bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polar Motion with Daily and Sub-daily Time Resolution
Authors: Beutler G. , Rothacher M. , Kouba J. , Weber R. 
Published: July 2016

AbstractSince 1992 the IGS ACs (International GPS Service Analysis Centers) have delivered daily estimates of polar motion (PM) and length of day (LOD) to the IERS (International Earth Rotation Service). The IGS combined PM and LOD series are available since January 1, 1995. Since June 1996 the IGS rapid and the final combined orbits are accompanied with two distinct IGS combined PM series with the same time resolution of one day. Both, the IGS final and rapid combined PM series also include combined PM rate data as well as LOD, starting in March 1997.Since 1995 the CODE Analysis Center of the IGS has produced PM and LOD estimates with a two-hour time resolution on a routine basis. A study of the time series with sub-daily time resolution clearly shows the half-daily and daily tidal signals. The results correspond very well to those obtained from satellite altimetry.These sub-daily time series are based on the same observational data from the IGS tracking network as those time series with a one-day time resolution. It would thus be possible with a minor analysis effort, without additional observational effort, to come up with a long and consistent series of PM and LOD with a time resolution of about 1 to 2 hours.
Tidal Variations of the Earth Rotation
Authors: Ferrándiz J.M. , Barkin Yu. V. , Getino J. 
Published: July 2016

AbstractThe equations for the rotation of a weakly deformable celestial body in non canonical Andoyer variables have been used to study the perturbation of Earth rotation due to tidal deformation raised by the Moon and Sun. A theory of the perturbed rotational motion of an isolated weakly deformable body in Andoyer variables and in components of the angular velocity has been developed. Mantle tidal deformations due to lunar and solar influences were analytically described and taken into account. Perturbations of the first order in the Earth’s polar motion were determined.
Correspondances Entre Une Theorie Generale Planetaire En Variables Elliptiques Et La Theorie Classique De Le Verrier
Authors: Duriez L. 
Published: July 2016

AbstractIn order to improve the determination of the mixed terms in classical theories, we show how these terms may be derived from a general theory developed with the same variables (of a keplerian nature). We find that the general theory of the first order in the masses already allows us to develop the mixed terms which appear at the second order in the classical theory. We also show that a part of the constant perturbation of the semi-major axis introduced in the classical theory is present in the general theory as very long-period terms; by developing these terms in powers of time, they would be equivalent to the appearance of very small secular terms (in t, t2, …) in the perturbation of the semi-major axes from the second order in the masses. The short period terms of the classical theory are found the same in the general theory, but without the numerical substitution of the values of the variables.
Mathematical Results of the General Planetary Theory in Rectangular Coordinates
Authors: Brumberg V.A. , Evdokimova L.S. , Skripnichenko V.I. 
Published: July 2016

AbstractMathematical construction of the general planetary theory has led to the series of two forms for the coordinates of eight major planets (excluding Pluto). The series of the first form are Poisson series where all orbital elements except the semi-major axes occur in literal shape. The series of the second form are polynomial-exponential series with respect to the time and serve to calculate the ephemerides. The arbitrary constants of the theory are related to the Keplerian elements. The terms of the zero and first degree in eccentricities and inclinations have been found in the second approximation with, respect to the disturbing masses. Among those of particular interest are the resonant terms caused by the commensurabilities of the mean notations of triplets of planets.
Testing the Models Against Observations
Authors: Tsuji Takashi 
Published: July 2016

AbstractTests of the model atmospheres of red giant stars by photometric observations and angular diameter measurements (including limb-darkening) revealed that the present models reasonably represent the thermal structure of the continuum-forming region of red giant atmospheres. On the other hand, tests by line spectra (including line-blanketed fluxes) revealed that classical model atmospheres of red giant stars cannot yet satisfactorily represent the line-forming region. Recent progress in observations also provide some tests of improved models incorporating non-LTE or sphericity effects. More importantly, recent observations offer the means to test some new approaches such as: hydrodynamical simulation of photospheric convection, modeling atmospheres with thermal bifurcation, and incorporating the effects of outer atmosphere having inhomogeneous structure consisting of warm chromosphere and cool molecular dissociation zone.
The Chemical Composition of Asymptotic Giant Branch Stars
Authors: Lambert David L. 
Published: July 2016

