bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Unusual Meteor Spectrum
Authors: Cook A. F. , Hemenway C. L. , Millman P. M. , Swider A. 
Published: July 2016

An extraordinary spectrum of a meteor at a velocity of about 18.5±1.0 km s-1 (approximate uncertainty) was observed from the Springhill Meteor Observatory with an image-orthicon camera at 1970 August 10 d2h 48m 518 UT. The radiant of the meteor was at an altitude of about 49°. It was first seen shoioing a yellow-red continuous spectrum alone at a height of 137±8 km (estimated uncertainty) which we ascribe to the first positive group of nitrogen bands. At 1.608 after its initial appearance the meteor had descended to 116±6 km above sea-level when it brightened rapidly from its previous threshold brighness into a uniform continuum. After a further 0.738 at a height of 106±6 km the D-line of neutral sodium appeared and 0.148 later (height 105±5 km) all the other lines of the spectrum also appeared. The continuum remained dominant to the end 0.408 later (height 87±5 km) or 3.878 after initial appearance.Water of hydration and entrained carbon flakes of characteristic dimension about 0.2 micron or less are proposed as constituents of the meteoroid to explain these phenomena.
Origin and Evolution of Recent Leonid Meteor Showers
Authors: McIntosh Bruce A. 
Published: July 2016

The four most prominent returns of the Leonid shoiver in the past decade fall into two broad classes. The 1966 and 1969 showers were of short duration, had a high proportion of small particles, and occurred with the longest apparent delay after the perihelion passage of the parent comet Temple-Tuttle. By contrast, the 1961 and 1965 returns were of long duration, and had more large particles. The 1961 return preceded the comet.There are three major influences on particle orbits: ejection velocity, radiation pressure, and close encounters with planets. The observations are explainable in a qualitative way on the basis of the first two. But some speculation concerning the results of planetary perturbations must be invoked.
Cosmic Dust in the Atmosphere and in the Interplanetary Space at 1 AU Today and in the Early Solar System
Authors: Fechtig H. 
Published: July 2016

Reliable measurements of cosmic dust abundances have been obtained by ionization detectors during particle impact and by collectors controlled either by inflight shadowing or by penetration-hole identification. A description of the techniques used is given.Crater-number densities observed on the lunar surface and on lunar samples represent an important source of information on cosmic dust fluxes. The related results from the Apollo 11 and 12 missions are reviewed. The overall knowledge gained from these measurements leads to the following flux model: The cumulative flux Φ vs mass m follows the extrapolation from larger meteoroid-size range (Watson’s Law) and can be described byThe Pioneer 8 dust experiment and lunar samples indicate a depletion of the flux at approximately 10-8g. However, cosmic dust particles exist in interplanetary space at least down to 0.3 μ. diameter. They are interpreted as nonmetallic particles in the solar system.The atmosphere shows an enhancement in particles of about one order of magnitude compared to the flux in interplanetary space at 1 AU. No depletion or cutoff could be detected. These particles are interpreted as lunar debris or as disintegrated products from fireballs.The numbers of large lunar craters (>140 m diameter) in Mare Tranquillitatis and in Oceanus Procellarum are compared with the meteoroid flux. These comparisons lead to a time-variable flux of Φ.e-Bt, with B = 2.6 and t = time in 109 yr. Thus, the meteoroidflux at the formation of the lunar maria was approximately 4 orders of magnitude higher than today.
Inner-Truncated Disks – Are They Tied to Bars?
Authors: Baggett W. E. , Baggett S. M. , Anderson K. S. J. 
Published: July 2016

An inner-truncated disk (ITD) brightness profile is one in which the inward extrapolation of the outer disk surface brightness significantly exceeds the observed surface brightness in a region near the galaxy center. Freeman (1970) identified these profiles as Type II profiles. Fourteen of Freeman’s (1970) sample of 36 external galaxies are designated as Type II (ITD); seven of the ITD’s are classified as barred galaxies and ITD’s are found at all morphological types.Ohta, Hamabe, & Wakamatsu (1990) report that luminosity profiles perpendicular to the bars of six early-type galaxies all exhibit the Freeman Type II shape, while the feature is lost when azimuthally averaged profiles of the same galaxies are studied. They postulate that the bar formation resulted in an azimuthal redistribution of the stars, but no net radial redistribution.
Photometrical Mapping in Barred Galaxies: Analysis of the Different Components
Authors: Bettoni D. , Fasano G. , Galletta G. 
Published: July 2016

