共查询到20条相似文献，搜索用时 312 毫秒
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针对FAST的天文观测要求,对其天文观测软件进行了设计与开发。首先介绍了FAST天文观测的原理,对天文观测软件进行了需求分析。而后提出了馈源天文运动轨迹规划算法,并进行了仿真。针对其轨迹要求给出了控制方法,对天文观测控制软件进行了设计与实现。最后通过现场实地实验,验证了本文所提的算法与软件的可行性。 相似文献
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2019年见证了太空领域所取得的多项突破。在太阳系内,一个探测器对小行星表面之下的物质进行了采样;天文学家对海王星存档图像的仔细筛查发现了它迄今最小的卫星。此前对冥王星进行了近距离探访的探测器又飞过了另一个更为遥远的天体,为了解行星演化的历史打开了新的窗口。一个新的探测器着陆到了火星上,意在首次了解火星表面之下正在发生些什么。 相似文献
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到了19世纪初,人们在探索星空的道路上已经走出了很远。1801年柏林天文台台长波德出版的《波德星图》（Uranographia）可以被视作此前时代的总结。这份印刷精美的古典星图以极高的精度标出了全天17240颗恒星的位置,包括了所有7等以上的恒星;加入了威廉姆赫歇尔等人发现的2000多个深空天体;还为各个星座划分了明确的边界。接下来的工作就将在这份蓝图上展开…… 相似文献
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提出了超导磁悬浮望远镜的概念,建立了模型,提出了稳定悬浮方案,并用有限元软件对磁悬浮望远镜的磁场进行了三维静态分析,为南极望远镜水平轴系结构设计提供了新的思路. 相似文献
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在新型冠状病毒的冲击下,2020年无疑是艰难的一年。天文学家发现了最遥远的星系群,探测到了银河系中的波动,证实了火星存在地质活动。参宿四发生了令人惊讶的变暗事件. 相似文献
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P. Kenneth Seidelmann B. A. Archinal M. F. A’hearn A. Conrad G. J. Consolmagno D. Hestroffer J. L. Hilton G. A. Krasinsky G. Neumann J. Oberst P. Stooke E. F. Tedesco D. J. Tholen P. C. Thomas I. P. Williams 《Celestial Mechanics and Dynamical Astronomy》2007,98(3):155-180
Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the
directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report
introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and
shapes of Saturn satellites and Charon, and the poles, rotation rates, and sizes of some minor planets and comets. A high
precision realization for the pole and rotation rate of the Moon is provided. The expression for the Sun’s rotation has been
changed to be consistent with the planets and to account for light travel time 相似文献
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J. Marvin Herndon 《Earth, Moon, and Planets》2006,99(1-4):53-89
Only three processes, operant during the formation of the Solar System, are responsible for the diversity of matter in the
Solar System and are directly responsible for planetary internal-structures, including planetocentric nuclear fission reactors,
and for dynamical processes, including and especially, geodynamics. These processes are: (i) Low-pressure, low-temperature
condensation from solar matter in the remote reaches of the Solar System or in the interstellar medium; (ii) High-pressure,
high-temperature condensation from solar matter associated with planetary-formation by raining out from the interiors of giant-gaseous
protoplanets, and; (iii) Stripping of the primordial volatile components from the inner portion of the Solar System by super-intense
solar wind associated with T-Tauri phase mass-ejections, presumably during the thermonuclear ignition of the Sun. As described
herein, these processes lead logically, in a causally related manner, to a coherent vision of planetary formation with profound
implications including, but not limited to, (a) Earth formation as a giant gaseous Jupiter-like planet with vast amounts of
stored energy of protoplanetary compression in its rock-plus-alloy kernel; (b) Removal of approximately 300 Earth-masses of
primordial volatile gases from the Earth, which began Earth’s decompression process, making available the stored energy of
protoplanetary compression for driving geodynamic processes, which I have described by the new whole-Earth decompression dynamics
and which is responsible for emplacing heat at the mantle-crust-interface at the base of the crust through the process I have
described, called mantle decompression thermal-tsunami; and, (c) Uranium accumulations at the planetary centers capable of
self-sustained nuclear fission chain reactions. 相似文献
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Q. L. Hou E. M. Kolesnikov L. W. Xie M. F. Zhou M. Sun N. V. Kolesnikova 《Planetary and Space Science》2000,48(15):110-1455
Ten Sphagnum fuscum peat samples collected from different depths of a core including the layer affected by the 1908 Tunguska explosion in the Tunguska area of Central Siberia, Russia, were analyzed by ICP-MS to determine the concentrations of Pd, Rh, Ru, Co, REE, Y, Sr, and Sc. The analytical results indicate that the Pd and Rh concentrations in the event- and lower layers were 14.0–19.9, and 1.23–1.56 ppb, respectively, about 3–9 times and 3 times higher than the background values in the normal layers. In addition, the patterns of CI-chondrite-normalized REE in the event layers were much flatter than in the normal layers, and differed from those in the nearby traps. Hence, it can be inferred from the characteristics of the elemental geochemistry that the explosion was probably associated with extraterrestrial material, and which, most probably, was a small comet core the dust fraction of which was chemically similar to carbonaceous chondrites (CI). In terms of the Pd and REE excess fluxes in the explosion area, it can be estimated that the celestial body that exploded over Tunguska in 1908 weighed more than 106 t, corresponding to a radius of >60 m. If the celestial body was a comet, then its total mass was more than 2×107 t, and it had >160 m radius, and released an energy of >107 t TNT. 相似文献
