JOINT LIGHTCURVE OBSERVATIONS OF 10 NEAR-EARTH ASTEROIDS FROM MODRA AND ONDŘEJOV

The effort in photometry of near-Earth asteroids (NEAs) at Modra Observatory has been enhanced following a recent collaboration with Ondřejov Observatory. We present a part of our collaborative work on measuring rotation lightcurve data for 10 NEAs. We derived following synodic periods P and amplitudes of their composite lightcurves: (3553), 3.1944 h, 0.08 mag; (22753), 10.24 h, 0.11 mag; (31669), 5.807 h, 0.07–0.27 mag; (40267), 4.9568 h, 1.01–1.11 mag; (66146), 2.3774 h, 0.12–0.15 mag; (88188), 2.6906 h, 0.06 mag; (103067), 9.489 h, 0.49 mag; 2001 CB₂₁, 3.302 h, 0.19 mag; 2004 LJ₁, 2.7247 h, 0.17–0.59 mag; 2004 XO₁₄, 8.417 h, 0.19–0.25 mag. While the derived periods are unique (the reliability code U=3) for most of the objects, those of (3553), (22753) and 2001 CB₂₁ are somewhat less reliable (U=2). We checked all the U=3 data for deviations from strict periodicity, but found no significant attenuation that would indicate the presence of a satellite. Absolute magnitudes in Cousins R band (H _R ) were derived for (3553), 16.05; (40267), 15.59; (88188), 16.04; 2004 XO₁₄, 15.84; errors of the first three H _R estimates are 0.20 mag, but that of 2004 XO₁₄ is <0.10 mag.     

库车坳陷克拉苏-依奇克里克构造带的构造演化

野外露头上的小尺度构造记录着整个褶皱逆冲带运动学演化进程。通过对库车褶皱逆冲带坎亚肯褶皱发育的小尺度构造的特征和相互叠加、切割关系的分析,认为克拉苏-依奇克里克构造带在新生代的构造挤压变形中经历了三个阶段,即平行层面的挤压缩短作用阶段、弯滑与弯流褶皱作用阶段和逆冲断层改造作用阶段。同时,对不同阶段出现的断层滑动数据进行反演和古应力恢复的结果表明,整个变形过程,最大主应力方向σ1(即构造缩短方向)集中分布在NNW—SSE,没有发生大的变化,说明三个阶段的构造变形是在同一稳定应力场下发生的,从而进一步证明所有的变形是同一次构造挤压下的渐进式序列变形,而不是多期构造挤压变形的结果。此次构造挤压变形主要发生在康村沉积期(12～5Ma),对于克依构造带的构造圈闭最终定型起着决定性作用。     

Distribution of arsenic and other minor trace elements in the groundwater of Ischia Island (southern Italy)

The island of Ischia belongs to the active volcanic area of Naples. It is formed from Quaternary volcanic rocks and exhibits intense hydrothermal activity, which is manifested through numerous springs, fumaroles and sporadic geysers. The content of minor and trace elements in groundwater has been analyzed, including some elements that are considered toxic for humans. Mean concentrations of As, B, Fe, Mn, Sb, and Se in samples from 43 aquifer points exceed the WHO recommended values and the limits set by European and Italian legislation (98/83/CE and DM 471, respectively). In general, the spatial distribution of the elements follows a common pattern: it is governed by a marked structural control, which favors hydrochemical processes that liberate the elements into the water.     

行星构造:寻求地球演化的踪迹

地质构造是记录地球内、外动力地质作用过程的标志.和地球相似,太阳系其他天体上也发育丰富的地质构造.以研究天体表面的地质构造及其动力学机制为目的的"行星构造学"是建立在构造地质学、遥感地质学和地球物理学等学科基础上的一门新兴前沿学科.由于天体的大小、组分和轨道位置不同,表面构造特征及其形成机制各异.对比研究地球和其他天体...     

Stability of relative equilibria in arbitrary axisymmetric gravitational and magnetic fields

Relative equilibria occur in a wide variety of physical applications, including celestial mechanics, particle accelerators, plasma physics, and atomic physics. We derive sufficient conditions for Lyapunov stability of circular orbits in arbitrary axisymmetric gravitational (electrostatic) and magnetic fields, including the effects of local mass (charge) and current density. Particularly simple stability conditions are derived for source‐free regions, where the gravitational field is harmonic (∇²U = 0) or the magnetic field irrotational (∇ × B = 0). In either case the resulting stability conditions can be expressed geometrically (coordinate‐free) in terms of dimensionless stability indices. Stability bounds are calculated for several examples, including the problem of two fixed centers, the J₂ planetary model, galactic disks, and a toroidal quadrupole magnetic field. This revised version was published online in July 2006 with corrections to the Cover Date.     

