bluuebunny/crossref_metadata_2025 huggingface dataset:
Unusual Chemical Compositions of Noctilucent-Cloud Particle Nuclei
Authors: Hemenway Curtis L.
Published: July 2016

On August 8, 1970, two Pandora sounding rocket payloads were launched from the ESRO range in Kiruna, Sweden during a noctilucent cloud display. Large numbers of sub-micron particles were collected, most of which appear to be made up of a high-density material coated with a low-density material. Typical electron micrographs are shown. Particle chemical compositions have been measured by use of dispersive x-ray analysis equipment attached to a Philips EM 300 electron microscope and have revealed that most of the high-density particle nuclei have atomic weights greater than iron.
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

We 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

We 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.
Molecular Bars in Spiral Galaxies
Authors: Turner Jean L.
Published: July 2016

Images of molecular gas in spiral galaxies show two types of bar structure: large-scale bars, which are correlated with the presence of stellar bars, and generally follow the spiral structure, and nuclear “bars” of a few hundred parsecs in size, which show no direct correlation with the presence of a stellar bar. The dynamical origin of nuclear molecular bars is unclear, although they are consistent with radial inflow of gas into the nucleus, and subsequent evolution of the gas structure.
The HI in the Large Barred Spiral NGC 1365
Authors: Jörsäter S. , van Moorsel G. A.
Published: July 2016

We 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

A 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

A 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

Detailed 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

High-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

Here 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.
The Two-Point Correlation Function of Ringed Galaxies
Authors: Wu Wentao , Dupke Renato A. , Rabaça Carlos R.
Published: July 2016

We calculate the two-point correlation function for a sample of ringed galaxies. Results are similar to that of general field galaxies. We also find evidence that these galaxies form very large scale structures.
3D Barred Model of the Milky Way Including Gas
Authors: Fux Roger , Friedli Daniel
Published: July 2016

We 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

The 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

Solar 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.
On the Use of Tautenburg Schmidt for Improvement of Astronomical Reference System
Authors: Sandig H. U.
Published: July 2016

In the fifties, Wright (1950) of Lick Observatory and Deutsoh (1954) of Pulkovo Observatory proposed to connect faint stars with suitable galaxies at two epochs, some twenty years separated, to determine absolute proper motions. The directions to the galaxies can be considered as stable. Any possible lateral movement cannot be detected even over several centuries and even for a movement with the velocity of light. Since that time, both observatories obtained over a thousand plates – Lick Observatory with a 50-cm double astrograph, Pulkovo with several 34-cm normal lastrographs. In the meantime, some second epoch plates were taken at both observatories and first results for proper motions and for the constants of rotation of our Galaxy are available (Vasilevskis et al., 1971; Fatchikhin, 1972). Bur there are some discrepancies in the preliminary results of Lick and Pulkovo.
Classical Methods for the Determination of Universal Time and Polar Motion
Authors: O’Hora N. P. J. , Yallop B. D.
Published: July 2016

A 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

Improvement 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

Three 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.
1.1.3 Preliminary Results of the Helios a Zodiacal Light Experiment
Authors: Link H. , Leinert C. , Pitz E. , Salm N.
Published: July 2016

Helios A was launched on December 10, 1974 into a highly elliptical orbit with a perihelion of 0.31 A.U., which was reached on March 15, 1975. The zodiacal light experiment on Helios, described in the preceding paper, worked flawlessly and provided the first observations of the zodiacal light from inside the Earth’ orbit. A typical example from the raw data of the 15° – photometer is shown in Fig.1. There is a strong intensity increase towards the sun and a remarkably flat intensity distribution at large elongations. The Milky way is superimposed on the zodiacal light at longitudes 135° to 180° and 315° to 360°. Due to the orbital motion of Helios the star background is being shifted with respect to the zodiacal light, which will facilitate its separation from the total observed intensity. The peak at the right side of Fig.1 is due to the star α CMi, which we intend to use for the calibration of the instrument in addition to the ground calibrations. A preliminary evaluation showed less than 20% difference between the two calibrations. This is typical for other stars and for the other photometers, too, and gives a safe upper limit for the accuracy of the absolute calibration. Temperature effects are comparatively small and have not been corrected so far.
1.1.13 A Temporal Study of the Radiance of the F-Corona Close to the Sun
Authors: Munro R.H.
Published: July 2016

During the Skylab mission – May 1973 through February 1974 – the High Altitude Observatory’s white light coronagraph observed the sum of the F-corona, electron scattered K-corona, and instrumental stray light between 0.4 and 1.6 degrees from the sun. In searching for temporal variations in the F-corona, measurements were confined to the solar polar regions to minimize the effects of the K-coronal component. Changes in instrumental stray light were eliminated by restricting measurements to a single region within the instruments’ field of view. The largest source of error is the photometric calibration of the individual rolls of film. Frames were specifically selected to encompass periods of time ranging from a few days to eight months. Generally no variation in the total radiance greater than three percent was detected for intervals on the order of a few weeks. This level of stability holds for most of the eight-month period, excepting a few instances when deviations of up to eight percent were observed where the calibration is most uncertain. A preliminary study of the asymmetry in the F-corona close to the sun and the possible effect of solar eruptions (e.g., flares and prominences) upon the F-corona will be discussed.
1.1.17 A Search for Forward Scattering of Sunlight from the Lunar Libration Clouds
Authors: Ross C.L.
Published: July 2016

