天琴RR型变星的绝对星等与运动学参数

对天琴ＲＲ型变星绝对星等运动学参数的测定及其对确定距离、球状星团年龄估计的影响,并对它们和其他距离指示器求得的结果的比较作了评述。由于不同作者采用的方法和资料不同,结果的不确定性较大。例如由直接和间接测定方法决定的天琴ＲＲ型变星的绝对星等分成较暗和较亮两类,由天琴ＲＲ型变星和其他距离批示器决定大麦哲伦云（ＬＭＣ）的距离模数和球状星团年龄估计并不完全一致。这表明还有一些天体测量和天体物理问题需要深入     

Two-integral distribution functions for axisymmetric systems

Some formulae are presented for finding two-integral distribution functions (DFs) which depend only on the two classical integrals of the energy and the magnitude of the angular momentum with respect to the axis of symmetry for stellar systems with known axisymmetric densities. They come from a combination of the ideas of Eddington and Fricke and they are also an extension of those shown by Jiang and Ossipkov for finding anisotropic DFs for spherical galaxies. The density of the system is required to be expressed as a sum of products of functions of the potential and of the radial coordinate. The solution corresponding to this type of density is in turn a sum of products of functions of the energy and of the magnitude of the angular momentum about the axis of symmetry. The product of the density and its radial velocity dispersion can be also expressed as a sum of products of functions of the potential and of the radial coordinate. It can be further known that the density multiplied by its rotational velocity dispersion is equal to a sum of products of functions of the potential and of the radial coordinate minus the product of the density and the square of its mean rotational velocity. These formulae can be applied to the Binney and the Lynden-Bell models. An infinity of the odd DFs for the Binney model can be also found under the assumption of the laws of the rotational velocity.     

The international planetary patrol program: An assessment of the first three years

Day-to-day and hour-to-hour changes in the large-scale atmospheric and surface features of the planets can now be studied more effectively than previously possible. Since 1969 a network of observatories has obtained almost uninterrupted photographic coverage during all apparitions of Jupiter and Mars, plus some of Venus. Patrol films and catalogues are available to the scientific community. Recent or current analyses include the distribution and motion of clouds on Mars, the development and decay of Martian dust storms, the seasonal, diurnal and random fluctuations in contrast between adjacent light and dark regions on Mars, the detection of vertical shear in the Jovian atmosphere, the longitudinal oscillation of the Red Spot, the dependence of rotation period on xenographic latitude and on time, the eruption and spread of SEB disturbances, and the retrograde circulation of the Venus cloud deck.     

Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006

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     

Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites

This paper is the entire report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites, including three annexes. Tables give the recemmended values for the directions of the north poles of rotation and the prime meridians of the planets and satellites. Reference surfaces for mapping these bodies are described. The annexes discuss the guiding principles, given in the body of the report, present explanatory notes, and provide a bibliography of the rotational elements and reference surfaces of the planets and satellites, definitions, and algebraic expressions of relevant parameters.     

Tectonics and Evolution of Novae and Coronae on Venus: Tectonophysical Modeling Based on Gravitational Models

This paper describes the results of tectonophysical modeling of the formation and evolution of novae and coronae—radial/concentric volcanotectonic structures typical of the surface of Venus. The formation of these structures is usually associated with the effect of the rising and subsequently relaxing mantle diapirs on the surface layers of the lithosphere. Two series of experiments with gravitational models reproduce the topographic changes and the evolution of structural patterns in the course of the formation of novae and coronae on Venus. For model materials, we chose (1) rubber (a Bingham liquid) to reproduce the behavior of the elastoviscous diapir material in one series of experiments and the lower part of the lithosphere in the other series and (2) flour to model tectonic structures in the upper, brittle part of the lithosphere. Regularities in the formation of the topographic and structural characteristics of novae and coronae have been demonstrated on models of different geometry. The process of formation of the dense radial fracturing in novae due to the mechanical elevation caused by the formation of a rising dome, which was suggested by many authors, is not corroborated by our models. In the course of modeling, we studied the influence of the relative dimensions of the diapir and the thickness of the overlying structures, or the relative depth of the neutral buoyancy surface of the diapir, on the topographic, morphological, and structural features of novae and coronae and on the possible paths of their evolution. Regularities are also revealed in the formation of tectonic structures in relation to the environment in which the diapir evolution occurs—in the brittle upper part of the lithosphere or in its lower, viscoplastic part.     