AbstractLow resolution spectroscopic and photometric studies of Magellanic Cloud AGB stars have shown that the M → S → C sequence is the result of the third dredge-up of 12C and s-process elements in AGB stars of low mass. In this paper, data on the chemical compositions of normal Galactic M → S → C stars are reviewed and shown to be broadly consistent with expectations for the third dredge-up on the AGB.
Peculiar Red Giants — What Kind of White Dwarfs do They Become?
Authors: Iben Icko 
Published: July 2016

AbstractAfter a brief commentary on the place of “peculiar red giants” in the overall scheme of stellar evolution, an outline is given of the various possibilities for post asymptotic giant branch (AGB) evolution. The behavior of a post-AGB model star is crucially dependent on where in a thermal pulse cycle the mass of the hydrogen-rich envelope is reduced to such an extent that departure from the AGB must follow on a thermal time scale. If departure from the AGB occurs while the model is still burning hydrogen, post-AGB behavior depends on the mass of the helium buffer zone (- zone containing predominantly helium which has been processed through the hydrogen-burning shell following the last thermal pulse on the AGB). If departure occurs at an arbitrary time during the hydrogen-burning phase, then: (1) in - 25% of all cases, the post-AGB model will experience a final helium shell flash, and, in consequence of additional mass loss, may become a non-DA white dwarf; (2) in - 60% of all cases, the model will cease burning hydrogen when the mass in its hydrogen-rich envelope is reduced to ∼ 10-4Mʘ and will evolve into a DA white dwarf; and (3) in - 15% of all cases, the model will experience a final hydrogen shell flash, but the outcome with regard to spectroscopic type is unclear. If departure from the AGB occurs while the model is burning helium, the result is either the same as in option (3) just described, or mass loss during the post-AGB helium-burning phase may turn the star into a non-DA white dwarf.
Relativistic Celestial Mechanics and Reference Frames
Authors: Damour T. , Soffel M. , Xu C. 
Published: July 2016

AbstractA new formalism for treating the relativistic celestial mechanics of systems of N, arbitrarily composed and shaped, weakly self-gravitating, rotating, deformabile bodies is presented. This formalism is aimed at yielding a complete description, at the first post-Newtonian approximation level, of (i) the global dynamics of such N-body systems (“external problem”), (ii) the local gravitational structure of each body (“internal problem”), and, (iii) the way the external and the internal problems fit together (“theory of reference systems”).
The ZMOA-1990 Nutation Series
Authors: Herring T.A. 
Published: July 2016

AbstractWe present a new nutation series for the Earth (ZMOA-1990) based on (1) the rigid Earth nutation series developed by Zhu and Groten [1989], (2) the normalized response for an elastic, elliptical Earth with fluid-outer and solid-inner cores developed by Mathews et al. [1990], and (3) corrections for the effects of ocean tides and anelasticity, computed to be consistent with the Mathews et al. [1990] normalized response function. In deriving this series, only two parameters of the geophysical model for the Earth have been modified from their values computed with PREM: the dynamic ellipticities of the whole Earth, e, and of the fluid outer core, ef. The adopted values for these parameters, determined from the analysts of very long baseline interferometry (VLSI) data, are e=0.00328915 which is about 1% higher than the value obtained from PREM and 6×10−5 times larger than the IAU adopted value, and ef=0.002665 which is 4.6% higher than the PREM value. The above values were obtained from an adjustment of −0.3 ʺ/cent to the IAU-1976 luni-solar precession constant for e, and from the amplitude of the retrograde annual nutation for ef. The ZMOA-1990 nutation series agrees with estimates of the in-phase and the out-of-phase nutation amplitudes obtained from VLBI data to within 0.5 mas for the terms with 18.6 year period, and to better than 0.1 mas for terms at all other periods except for the out-of-phase terms with annual period (differences 0.39 mas, retrograde, and 0.13 mas, prograde), and for the in-phase term with prograde 13.66 day period (difference −0.25 mas).
Influence of the Solid Inner Core and Compressibility of the Fluid Core on the Earth Nutation
Authors: Diakonov Sergei 
Published: July 2016

