bluuebunny/crossref_metadata_2025 huggingface dataset:
Coseismic Excitation of the Earth’s Polar Motion
Authors: Chao B.F. , Gross R.S.
Published: July 2016

Apart from the “shaking” near the epicenter that is the earthquake, a seismic event creates a permanent field of dislocation in the entire Earth. This redistribution of mass changes (slightly) the Earth’s inertia tensor; and the Earth’s rotation will change in accordance with the conservation of angular momentum. Similar to this seismic excitation of Earth rotation variations, the same mass redistribution causes (slight) changes in the Earth’s gravitational field expressible in terms of changes in the Stokes coefficients of its harmonic expansion. In this paper, we give a historical background of the subject and discuss the related physics. We then compute the geodynamic effects caused by earthquakes using Chao and Gross’ (1987) formulas based on Gilbert’s (1970) normal-mode summation scheme. The effects are computed using the centroid moment tensor (CMT) solutions for 15,814 major earthquakes from Jan., 1977, through Feb., 1999, as provided in the Harvard CMT catalog. The computational results update those of Chao and Gross (1987) and Chao et al. (1996), further strengthening their findings and conclusions: (i) the strong tendency for earthquakes to make the Earth rounder and more compact (however slightly) continues; (ii) so does the trend in the seismic “nudging” of the rotation pole toward the general direction of ~ 140°E, roughly opposite to that of the observed polar drift, but two orders of magnitude smaller in drift speed.
Secular Variation of Carloforte Latitude
Authors: Poma A. , Uras S.
Published: July 2016

The long series (1899.9–1979.0) of latitude observations made at Carloforte in the framework of the International Latitude Service is analyzed to determine a secular trend. The value of the linear rate obtained from the classical astrometric results agrees fairly well with the value derived from recent SLR and GPS observations carried out at the Cagliari Observatory.
On High Frequency Polar Motion and Length of Day Variations
Authors: Arfa-Kaboodvand K. , Groten E.
Published: July 2016

The 0.042-day Earth rotation data (diurnal and semidiurnal) computed by the International GPS Service were used to analyze the daily/sub-daily variations of polar motion (PM) and length of day (LOD). Systematic and advanced spectral analytical investigations of the degree of periodic variability have been carried out. They show that the prominent periodical components can be found at the tidal frequencies of zonal, tesseral and sectorial waves. These investigations should give better insight into the physical processes, which influence Earth orientation (i.e. due to the atmospheric and oceanic motions, tidal forces etc.). It should be the basis for the detailed modeling of excitation functions in the sub-diurnal range of the high-frequency spectrum.
Determination of the Long Period Nutation Terms from Optical Astrometry and VLBI Data
Authors: Yaya P. , Bizouard C. , Ron C.
Published: July 2016

A 100-year long optical astrometric series of the Earth Orientation Parameters produced by a Czech team (Vondrák et al., 1998) has been analysed in order to determine components of nutation. Our interest is mostly focused on the long periodic terms: 18.6-year term, 9.3-year term and linear trend, still correlated in VLBI series which cover only the last 20 years. A comparison has been made with the corresponding values determined from the VLBI series.
On Double Periodicity in the Light Variation of Variable Stars
Authors: Tsessevich V.P.
Published: July 2016

Double periodicity of light variations is shown in different ways in stars of different types. So the light curves of μ Cephei of RV Tauri-type giant stars are composed of more or less fast waves superposed on slow ones, such that between the duration of the short and long cycles there is a correlation.
Multiple Periodic RR Lyrae Stars Observational Review
Authors: Szeidl B.
Published: July 2016

In this review paper I concentrate exclusively on the multiple periodic RR Lyrae stars and I do not wish to discuss the general problems of cluster variables. There are some excellent review papers on them (e.g. Preston, 1964).

The majority of the RR Lyrae stars repeat their light curves from cycle to cycle with astonishing regularity. It was, however, discovered already in the early days of variable star research that some of them showed conspicuous changes in the height of maxima of their light curve and simultaneously the time of maxima could not be fitted in by a linear formula.
MAC Revisited: Mechanised Algebraic Operations on Fourth Generation Computers
Authors: Deprit A.
Published: July 2016

Via the facilities provided by PL/I, the operating system is extended to allow automatic manipulations of Poisson series in literal form.
New Results on the Commensurability Cases of the Problem Sun-Jupiter-Asteroid
Authors: Schubart Joachim
Published: July 2016

The short-period terms are removed by averaging from special equations of motion for commensurability cases of the three-dimensional, elliptic, restricted three-body problem. Some examples of retrograde motion corresponding to the -1/1 commensurability, and an application to Hilda-type motion demonstrate the possibilities given by the method.
Triple Collision as an Unstable Equilibrium
Authors: Waldvogel Jörg
Published: July 2016

The family of trajectories near a triple collision solution in the planar problem of three bodies is investigated by means of linearization in the neighborhood of the parabolic free fall. The local topological structure of this family is found to be that of a saddle point in the R8. The corresponding stable manifold is the set of all triple collision solutions, whereas the instable manifold is formed by the parabolic solutions.