AbstractWe analyzed a sample of SBO galaxies in order to disentangle the structure of the bar and of the other components inside the galaxies. The disk and the bulge components, modeled by using the luminosity and geometrical profiles, have been subtracted from each galaxy image in order to obtain the image of the bar. This allowed us to analyze in detail the bar structure, in particular its shape and its luminosity profile. Both uniform and saddle-shaped bars have been detected.
CCD Photometry of the Weakly Barred Triple-Ringed Galaxy IC 4214
Authors: Saraiva M. F. 
Published: July 2016

AbstractWe present a brief report on the B, V, R, I, and Hα CCD surface photometry of the southern SABab galaxy IC 4214. We obtained isophote maps, luminosity profiles, and basic geometric and photometric parameters in BV RI, and mapped the distribution of the gas through continuum subtracted Hα emission line images.
The HI in the Large Barred Spiral NGC 1365
Authors: Jörsäter S. , van Moorsel G. A. 
Published: July 2016

AbstractWe have made high resolution HI observations using the VLA1 of the barred spiral galaxy NGC 1365. This galaxy contains 15.2 × 109M⊙ of HI. The velocity field is strongly affected by the bar only in the inner parts. NGC 1365 has a warp and it has 4 well developed spiral arms and 2 rudimentary ones. NGC 1365 has an unusually dropping rotation curve.
Gas Kinematics of the Disk and Bar of the Galaxy Mrk 533
Authors: Afanasiev V. L. , Kostiuk I. P. 
Published: July 2016

The Seyfert 2 galaxy Mrk 533 has the morphological description of SA(r)bc pec in RC3 and SBb in UGC. It is a member of the compact group of galaxies H96. Radio observations (Unger et al. 1988) show three radio sources.3-D observations with a Fabry-Perot scanning interferometer (the number of spectral channels is 32 by 0.44 Å, angular size of 1 px is , the accuracy of radial velocity determination is 10 km s−1) and multi-pupil integral spectrograph observations (the dispersion is 1.16 Å px−1, lens array is 10×16, angular size of each lens is × ) were obtained in the red spectral range at the 6-m telescope. The estimated seeing was about 2″. In the central region of the galaxy (r ≥ 5″, interferometer observations) the Hα line profile was fitted by two Gaussians. The first component, Kl, corresponds to the galaxy disk. The second component, K2, is visible only in the central part and is brighter than K1 in the same pixels. Profiles of Hα and [NII] Λ6584/48 (integral spectroscopy observations) were fitted by two Gaussians. They are a broad component in Hα and [NII] with FWHM ~ 1000 km s−1 and a narrow component of three times less FWHM. The lower spectral resolution of this observation made it impossible to separate the narrow component into the two ones visible in the Fabry-Perot observations.
Barred Galaxies: Intrinsic or Extrinsic?
Authors: Noguchi M. 
Published: July 2016

AbstractA unified picture is presented for the formation of bars in galaxies of different morphological types based on a simple model of the growth of galactic disks by gas infall from haloes. The infall timescale is found to be a key parameter which determines the dynamical property of the resulting disk. It is suggested that the bars in early-type disk galaxies have been formed in tidal interactions with other galaxies whereas those in late-type galaxies formed spontaneously due to gravitational instability (bar instability) in their disks.
Dynamical Friction in Disk Galaxies: The Radial Dependence
Authors: Wahde Mattias , Donner Karl Johan 
Published: July 2016

AbstractA simple formula is derived for the force of dynamical friction acting on a satellite galaxy which is moving on a nearly circular orbit around its parent galaxy. Using this formula, estimates of the decay time are computed. The results are then compared with the corresponding results from numerical simulations, and are found to be in good agreement.
Estimating The Gravitational Potential from IR Images
Authors: Quillen A. C. 
Published: July 2016

