bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization of Thermal Radiation from Neutron Stars
Authors: Zavlin V. E. , Pavlov G. G.
Published: July 2016

The degree of polarization of thermal radiation from a neutron star depends on photon energy, surface temperature and magnetic field, and it oscillates with the star rotation period. Observations of this polarization provide a new tool for investigating properties of these objects.
Low–Mass He WDs and Millisecond Pulsars Age Determination
Authors: Antipova J. , Ergma Ene , Sarna M. J.
Published: July 2016

It is accepted that the formation of a millisecond binary pulsar (MBP) with a low–mass companion may be explained as the end–point of close binary evolution in which an old pulsar is spun–up by accretion from the red giant (Bhattacharaya & van den Heuvel 1991). In this paper we shall discuss the cooling properties of the helium white dwarfs (WD) in short orbital period MBP systems PSR J0437–4715, PSR J0751+1807 and PSR J1012+5307, without referring to the rotational history of neutron stars (NS).

Below we discuss observational data for several system for which the results of our calculations (Sarna, Antipova, & Muslimov 1998; Sarna, Ergma, & Antipova 1999) may be applied, by taking into account the orbital parameters of the system, the pulsar spin-down time, and the WD cooling time-scale.
The evolution of helium white dwarfs: Applications for millisecond pulsars
Authors: Driebe T. , Blöcker T. , Schönberner D.
Published: July 2016

Low-mass white dwarfs with helium cores (He-WDs) are known to result from mass loss and/or exchange events in binary systems where the donor is a low mass star evolving along the red giant branch (RGB). Therefore, He-WDs are common components in binary systems with either two white dwarfs or with a white dwarf and a millisecond pulsar (MSP). If the cooling behaviour of He-WDs is known from theoretical studies (see Driebe et al. 1998, and references therein) the ages of MSP systems can be calculated independently of the pulsar properties provided the He-WD mass is known from spectroscopy.
Protoneutron stars and neutron stars
Authors: Gondek-Rosińska D. , Haensel P. , Zdunik J. L.
Published: July 2016

We find constraints on minimum and maximum mass of ordinary neutron stars imposed by their early evolution (protoneutron star stage). We calculate models of protoneutron stars using a realistic standard equation of state of hot, dense matter valid for both supranuclear and subnuclear densities. Results for different values of the nuclear incompressibility are presented.
Discovery of a supernova remnant with a central X-ray source: AX J184453.3-025642 in G 29.6+0.1
Authors: Gotthelf E. V. , Vasisht G. , Gaensler B. , Torii K.
Published: July 2016

We report preliminary results from our follow-up X-ray and radio study of AX J1845–0258, the 7-s X-ray pulsar whose characteristics are similar to those found for the anomalous X-ray pulsars (AXPs). We have located a faint X-ray source within the pulsar’s error circle implying a dramatic reduction in flux, however, the source is too faint to provide a confirmation of the expected pulsations. Centered on this X-ray source is a newly discovered supernova remnant, evident in both radio and X-ray emission. This is the third example of an AXP-like object associated with a supernova remnant.
The First Decade of the IERS
Authors: Mueller Ivan I.
Published: July 2016

The International Earth Rotation Service (IERS) was established in 1987 by the International Astronomical Union (IAU) and the International Union of Geodesy and Geophysics (IUGG), and it began operation on 1 January 1988. The primary objectives of the IERS are to serve the astronomical, geodetic and geophysical communities by providing the following:

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The International Celestial Reference System (ICRS) and its realization, the International Celestial Reference Frame (ICRF).

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The International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF).

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Earth orientation parameters required to study Earth orientation variations and to transform between the ICRF and the ITRF.

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Geophysical data to interpret time/space variations of the ITRF with respect to the ICRF, i.e., of the Earth orientation parameters, and to model such variations.

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Standards, constants and models (i.e., conventions) encouraging international adherence.

This presentation primarily covers the first three IERS functions from the operational point of view.
Long-term Earth Orientation Monitoring Using Various Techniques
Authors: Gambis D.
Published: July 2016

A continuous composite series of polar motion components extending from 1846 until now called EOP (IERS) C01 is available at the Earth Orientation Section of the Central Bureau of the IERS. This series is the basis of the IERS system. It relies on different series derived from optical astrometry until 1972 and geodetic techniques since. It is given at 0.1 year intervals (1846–1889) and 0.05 year intervals (1890-now). Its accuracy has dramatically improved from 100 mas in 1846 to about 0.2 mas at present.