Photometric study of the major satellites of Uranus

In this paper, we analyze the results of ground-based and space-born photometric observations of the major satellites of Uranus—Miranda, Ariel, Umbriel, Titania, and Oberon. All sets of photometric observations of the satellites available in the literature were examined for uniformity and systematic differences and summarized to a unified set by wavelength ranging from 0.25 to 2.4 μm. This set covers the interval of phase angles from 0.034° to 35°. The compound phase curves of brightness of the satellites in the spectral bands at 0.25, 0.41, 0.48, 0.56, 0.75, 0.91, 1.4, and 1.8 μm, which include a pronounced opposition surge and linear part, were constructed. For each satellite, the geometric albedo was found in different spectral bands taking into account the brightness opposition effect, and its spectral dependence was studied. It has been shown that the reflectance of the satellites linearly depends on the wavelength at different phase angles, but has different spectral gradients. The parameters of the phase functions of brightness, including the amplitude and the angular width of the brightness opposition surge, the phase coefficient, and the phase angle at which the nonlinear increase in brightness starts, were determined and their dependences on wavelength and geometric albedo were analyzed. Our investigations show that, in their optical properties, the satellites Miranda and Ariel, Titania and Oberon, and Umbriel present three types of surfaces. The observed parameters of the brightness opposition effect for the Uranian satellites, some ice satellites of Jupiter and Saturn, and the E-and S-type asteroids are analyzed and compared within the framework of the coherent backscattering and mutual shadowing mechanisms.     

High-sensitivity STEP-F spectrometer-telescope for high-energy particles of the CORONAS-PHOTON satellite experiment

The STEP-F satellite telescope for measuring electrons and protons of the Photon scientific equipment is described. Its design features are given. The device detects electrons, protons, and α-particles in the energy range 0.18–2.3, 7.4–55.2, and 298–160.0 MeV, respectively. Geometric factors vary in the range of 12.4–21.7 cm² sr, depending on the energy of the particles. In addition, there are three channels of mixed recording of particles of different types and channels of recording of the secondary electromagnetic radiation generated in the construction materials of the device and spacecraft. Methods and results of the computer simulation of the passage of the particle through detector materials are presented, along with configuration, calibration measurements, and tests (both standalone and integrated) within the complex of scientific instrumentation and spacecraft. Updated data on geometric factors of the device and energy ranges of the direct detection of charged high-energy particles and of channels of mixed recording of several types of particles are given. Special software is described for the rapid analysis of the processed data of the STEP-F telescope, and the visualization of time variations of particle fluxes with different time resolution in some periods of high solar activity and in its absence.     

Jovian satellite-satellite eclipses and occultations

Toward the end of 1973 and in the first part of 1974, when the planes of the orbits of the four large Galilean satellites cross the Sun and the Earth, satellite-satellite eclipses and occultations will occur. Calculations indicate that during this period 350 such events will occur, most of them potentially observable. From observation of a few of these events the ephemerides of the satellites can be improved, radii and limb darkening curves determined, and crude information about the degree and extent of albedo fluctuations deduced. If a concerted effort were made and a large fraction of these events carefully observed it would be possible to invert the light curves to obtain albedo maps of most of the surface area at a typical resolution of about 100km for JI and JII and somewhat poorer for JIII and JIV. In 1979—the next opportunity—there will be considerably fewer events, and only a relative few of them will be observable at night.     

冕洞边界区磁结构的探讨──Ⅱ．太阳活动20、21周的冕洞及其边界区磁结构的变化

本文分析讨论了太阳活动２０、２１周的冕洞及其边界区磁结构的变化。它包括：冕洞区光球磁场强度、磁极性的变化；冕洞面积与高速太阳风风速的关系；冕洞边界周围的环境。重点探讨太阳活动下降、极小相低纬、赤道冕洞区与其边界区磁结构的变化。     

Optical properties of spheroidal particles

A new exact solution of the diffraction problem for the homogeneous spheroid on the basis of the method of separation of variables is given. This solution is considerably more efficient than the one of Asano and Yamamoto from the computational point of view. The expressions for various characteristics of the scattered radiation are obtained. The radiation pressure on spheroidal particles is considered taking into account the radial and transversal components. The method of calculations and various tests, which were used to control the computer programs, are described. Numerical results for forward and arbitrary angles scattering by prolate and oblate spheroids with the refractive indices typical for ice and silicates are presented. The dependence of the results on the propagation direction and the polarization of the incident radiation, size of particle and its aspect ratio are examined. The asymptotics for the characteristics of the scattered radiation for the extremely prolate and extremely oblate spheroids are derived. The range of the validity of these approximations is studied. Astrophysical applications include: a) the calculations of the interstellar extinction, interstellar linear and circular polarization curves for the ensemble of partially oriented spheroidal grains, and b) the consideration of the profiles and polarization of the interstellar feature 2200 for the partially oriented graphite spheroids. Appendices contain the expressions for integrals of products of the angular spheroidal functions and the asymptotics for the oblate spheroidal functions.     