In important cases of nonzero total energy the family of close encounters is quantitatively described in terms of hypergeometric functions. By means of homothetic transformations the close triple encounters are then related to three-body motion with zero energy and zero angular momentum. In this way almost all close encounters near a homothetic solution can be treated by using a small number of particular solutions of the three-body problem that may be calculated once for all.

In practical examples the first order theory presented here predicts the escape velocity after a close triple encounter with a relative accuracy comparable to the closeness of the encounter.
The Spatial, Temporal, and Photometric Properties of AGB Stars
Authors: Kleinmann S. G.
Published: July 2016

The Two Micron Sky Survey (Neugebauer & Leighton 1969;TMSS) provides a census of AGB stars which is relatively insensitive to interstellar or circumstellar reddening, temporal variations, or differences in photospheric temperature. This paper summarizes results from recent analyses of all carbon, S type, and mass-losing M stars in the TMSS, including local surface densities, scale heights, and mass loss rates. All three groups are concentrated toward the plane; the mass-losing M stars appear least concentrated toward the plane but most strongly concentrated toward the galactic center. Results from the IRAS survey were used to determine the range of infrared colors of stars in each class, and to estimate their mass loss rates. Carbon stars have relatively higher 60 μm flux densities than oxygen-rich stars, and have relatively higher mass loss rates. The total mass loss rate is dominated by a small fraction of the stars in this sample. IRAS photometry and IRAS Low Resolution Spectometer data do not unambiguously distinguish carbon-rich and oxygen-rich stars in this sample. Future searches for stars with the greatest mass loss rates might concentrate on sources found to be variable in the IRAS survey, since a large fraction of the TMSS stars with the most massive envelopes are known Miras or infrared variables.
Photometric observations of RCB stars In the LMC
Authors: Lawson W.A. , Cottrell P.L.
Published: July 2016

We present UBV photometric observations of two R Coronae Borealis (RCB) stars, W Mensae and HV12842, which are members of the Large Magallenic Cloud (LMC). These data have been obtained over the last two years using single-channel photometers on both the 0.6m and lm telescopes at Mount John. They form part of an ongoing long-term program to investigate photometric and spectroscopic variations in the hydrogen-deficient carbon (HdC) stars both in the LMC and in our Galaxy.
S-Process Dispersion in G and K Field Giants
Authors: McWilliam Andrew
Published: July 2016

A model atmosphere abundance analysis has been performed for a large number of G and K giants in a limited set of lines. The study was aimed at measuring the frequency of mild barium stars among GK giants in order to provide a test for the evolutionary status of the mild barium stars.
Heavy Element Abundances In FG Satittae
Authors: Kipper T. , Kipper M.
Published: July 2016

The spectrogram of FG Sge obtained by the 6-m telescope in 1986 is analyzed. The iron peak elements are underabundant relative to the sun, and the heavy elements (Z>39) have abundances up to 3 dex (1, 000 times) higher than in the Sun.
The Spectrum of TX Psc
Authors: Jorgensen Uffe G.
Published: July 2016

TX Psc is one of the very few carbon stars for which spectroscopic data from the blue toward the near infrared can be found in the literature. We present calculations of the first synthetic spectra that are in agreement with all the major spectral features in the observed spectrum, including the H∼ peak and the 3 μm band. The spectra are calculated on the basis of available observational estimates of the basic stellar parameters and model atmospheres that include absorption from HCN, C2H2 and C3 in the opacity calculation.
Spectroscopic and Polarimetric Observations of AC Her and UU Her
Authors: Nook M.A. , Cardelli J.A. , Nordsieck K.H.
Published: July 2016

We present preliminary results obtained between March and August of 1987 of a two-year spectropolarimetric study of 10 RV Tauri stars. The observations were made at the University of Wisconsin's Pine Bluff Observatory using the 36 inch cassegrain telescope with a Lyot polarimeter. The spectral resolution of the instrument was 6 A and covered the range between 4350 A and 7500 A. The polarimetry covered the same wavelength range but is binned in four broad bands at 4828 A, 5361 A, 6025 A, and 6877 A.
CO in OH/IR-Stars - on Excitation and Mass Loss
Authors: Heske A. , Habing H.J. , van der Veen W.E.C.J. , Omont A. , Forveille T.
Published: July 2016

Observations of CO in long period variables have been widely used to determine mass loss rates by applying models for CO line formation (e.g. Knapp and Morris, 1985) which use a simple method to take the impact from infrared radiation into account. Recent 00(2-1) and (1-0) observations of some more evolved OH/IR stars yielded much too low mass loss rates using these simple models, thus indicating that they cannot be extrapolated to far evolved AGB stars with optically thick circumstellar envelopes.
He I λ10830 in the S Star HR 1105
Authors: Brown Jeffery A. , Johnson Hollis R. , Hinkle Kenneth H.
Published: July 2016

Shcherbakov (1979) first reported that the S star HR 1105 shows a strong and variable He I X10830 line. We confirm this report and present spectra of HR 1105 around 10830 A taken over approximately 0.3 orbit, from a program to obtain full orbital coverage for this 600-day system. Using Griffin's (1984) orbital solution, we have phased in the data presented by Shcherbakov with our own and found that for two coincidences of phase, the 10830 profiles at different epochs but same orbital phases are identical within the limitations of the data. The earlier observations were taken eight orbits (13 years) before ours.
The 8-22μm Excess in Carbon Stars From IRAS LRS Spectra
Authors: Little S. J. , Little-Marenin I. R.
Published: July 2016