Now the IERS combined solutions involve mainly the contributions of VLBI, GPS and SLR techniques. It is regularly recomputed to take advantage of the improvement of the various recent individual contributions and of the refinement of the analyses procedures.

The objective of this paper is to describe this long-term polar motion series and to present the evolution and the state of the art of the multi-technique EOP combined solutions and the predictions regularly computed at the IERS/CB.
Anaglif Representation of Polar Motion over the Last Century
Authors: Nagy S.
Published: July 2016

This is a special demonstration of the polar motion over the last century. Our figures represent the (xp, yp) coordinates of Earth’s axis, and the elapsed time along the z-axis. The figures remind us of a spiral spring. For the sake of illustration we used the so-called anaglif projection. Red and green glasses must be used to see the figures. The whole century (1899–1999) is too long for one diagram. So we divided the database into ten parts and present ten figures. The historic data was taken from IERS EOP C01 database and the new data from the IERS Bulletin B (1997,1998). The EOP C01 database contains only twenty (xp, yp) pairs per year. This is not sufficient for the refined representation, therefore we used the cubic spline interpolation for densification. The ten figures presented provide a quick review of the history of the polar motion over the last century: small amplitude in the twenties and thirties, with powerful fluctuation in the fifties. It is remarkable how the spiral leaves the Conventional International Origin (CIO) westwards due to the secular polar motion.

Remark: a series of figures is available upon request from the author (e-mail: nagy@sgo.fomi.hu).
Tectonic and Cryospheric Excitation of the Chandler Wobble and A Brief Review of the Secular Motion of Earth’s Rotation Pole
Authors: Dickman S.R.
Published: July 2016

I had originally planned to focus this talk on two novel sources of Chandler wobble excitation: tectonic, associated with aseismic processes occurring for example at subduction zones; and cryospheric, associated with the transient oceanic responses to episodes of ice-cap melting. I was also asked by the conference convenors to present a brief historical review of the secular motion of Earth’s rotation pole. In the course of preparing that review, I was struck by the exceedingly controversial nature of the topic, from beginning to end; as a result, the review will be somewhat lengthy, and I will not have time to discuss cryospheric excitation of wobble.
Regional Signals in Atmospheric and Oceanic Excitation of Polar Motion
Authors: Nastula Jolanta , Ponte Rui M. , Salstein David A.
Published: July 2016

Atmospheric and oceanic variability have been shown to play a role in the excitation of polar motion. Regional patterns of atmospheric and oceanic excitation are analysed and compared. The equatorial excitation functions, χ1 an χ2, for the ocean are computed using velocity and mass fields from a near-global ocean model, driven by observed surface winds stresses, surface heat and freshwater fluxes, for the period from January 1985 to June 1997. To understand the relative role of the ocean versus the atmosphere, we used atmospheric excitation functions computed from the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalyses. We consider regional mass terms [bottom pressure and atmospheric surface pressure with the inverted barometer (IB) correction] and regional motion terms as well (currents and winds). Results here confirm recent findings that oceans supplement the atmosphere as an important source for polar motion excitation. Regional signals in the oceanic bottom pressure terms have comparable amplitudes to those in the atmospheric pressure-IB terms. The regional wind term amplitudes, however, are several times larger than the values for both regional oceanic currents term and atmospheric pressure-IB term. Power in regional oceanic excitation is distributed between seasonal and subseasonal timescales while in the case of atmospheric excitation it is concentrated rather at seasonal timescales.
Polar Motion with Daily and Sub-daily Time Resolution
Authors: Beutler G. , Rothacher M. , Kouba J. , Weber R.
Published: July 2016

Since 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

The 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

In 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

Mathematical 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.
The Kinematics of Peculiar Red Giants
Authors: Feast M.W.
Published: July 2016

The ages, masses and evolutionary state of peculiar red giants are discussed on the basis of kinematic and other data.
The Ratio of the Numbers of Carbon Stars to M Stars in Galaxies
Authors: Frantsman Yu. L.
Published: July 2016

Simulated populations of the AGB stars were calculated with different assumptions about mass loss, initial chemical composition and dredge-up efficiency. The early-AGB (E-AGB) phase was taken into account. The numbers of carbon and oxygen stars per 106 generated stars and the ratio (NC/NM) of these numbers were obtained. It is possible to match theoretically obtained NC/NM with the observations only if the luminosity of observed stars Mbol < -3.5; otherwise it is necessary to take into account the E-AGB phase. The data in the Table are for all AGB stars in the Galaxy and for stars with Mbol < -1.80 in the LMC.
Kinematics of Short-Period Mira Variables - A Progress Report
Authors: Hron J.
Published: July 2016