First Results from SOHO

SOHO, the Solar and Heliospheric Observatory, is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. Three helioseismology instruments are providing unique data for the study of the structure and dynamics of the solar interior, from the very deep core to the outermost layers of the convection zone. A set of five complementary remote sensing instruments, consisting of EUV, UV and visible light imagers, spectrographs and coronagraphs, give us our first comprehensive view of the outer solar atmosphere and corona, leading to a better understanding of the enigmatic coronal heating and solar wind acceleration processes. Finally, three experiments complement the remote sensing observations by making in- situ measurements of the composition and energy of the solar wind and charged energetic particles, and another instrument maps the neutral hydrogen in the heliosphere and its dynamic change by the solar wind. This paper reports some of the first results from the SOHO mission. This revised version was published online in July 2006 with corrections to the Cover Date.     

The international outer planets watch atmospheres node database of giant-planet images

The Atmospheres Node of the International Outer Planets Watch (IOPW, formerly known as International Jupiter Watch; Russell et al., 1990) intends to encourage and coordinate the imaging observations and study of the atmospheres of the Giant Planets. The main activity of the atmospheres node is to provide an interaction between the professional and amateur astronomical communities maintaining a large database of images of the giant planets (primarily Jupiter and Saturn but with increasing contributions of Uranus and Neptune too). The observational datasets of Jupiter and Saturn correspond to images obtained in the visible range (300 nm-1 μm), during the last decade, most of them performed by amateur observers. We here describe the organization and structure of the database as posted on the Internet and in particular the PVOL software (Planetary Virtual Observatory Laboratory) designed to manage the site in the spirit of the Virtual Observatory projects. We also describe with examples the important role of the amateur-professional collaboration in the study of the atmospheres of Jupiter and Saturn in an epoch of large telescopes and spacecraft observations of both planets.     

Effect of Hall Current and Finite Larmor Radius Corrections on Thermal Instability of Radiative Plasma for Star Formation in Interstellar Medium (ISM)

The effects of finite ion Larmor radius (FLR) corrections, Hall current and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effects of finite electrical resistivity, thermal conductivity and permeability for star formation in interstellar medium have been investigated. A general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. The wave propagation is discussed for longitudinal and transverse directions to the external magnetic field and the conditions of modified thermal instabilities and stabilities are discussed in different cases. We find that the thermal instability criterion gets modified into radiative instability criterion. The finite electrical resistivity removes the effect of magnetic field and the viscosity of the medium removes the effect of FLR from the condition of radiative instability. The Hall parameter affects only the longitudinal mode of propagation and it has no effect on the transverse mode of propagation. Numerical calculation shows stabilizing effect of viscosity, heat-loss function and FLR corrections, and destabilizing effect of finite resistivity and permeability on the thermal instability. The outcome of the problem discussed the formation of star in the interstellar medium.     

从KARST到FAST---中国天眼的概念起源与决策过程

在大科学时代,大科学工程的建设日益复杂,设计者需综合考虑设备性能、技术储备、经费、风险、环境等因素才能进行合理决策.在国内外天文学发展的背景中,梳理了500 m口径球面射电望远镜(Five-hundredmeter Aperture Spherical radio Telescope, FAST)概念形成的过程以及FAST团队在其中所做的决策,包括大望远镜中国方案的设想、先导单元的提出、主动反射面技术的采用等,并对决策过程进行了分析探讨. FAST诞生于我国与国际天文学发展的互动与融合进程,实现了从跟进到占据先机的转变,可为在相关基础薄弱的领域建设大科学工程提供参考.     

Mars geodesy,rotation and gravity

This review provides explanations of how geodesy, rotation and gravity can be addressed using radioscience data of an orbiter around a planet or of the lander on its surface.The planet Mars is the center of the discussion.The information one can get from orbitography and radioscience in general concerns the global static gravitational field, the time variation of the gravitational field induced by mass exchange between the atmosphere and the ice caps, the time variation of the gravitational field induced by the tides, the secular changes in the spacecraft's orbit induced by the little moons of Mars named Phobos and Deimos, the gravity induced by particular targets, the Martian ephemerides, and Mars' rotation and orientation.The paper addresses as well the determination of the geophysical parameters of Mars and, in particular, the state of Mars' core and its size, which is important for understanding the planet's evolution.Indeed, the state and dimension of the core determined from the moment of inertia and nutation depend in turn on the percentage of light elements in the core as well as on the core temperature, which is related to heat transport in the mantle.For example, the radius of the core has implications for possible mantle convection scenarios and, in particular, for the presence of a perovskite phase transition at the bottom of the mantle.This is also important for our understanding of the large volcanic province Tharsis on the surface of Mars.     