Observations to determine the radiance of forward scattered sunlight from particles in lunar libration regions have been attempted with the white light coronagraph on Skylab. The libration regions could not be distinguished against the solar K + F coronal background; the upper limit to the libration cloud radiance is determined to be 2.5 × 10−11 Bo, where Bo is the radiance of the mean solar disk. Employing models of the particle type and size distribution in the libration clouds, density enhancements have been calculated on the basis of the upper limit of the forward scattered radiance presented herein, and on the basis of earlier observations of the libration region backscattered radiance. The cases where the power law particle size distribution exponent K and complex index of refraction m are 2.5, 1.33-0.051 and 2.5, 1.50-0.051, respectively, are inconsistent with the forward and backscatter observations. Finally, the brightness contrast of remaining possible models of the libration clouds with respect to the K- and F-coronal background is calculated, and is shown to be a maximum in the vicinity of elongation angle ~30°.
1.3.6 Scattering Functions of Dielectric and Absorbing Irregular Particles
Authors: Zerull R.
Published: July 2016

Most model computations for the analysis of interplanetary dust are based on scattering functions of homogeneous spheres (Mie-theory). To investigate the influence of this restriction, scattering properties of nonspherical particles were studied by microwave analog experiments. The results of earlier investigations on dielectric rough spheres, cubes and octahedrons (Zerull, 1973; Zerull and Giese, 1974) may be shortly summarized as follows: Roughness (~ wavelength) does not significantly change the scattering behaviour of spheres, whereas cubes and octahedrons scatter evidently different than equivalent spheres. The dominant differences are increased intensity at medium scattering angles but no further increase towards backscattering, and nearly neutral polarization. These results encouraged to continue the investigations with really irregular particles of dielectric as well as absorbing material.
1.3.7 The Compatibility of Recent Micrometeoroid Flux Curves With Observations and Models of the Zodiacal Light
Authors: Giese R.H. , Grün E.
Published: July 2016

Increased sophistication in both, direct impact detectors and zodiacal light measurements encourages to discuss the compatibility of the results obtained by these quite different methods of investigating interplanetary dust. Taking recent measurements of particle fluxes and velocities obtained by the space missions of Pioneer 8/9 (Berg and Grün 1973), Heos 2 (Hoffmann et al. 1975), and comparing them with submicron-sized craters on lunar surface samples (Schneider et al. 1973, Fechtig et al. 1974) there seem to be two types of interplanetary dust populations: larger (>10−12g) micrometeorites orbiting around the sun as the classical zodiacal dust cloud and a second component of very small (<10−12g) particles coming radially from the direction of the sun with high velocities (>50 km/s). On the basis of the flux data referred to above and adopting for both components velocities of 10 or 50 km/s relative to the detector, respectively, a differential distribution function n(a) · da was found for the particle radii (a) as shown at a logarithmic scale in fig. 1. A density of 3 g/cm3was adopted in order to convert particle masses into radii. The regions A, B, C (see Table 1) correspond approximately to the regimes of “submicron particles”, the classical zodiacal cloud particles, and the meteoritic component of the interplanetary dust complex. From this information the brightness I(ε) of the zodiacal light in the ecliptic plane can be computed as a function of elongation by approximating the distribution function n(a) in the different regions by simple power laws a−k·da and by adopting a resonable scattering function σ(θ) for the average scattering behaviour of one particle of the mixture depending on the scattering angle θ. By use of an inverse (v = 1) decrease of particle number densities n = no· r−vwith solar distance r(AU), where nois the number density at r=1 AU, one obtains with a particle size distribution law n(a)da ~ a−kda in the different intervals of sizes (Table 1) the intensity of the zodiacal light (in stars of 10th magnitude per square degree, S10) as shown in fig. 2. The two models (Maximum, Minimum) correspond to an upper and to a lower limit of particle number densities compatible with the in situ measurements, respectively.
2.1.3 Composition of Impact-Plasma measured by a HELIOS-Micrometeoroid-Detector
Authors: Dalmann B.-K. , Grün E. , Kissel J.
Published: July 2016

The composition of the impact-plasma, produced by dust particles hitting an Au-target was measured, using a model of the HELIOS-mlcrometeoroid-detector. The 2 MV dust accelerators of the MPI für Kernphysik, Heidelberg, and the NASA Ames Research Center were used to accelerate particles consisting of Al, Al2O3, SiO2, Soda-Lime-Glass, Polystyrene and Kaolin to velocities between 2 km/sec and 15 km/sec. Fe-projectiles could be accelerated up to 40 km/sec. The masses of the dust grains were between 10−15 g and 3 × 10−10 g. The experiments showed, that because of the characteristic features of the measured spectra it is possible to separate noise events from impacts even at a high noise background. The smallest particles (m 10−15 g) triggering the experiment produce spectra well above the noise level (more than a factor 10) because of the high sensitivity of the ion-detector (multiplier).
2.1.6 The Cosmic Dust Environment at Earth, Jupiter and Interplanetary Space: Results from Langley Experiments on MTS, Pioneer 10, and Pioneer 11
Authors: Alvarez J.M.
Published: July 2016