While calculating low frequency oscillations of the Earth liquid core spherical harmonic representation of the deformation field is usually used [1-3]:Substitution of (1) into the equations of motion gives an infinite system of differential equations for scalar functions Sɭm and Tɭm . Approximate solutions of such a system are obtained by truncating of the system. But results of [4] show that sometimes such method divergences.
Correction of Fundamental Catalogue Constants
Authors: García A.López , Ortí J.A.López , Machí R.López , Castillo F.Marco 
Published: July 2016

AbstractOne of the main problems in positional astronomy is determining the equator and vernal equinox of the reference system.In this paper we display a method of amendment of minor planets elements taking into account the perturbations in the coefficients of the equations of condition, also including the corrections of the vernal equinox and obliquity in the fitting.
Tectonically-Induced Divergences of Earth Rotation Series
Authors: Gross R.S. , Steppe J.A. 
Published: July 2016

AbstractThe stability of the Terrestrial Reference Frame (TRF) is studied by analyzing divergences of independently determined Earth rotation series. These series, which have been (nominally) determined within the same TRF, are found to differ by up to 4.7 mas in bias and up to 0.80 mas/yr in rate. These bias-rate differences could reflect errors in the various models used during the data reduction process.
CQSSP: A New Technique for Establishing the Tie Between the Stellar and Quasar Celestial Reference Frames
Authors: Schildknecht T. , Bauersima I. , Hugentobler U. , Verdun A. , Beutler G. 
Published: July 2016

AbstractUsing artificial satellites as transfer objects the project “Coupled Quasar-Satellite-Star Positioning” represents an independent method for linking quasar and stellar reference frames. Optical observations of close approaches between reference stars and satellites yield satellite positions in the stellar reference frame. On the other hand high precision satellite orbits in the International Earth Rotation Service (IERS) terrestrial reference frame are obtained from laser or radiometric observations. Using IERS earth rotation parameters and adopted transformation models the satellite and eventually the star positions can be expressed in the IERS quasar celestial reference frame. In this paper we describe the CQSSP project and assess its capability for providing an accurate tie between tho two metioned celestial reference frames.
Is a Sunspot in Static or Dynamic Equilibrium?
Authors: Venkatakrishnan P. 
Published: July 2016

Extended abstractSunspots have been studied ever since their discovery by Galileo, but the investigation of sunspot structure remains a current issue. The theoretician’s ideal, isolated sunspot is rarely observed. However, most of the discussions about the stability and dynamics of sunspots are based on this ideal model. In what follows, we shall examine the evolution of a similar idealised model of a sunspot and comment on the implications of this study on the use of sunspots as tracers of sub-photospheric dynamics.To simplify matters, let us assume a sunspot where the vertical orz-component of the field varies withρdirection asThis component alone will produce a cylindrical spot model quite unlike what is generally observed. However, this cylindrical model can serve as; an approximation for a sunspot when we consider a small height range of the spot. As can be seen later, this assumption is not central to the issue being discussed. Generally, any such model is considered to be in static equilibrium because the electrical resistivity of the plasma is very high, leading to diffusion times that are much larger than the life-time of the sunspot. In a recent paper Schrijver, C. J.et al. (1998) showed that reconnection events at the network boundary enhance the effective mean free path for magnetic field diffusion to 30000 km. They also note that the typical time between events is about 6 hours or roughly 20000 s. Thus the magnetic diffusivityηrealised by this process is 1015cm2s−1. This diffusion cannot be ignored as can be seen in what follows.
Large-scale Motion of Solar Filaments
Authors: Ambrož Pavel , Schroll Alfred 
Published: July 2016

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.
Models of Flux Tubes from Constrained Relaxation
Authors: Mangalam A. , Krishan V. 
Published: July 2016

