。     

强IRAS远红外源的CO谱线预测

用紫金山天台青海站的１３．７ｍ射电望远镜以２７个强ＩＲＡＳ远红外源（流量Ｆ１００μｍ≤５００Ｊｙ）进行了ＣＯ（１－０）的谱线预测。观测表明,２７个强ＩＩＲＡＳ源全部与分子云成协,产与大质量星的形成或早期演化有关。其中１３个源是第一次给出ＣＯ（１－０）的谱线测量结果,本对这一类源ＣＯ发射的性质进行了简单的讨论。     

Taurus—Auriga外围区ROSAT定点观察选WTTS的光学证认与研究

低质量恒星形成区Ｔａｕｒｕｓ－Ａｕｒｉｇａ外围区ＲＯＳＡＴ定点观测选弱发射线Ｔ Ｔａｕｒｉ星候选体（ＷＴＴＳ）的光谱证认新发现４个ＷＴＴＳ。本给出了目标源的ＵＳＮＯ Ｒ星等、ＵＳＮＯ坐标（Ｊ２０００）、分类光谱型、Ｈα发射／吸收线和富ＬｉＸ射线源,包括新发现ＷＴＴＳ的ＬｉＩ吸收线强度等参量以及ＷＴＴＳ的特征光谱。并利用Ｈｉｐｐａｒｃｏｓ星表对部分目标源进行了视差和自行的研究。另外,本第一次给出     

5个新发现的X选BL Lac天体

利用ＲＯＳＡＴＶＬＡ方法筛选，从ＲＯＳＡＴＸ射线源中选出了一批新的ＢＬＬａｃ天体和类星体的候选体．１９９６年１２月８日至１７日，利用北京天文台２．１６ｍ望远镜和新从美国引进的ＯＭＲ摄谱仪，对这批新候选体进行了光谱认证．经ＳＵＮ工作站处理，又发现了５个新的Ｘ选ＢＬＬａｃ天体．此外，还对去年作者在ＯＭＲ引进之前发现的ＢＬＬａｃ天体进行了检验，结果发现，去年发现的７个ＢＬＬａｃ天体中，２３２２＋３４３的ＣａＩＩＨ＆Ｋ“Ｂｒｅａｋｓｔｒｅｎｇｔｈ”为２６．９％，稍大于判据２５％，因此，２３２２＋３４３到底是ＢＬＬａｃ天体还是射电星系还有待于进一步测光及偏振观测的验证．     

Instructions for authors

正Research in Astronomy and Astrophysics publishes original research papers and reviews on all branches of astronomy and astrophysics.Reviews are by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length to 6 printed pages).Authors who submit a paper are expected to be able to certify that the paper is original work,     

Alkali and halogen chemistry in volcanic gases on Io

We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10⁻⁶ to 10⁺¹ bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I₂ (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F.     

The climatic and physiographic controls of the eastern Mediterranean over the late Pleistocene climates in the southern Levant and its neighboring deserts

Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr^− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant.     

Active hot star shells

Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells. Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fitting X-ray Afterglow Light curves of Gamma-ray Bursts by Using the Magnetar Energy Injection Model

The central compact object for some gamma-ray bursts (GRBs) may be a strongly magnetized millisecond pulsar. It can inject energy to the outer shock of the GRB by through the magnetic dipole radiation, and therefore causes the shallow decay of the early afterglow. Recently, from a large number of GRB X-ray afterglows observed by Swift/XRT(X-ray telescope), it is revealed that many of them exhibit the shallow decay about 10²∼10⁴ s after the burst prompt emission. We have fitted the X-ray afterglow light curves of 11 GRBs by using the energy injection model of a magnetar with the rotation period in the millisecond order of magnitude. The obtained result shows the validity and universality of the magnetar energy injection model in explaining the shallow decay of afterglows, and simultaneously provides some constraints on the magnetic field strength and rotation period of the central magnetar.     

Dynamical study of wide pairs of stars based on data from the WDS catalog

Using the method of apparent motion parameters, we have studied the relative motion of the components in 561 pairs of wide (ρ > 2″) and relatively nearby (Hipparcos parallaxes > 0.01″) visual double stars based on data from the WDS catalog. The minimum masses of the double stars have been calculated at given parallaxes. We have identified 358 optical pairs. For 11 stellar pairs, we have found the minimum mass to exceed the estimate corresponding to their spectral types and luminosities. This excess is 5–7 M _⊙ for two stars, ADS 7446 and 9701.     

Microscopic black hole detection in UHECR: the double bang signature

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature. The characteristics of these events and the capability of large cosmic ray experiments to detect them are discussed.     

Instructions for authors

正Research in Astronomy and Astrophysics publishes original research papers and reviews 011 all liranchcs of astronoiriy and astrophysics.Reviews arc by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length