AbstractDetailed studies of stellar and gas dynamics have been carried out primarily in model galaxies which are not good approximations to the shapes of real galaxies (Athanassoula 1991). The high quality of recently available near-IR images of galaxies makes it possible to make realistic mass models of the matter that is traced by starlight. The gravitational potential derived from the mass model of a galaxy can be used to conduct stellar and gas dynamical studies in the galaxy, and the results can be compared to observed velocity fields and other observations of these galaxies. In this report we discuss how accurately the gravitational potential can be estimated based on an infrared image of the galaxy. We describe two uses of such an estimate of a gravitational potential: stellar orbits integrated in the barred galaxy NGC 4314 and an estimate of the gas inflow rate along the bar in NGC 7479.
M100 and NGC 6951: Morphological Clues to Central Dynamics
Authors: Knapen J. H. , Shlosman I. , Beckman J. E. , Heller C. H. , Peletier R. F. , de Jong R. S. , Nadeau D. , Doyon R. 
Published: July 2016

AbstractHigh-resolution optical and NIR observations are used to constrain a dynamical model of the circumnuclear star forming (SF) region in the barred galaxy M100 (NGC 4321). Small leading arms observed in our K-band image of the nuclear region have been reproduced in numerical modeling of M100, a galaxy with a double inner Lindblad resonance (ILR). We also present preliminary optical and NIR observations of NGC 6951: a barred galaxy with circumnuclear SF showing a distinctly different behavior to M100 at 2.2µm.
Structural Components of NGC 5850
Authors: Prieto M. , López J. A. , Varela A. M. , Muñoz-Tuñón C. , Gottesman S. 
Published: July 2016

AbstractHere we present a study of the structural components of the barred galaxy NGC 5850 using U, B and I photometry. After subtracting a bulge+disk model from the observed image, we obtain the bar and other non-axisymmetric structures. We determine the position of the ILR from the ellipticity and position angle profiles of the isophotes.
3D Barred Model of the Milky Way Including Gas
Authors: Fux Roger , Friedli Daniel 
Published: July 2016

AbstractWe present a 3D N-body simulation of the Milky Way including 4 × 105 star- and dark-like particles and 2 × 104 gas particles, initially distributed according to an axisymmetric, observationally constrained, mass model. The whole system is self-gravitating and the gas hydrodynamics is solved using the SPH method. The simulation leads to the spontaneous formation of a central bar that strongly affects the gas dynamics. We compute (l – V) diagrams for both the gaseous and the stellar particles as a function of the angle of the bar with respect to the observer and compare the results for the gas with HI and CO observations.
Terrestrial Coordinate Systems Solidly Connected with the Earth
Authors: Bursa M. 
Published: July 2016

AbstractThe principles and the suppositions for the basic definition of terrestrial coordinate systems solidly connected with the Earth are discussed: Problem of determining the position of the Earth’s center of mass (or of the centers of geodetic reference ellipsoids). Problem of defining the conventional geocentric and geodetic reference axes as well as axes of the principal terrestrial ellipsoid of inertia. Problem of determining directions of geodetic reference axes using geometrical satellite methods and the actual accuracy of the solution.
Celestial Reference Systems Derivable from Solar System Dynamics
Authors: Duncombe R. L. , Seidelmann P. K. , Van Flandern T. C. 
Published: July 2016

AbstractSolar system dynamics define a number of planes which could be the basis of a coordinate system. The equatorial, ecliptic, invariant, and planetary orbit planes are compared to an inertial coordinate system. Selection of a fiducial point requires consideration of precession and equinox motion and the relationships between the coordinate system of the celestial sphere, observed hour angles and the terrestrial longitude system. A time system might be based on the rotation of the Earth, the motion of the Sun, Moon and planets, or some nondynamical repetitive phenomena. Consideration must be given to the difficulties of the various systems, such as the irregrular rotation of the Earth, the uncertain tidal friction and anomalies of the Moon’s motion, the rapidity and accuracy of time determination-, and relativistic effects.
Classical Methods for the Determination of Universal Time and Polar Motion
Authors: O’Hora N. P. J. , Yallop B. D. 
Published: July 2016

AbstractA brief historical survey of important improvements in the classical methods for the determination of universal time and of polar motion over the last 25 years is outlined. Some of the errors that affect the results and estimates of the ultimate accuracy that may be achieved by these methods are discussed. Attention is drawn to the value of the observations in the field of astrometry and to the desirability of the continuation of the classical methods for use in this field.
On Constructing the Inertial System of High Accuracy by VLBI Methods
Authors: Krasinsky C. A. 
Published: July 2016

