On the depth of the lunar regolith

The aim of this paper is to point out that if the sinuous rilles on the Moon represent trenches in the mare ground in which they meander, the existence of a great number of individual boulders on their slopes - as discovered on the high-resolution photographs taken by US Lunar Orbiters 4 and 5 in 1967 - suggests that the solid substrate of the lunar globe is covered by broken-up debris produced by cosmic abrasion - and hereafter referred to as lunar regolith - of thickness comparable with the depth of the respective rilles - at least of those lacking flat floors; which is generally in the order of 200–300 m. This depth is much greater than that indicated previously by other methods possessing more limited depth in range; and need not apply uniformly all over the Moon. In point of fact, marial regions abounding in sinuous rilles may represent loci where the lunar regolith has developed its maximum depth.     

Physics of the earth and the solar system

Book Review

Physics of the earth and the solar systemB. Bertotti and P. Farinella, Kluwer Academic Publishers, (Volume 31 of Geophysics and Astrophysics Monographs) xv + 479 pp., subject index; price, £74.00, $99.00, Dfl 200 (hardcover); ISBN 0-7923-0535-3     

On the rotation periods of the components of the triple system TYC 9300-0891-1AB/TYC 9300-0529-1 in the Octans Association

Stellar rotation depends on different parameters such as age, mass, initial chemical composition, initial angular momentum, and environment characteristics. The range of values of these parameters causes the dispersion in the rotation period distributions observed in young stellar clusters/associations. We focus our investigation on the effects of different circumstellar environments on stellar rotation. More specifically, we consider the effects of a perturber stellar companion on the accretion-disc lifetime at early evolution stages.We are searching in stellar Associations for visual triple systems where all stellar parameters are similar, with the only exceptions of the unknown initial rotation period, and of the circum-stellar environment, in the sense that one of the two about equal-mass components has a close-by third ‘perturber’ component.In the present study we analyze the 35-Myr old visual triple system TYC 9300-0891-1AB + TYC 9300-0529-1 in the young Octans stellar association consisting of three equal-mass K0V components. We collected from the literature all information that allowed us to infer that the three components are actually physically bound forming a triple system and are members of the Octans Association. We collected broad-band photometric timeseries in two observation seasons. We discovered that all the components are variable, magnetically active, and from periodogram analysis we found the unresolved components TYC 9300-0891-1AB to have a rotation period P = 1.383 d and TYC9300-0529-1 a rotation period P = 1.634 d.TYC 9300-0891-1A, TYC 9300-0891-1B, and TYC 9300-0529-1 have same masses, ages, and initial chemical compositions. The relatively small 16% rotation period difference measured by us indicates that all components had similar initial rotation periods and disc lifetimes, and the separation of 157 AU between the component A and the ‘perturber’ component B (or vice-versa) has been sufficiently large to prevent any significant perturbation/shortening of the accretion-disc lifetime.     

Astron Cleared the Path to the Spektr-UF Program

Solar System Research - Ultraviolet space telescope Т-170М is a base element of the space observatory of the Spektr-UF program. Acquisition of high-resolution UV-range spectra and...     

考虑地球扁率摄动影响的初轨计算方法

在二体问题意义下的短弧定轨,Laplace型方法是最主要最典型的一种初轨计算方法。若测角资料达到10^-4-10^-5精度(相当于2″—20″之间),那么要使定轨精度达到与其相应的程度,地球非球形引力位中的扁率项摄动应该考虑,在此前提下,同样可以采用相应的Laplace型定轨方法。即给出这种严格包含扁率摄动的初轨计算方法的原理和具体计算过程以及计算实例,除采用多资料定轨方法外,这种方法也是提高初轨计算精度的一种途径,它同样可用于多资料的情况,这种方法对于大扁率主天体(即中心天体)的卫星定轨将更有实用价值。     

Historical Evidence for the Birth of the Newly Discovered Pulsar PSR J1833-1034

Stimulated by the recent discovery of PSR J1833-1034 in SNR G21.5-0.9 and its age parameters presented by two groups of discovery, we demonstrate that the PSR J1833-1034 was born 2053 years ago from a supernova explosion, the BC 48 guest star observed in the Western Han (Early Han) Dynasty by ancient Chinese. Based on a detailed analysis of the Chinese ancient record of the BC 48 guest star and the new detected physical parameters of PSR J1833-1034, agreements on the visual position, age and distance between PSR J1833-1034 and the BC 48 guest star are obtained. The initial period P0 of PSR J1833-1034 is now derived from its historical and current observed data without any other extra assumption on P0 itself, except that the factor PP is a constant in its evolution until now.     