We have measured the excess IR emission from carbon mira and SR variable stars from IRAS LRS spectra. The 8-22μm excess is defined as the ratio of flux above a 2500K energy distribution fit to the LRS spectrum at about 8μm. The carbon star LRS spectra show both emission and absorption features, which are incorporated into our 8-22pm excess. The most prominent feature in carbon stars is the 11.2μm SiC dust emission feature extending from 10μm to 13.8 μm. We observe another emission feature of unknown origin which peaks between 8.4-8.7μm. The SiC emission feature is occasionally blended on the red side by an absorption feature (attributed to gaseous HCN + C2H2) which extends from about 12-16μm. Many of the spectra appear to turn down at the 8μm end due (?) to an HCN + C2H2 absorption feature located at 7.1μm. Carbon stars do not generally show as large an excess as the M mira variables do. The figure below shows our measured excesses for both carbon miras and carbon semi-regular variables. There appears to be little correlation of excess with period, however the mira variables show about twice the range of variation of excess that the semi-regular variables do. We find little correlation between our measured 8-22μm excess and the excesses of Jura (Ap. J., 303, 327, 1986) based on the ratio of 12μm flux to 2μm flux. Our data do support hi s conclusion that longer period variable stars show larger average excesses, but this is only true for mira variables in our analysis.
Improving the Reference Frame by Radio–and Optical Astrometry of Radio Stars
Authors: de Vegt Chr. , Zacharias N. , Johnston K.J. , Hindsley R.
Published: July 2016

A longterm program of precise radio – and optical astrometry of selected radio stars has been conducted in the last decade by our observatories using the VLA and astrographs on both hemispheres. Positions of 54 stars north of −26 deg. declination including 6 MASER stars have been obtained. The program status and some results from the southern hemisphere are reported.
Lateral Image PZT. Description and Operating Method
Authors: Garcia A.Lopez , Machi R.Lopez , Navarro J.L.Valdes , Orti J.A.Lopez
Published: July 2016

We faced the problem of designing and building a Photographic Zenith Tube with mercury basin and lateral plate-holder system providing enough accuracy to allow the determination of astronomical coordinates. This instrumentis intended to work as a prototype of a bigger and more accurate one to be designed and developed in the future (Lopez, A. et al.: 1983).
Note on the Definition of the International Atomic Time Tai
Authors: Li Z.X.
Published: July 2016

Relations among the three concepts (TAI, coordinate time, and proper time)are discussed and comments of the definition of the TAI are given.
A Source of Systematic Error, Δδα, in Absolute Catalogs Compiled from Meridian Circle Observations
Authors: Miyamoto M. , Suzuki S.
Published: July 2016

Automated photoelectric meridian circles are able nowadays to have the full set of graduation errors of the decimation circle determined within a few days. Thus, the modern meridian circles can be monitored, and the annual and secular changes of the graduations can be easily detected to provide the graduation corrections at any date. In order to remove systematic declination errors in the form Δδα from absolute catalogs, these continuous changes should be taken into account.
Evidence of Systematic Errors in FK5
Authors: Morrison L.V. , Argyle R.W. , Requième Y. , Helmer L. , Fabricius C. , Einicke O.H. , Buontempo M.E. , Muinñs J.L. , Rapaport M.
Published: July 2016

The primary purpose of the FK5 is to provide an absolute optical reference frame against which to measure the positions and motions of other objects. One of the main tasks of meridian circles is to check and improve that reference frame by repeated observation of the fundamental stars. The meridian circle at Bordeaux, France and the Carlsberg Automatic Meridian Circle (CAMC) at La Palma are carrying out programmes of observation of FK5 stars partly with this aim in view.

The positions from which the systematic differences are derived are the means of at least 10, but normally about 30 (Bordeaux) and 50 (CAMC), independent observations of each FK5 star made in the period 1984–87. The systematic differences are displayed in pairs of 3-dimensional plots, Bordeau–FK5 and CAMC–FK5. The similarities of the corresponding pairs of plots is striking, particularly in declination. This implies that systematic errors exist in the FK5 which reach about in places at the epoch 1986.0.
A Note on the Astrometric Precision of Minor Planet Observations
Authors: Pascu D.
Published: July 2016

For years, interest in precise positions of minor planets has centered on tying the dynamical reference frame with the stellar frame and determining catalog zone errors. Photographic methods are generally used in obtaining observed spherical equatorial coordinates (R.A., Dec.) or crossing-point observations. Estimates of the external precision of the equatorial coordinates are overly pessimistic, while those for crossing-point observations, too optimistic.

It is estimated that equatorial positions for the brighter (m < 11) minor planets can be determined with an external precision not worse than +/−0.2 arcsec (m.e.), and perhaps as low as +/−0.1 arcsec (m.e.), depending on the reference catalog zonal errors.