AbstractImprovement of the accuracy of angular measurements to values of, which theoretically may be achieved by VLBI methods, demands an inertial coordinate system of the corresponding quality. Such a system cannot depend on parameters of the Earth’s orbital and rotational motion and must be based on other principles than the adopted system. An approach which seems most natural was developed by E.P. Fedorov who proposed construction of the inertial system by determining the mutual angular distances between objects on the celestial sphere. In this paper, a method of synchronous and quasi-synchronous observations is developed which may realize this idea.
On Some Problems of BIH and IPMS Services
Authors: Melchior P. 
Published: July 2016

The ideas I shall try to develop are probably not original but I hope they reflect a general opinion of those who have looked into the problem of the Earth’s rotation.We must examine here related points:1. The polar motion and the variation of UT1.2. The system of reference with respect to which these periodic or secular variations are described.
Coordinate Systems in Lunar Ranging
Authors: Mulholland J. D. 
Published: July 2016

AbstractThree distinct coordinate systems are required in the interpretation of the lunar range observations: a celestial frame and two-body-fixed frames. However, there is no coordinate system that is uniquely, or even preferentially, related to the observations themselves. Effectively, one specifies the coordinate systems by the procedures used in data reduction and parameter improvement. Each of the three systems effects the others in some way, and internal inconsistencies are quite possible. The discussion examines some of the more important aspects of this problem.
2.3.1 Submicron Particles from the Sun
Authors: Hemenway Curtis L. 
Published: July 2016

AbstractA review is given which suggests that cosmic dust theoretical and experimental studies are still beset with uncertainty and inaccuracy. A significant body of interrelated evidence exists which indicates that the solar system has two populations of dust particles, a submicron population generated and emitted by the sun and a larger size population spiraling inward toward the sun. The submicron component may provide the missing coupling mechanism between solar sunspot activity and meteorological activity in the earth’s atmosphere.
2.3.7 Near-Earth Fragmentation of Cosmic Dust
Authors: Fechtig H. , Hemenway C. 
Published: July 2016

AbstractCosmic dust fragmentation in near-earth space is strongly suggested by the high fluxes (~102/m2s) of submicron particles observed in the upper atmospheric collection experiments, the lower fluxes (~10-l/m2s) observed in near-earth space by the lower sensitivity detection experiments and the much lower fluxes (~10−4/m2s) observed in the deep-space experiments. Various possible fragmentation mechanisms are discussed.
4.1 Meteors and Interplanetary Dust
Authors: Millman Peter M. 
Published: July 2016

AbstractThe contribution of meteor observations to our knowledge of meteoroids and interplanetary dust is reviewed under four headings – flux, mass distribution, physical structure and chemical composition. For lower limits of particle mass ranging from 1 g to 10−5 g the mean cumulative flux into the earth’s atmosphere varies from 2 × 10−15 to 6 × 10−9 particles m−2 s−1 (2Πster)−1, and the mean size distribution of these particles is given by log N = C – 1.3 log M, where N is the cumulative number of particles counted down to a lower mass limit M, and C is a constant. The physical structure of meteoroids in the above range is essentially fragile, with generally low mean bulk densities that tend to increase with decrease in mass. A minor fraction, about 10 or 15 per cent, with orbits lying inside that of Jupiter, have densities several times the average densities, approaching those of the carbonaceous chondrites. The mean chemical composition of meteoroids seems to be similar to the bronzite chondrites for the elements heavier than number 10, but with the probable addition of extra quantities of the light volatiles H, C and O.
On the Spectrophotometry Identification of Late type Binaries in Open Clusters
Authors: Bettis C. , Branch D. 
Published: July 2016

AbstractUsing both measured values and model atmospheres, the equivalent widths of the Na D lines of hypothetical late type main sequence binaries are calculated. Enhancements in the D lines of 90% over the value for a single star whose B — V color is the same as the composite B — V are possible. It is suggested that this effect may be used to identify binaries in galactic clusters, in particular those binaries whose components differ by more than 3 mag in brightness.
Psi Sagittarii, A System with Three Evolved Components
Authors: Fekel F. C. 
Published: July 2016