AbstractWe study the relaxation of a compressible plasma to an equilibrium with flow. The constraints of conservation of mass, energy, angular momentum, cross-helicity and relative magnetic helicity are imposed. Equilibria corresponding to the energy extrema while conserving these invariants for parallel flows yield three classes of solutions and one of them with an increasing radial density profile, relevant to solar flux tubes is presented.
The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23
Authors: Bao S. D. , Ai G. X. , Zhang H. Q. 
Published: July 2016

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.
Seismic Tomography of the Near Solar Surface
Authors: Gizon L. , Duvall T. L. , Larsen R. M. 
Published: July 2016

AbstractSurface gravity waves have been used to probe flows in the two megameters beneath the photosphere using the techniques of time-distance helioseismology. The results suggest that supergranule velocities are smaller than at the surface. The outward flow outside a sunspot penumbra (the moat) is observed, as is an inward flow in the region beyond the moat.
Helioseismic Solar Cycle Changes and Splitting Coefficients
Authors: Tripathy S. C. , Jain Kiran , Bhatnagar A. 
Published: July 2016

AbstractUsing the GONG data for a period over four years, we have studied the variation of frequencies and splitting coefficients with solar cycle. Frequencies and even-order coefficients are found to change significantly with rising phase of the solar cycle. We also find temporal variations in the rotation rate near the solar surface.
The Current Status of Kinematic Solar Dynamo Models
Authors: Choudhuri Arnab Rai 
Published: July 2016

AbstractThis review provides a historical overview of how research in kinematic solar dynamo modeling evolved during the last few decades and assesses the present state of research. The early pioneering papers assumed the dynamo to operate in the convection zone. It was suggested in the 1980s that the dynamo operates in a thin layer at the bottom of the convection zone. Some researchers in recent years are arguing that the poloidal field is produced near the surface—an idea that goes back to Babcock (1961) and Leighton (1969).
On the Chaotic Nature of Solar Activity
Authors: Kurths J. , Feudel U. , Jansen W. 
Published: July 2016

AbstractApplying modern techniques of time series analysis, there are serious indications that the dynamics of the global solar activity is a low dimensional chaos. A simple non-linear dynamo model is qualitatively studied exhibiting a rich dynamical behaviour from steady state via some bifurcation to a chaotic regime.
Vector Laypunov Functionals and Stabilities and Chaoticities of Functional Differential Equations Occurring in Celestial Mechanics and Stellar Dynamics
Authors: Sastry D.R.K. 
Published: July 2016

AbstractVector laypunov functions and stabilities and chaoticities of Functional Differential Equations occurring in Celestial Mechanics and Stellar Dynamics have been discussed. Fuzzy dynamical systems are more realistic while considering problems occurring in Celestial Mechanics and Stellary Dynamics.
Stochastic Trajectories of Space Vehicles with Gravitational Manoeuvres
Authors: Krivov A.V. , Sokolov L.I. , Titov V.B. 
Published: July 2016

AbstractThe theoretical aspect of close flybies of space-crafts near planets-gravitational manoeuvres have been studied. It is proved that the space-craft motion with gravitational manoeuvres admits the existence of routing scheme and, consequently shows the existence of quasi-random motion.
Stochastic Behaviour of Planetary Orbits During the Accumulation Process
Authors: Ziglina I.N. , Schmidt O.Yu. 
Published: July 2016

AbstractThe evolution of orbital elements of a growing planet during the accumulation process is considered. The planetary orbit undergoes perturbations because of random encounters and collisions with bodies of its accretion zone and also because of gravitational interaction with an already formed massive planet (“Jupiter”). The mass and velocity distributions of the swarm bodies are assumed to be given time-dependent functions. The Fokker-Planck equation describing the behaviour of the distribution function of orbital elements of the growing planet is worked out and solved. The present mean values of the eccentricities and inclinations of orbits of the terrestrial planets can be explained in the case of their accumulation from a single swarm of bodies with mean mass ~ 10−2 M⊕ and with mean eccentricities and inclinations ~ 0.2.
Statistical Studies of Orbits in Stellar Systems
Authors: Sagintaev B.S. , Chumak O.V. 
Published: July 2016