Intersatellite observations are a type of crossing-point observation in which the images of two different objects appear in the same exposure. This is the most precise type of crossing-point observation and gives an estimate for the lower limit to the external precision of this observation type. Recent studies of satellite observations indicate that this lower limit is in the +/−0.05 to +/−0.08 arcsec (m.e.) range.
Optical Positions of Radiostars by the Danjon Astrolabe at Cagliari and Further Projects
Authors: Poma A. , Zanzu T.
Published: July 2016

Precise positions of optical counterparts of radiosources are needed in connecting optical and radio reference frames. The Cagliari Astronomical Observatory has planned systematic observations with the Danjon astrolabe of objects from the high priority Hipparcos radio-stars list. A preliminary result of the position of radiosource HR 5110 is presented.
Intermediate Star Reference Systems in the Vicinity of Radio Sources
Authors: Tel’nyuk-Adamchuk V.V. , Kumkova I.I. , Sadzakov S. , Toma E. , Volianska M.Yu.
Published: July 2016

In the framework of CONFOR program the formation of star lists of two intermediate reference star systems is being carried out. The first list, RRS2, contains meridian stars in the fields centered at extragalactic radio/optical sources. The second one is formed on the base of 12-14 magnitude stars. The observations are in progress now. The main purpose of this program is to form a base for investigation of mutual orientation of fundamental reference system and new ones.
Long-Term Nutation and the Length Day Variation from VLBI Observations
Authors: Yagudina E.I. , Sudnik I.S.
Published: July 2016

The shift of the celestial pole with respect to its 1980 position in longitude (Δψ) and obliquity (Δε) from the available VLBI measurement of 1984 year within IRIS project is estimated. Formal uncertainties of the angles Δψ and Δε are 5.9 mas and 2.7 mas respectively. The day length variation was obtained from the same data. Then attempt was made to obtain annual and semiannual nutation amplitudes. The values are in reasonable agreement with the determinations of other workers.
Improvement of the Optical Reference System by Photographic Astrometry: First Results of Simulations with Global Block Adjustment Methods
Authors: Zacharias N.
Published: July 2016

Block adjustment (BA) simulations of an entire hemisphere show major improvements in individual as well as systematic accuracy of star positions obtained by photographic astrometry, independent of systematic errors of the reference star catalog used. Results for the accuracy estimates obtained from a patch-like plate pattern in the sky are not valid for closed plate pattern. The importance of BA methods for the realisation of a reference system is stressed.
Active Region Magnetic Fields
Authors: Howard Robert F.
Published: July 2016

The tilt angles of sunspot groups are defined, using the Mount Wilson data set. It is shown that groups with tilt angles greater than or less than the average value (≈5 deg) show different latitude dependences. This effect is also seen in synoptic magnetic field data defining plages. The fraction of the total sunspot group area that is found in the leading spots is discussed as a parameter that can be useful in studying the dynamics of sunspot groups. This parameter is larger for low tilt angles, and small for extreme tilt angles in either direction. The daily variations of sunspot group tilt angles are discussed. The result that sunspot tilt angles tend to rotate toward the average value is reviewed. It is suggested that at some depth, perhaps 50 Mm, there is a flow relative to the surface that results from a rotation rate faster than the surface rate by about 60 m/sec and a meridional drift that is slower than the surface rate by about 5 m/sec. This results in a slanted relative flow at that depth that is in the direction of the average tilt angle and may be responsible for the tendency for sunspot groups (and plages) to rotate their magnetic axes in the direction of the average tilt angle.
Sunspot Groups as Tracers of Sub-Surface Processes
Authors: Gokhale M. H.
Published: July 2016

Data on sunspot groups have been quite useful for obtaining clues to several processes on global and local scales within the sun which lead to emergence of toroidal magnetic flux above the sun’s surface. I present here a report on such studies carried out at Indian Institute of Astrophysics during the last decade or so.
Cyclical Variability of Prominences, CMEs and Flares
Authors: Ballester J. L.
Published: July 2016

Solar flares, prominences and CMEs are well known manifestations of solar activity. For many years, qualitative studies were made about the cyclical behaviour of such phenomena. Nowadays, more quantitative studies have been undertaken with the aim to understand the solar cycle dependence of such phenomena as well as peculiar behaviour, such as asymmetries and periodicities, occurring within the solar cycle. Here, we plan to review the more recent research concerning all these topics.
Temporal Variation of Large Scale Flows in the Solar Interior
Authors: Basu Sarbani , Antia H. M.
Published: July 2016

We attempt to detect short-term temporal variations in the rotation rate and other large scale velocity fields in the outer part of the solar convection zone using the ring diagram technique applied to Michelson Doppler Imager (MDI) data. The measured velocity field shows variations by about 10m/s on the scale of few days.
Observation of Hysteresis between Solar Activity Indicators and p-mode Frequency Shifts for Solar Cycle 22
Authors: Tripathy S. C. , Kumar Brajesh , Jain Kiran , Bhatnagar A.
Published: July 2016