The composition,structure, temperature and dynamics of the upper thermosphere in the polar regions during October to December 1981

During the period October to December 1981, the Dynamics Explorer-2 (DE-2) spacecraft successively observed the South polar and the North polar regions, and recorded the temperature, composition and dynamical structure of the upper thermosphere. In October 1981, perigee was about 310 km altitude, in the vicinity of the South Pole, with the satellite orbit in the 09.00–21.00 L.T. plane. During late November and December, the perigee had precessed to the region of the North Pole, with the spacecraft sampling the upper thermosphere in the 06.00 18.00 L.T. plane. DE-2 observed the meridional wind with a Fabry-Perot interferometer (FPI), the zonal wind with the wind and temperature spectrometer (WATS), the neutral temperature with the FPI, and the neutral atmosphere composition and density with the neutral atmosphere composition spectrometer (NACS). A comparison between the South (summer) Pole and the North (winter) Pole data shows considerable seasonal differences in all neutral atmosphere parameters. The region of the summer pole, under similar geomagnetic and solar activity conditions, and at a level of about 300 km, is about 300 K warmer than that of the winter pole, and the density of atomic oxygen is strongly depleted (and nitrogen enhanced) around the summer pole (compared with the winter pole). Only part of the differences in temperature and composition structure can be related to the seasonal variation of solar insolation, however, and both polar regions display structural variations (with latitude and Universal Time) which are unmistakeable characteristics of strong magnetospheric forcing. The magnitude of the neutral atmosphere perturbations in winds, temperature, density and composition within both summer and winter polar regions all increase with increasing levels of geomagnetic activity.The UCL 3-dimensional time dependent global model has been used to simulate the diurnal, seasonal and geomagnetic response of the neutral thermosphere, attempting to follow the major features of the solar and geomagnetic inputs to the thermosphere which were present during the late 1981 period.In the UCL model, geomagnetic forcing is characterized by semi-empirical models of the polar electric field which show a dependence on the Y component of the Interplanetary Magnetic Field, due to Heppner and Maynard (1983), It is possible to obtain an overall agreement, in both summer and winter hemispheres, with the thermospheric wind structure at high latitudes, and to explain the geomagnetic control of the combined thermal and compositional structure both qualitatively and quantitatively. To obtain such agreement, however, it is essential to enhance the polar ionosphere as a consequence of magnetospheric particle precipitation, reflecting both widespread auroral (kilovolt) electrons, and “soft” cusp and polar cap sources. Geomagnetic forcing of the high latitude thermosphere cannot be explained purely by a polar convective electric field, and the thermal as well as ionising properties of these polar and auroral electron sources are crucial components of the total geomagnetic input.     

BeppoSAX–ROSAT PSPC observations of the Shapley supercluster: A3562

We present a combined analysis of the BeppoSAX and ROSAT PSPC observation of the cluster of galaxies A3562, a massive member of the core of the Shapley supercluster. With a complex and interacting structure composed from two groups of galaxies and A3558 to the west, the surface brightness of A3562 shows excess in the sectors to east and south when compared with an azimuthally averaged model of the emission. The emission tends to be flatter, and the distribution of the gas broader, along the merging axis and in opposition to the two groups. We present the first determination of the gradients of the gas temperature and metallicity for a cluster in the Shapley region at large distance from the cluster centre. From an analysis of the BeppoSAX data in annuli and sectors, we observe both the profiles to be flat within 8 arcmin (∼0.62 Mpc), with emission-weighted values of kT =5.1±0.2 keV and Z =0.39±0.05 Z_⊙. The value of the temperature is consistent with recent ASCA measurements and is significantly higher than previous estimates obtained from ROSAT and EXOSAT . We discuss the possible reasons for this disagreement. Between 8 and 20 arcmin, the plasma temperature declines to about 3.2 keV. When a polytropic profile is used to represent the gas temperature profile, the best-fitting polytropic index is 1.16±0.03. These results imply a total mass within the virial radius of between 40 and 80 per cent lower than the optical estimate, and a gas mass fraction of about 30 per cent.     

The analysis of the characteristics of variation and change patterns of sunspot cycles

The paper focus on the variation character of sunspot number and solar cycles based on the new version sunspot number (SSN) data. According to seven main variables describing solar cycles, including peak value, the length of cycle, the length of ascending phase, the ratio of the ascending time to the descending time, slope, half width, and area under the curve of solar cycle, clustering, principal component and factor analysis, are applied to analyze variation characteristic and patterns of the 24 solar cycles. We cluster these 24 cycles to find groups in these solar cycles, and search for the main factor determining strength, length and occurrence time of the peak, and the furthest cycle from the average. The cycles within a cluster will be similar or related to one another and different from or unrelated to the cycles in other clusters. These results could help us search for similar cycles conveniently, obtain the understanding of the characteristics of solar cycle variation and analysis of sunspot number change and evolution characteristics, and analyze the origin and the variation mechanism of solar cycle.