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Ever since their discovery the regular satellites of Jupiter and Saturn have held out the promise of providing an independent set of observations with which to test theories of planet formation. Yet elucidating their origins has proven elusive. Here we show that Iapetus can serve to discriminate between satellite formation models. Its accretion history can be understood in terms of a two-component gaseous subnebula, with a relatively dense inner region, and an extended tail out to the location of the irregular satellites, as in the SEMM model of Mosqueira and Estrada (2003a,b) (Mosqueira, I., Estrada, P.R. [2003a]. Icarus 163, 198-231; Mosqueira, I., Estrada, P.R. [2003b]. Icarus 163, 232-255). Following giant planet formation, planetesimals in the feeding zone of Jupiter and Saturn become dynamically excited, and undergo a collisional cascade. Ablation and capture of planetesimal fragments crossing the gaseous circumplanetary disks delivers enough collisional rubble to account for the mass budgets of the regular satellites of Jupiter and Saturn. This process can result in rock/ice fractionation as long as the make up of the population of disk crossers is non-homogeneous, thus offering a natural explanation for the marked compositional differences between outer solar nebula objects and those that accreted in the subnebulae of the giant planets. For a given size, icy objects are easier to capture and to ablate, likely resulting in an overall enrichment of ice in the subnebula. Furthermore, capture and ablation of rocky fragments become inefficient far from the planet for two reasons: the gas surface density of the subnebula is taken to drop outside the centrifugal radius, and the velocity of interlopers decreases with distance from the planet. Thus, rocky objects crossing the outer disks of Jupiter and Saturn never reach a temperature high enough to ablate either due to melting or vaporization, and capture is also greatly diminished there. In contrast, icy objects crossing the outer disks of each planet ablate due to the melting and vaporization of water-ice. Consequently, our model leads to an enhancement of the ice content of Iapetus, and to a lesser degree those of Titan, Callisto and Ganymede, and accounts for the (non-stochastic) compositions of these large, low-porosity outer regular satellites of Jupiter and Saturn. For this to work, the primordial population of planetesimals in the Jupiter-Saturn region must be partially differentiated, so that the ensuing collisional cascade produces an icy population of ?1 m size fragments to be ablated during subnebula crossing. We argue this is likely because the first generation of solar nebula ∼10 km planetesimals in the Jupiter-Saturn region incorporated significant quantities of 26Al. This is the first study successfully to provide a direct connection between nebula planetesimals and subnebulae mixtures with quantifiable and observable consequences for the bulk properties of the regular satellites of Jupiter and Saturn, and the only explanation presently available for Iapetus’ low density and ice-rich composition. 相似文献
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The family of (490) Veritas is a young, dynamically heterogeneous asteroid family, located in the outer main belt. As such, it represents a valuable example for studying the effects of chaotic diffusion on the shape of asteroid families. The Veritas family can be decomposed into several groups, in terms of the principal mechanisms that govern the local dynamics, which are analyzed here. A relatively large spread in proper eccentricity is observed, for the members of two chaotic groups. We show that different types of chaos govern the motion of bodies within each group, depending on the extent of overlap among the components of the corresponding resonant multiplets. In particular, one group appears to be strongly diffusive, while the other is not. Studying the evolution of the diffusive group and applying statistical methods, we estimate the age of the family to be τ=(8.7±1.7) Myr. This value is statistically compatible with that of 8.3 Myr previously derived by Nesvorný et al. [Nesvorný, D., Bottke, W.F., Levison, H.F., Dones, L., 2003. Astrophys. J. 591, 486-497], who analyzed the secular evolution of family members on regular orbits. Our methodology, applied here in the case of the Veritas family, can be used to reconstruct the orbital history of other, dynamically complex, asteroid families and derive approximate age estimates for young asteroid families, located in diffusive regions of the main belt. Possible refinements of the method are also discussed. 相似文献
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Alessandra Celletti Gabriella Pinzari 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):1-52
The discovery of the asteroid Ceres by Piazzi in 1801 motivated the development of a mathematical technique proposed by Gauss,
(Theory of the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, 1963) which allows to recover the orbit
of a celestial body starting from a minimum of three observations. Here we compare the method proposed by Gauss (Theory of
the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, New York, 1963) with the techniques (based on three
observations) developed by Laplace (Collected Works 10, 93–146, 1780) and by Mossotti (Memoria Postuma, 1866). We also consider
another method developed by Mossotti (Nuova analisi del problema di determinare le orbite dei corpi celesti, 1816–1818), based
on four observations. We provide a theoretical and numerical comparison among the different procedures. As an application,
we consider the computation of the orbit of the asteroid Juno. 相似文献
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河外旋涡星系外区普遍存在翘曲结构,其特征可用干翘曲参数来描述,包括翘曲角、翘曲半径、不对称度等。一些翘曲星系表已相继发表,并用于相关的统计分析。关于翘曲盘的形成已提出多种理论机制,如星系间的潮汐相互作用、星系际介质的吸积、盘与暗晕的角动量错向以及星系际磁场的作用等。 相似文献