Using intermediate degreep-mode frequency data sets for solar cycle 22, we find that the frequency shifts and magnetic activity indicators show a “hysteresis” phenomenon. It is observed that the magnetic indices follow different paths for the ascending and descending phases of the solar cycle while for radiative indices, the separation between the paths are well within the error limits.
The Role of Magnetic Buoyancy in a Babcock-Leighton Type Solar Dynamo
Authors: Nandy Dibyendu , Choudhuri Arnab Rai
Published: July 2016

We study the effects of incorporating magnetic buoyancy in a model of the solar dynamo—which draws inspiration from the Babcock-Leighton idea of surface processes generating the poloidal field. We present our main results here.
Lyα and β of H I, h and k of Mg II, H and K of Ca II Profiles of a Quiescent Prominence Obtained with the LPSP Instrument of OSO 8
Authors: Vial J.C. , Lemaire P. , Gouttebroze P.
Published: July 2016

Simultaneous spectra have been recorded in the six lines, with a 1″ × 40″ entrance slit and a spectral resolution of 60 mÅ in Lyβ, 30 mÅ in Lyα, 85 mÅ in Mg II and 60 mÅ in Ca II.

Lyβ and Lyα lines are reversed: peak to peak distances are 0.31 Å and 0.34 Å, peak-to-center intensity ratios are 2 and 1.4 for Lyβ and Lyα, respectively.

Inferred opacities at line centers are of the order of 105. Prominence intensities are 0.4 times disk intensities in both lines (Lyα is in the range of computed models by Heasley and Milkey, 1978).
The Prominence-Corona Interface; A Review
Authors: Schmahl E.J.
Published: July 2016

The relation between cool prominences and their hot coronal environment was a subject which entailed more speculation than observation before the advent of orbital or rocket-based telescopes, because of the difficulty of making appropriate observations. After the first few UV and EUV observations of prominences, Orrall coined the phrase “prominence-corona interface” to refer to the very thin transition layer between the 6 to 10 thousand degree threads of prominences and the ambient million degree corona. The title of this talk refers to the interface, but it seems important to take a broader perspective of the entire coronal environment of prominences, first, because the “interface” is not physically independent of the larger scale structures, and, second, because the observations of the interface require an understanding of the larger scales for their interpretation.
High Resolution Ca II K Spectra of the September 8, 1977 Loop System
Authors: Albregtsen F. , Engvold O.
Published: July 2016

The spectral observations were recorded with the main spectrograph of the tower telescope of Oslo Solar Observatory. Twentyfive exposures of the Ca II K line were made between 0953 UT and 1031 UT. The exposure time was 15 s and the spectral dispersion 12.1 mm/Å. The spectrographic slit positions were recorded by an Hα slit jaw camera.
Coronal Manifestations of Eruptive Prominences, Observation and Interpretation
Authors: Rust David M.
Published: July 2016

To appreciate the curious nature of the coronal manifestations of eruptive prominences, we must first recall how the corona around a quiescent prominence appears. The cool prominence material threads arcades of coronal loops, but is invisible in coronal lines. If one defines the corona as a million-degree gas above the chromosphere, then one must admit that there is no detectable corona where there is a filament. Simultaneous limb photographs in Ha and in coronal lines show that filaments outside of active regions reside in dark cavities in the corona. Active region filament cavities would be difficult to see because of the compact loop systems that characterize the corona there, but extrapolating from our experience with non-active region filaments, we can say, at least, that the loop arcade pattern inside active regions is the same as outside and that there is no evidence for any high-temperature, filament-shaped features in active regions.
On the Measure-Preserving Mappings with Three-Dimensions
Authors: Sun Yi-Sui
Published: July 2016

We have systematically made the numerical exploration about the perturbation extension of area-preserving mappings to three-dimensional ones, in which the fixed points of area preserving are elliptic, parabolic or hyperbolic respectively. It has been observed that: (i) the invariant manifolds in the vicinity of the fixed point generally don’t exist (ii) when the invariant curve of original two-dimensional mapping exists the invariant tubes do also in the neighbourhood of the invariant curve (iii) for the perturbation extension of area-preserving mapping the invariant manifolds can only be generated in the subset of the invariant manifolds of original two-dimensional mapping, (iv) for the perturbation extension of area preserving mappings with hyperbolic or parabolic fixed point the ordered region near and far from the invariant curve will be destroyed by perturbation more easily than the other one, This is a result different from the case with the elliptic fixed point. In the latter the ordered region near invariant curve is solid. Some of the results have been demonstrated exactly.

Finally we have discussed the Kolmogorov Entropy of the mappings and studied some applications.
Roche Instability in Binary Stellar Systems
Authors: Namboodiri P.M.S. , Kochhar R.K.
Published: July 2016

The stability of a galaxy against disruption when it encounters a point mass perturber has been investigated by numerical simulations. The merging process dominates in the case of encounters of binaries of comparable mass and disruption is important in cases where the components have different masses. The disruption of a galaxy occurs when its mean density is less than a critical density - the Roche density. The change in the energy falls steeply near the Roche density in the case of encounters in which the relative orbit of the perturber is circular.
Dynamical Mechanisms for Transferring Comets In and Out of the Oort Cloud
Authors: Valtonen M.J. , Zheng J.Q.
Published: July 2016