AbstractThe visual binary Psi Sagittarii (ADS 12214, HR 7292) is a spectroscopic triple system with orbital periods of 10.78 days and 20.0 years. Periastron passage in the long period crbit occurred on JD 2442410 ± 30 days. Masses derived from the parameters of the spectroscopic and visual orbits are 2.7 m⊙ for the visual primary, 2.1 m⊙ for the short period pair primary, and 1.7 m⊙ for the short period pair secondary. The distance to the system is 100 parsecs. The orbital inclination of the close pair is nearly the same numerically as that of the visual orbit. Suggested spectral classifications indicate that all three components have evolved off the main sequence. Mass exchange in the close pair has not yet occurred.
A Complete Family of Periodic Solutions of the Planar Three-Body Problem and their Stability
Authors: Hénon M. 
Published: July 2016

AbstractWe give a complete description of a one-parameter family of periodic orbits in the planar problem of three bodies with equal masses. This family begins with a rectilinear orbit, computed by Schubart in 1956. It ends in retrograde revolution, i.e., a hierarchy of two binaries rotating in opposite directions. The first-order stability of the orbits in the plane is also computed. Orbits of the retrograde revolution type are stable; more unexpectedly, orbits of the “interplay” type at the other end of the family are also stable. This indicates the possible existence of triple stars with a motion entirely different from the usual hierarchical arrangement.
Planetary Systems and Stellar Multiplicity
Authors: Huang Su-Shu 
Published: July 2016

AbstractIn this paper we have discussed the origin of planetary systems on one hand and binary and multiple stars on the other. First we show that phenomenological differences between these two kinds of celestial objects are due to their genetic difference. The basic point is that formation of a planetary system around a star has to be a minor event in the life history of the star while formation of a binary or multiple system has to be an event that is important equally to all components of the system. Thus the planetary system evolves from a rotating disk of gaseous and dust particles that comes into being after the star has already been there. It is therefore reasonable to suggest that the rotating disk results from transfer of angular momentum from the central star to the surrounding medium which is likely a residue left over in the process of formation of the central star.Binary and multiple systems cannot be formed in this way because they do not show the characteristics of having come out of a rotating disk. The dominant mechanism of their formation is that they were formed naturally as they are, each from perhaps a single condensation in the interstellar medium. However such a single mechanism of formation cannot satisfactorily explain the observed spread of binaries in mean separations between two components (or equivalently orbital periods). But the disagreement may be removed by including a small number of binaries formed by other processes and by considering the change of orbital elements of binaries after their formation. Trapezia were likely formed also by more than one mechanism.That several stars could be formed, from a single condensation requires the” existence oí pre-stellar nuclei which are briefly: discussed at the end of the paper.
A Proposal for Non-Ambiguous Designation of Stars and Stellar Objects
Authors: Spite F. 
Published: July 2016

SummaryThe number of new lists of stars and stellar objects published each year increases rapidly. From the designation of a star it is often difficult to trace back the original list or the basic data relevant to the star or stellar object. Designations are sometimes ambiguous. A few proposals are presented to try to improve the present situation.
Ultraviolet Photometry from the S2/68 Observations in the TD1 Satellite
Authors: Nandy K. 
Published: July 2016

SummaryAn ultraviolet photometric system based on observations obtained from the ultraviolet Sky Survey Telescope in the TD1 satellite is described. The system considered here consists of ultraviolet magnitudes at λ1 = 2740A, λ2 = 2190A and λ3 = 1490A. The extinction free parameters derived from the observed ultraviolet colours enable determination of interstellar reddening, spectral type and luminosity. This photometric system has been evaluated by comparing these parameters with other classification parameters.
The Hubble constant and the local expansion field
Authors: Tammann G. A. 
Published: July 2016

RésuméOn présente une brève revue des méthodes de détermination les distances extragalactiques actuellement disponibles. Plusieurs voies distinctes conduisent à Ho = 50 – 55 km s-1 Mpc-1. L’expansion de Hubble dans le superamas local est extrèmement régulière: les vitesses particulières moyennes de six groupes et de l’amas Virgo sont inférieures à 65 km s-1; et de l’absence de vitesses négatives pour les galaxies de champ, on déduit une limite supérieure de σ (v) inférieure à 40 km s-1. Il n’y a aucun signe d’un changement de Ho avec la distance. Une limite supérieure de l’anisotropie de l’expansion, pour les distances correspondant à v0 ~ 5200 km s-1, est donnée par: |∂Ho/Ho| < 0.07.