The acceleration and the deceleration of the tumbling period of Rocket Intercosmos 11 during the first two years after launch

We have analysed the development of the tumbling period of Rocket Intercosmos 11 (1974-34-B) during the first 2 years after launch. We interpret the period increase, observed from August 1974 to June 1976, as being caused by torque moments due to eddy currents induced in the hollow cylinder by the magnetic field of the Earth. The spin-decay time of 1974-34-B was 1.13 yr. This compares well to results derived by Williams and Meadows in 1978 for other Soviet rocket bodies.The tumbling acceleration of 1974-34-B, observed in June 1974, is interpeted as outgassing effect of rest propellant which remained inside the rocket after burn-off. A model of the outgassing acceleration is developed and compared to the period measurements of 1974-34-B. A reasonable good agreement between observed and predicted periods can be derived by using a nonlinear regression fit. An initial mass ratio of the rest propellant and the empty rocket cylinder is estimated.     

Upper limit on the cosmic-ray photon flux above 10 eV using the surface detector of the Pierre Auger Observatory

A method is developed to search for air showers initiated by photons using data recorded by the surface detector of the Auger Observatory. The approach is based on observables sensitive to the longitudinal shower development, the signal risetime and the curvature of the shower front. Applying this method to the data, upper limits on the flux of photons of 3.8×10^-3, above , are derived, with corresponding limits on the fraction of photons being 2.0%, 5.1%, and 31% (all limits at 95% c.l.). These photon limits disfavor certain exotic models of sources of cosmic rays. The results also show that the approach adopted by the Auger Observatory to calibrate the shower energy is not strongly biased by a contamination from photons.     

On the level of h2 quadrupole absorption in the Jovian atmosphere

The hydrogen quadrupole absorption lines are uniquely characterized by the property of being collision narrowed. For the 3-0 and 4-0 bands the lines continue to narrow to below the pressure levels in the Jovian atmosphere where they appear to be formed. Since the collision narrowing is the reverse of the case for ordinary molecular absorptions the use of the Curtis-Godson approximation must be reconsidered. We have done this using the line shape for this process derived by Galatry and find that the Curtis-Godson approximation represents the absorption very well through the inhomogeneous Jovian atmosphere. The hydrogen quadrupole absorptions, 3-0 S (l) and 4-0 S (l), have been analysed by a procedure which has been shown to give self-consistent results for the methane 3v3 manifolds. The 3-0 S(1) line is strongly saturated and even the weak 4-0 S(l) line (equiv width ～ 8mÅ) exhibits a 10% saturation. We derive a mixing ratio (by volume) of approx 7 x 10^?4 for methane to hydrogen in agreement with earlier results.     

Speckle interferometry of metal-poor stars in the solar neighborhood. II

The results of speckle interferometric observations of 115 metal-poor stars ([m/H] < ?1) within 250 pc from the Sun and with proper motions µ ? 0.2″/yr, made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, are reported. Close companions with separations ranging from 0.034″ to 1″ were observed for 12 objects—G76-21, G59-1, G63-46, G135-16, G168-42, G141-47, G142-44, G190-10, G28-43, G217-8, G130-7, and G89-14—eight of them are astrometrically resolved for the first time. The newly resolved systems include one triple star—G190-10. If combined with spectroscopic and visual data, our results imply a single:binary:triple:quadruple star ratio of 147:64:9:1 for a sample of 221 primary components of halo and thick-disk stars.     

Speckle interferometry of metal-poor stars in the solar neighborhood. I

We report the results of speckle-interferometric observations of 109 high proper-motion metalpoor stars made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. We resolve eight objects—G102-20, G191-55, BD+19° 1185A, G89-14, G87-45, G87-47, G111-38, and G114-25—into individual components and we are the first to astrometrically resolve seven of these stars. New resolved systems included two triple (G111-38, G87-47) and one quadruple (G89-14) star. The ratio of single-to-binary-to-triple-to-quadruple systems among the stars of our sample is equal to 71:28:6:1.     

脉冲型耀斑中阿尔芬波湍流加速3He和重离子机制探讨

基于在^3He丰富事件中，高能^3He和重离子具有相似的幂律谱分布这一观测结果，通过数值求解Fokker-Planck方程，探讨经阿尔芬波湍动速后的离子分布随时间的演化特征。计算结果表明：加速源区的等离子体密度和阿尔芬波湍动能量密度对粒子能谱分布起主要作用，如果取加速源区等离子体密度n=(0.1-1)10^10cm^-3、磁场强度B=50-100Gs、湍动能量密度为0.4-2ergs cm^-3，则在1秒左右的时间内，湍动阿尔芬波能够将^3He和重离子加速到10MeV/nucleon量级，能谱指数为2.0-3.5。理论计算与观测结果基本一致。     