We study scenarios where comets are not original members of the Solar System but have been acquired from the surrounding medium through dynamical evolution. This leads to estimates of the present day number density of comets in the interstellar medium which are not in contradiction with observational upper limits. We also consider the dynamical transfer of Oort Cloud comets into short period comets. The process is very sensitive to the inclination of the comet orbit which leads to strong bias in favour of low inclinations in short comet orbits.
Quasi-Lntegrals of the Plane Restricted Three-Body Problem
Authors: Nezhinskij E.M.
Published: July 2016

The paper is concerned with studying the domain of possible motion and a field of the test body velocities in the plane restricted problem of three bodies. The study is based on existence of a quasi-integral of areas (similar to an integral of areas in the problem of two bodies) as well as on the Jacobi integral. The method of constructing the quasi-integrals is a standard one (see, for example, [1],[2].
Application of Szebehely’s Inverse Problem to Non-Stationary Dynamical Systems
Authors: Omarova G.T. , Kozhanov T.S.
Published: July 2016

A first-order linear partial differential equation is presented, giving the non-stationary potential functions U=U (x,y,t) which give rise to a given family of evoling planar orbits f(x,y,t) = c in two-dimensional dynamical system. It is shown, that this equation is applied in celestial mechanics of variable mass.
Planar Oscillation of the Satellite Near Parametric Resonance in the Elliptic Orbit
Authors: Singh Ram Binoy
Published: July 2016

This paper is devoted to the study of motion of an artificial satellite relative to its centre of mass near parametric resonance in elliptic orbit. It is well known fact that the satellite, of the form of an ellipsoid with three unequal axes, while moving about the central planet, oscillates about the stable position of equilibrium (the longest axis of the satellite coinciding with the radius vector of its centre of mass). The oscillation of the satellite about this position of equilibrium in the orbital plane of its centre of mass is described by a well known second order nonlinear differential equation with a periodic sine force. Naturally there will be resonance cases (main as well as parametric) for such a systems. In the previous author’s work, it was discovered a series of parametric resonances for the system, which corresponds to n = ½k where k is a non-zero integer and n is a parameter depending on the shape of the satellite. The parametric resonance, for k = 1, has been considered here. The first approximate solution of the equation of motion has been obtained by Eogoliubov-Krilov method with e (the eccentricity of the orbit of the centre of mass of the satellite) as the small parameter. This method enables us to visualise the oscillation of the satellite for the resonance case as well as near the resonance. Three stationary values of the amplitudes and phase of oscillation have been obtained, out of which only one is stable near this particular parametric resonance. At the resonance there appear only one stationary regime of oscillation with a very small amplitude.
Study of Cosmic Dust Particles on Board LDEF and MIR Space Station
Authors: Mandeville J.C.
Published: July 2016

Interplanetary and near-earth space contains solid objects whose size distribution continuously covers the interval from submicron sized particles to km sized asteroids or comets. Two French experiments partly devoted to the detection of cosmic dust have been flown recently in space. One on the NASA Long Duration Exposure Facility (LDEF), and one on the Soviet MIR Space Station. A variety of sensors and collecting devices will make possible the study of cosmic particles after recovery of exposed material. Flux mass distribution is expected to be derived from craters counts, with a good accuracy. Remnants of particles, suitable for chemical identification are expected to be found within stacked foil detectors. Discrimination between extraterrestrial particles and man-made orbital debris will be possible.
The Munich Dust Counter — A Cosmic Dust Experiment on Board of the Muses-A Mission of Japan
Authors: Igenbergs E. , Hüdepohl A. , Uesugi K. , Hayashi T. , Svedhem H. , Iglseder H. , Koller G. , Glasmachers A. , Grün E. , Schwehm G. , Mizutani H. , Yamamoto T. , Fujimura A. , Ishii N. , Araki H. , Yamakoshi K. , Nogami K.
Published: July 2016

The Munich Dust Counter (MDC) is a scientific experiment on board of the MUSES-A mission of Japan. It is the result of a cooperation between the Institute of Space and Astronautical Science (ISAS) of Japan and the Chair of Astronautics of the Technische Universität München (TUM) of Germany. The MDC is an impact ionization detector designed to determine mass and velocity of cosmic dust. Here a short overview over the MUSES-A mission is given to show the measurement situation of the MDC experiment. The measurement principle of the instrument together with a discussion of the scientific objectives and the design of the experiment is summarized.
Physical and Mineralogical Properties of Anhydrous Interplanetary Dust Particles in the Analytical Electron Microscope
Authors: Bradley J. P.
Published: July 2016

The fine grained mineralogy and petrography of anhydrous “pyroxene” and “olivine” classes of chondritic interplanetary dust have been investigated by numerous electron microscopic studies. The “pyroxene” interplanetary dust particles (IDPs) are porous, unequilibrated assemblages of mineral grains, metal, glass, and carbonaceous material. They contain enstatite whiskers, FeNi carbides, and high-Mn olivines and pyroxenes, all of which are likely to be well preserved products of nebular gas reactions. Solar flare tracks are prominent in most “pyroxene” IDPs, indicating that they were not strongly heated during atmospheric entry. The “olivine” IDPs are coarse grained, equilibrated mineral assemblages that have probably experienced strong heating. Since most “olivine” IDPs do not contain tracks, it is possible that this heating occurred during atmospheric entry.
The Zodiacal Cloud Complex
Authors: Levasseur-Regourd A.C. , Renard J.B. , Dumont R.
Published: July 2016