AbstractThis work is devoted to research of an evolution of dynamical systems with the factors, changed by accident, are investigated by statistical methods. The method of stochastic equations are applied for the study of the probe ensemble of stars, working in a field, where the regular component has spherical symmetry.
A Method of Numerical Extending of Periodical Motions of Hamiltonian Systems with Respect to Parameters
Authors: Karimov S.R. , Sokolsky A.G. 
Published: July 2016

AbstractThe method proposed is a generalization of the method described in [1]. It is represented in terms of the Hamiltonian formalism with all the advantages arising from it. A complete presentation of the method is given in the paper [2].
Collection of Stratospheric Microparticles above the Sulfate Layer Using Balloon-Borne Collectors
Authors: Stephens J. R. , Nakada Y. , Onaka T. , Rietmeijer F.J.M. 
Published: July 2016

AbstractWe report preliminary analytical electron microscope (AEM) analysis of nearly 300 stratospheric particles collected using balloon-borne collectors at 34-36 km altitude. The particles are predominantly silica, plagioclase feldspar, Mg, Fe-silicates and rare barite, metal oxides, and unidentified Fe, Ni, Zn, and Pb particles. The majority of these generally submicron-sized particles are comparable to volcanic particles collected at 20 km altitude from the 1982 eruption of the El Chichon volcano. Because of the uniqueness in altitude and collected particle sizes the collection may also contain interplanetary dust particles of types poorly represented in present collections.
Preliminary Study on Neogene Microtektites in the Core Collected from North Pacific
Authors: Hanchang Peng , Zhenkun Liu , Shijie Zhuang , Xueying Mao , Zhifang Chai 
Published: July 2016

Abstract:A great number of microtektites were found in core collected from North Pacific. Because abundant microtektites are restricted to a 20-30 cm thick zone of core, we called this zone is miicrotektite layer. The age of sediments concentrated microtektites is from the Pliocene to the Pleistocene epoch. Research results indicate that these microtektites are similar to the North American tektites and the Australasian tektites, but they have the unique property on the chemistry.
Condensation Experiments of Mg-Silicate Minerals
Authors: Tsuchiyama A. 
Published: July 2016

AbstractCondensation experiments were performed in the simple but most fundamental system Mg-Si-O-H with forsterite vaporization source. At temperatures above about 1000°C, euhedral crystals of forsterite (Mg2SiO4) of a few μm were formed. These crystals are similar to olivines in Allende matrix. At temperatures below about 1000°C, whiskers of forsterite and enstatite (MgSiO3) were formed by vapor-liquid-solid growth mechanism. These whiskers are different from enstatite whiskers in interplanetary dust, which were probably formed at small super coolings.
Temporal and Spatial Variations of the Atmospheric Diffuse Light
Authors: Kwon S. M. , Hong S. S. , Weinberg J. L. 
Published: July 2016

AbstractThe Barbier’s relation for the diffusely scattered airglow has been modified in such a way that it may describe, with simple changes of two parameter values, the dependence on zenith distance of the atmospheric diffuse light at any time of the night.
Scattering Calculations on the Basis of the Fredholm Integral Equation Method
Authors: Matsumura M. , Seki M. 
Published: July 2016

AbstractThe Fredholm integral equation method (FIM) is one of the solutions to the soattering of electromagnetic radiation by homogeneous and isotropio ellipsoidal particles. Some numerical calculations are performed with the FIM. The results for spherical particles are compared with those by the Mie theory. It is confirmed that the agreement between them is satisfactory for all the models calculated.On the basis of the present method, we examine profiles of the absorption band around»= 10μmfor spherical and ellipsoidal particles composed of crystalline olivine. It is found that the profile strongly depends on the shape of the particle. Even when the particle is moderately elongated (axial ratios are 2: √2:1), the profile is Signifioantly different from that for a sphere.