First results of an observing program recently started at the Figl Observatory for Astrophysics, Austria, are presented. Radial velocities derived by a correlation technique from the TiO bandheads near 7050 Å will be used to identify the stellar populations present among the short period (P ≤ 200d) Mira variables. From the first observations with the Reticon-equipped Echelle Spectrograph of the FOA (resolution 0.3 Å at 7000 Å) we conclude that for Mira stars with a limiting visual magnitude of about 10m velocities can be determined with an external accuracy of 6 km/s.
Testing the Models Against Observations
Authors: Tsuji Takashi
Published: July 2016

Tests 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

Low 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.
Long-Period Radial-Velocity Variations of Arcturus
Authors: Irwin Alan W. , Campbell Bruce , Morbey C.L. , Walker G.A.H. , Yang S.
Published: July 2016

We have measured the relative radial velocity of Arcturus using the HF absorption cell technique on 43 occasions from 1981 through 1985. The range of our velocities is 500 m s-1, which is much larger than our estimated internal errors (typically 10 m s-1). This confirms the radial velocity variability of Arcturus that has been previously reported by our group and others based on shorter observational time spans.
Fluxes in M Giants With Improved Water Vapor Opacity
Authors: Alexander D.R. , Augason G.C. , Brown J.A. , Johnson H.R.
Published: July 2016

In the atmospheres of cool oxygen-rich stars, water vapor is the most important molecular absorber. Yet no laboratory or theoretical spectrum exists for water vapor of sufficient detail to be useful for radiative transfer calculations in a stellar atmosphere. Because of the complexities of its bent triatomic structure, this deficiency is not likely to the be resolved soon. We have, therefore, undertaken the preparation of a synthetic spectrum for water vapor.
Peculiar Red Giants — What Kind of White Dwarfs do They Become?
Authors: Iben Icko
Published: July 2016

After 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.
IRAS09371+1212: A Unique Red Giant With Strong Emission in the 40-70 Micron Bands of Ice
Authors: Omont A. , Moseley S.H. , Forveille T. , Harvey P.M. , Likkel L.
Published: July 2016

IRAS 09371+1212 (sometimes called the Frosty Leo nebula) is up to now an absolutely unique object. Its stellar nature has been proved by the detection of circumstellar CO (J = 1-0) by Forveille et al. (1987), and by its stellar M giant spectral type, although its infrared colors and its visible appearance could have suggested a galaxy (Condon and Broderick 1986). It displays unique IRAS far infra-red colors which have been attributed by Forveille et al. (1987) to a strong emission in the 40-70 micron bands of ice. The presence of an extremely large quantity of ice is confirmed by extraordinary strength of its 3.1 micron absorption band (Rouan et al. 1988; Hodapp et al. 1988; Geballe et al. 1988).
Fluorescence in the Outer Atmospheres of Red Giant Stars
Authors: Carpenter K.G.
Published: July 2016

The outer atmosphere of a cool red giant star is an ideal locale for the operation of line fluorescence processes. Low plasma densities imply low rates of collisional de-excitation and thus allow radiative decay of levels populated by selective radiative pumping. There are many strong sources of line radiation (i.e. possible pumps) and numerous possible upward transitions from highly populated low-lying levels of abundant elements such as Fe II, thus providing many chance coincidences between potential pumps and lines to be pumped. These conditions ensure that many of the chromospheric emission features observed in the UV spectrum of such a star are affected by fluorescence. Many of the observed emission features originate from energy levels populated solely by radiative fluorescent excitation, including strong lines of S I, O I, CO, Ni II, Si I, Fe I and Fe II, as well as weaker lines from Cr II and Co II. Important pumps active in these atmospheres include hydrogen Lyman alpha, and individual lines of 0 I, C I, Si II, Fe II, and Mg II. In the case of Fe II, there are many additional features arising from upper levels whose populations, although primarily maintained by collisions, are also significantly affected by radiative fluorescent excitation. In fact, there may be virtually no level in Fe II not affected to one degree or another by direct decays or cascades down from levels populated by fluorescence, driven either by Lyman alpha or, in some cases, by lines of Fe II itself (“self-fluorescence“).
Summary of Some Observations of Peculiar Red Giants With the IRAM 30M Radiotelescope
Authors: Omont A. , Guilloteau S. , Lucas R. , Benayoun J.J. , Cernicharo J. , Nercessian E. , Jura M. , Morris M. , Goldsmith P.F. , Lis D.C.
Published: July 2016