太阳系探测的进展与比较行星学的主要科学问题

回顾了太阳系的探测历程,综合分析了太阳系探测的发展趋势。未来的太阳系探测将以月球与火星探测为主线,适度开展太阳系其他行星及其卫星、小行星和彗星的考察性探测。21世纪将是全面探测太阳系并为人类社会长期可持续发展服务的新时代。随着太阳系探测的进展,通过系统比较地球与类地行星的大气层与水体的形成演化过程、地形地貌与地质构造特征、岩石类型、热历史与内部结构等方面的共性与特性研究,表明行星的质量大小和行星与太阳的距离的相互耦合,制约了行星的形成和演化的复杂过程。比较行星学已成为指导太阳系探测的科学理论体系。     

The Eddington Mission

The Eddington mission was given full approval by the European Space Agencyon the 23rd May 2002, as part of the new `Cosmic Vision' Science programme, with launch scheduled for 2007/8. Its twin scienceobjectives are asteroseismology and planet finding.In its current design it consists of 4 × 60 cm folded Schmidt telescopes, eachwith 6° × 6° field of view and its own CCD array camera.The current observing plan is to spend 2 years primarily devoted to asteroseismologywith 1–3 months on different target fields monitoring up to 50,000 stars per field,and 3 years continuously on asingle target field monitoring upwards of 100,000 stars as required for planetsearching. The asteroseismic goal is to be able to detect oscillationsfrequencies with a precision 0.1–0.3 Hz.     

Atmospheric chemistry on Venus, Earth, and Mars: Main features and comparison

This paper deals with two common problems and then considers major aspects of chemistry in the atmospheres of Mars and Venus. (1) The atmospheres of the terrestrial planets have similar origins but different evolutionary pathways because of the different masses and distances to the Sun. Venus lost its water by hydrodynamic escape, Earth lost CO₂ that formed carbonates and is strongly affected by life, Mars lost water in the reaction with iron and then most of the atmosphere by the intense meteorite impacts. (2) In spite of the higher solar radiation on Venus, its thermospheric temperatures are similar to those on Mars because of the greater gravity acceleration and the higher production of O by photolysis of CO₂. O stimulates cooling by the emission at 15 μm in the collisions with CO₂. (3) There is a great progress in the observations of photochemical tracers and minor constituents on Mars in the current decade. This progress is supported by progress in photochemical modeling, especially by photochemical GCMs. Main results in these areas are briefly discussed. The problem of methane presents the controversial aspects of its variations and origin. The reported variations of methane cannot be explained by the existing data on gas-phase and heterogeneous chemistry. The lack of current volcanism, SO₂, and warm spots on Mars favor the biological origin of methane. (4) Venus’ chemistry is rich and covers a wide range of temperatures and pressures and many species. Photochemical models for the middle atmosphere (58-112 km), for the nighttime atmosphere and night airglow at 80-130 km, and the kinetic model for the lower atmosphere are briefly discussed.     

A search of outer Trojans on ASTROVIRTEL images

This paper discusses the main results of a search of outer Trojans on ESO/ESA ASTROVIRTEL images, and the usefulness and the limitations of such an archive for the discovery and dynamical classification of minor bodies. The work was performed in the frame of a program having the aim to detect bodies orbiting around the Lagrangian points of the outer planets. A large number of images taken from 1999 to 2001 with the wide field imager (WFI) camera of the 2.2 m telescope of ESO at La Silla for entirely different scientific reasons, but happening to be in the wanted Lagrangian positions, was retrieved with a dedicated search engine. The moving objects present on these images were detected and examined with specific software tools that permitted one to find out about 1500 minor bodies (mostly previously unknown). More than 5000 positions were sent to the Minor Planet Center, and the search was given the designation I03. The total sky area covered by I03 is of approximately 50 square degrees, and in some areas the limiting magnitudes were fainter than the 24th in the R band. A preliminary classification of the kinematics of the I03 discoveries (using a dedicated code, named AMIGO apparent motion interpretation of generic orbits) has produced several Trojan candidates of Jupiter and of the outer planets. Furthermore, pre-discovery positions have been provided for one NEO, three Jupiter Trojans and three TNOs.     

行星(月球)自转监测望远镜的原理样机地面验证实验

类地行星(月球)自转监测望远镜的科学目标是在行星(月球)表面现场测量行星(月球)自转并研究其内部结构和物理性质.为了验证全新的观测原理和资料处理方法,项目团队设计制造了一套原理样机,在一台商用天文望远镜的光路前端增加3面反射镜组,使其具有同时观测3个视场的能力.自2017年起在地面上开展了观测实验,获得了混合有3视场星象的图像.通过计算星象在前后图像上的位移实现了归属视场识别,使得观测效果与分视场独立观测等同,证明了用一台设备同时观测多视场的可行性.处理图像并通过3个视场中心的指向变化归算地球自转轴的空间指向,与理论值比较偏差平均约1′′,证明了观测原理和数据处理方法有效.对各种观测误差来源进行了分析,包含大气折射、仪器热稳定性和光学分辨能力的影响等,指出采用更长焦距的望远镜可以提高空间分辨率,优化形变控制可以提高观测稳定性.改进多视场同时观测中的光学设计也有助于精度的提高.