The physical properties of the interplanetary dust grains are, out of the ecliptic plane, mainly derived from observations of zodiacal light in the visual or infrared domains. The bulk optical properties (polarization, albedo) of the grains are demonstrated to depend upon their distance to the Sun (at least in a 0.1 AU to 1.7 AU range in the symmetry plane) and upon the inclination of their orbits (at least up to 22°). Classical models assuming the homogeneity of the zodiacal cloud are no longer acceptable. A hybrid model, with a mixture of two populations, is proposed. It suggests that various sources (periodic comets, asteroids, non periodic comets...) play an important role in the replenishment of the zodiacal cloud complex.
On The Gegenschein and the Symmetry Plane
Authors: Hong S. S. , Kwon S. M.
Published: July 2016

Using 3-dim density models of the zodiacal cloud, we have calculated brightness of the zodiacal light over an extended region around the anti-solar point. The isophotal contours of the model Gegenscheins differ from each other, morphologically, to the degree that they can differentiate the competing density models. The recently reduced Gegenschein observations of 2° resolution clearly favour the ellipsoid-type models to the fan-types, and also suggest that the surface of the densest dust concentration in the outer part of the cloud has its ascending node at longitude 100 ± 20° and is inclined 2 ± 0°.5 with respect to the ecliptic plane.
Synthetic Maps of the Brightness and Polarization of the F-Corona
Authors: Fang Y. , Lamy P.L. , Llebaria A.
Published: July 2016

The Wide-Field Light and Spectrometric Coronograph (LASCO) to be flown on SOHO in 1995 is designed to perform accurate photopolarimetric observations of the solar corona. For simulation purpose but also to have a two-dimensional model of the F-corona, we have realized synthetic maps of its brightness and polarization
Dust in Planetary Ring Systems
Authors: Showalter Mark R.
Published: July 2016

Each of the outer gas giants Jupiter, Saturn, Uranus and Neptune is now known to be encircled by a system of rings. Some of these, such as the A, B, and C rings of Saturn and the nine narrow Uranian rings, are rather optically thick and are composed primarily of large bodies (1 cm to 10 m). However, every other system has been found to contain a large population of micron-sized dust. Such rings reveal the effects of a variety of physical processes that are also acting on interplanetary and interstellar grains. When such rings are examined as members of a general class, recurring patterns begin to emerge.
Convection in the Sun
Authors: Massaguer Josep M.
Published: July 2016

The present knowledge of the dynamics and structure of the solar convection zone is reviewed with the aim of checking current assumptions and conjectures against laboratory experiments and numerical modeling of thermal convection. Buoyancy is the only forcing considered. Rotation and magnetic fields are explicitly avoided. Nor are departures from planar geometry considered, except as regards large scale structures. Local theories are reviewed in section §2, hydrodynamic models in §3, non-local theories in §4, the global structure of the convection zone is discussed in §5 and the flow patterns in §6.
Solar and Stellar Cycles
Authors: Belvedere Gaetano
Published: July 2016

The increasing observational evidence offered by photometric and spectroscopic data of magnetic cycles in lower main sequence stars, has confirmed the general expectation that the same basic dynamo mechanism operates in the Sun and main sequence in stars with outer convective envelopes.

Unfortunately, no clear correlation has been found, up to date, with stellar parameters as mass, rotation rate and age, even if irregular activity and shorter cycle periods seem to be characteristic of stars more massive than the Sun, while hyperactive fast rotating components of binary systems like RS CVn’s and BY Dra’s show a tendency for cycles as long as several decades.

Although dynamo theory has probably captured die essential physics of the convection-rotation interaction giving rise to stellar magnetic activity, as evidenced, for instance, by the correlation between proxy activity, indicators and the Rossby parameter related to the dynamo number, the reliability of the present theoretical background should be measured by its capacity of interpreting and predicting characteristics and periodicities (or aperiodicities) of stellar cycles. This should be done in the framework of the nonlinear approach, which, in principle can describe multimodal dynamo behaviour with a variety of time scales.

The fundamentals of the theory must be tested, however, in the closest astrophysical laboratory, our Sun. Serious problems to a dynamo mechanism operating in the convection zone have been posed by most recent helioseismological results, which, on the other hand, do not rule out the possibility of dynamo action in the transition layer between the convective and die radiative zones, which is suggested independently by the global solar cycle features. Indeed, assuming the correct sign of helicity in the transition layer, the helioseismological data on the radial gradient of angular velocity support both equatorward propagation of dynamo waves at lower latitudes and poleward propagation at higher latitudes, which is evidenced by different tracers of the solar cycle.
The Solar Dynamo
Authors: Rädler K.-H.
Published: July 2016