We present a brief description of the main results obtained on the following topics: (1) Sulfur-bearing molecules in O-rich envelopes: SO2(104 and 160 GHz), H2S (169 and 217 GHz) in 15 stars, SO (86 GHz) in 7 stars (all new detections except H2S in 0H231.8+4.2). Excitation temperatures and line profiles could suggest in some stars a main contribution from external layers for SO2 and internal layers for H2S.
Some Condensation Calculations Using Chemical Equilibria
Authors: Sharp Christopher M.
Published: July 2016

A number of extensive chemical equilibrium calculations have recently been performed for temperatures below 2000 K, with mixtures containing over 200 gaseous species and the allowance for the formation of over 60 condensates. These calculations were based on the minimization of the Gibb's free energy.
Relativistic Celestial Mechanics and Reference Frames
Authors: Damour T. , Soffel M. , Xu C.
Published: July 2016

A 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 Extragalactic Radio/Optical Reference Frame
Authors: Johnston Kenneth J. , Russell Jane L. , de Vegt Christian , Zacharias N. , Hindsley R. , Hughes J. , Jauncey D.L. , Reynolds J.E. , Nicholson G. , Ma C.
Published: July 2016

The celestial positions of extragalactic radio sources may be determined to a precision of less than a milliarcsecond. Further, since these sources are believed to be at great distances from the galaxy, little or no proper motion is expected on scales of order a milliarcsecond. Therefore a reference frame based on the positions of carefully selected sources so that display compact radiation on scales less than a milliarcsecond will noticeably improve the precision of present celestial reference frames. If the radio objects making up the reference frame also emit radiation at optical wavelengths, and assuming the optical/radio radiation is coincident, the radio frame can update the optical frame to the accuracy of the individual optical positions.
The ZMOA-1990 Nutation Series
Authors: Herring T.A.
Published: July 2016

We 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

One 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

The 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

Using 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 abstract

Sunspots 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 as

This 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

Precise 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

We 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

We 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

Surface 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

Using 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

This 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).
Possible Amount of Magnetic Flux Reconnected Through Quiescent Prominences Outside the Active Regions
Authors: Gokhale M.H. , Sivaraman K.R.
Published: July 2016

Quiescent prominences are known to occur invariably above the neutral lines in the large scale photospheric fields. This suggests that such prominences may be coronal current sheets across which the magnetic fields reconnect (cf. e.g. Raadu and Kuperus, 1973). In the absence of any satisfactory model for quiescent prominences (cf. Report of Working Group 1 in this Colloquium), the reconnection hypothesis remains as yet unsettled. However, if it is true, we have here an evidence to show that the quiescent prominences outside the active regions might account for the reconnection of almost all the photospheric magnetic flux emerging in the active regions as required by the theories of the 11-yr cycle of activity (e.g. Babcock, 1961).
Slowly-Moving Disturbances in the X-Ray Corona
Authors: Rust D.M. , Švestka Z.
Published: July 2016

From 28 May through 27 November 1973, the S-054 X-ray telescope on Skylab took almost 1000 pictures of the Sun with exposure times (64 sec) long enough to show the faint structures of the inner corona. These pictures of the X-ray (≈ 2-54 Å) corona were made into a synoptic movie on which it is possible to see many variations in brightness and structure that escape notice in studies of individual images. In particular, the movie has led to the discovery of disturbances propagating with velocities under 100 km/sec and extending over distances of the order of one solar radius. The disturbances reveal themselves as brightened coronal structures at progressively greater distances from a central point, usually an active region with an activated or disappearing filament. In a number of cases these coronal brightenings were accompanied by quiescent filament disappearances.
On the Chaotic Nature of Solar Activity
Authors: Kurths J. , Feudel U. , Jansen W.
Published: July 2016

Applying 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

Vector 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

The 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

The 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

This 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

The 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].
Application of Non-Standard Numerical methods to Satellite Problems
Authors: Pérez M. Teresa
Published: July 2016

In this paper we have tested some non-standard numericcal methods to integrate the two-body problem. The integration has been performed with Bettis methods, a symplectic algorithm and special spherically exact scheme. The results have been compared with those obtained with traditional integrators.
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

We 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

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

Condensation 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

The 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

The 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.
Long Dust Trails of Short Period Comets
Authors: Keller H.U. , Richter K.
Published: July 2016

