共查询到19条相似文献，搜索用时 656 毫秒
1.
恒星光干涉仪定天镜的转动是五相步进电机来驱动的，它需要的控制信号由软件实现。软件设计是系统中最困难的部分，尽可能地用软件实现硬件功能，不仅可以降低成本，更重要的是，便于更新及升级。在观测过程中全自动化的前提下，着重提出了我国恒星光干涉仪实验系统中定天镜子系统的软件设计方案。 相似文献
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恒星光干涉议定天镜的转动是用五相步进电机来驱动的，它需要的控制信号由软件实现。软件设计是控制系统中最困难的部分，尽可能地用软件实现硬件功能，不仅可以降低成本，更重要的是，便于更新及升级。在观测过程全自动化的前提下，着重提出了我国恒星光干涉议实验系统中定天镜子系统的软件设计方案。 相似文献
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本文介绍了为将已有的日食光谱仪主要部件用于1997年漠河日全食光谱观测而做的三种仪器设计方案,涉及定天镜位置、成象系统和光谱仪的光路安排。并与1983年日全食的情况对比,讨论其可行性及对观测和结果的影响。最后根据实际情况决定了观测采用的方案。 相似文献
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南京大学太阳塔于1979年在南京郊区建成,1988年参加了全国联测,它的主要性能如下: 定天镜口径:46cm 成象镜口径:33cm 太阳象直径:20cm 多波段光谱仪可观测谱线:H_α,H_β,H_γ,H_(9-12),CaⅡ H, K 光谱观测时间分辨率:～10~s 光谱仪色散度:1.2-1.5mm/A 表1列出了1988年联测期间成功观测到的耀斑光谱(表1见下页)。 相似文献
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LAGEOS卫星精密定轨及残差分析 总被引：6，自引：2，他引：6
介绍LAGEOS卫星用卫星激光测距(SLR)资料精密定轨和在精密定轨基础上的残差分析处理．SLR资料的分析处理方法、采用的力学模型和解参数的多少根据目标的不同而不同．对不同的方案进行了详细分析、比较．其关键是对LAGEOS卫星进行精密定轨．得出了目前上海天文台在SLR资料的分析处理中已采用的解算模式．作为例证，该解算模式分析处理了1998年12月31日至1999年6月29日LAGEOS卫星的SLR资料，得到每3天一个弧段的精密轨道．结果显示每3天一个弧段的定轨残差rms都小于2厘米．上海天文台从1999年10月1日开始了全球LAGEOS—l和LAGEOS—2资料的快速分析服务，结果可从APSG的网址：http：／／center．shao．ac．cn／APSG／result获得． 相似文献
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1980年2月16日日全食时,我们在云南省瑞丽县用一架无缝光谱仪成功地进行了一次闪光光谱观测。仪器由定天镜供光,平均色散度为5.7/mm。光谱底片的高度分辨率为185 km。 观测资料初步分析如下:在4799—5845波段内,证认了1042条色球谱线,其中72条是文献[1]和[2]中未见列出的;确定了色球底的位置;用食既前的太阳边缘的无缝光谱和日食前一天的日心有缝光谱进行了绝对强度定标;测量计算了各条谱线在色球底层附近的强度。 此外,还拍摄到了5303(FeXIV),5445和5694(CaXV)三条日冕线。 相似文献
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环月飞行器精密定轨的模拟仿真 总被引：11，自引：2，他引：11
以中国正在实施的探月计划“嫦娥1号”工程为背景，分析了在中国联合S波段(USB)测控网和甚长基线射电干涉(VLBI)跟踪网的现有空间分布、观测精度水平下的环月飞行器精密定轨．采用的方法是模拟仿真计算，即首先模拟观测数据，然后在计入各误差源的影响后进行求解，并对解算结果进行比较．模拟仿真的工具是美国宇航局哥达德飞行中心的空间数据分析软件系统GEODYN．环月飞行的主要误差源是月球重力场，为此首先讨论了目前精度最高的月球重力场模型JGL165P1的(形式)误差．在模拟了测距、测速以及VLBI的时延、时延率数据后，计入月球重力场的误差进行精密轨道确定．定轨时采用了减缩动力学(reduced dynamic)方法，即选用合适的经验加速度参数吸收重力场误差对定轨的影响．结果表明对于一个不将月球重力场作为主要科学目标的探月计划(如“嫦娥1号”)，减缩动力学方法是一个简单、有效地提高环月飞行器定轨精度的方法． 相似文献
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《中国天文和天体物理学报》2014,(10)
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, 相似文献
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Laura Schaefer 《Icarus》2005,173(2):454-468
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. 相似文献
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《中国天文和天体物理学报》2014,(9)
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 相似文献
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Yehouda Enzel Rivka Amit Uri Dayan Onn Crouvi Ron Kahana Baruch Ziv David Sharon 《Global and Planetary Change》2008,60(3-4):165-192
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. 相似文献
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Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236
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. 相似文献
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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. 相似文献
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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. 相似文献
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V. Cardoso M.C. Espírito Santo M. Paulos M. Pimenta B. Tom 《Astroparticle Physics》2005,22(5-6):399-407
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. 相似文献