Absolute calibration of solar radio flux density in the microwave region

The absolute calibration of solar radio flux density in the microwave region, which showed considerable discrepancies until 1966, has become completely uniform through international cooperative work. A complete history is described to avoid confusion, and correction factors are derived to convert the published values into absolute values for long series of routine observations. It is also shown that the most reliable calibration can be made by using a large pyramidal horn and by using sky and room temperature as calibration standards.Abbreviation of Stations for Table II, Figures 2 and 3 BERL Heinrich-Hertz-Institut, Berlin Adlershof - BORD The Observatory, the University of Bordeaux - GORK Radiophysical Research Institute, Gorky - HIRA Hiraiso Radio Observatory - HUAN Geophysical Institute of Peru, Huancayo - IRKU Irkutsk Radioastronomical Observatory - KIEL Radio Observatory, Kiel University - Radio Observatory, Kiel University - KSLV Kislovodsk Radioastronomical Observatory - MANI Manila Observatory - ONDR Ondejov Observatory - OTTA National Research Council, Ottawa - PENT Dominion Radioastronomical Observatory, Penticton - SANM Observatory of Cosmic Physics, San Miguel - SAOP Mackenzie University, Sao Paulo - SGMR Sagamore Hill Radio Observatory - SYDN University of Sydney - TOKO Tokyo Astronomical Observatory - TYKW Toyokawa Observatory, Nagoya University - UCCL Belgian Royal Observatory, Uccle     

Numerically investigating the peculiar periphery of a supernova remnant in the medium with a density gradient: the case of RCW 103

The young shell-type supernova remnant RCW 103 has peculiar properties in the X-ray morphology obtained with Chandra.The southeastern shell is brighter in the X-rays,and the curved border of the shell in this region is flatter than the other part.We investigate the formation of the peculiar periphery of the supernova remnant RCW 103 using 3D hydrodynamical simulation.Assuming that the supernova ejecta has been evolved in the medium with a density gradient,the detected shape of the periphery can be generally reproduced.For RCW 103,with the ejecta mass of 3.0 M,the density of the background material of 2.0 cm^-3,and a gradient of 3.3-4.0 cm^-3pc^-1,the X-ray periphery can be generally reproduced.The simulation turned out that the asymmetry of the SNR RCW 103 is mainly due to the inhomogeneous medium with a density gradient.     

Behavior of the Line Profiles of the Sodium Doublet and the Calcium Triplet in the Spectrum of R CrB in the Shallow Minima of 1998-1999

The behavior of profiles of the Na I D line and of the infrared Ca II triplet for the star R Coronae Borealis (R CrB) during shallow light minima of 1998-1999 is traced using high-resolution spectra. During a light maximum, the sodium lines had an absorption profile with a shift of —(2-4) km/sec. During a light minimum, a narrow emission feature, which has an almost constant absolute intensity and a shift of —(8-10) km/sec, and an intense circumstellar absorption feature, which has a variable profile and a variable relative shift corresponding to an increase to 220 km/sec in the velocity of mass ejection, appeared in the cores of absorption lines. For several days before the onset of a light minimum, all three calcium lines exhibited a narrow emission feature in the line core with a shift of —(1-5) km/sec. All the subsequent changes in a line involved mainly the shape of the absorption line profile. The narrow emission feature's absolute intensity and relative position were maintained during all our observations. The behavior of the Na I D line profiles can be described qualitatively within the framework of the model of a spherical dust shell.     

On a transformation of the differential equations of the lunar theory

This work contains a transformation of Hill-Brown differential equations for the coordinates of the satellite to a type which can be integrated in a literal form using an analytical programming language. The differential equation for the parallax of the satellite is also established. Its use facilitates the computation of Hill's periodic intermediary orbit of the satellite and provides a good check for the expansion of the coordinates and frequencies. The knowledge of the expansion of the parallax facilitates the formation of differential equations for terms with a given characteristic. These differential equations are put into a form which favors the solution by means of iteration on the computer. As in the classical theory we obtain the expansions of the coordinates and of the parallax in the form of trigonometric series in four arguments and in powers of the constants of integration. We expand the differential operators into series in squares of the constants of integration. Only the terms of order zero in these expansions are employed in the integration of the differential equations. The remaining terms are responsible for producing the cross-effects between the perturbations of different order. By applying the averaging operator to the right sides of the differential equations we deduce the expansion of the frequencies in powers of squares of the constants of integration.Basic Notations f the gravitational constant - E the mass of the planet - M the mass of the satellite - t dynamical time - x, y, z planetocentric coordinates of the satellite - u x+y–1 - s x–y–1 - the planetocentric distance of the satellite - w 1/ - ₀ the variational part of - w ₀ the variational part ofw, - n the mean daily sidereal motion of the satellite - a the mean semi-major axis of the satellite defined by means of the Kepler relation:a ³ n ²=f(E+M) - a the mean semi-major axis defined as the constant factor attached to the variational solution - e the constant of the eccentricity of the satellite - the sine of one half the orbital inclination of the satellite relative to the orbit of the sun - c(n–n) the anomalistic frequency of the satellite - c ₀ the part ofc independent frome,e, and - g(n–n) the draconitic frequency of the satellite, - g ₀ the part ofg independent frome,e, and - exp (n–n)t–1 - D d/d - e the eccentricity of the solar planetocentric orbit - a the semi-major axis of the solar orbit - n the mean daily motion of the sun in its orbit around the planet - m n/(n–n) - a/a-the parallactic factor - the disturbing function     