The phenomena of solar activity are connected with a general magnetic field of-the Sun which is due to a dynamo process essentially determined by the α-effect and the differential rotation in the convection zone. A few observational facts are summarized which are important for modelling this process. The basic ideas of the solar dynamo theory, with emphasis on the mean-field approach, are explained, and a critical review of the dynamo models investigated so far is given. Although several models reflect a number of essential features of the solar magnetic cycle there are many open questions. Part of them result from lack of knowledge of the structure of the convective motions and the differential rotation. Other questions concern, for example, details of the connection of the α-effect and related effects with the convective motions, or the way in which the behaviour of the dynamo is influenced by the back-reaction of the magnetic field on the motions.
The Evolution of the Sun’s Angular Momentum
Authors: Soderblom David R. , Stauffer John R.
Published: July 2016

We discuss the observational data that are available to illustrate the rotational history of the Sun, and those data that are particularly pertinent to the interiors of the Sun and stars.
The Galactic Nova Rate
Authors: Della Valle M. , Claudi R.
Published: July 2016

The recently estabilished values of M31 and M33 nova rate, rM31 = 29 ± 4 novae yr−1 (Capaccioli et al.,1989), rM33 = 4 ± 2 novae yr−1 (Della Valle, 1988), seems to be at variance with the present estimates for the galactic nova rate, r = 260 novae yr−1 (Sharov,1972) and r = 73 ± 24 novae yr−1 (Liller and Meyer,1987), if we take into account the luminosity class and the Hubble type of the Galaxy. Assuming the nova production per unit of B–luminosity about constant for spiral galaxies and adopting the derived values of the nova rate of M31, M33 and LMC as calibrators, we estimate a galactic nova rate of rGal = 15 ± 5 novae yr−1.
Optical Imagery of Nova Remnants
Authors: Wade Richard A.
Published: July 2016

Resolved nebular remnants of classical novae are discussed in terms of size, surface brightness, and shape. A list of 26 known resolved remnants is given. The conditions necessary for visibility of a resolved remnant are discussed. The structure of remnants can be studied at optical wavelengths by direct imaging and by long-slit or otherwise spatially resolved spectroscopy of emission lines. Based on recent spatiokinematic studies, most nebular remnants are prolate in outline, with sub-structure that has been characterized as consisting of “polar blobs” and “equatorial rings”. The mechanism that shapes the remnants is not yet known with certainty. There is room for much additional work in discovering new remnants and in characterizing those that are known.
Infra-Red Emission from Classical Novae
Authors: MacDonald Jim
Published: July 2016

During the evolution of a classical nova outburst, there are four times at which a significant infra-red (IR) flux is expected. The first Isothermal Dust Phase has been observed in a number of novae and analyses of this phase give valuable information on the properties of the emitting dust. In order of time from visual maximum, the three later phases are due to IR emission from X-ray heated grains, fine-structure line emission from a cold phase of the nova nebula, and grain cooling from shocked gas at the interface between the nova ejecta and the interstellar medium. In the next sections, theoretical estimates of the peak IR luminosity, flux distribution and time of peak emission for each of these phases are discussed.
Chemical Routes to Dust Formation in the Ejecta of Novae
Authors: Rawlings J.M.C. , Williams D. A.
Published: July 2016

The chemistry of the formation of nucleation sites in the ejecta of novae has been investigated. Previous authors (e.g. Clayton and Wickramasinghe 1976) have noted that grain growth is rapid once nucleation sites have formed but the assumption is generally made that the ejecta is in LTE during the nucleation phase. This is obviously not the case as the ejecta is illuminated by an intense radiation field so that the lifetimes of the larger species are of the order of one second, even the ejecta kinetic temperature is only 1000-2000 K. We propose that nucleation sites form by heterogeneous chemical reactions in a highly non-equilibrium chemistry.
Thermonuclear Runaway Model
Authors: Sparks Warren M. , Kutter G. Siegfried , Starrfield Sumner , Truran James W.
Published: July 2016

The nova outburst requires an energy source that is energetic enough to eject material and is able to recur. The Thermonuclear Runaway (TNR) model, coupled with the binary nature of nova systems, satisfies these conditions. The white dwarf/red dwarf binary nature of novae was first recognized as a necessary condition by Kraft (1963,1964, and these conference proceedings). The small separation characteristic of novae systems allows the cool, red secondary to overflow its Roche lobe. In the absence of strong, funneling magnetic fields, the angular momentum of this material prevents it from falling directly onto the primary, and it first forms a disk around the white dwarf. This material is eventually accreted from the disk onto the white dwarf. As the thickness of this hydrogen-rich layer increases, the degenerate matter at the base reaches a temperature that is high enough to initiate thermonuclear fusion of hydrogen. Thermonuclear energy release increases the temperature which in turn increases the energy generation rate. Because the material is degenerate, the pressure does not increase with temperature, which normally allows a star to adjust itself to a steady nuclear burning rate. Thus the temperature and nuclear energy generation increase and a TNR results. When the temperature reaches the Fermi temperature, degeneracy is lifted and the rapid pressure increase causes material expansion. The hydrogen-rich material either is ejected or consumed by nuclear burning, and the white dwarf returns to its pre-outburst state. The external source of hydrogen fuel from the secondary allows the whole process to repeat.