Comets constitute an important source for the zodiacal dust cloud. Mainly large particles are contributed because the smaller particles are emitted into hyperbolic orbits relative to the sun. Radiation pressure force reduces the effective solar gravitational attraction. Information about large cometary particles can be derived from a variety of sources requiring quite different observational techniques. Many distinct meteor streams are connected to orbits of short period comets. These streams contain large dust particles that are very little influenced by radiation pressure force. In some cases such as the η Aquarids and Orionids connected to comet Halley the total mass and the age of the meteors have been derived (Hughes, 1987; Hajduk, 1987). The mass of the streams is 5 to 10 times larger than the present mass of the nucleus and their lifetime corresponds to 2000 to 3000 orbital periods. Visible meteors are typically 10−2g and more of centimetre size.
On the Anti-Tail of Comet Bradfield (1987XXIX)
Authors: Akisawa Hiroki , Oka Takuma , Sugawara Ken
Published: July 2016

The anti-tail of comet Bradfield 1987XXIX (= 1987s) was observed when the earth passed through the orbital plane of this comet on December 20, 1987. The time variation of this phenomenon was monitored continuously by Japanese amateur astronomers. Analyzing these photographs by using the Bessel-Bredkhin theory, we deal with the dust particles in the anti-tail.
Formation Mechanisms of the Split Tail of Comet Bradfield 1987XXIX
Authors: Sugawara Ken , Watanabe Jun-ichi
Published: July 2016

Comet Bradfield 1987XXIX showed a well-developed split tail, which is a dust tail feature divided into two branches by a dark gap. Similar structures have been observed in several comets. The split tail of comet Seki-Lines is one of them; some authors tried to explain it by rapid dust vaporization or self-regulation model. However, these models can not explain in the case of comet Bradfield 1987s. It was suggested in our previous works that the trend of variation of position angle of the dark gap coincides well with that of the plasma tail or projected radial vector. We discuss the formation mechanisms of the split tail from the view point of dust-plasma interactions.
Lifetime of Meteor Streams Associated with Comet Halley
Authors: Hajdukova M. , Hajduk A.
Published: July 2016

Critical examination of the orbital parameters of particles ejected from comet Halley rejects the low age hypotheses for meteor showers associ- ated with the comet. The diffusion of the orbits of large particles is too slow for explaining the observed structural features of the stream. The mass-loss process as derived from space observations compared with the mass of the stream of particles deduced from flux data lead to comet lifetimes of the order of 105years.
Evolution of Maser Sources
Authors: Burdjuzha V.V. , Ruzmaikina T.V.
Published: July 2016

H2O and OH maser sources are observed in the direction of compact regions of HII and IR stars and molecular complexes. Besides, the maser sources are observed in the direction of star formation regions and are associated with Herbiga-Aro objects and T-Tau stars.
A Model for a Chemical Evolution of Galactic Discs.
Authors: Chiosi C.
Published: July 2016

In this paper we discuss a simple model for the chemical evolution of galactic disks, aiming at understanding the observed metallicity gradients in spiral galaxies. The model in corporates both the recent results of Talbot and Arnett (1975), who proposed a rate of star formation driven by the surface mass density, and those of Lynden-Bell (1975), who investigated the consequences of significant infall of gas into the system. A similar attempt was made by Chiosi (1977) for the solar neighbourhood. The result was that the metallicity distribution of nearby stars can be easily interpreted if the time scale for accretion of gas into the solar pool, or in other words the duration of the disk formation phase, is of the or der of 2-3 109ys. Such a result is qualitatively in agreement with the models of Larson (1972), Ostricker and Thuan (1975), and also is implicit in the collapse models for the formation of disk galaxies, Larson (1976).
The Galaxy Magnetic Field
Authors: Ruzmaikin A.A.
Published: July 2016

The origin and dynamics of magnetic fields depend crucially on the dynamics of a gas in the Galaxy. In turn the magnetic field is needed to isotropize the cosmic rays (the influence on chemistry) and is of importance for the formation of stars (local dynamics). Thus the appearance of this topic at the Colloquium is justified.
On the Bulk Yields of Nucleosynthesis from Massive Stars
Authors: David Arnett W.
Published: July 2016

Preliminary estimates are made of the absolute yields of abundant nuclei synthesized in observed stars. The compositions of helium stars of mass 3 ≤ Mα / Mʘ≤ 64 are presented, taken at the instant of instability. These stars of mass Mα are identified with stars of main sequence mass M. The amount of synthesized matter for each mass M ≥ MʘHe is estimated (Table 1). Using a variety of choices for the initial mass function (IMF) the yield per stellar generation is calculated. For standard choices of the IMF the absolute and relative yields of12C,16O,20Ne,24Mg, the Si to Ca group and the iron group agree with solar system values, to the accuracy of the calculations.