On the instability region around the 5 : 3 Jovian resonance

Variations in the dynamic parameters of Phobos have been determined after reaching critical value of the semi-major axis = 7247 km at which zero-gravity on the surface of Phobos near the equator will take place. The rate of the variations will increase significantly, e.g., in the tidal energy dissipation by one order in magnitude. The total dissipated mechanical energy during the whole tidal history of the system has been estimated as -5.5 × 10²¹ kg m² s^-2, the total decrease in the second zonal Stokes parameter of Phobos as -6.6 × 10^-2.     

Observations of the X-ray binaries 4U 1700-37 and GRO J1655-40 during the Grif experiment onboard the mir orbiting station

Various areas of the sky, including the Galactic-center region and the region with the X-ray binaries 4U 1700-37 and GRO J1655-40, were observed in the hard (10–300 keV) energy range during the Grif experiment onboard the Mir orbiting station. An epoch-folding analysis of the data has revealed periodicities with periods of 82 and 62 h, which are equal to the orbital periods of 4U 1700-37 and GRO J1655-40. Previously, these periodicities were observed during the Prognoz-9 X-ray experiment. Periodicities with periods in the range of days, 98 and 152 h, which were also observed during the Prognoz-9 experiment, were not revealed by the Grif data. We obtained upper limits on the intensities of these periodicities in various energy ranges. For the 62-h periodicity, we constructed an average 25–50-keV light curve and estimated the spectral flux density, which characterizes the intensity of the periodic component at different energies in different observing intervals during 1995–1997. The Prognoz-9 and Grif observations of GRO J1655-40 are compared with its CGRO, RXTE, and BeppoSax observations. The orbital periodicity is shown to manifest itself in the hard emission from the extremely bright X-ray transient GRO J1655-40, a likely black-hole candidate, even at the epochs between its X-ray outbursts.     

Absolute intensities in the solar X-ray spectrum near minimum activity

Rocket measurements of absolute intensities in the solar X-ray spectrum on November 4, 1964 around 16:35 UT yield the following results : 1.8·10^-2 erg cm^-2 sec^-1 (wavelength band 44–60 Å); and 1.5·10^-3 erg cm^-2 sec^-1 (wavelength band 8–15Å). These values were obtained under nearly quiet minimum conditions of the sun.     

The evolution of the moon: A finite element approach

Thermal convection has considerable influence on the thermal evolution of terrestrial planets. Previous numerical models of planetary convection have solved the system of partial differential equations by finite difference methods, or have approximated it by parametrized methods. We have evaluated the applicability of a finite element solution of these equations. Our model analyses the thermal history of a self-gravitating spherical planetary body; it includes the effects of viscous dissipation, internal melting, adiabatic gradient, core formation, variable viscosity, decay of radioactive nucleides, and a depth dependent initial temperature profile. Reflecting current interest, physical parameters corresponding to the Moon were selected for the model.Although no initial basalt ocean is assumed for the Moon, partial melting is observed very early in its history; this is presumably related to the formation of the basalt maria. The convection pattern appears to be dominated by an L-2 mode. The present-day lithospheric thickness in the model is 600 km, with core-mantle temperatures close to 1600 K. Surface heat flux is 25.3 mW m^–2, higher than the steady state-value by about 16%.The finite element method is clearly applicable to the problem of planetary evolution, but much faster solution algorithms will be necessary if a sufficient number of models are to be examined by this method.Notation coefficient of thermal expansion - _ij Kronecker delta - absolute or dynamic viscosity - perturbation in temperature - thermal diffusivity - kinematic viscosity - density - stress tensor - B.P. before present - c specific heat at constant pressure or volume (Boussinesq approximation) - d depth of convection - E ^* activation energy for creep - g gravity - Ga billions of years - H(t) heat generation per unit mass per unit time at timet - k Boltzmann's constant - K mean thermal conductivity - Ma millions of years - p pressure - q heat flux - q _ss steady-state heat flux - Ra Rayleigh number - S volumetric heat sources, includes radioactivity and viscous dissipation - t time - T temperature - u verocity vector - V ^* activation volume for creep