Langley Research Center cosmic dust experiments aboard the Earth orbiting Meteoroid Technology Satellite (MTS) and the Pioneer 10 and 11 Jupiter fly-by spacecraft are described and discussed.
2.2.3 The Long Term Population of Interplanetary Micrometeoroids
Authors: Poupeau G. , Walker R.M. , Zinner E. , Morrison D.
Published: July 2016

Three problems will be discussed: A) The relationship between mlcro-meteoroids and solar flare particles averaged over the recent geologic past (~1 my); B) the past record of this relationship as measured in lunar soils and lunar and meteoritic breccias; C) the determination of the time at which different extraterrestrial samples were exposed to free space. Data bearing on these points obtained from studies of special lunar rocks and from measurements on individual crystals removed from lunar cores will be presented. Progress in using ion-probe mass spectrometry to link measurements of micro-impact craters with the past properties of the solar wind will also be discussed. Comparing microcraters and solar flare tracks in individual crystals from lunar cores, we find no evidence of any extraordinary variations for a time span covering an interval of ~109 yrs. Crystals 100µ to 400µ in size in mature lunar soil samples appear to have been exposed 3 to free space at the top of the lunar regolith for times from 103 to 104 yrs.
2.2.6 Microcraters Produced by Oblique Incidence of Projectiles
Authors: Stähle V. , Nagel K. , Schneider E.
Published: July 2016

Using a Van de Graaff dust accelerator an experimental program has been carried out in order to study crater parameters as a function of projectile incidence angle. Iron particles were shot into quartz glass targets. The angle of incidence which is the angle between target normal and the impact direction of the projectile has been varied from 0° to 70° in steps of 10°. Projectile masses ranged from 10−11 to 10−13g with velocities between 3 and 20 km/sec and projectile masses at 10−2 g with 4 km/sec impact velocity using a light gas gun at the Ernst-Mach-Institut, Freiburg i.Br. The so called circularity index which is the ratio of the crater area to the area of the smallest circle around the crater is a measure of the asymmetry of a crater. The circularity index decreases linearly with increasing angle of incidence. Also a small increase of the circularity index with increasing projectile velocity has been found i.e. the craters have a rounder shape with increasing velocity at the same angle. The circularity index appears to be independent from the projectile mass in the mass range from 10−11 to 10−2 g for stainless steel targets.
2.2.7 Measurements of Impact Ejecta Parameters in Crater Simulation Experiments
Authors: Schneider E.
Published: July 2016

Ejecta parameters such as masses and velocities as a function of ejection angle have been determined in impact experiments performed with a light gas gun. Impact plasma detectors and secondary targets mounted around the primary impact site served for the detection of secondary particles.
2.3.1 Submicron Particles from the Sun
Authors: Hemenway Curtis L.
Published: July 2016

A 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

Cosmic 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

The 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.
4.3 Possible Evidence of Meteoroid Fragmentation in Interplanetary Space from Grouping of Particles in Meteor Streams
Authors: Porubčan Vladimír
Published: July 2016

The clustering of micrometeoroid impact events on satellite--borne detectors (see e.g. Hoffmann et al., 1975) poses a question whether similar phenomena can be identified as well among larger particles observable as meteors. In fact, there is a strong conviction maintained by many observers that meteors within the streams are observed to be clustered in pairs or larger groups more frequently than one could expect from chance distributions. The rate of the dispersive effects indicates that the lifetime of any group of meteor particles is very limited. If real, the groups must be due to recent fragmentation of larger meteoroids.
5.6 Radial Distribution of Meteoric Particles in Interplanetary Space
Authors: Rhee John W.
Published: July 2016

An attempt has been made to derive heliocentric distribution of meteoric particles in interplanetary space. Poynting-Robertson effect, collision process, and cometary dust injection have been included in this study. Three different radial distribution functions for different sizes have been derived. The number density appears to depend on particle size.
5.8 Lunar Ejecta in Heliocentric Space
Authors: Alexander W.M. , Richards M.A.
Published: July 2016

Studies of the parameters of micron and submicron ejecta particles from laboratory hypervelocity impact experiments have been accomplished using a light-gas-gun to accelerate milligram particles to velocities of 4 km/s onto a basalt like rock target.
Multiplicity among Visual Binaries
Authors: Worley Charles E.
Published: July 2016

A brief review of the history of multiple-star discovery is followed by a discussion of selection effects, discovery probability, and detection techniques. The incidence of multiplicity and the properties of multiples in various samples of binaries are investigated.
On the Spectrophotometry Identification of Late type Binaries in Open Clusters
Authors: Bettis C. , Branch D.
Published: July 2016

Using 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

The 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

We 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.
The Lifetime of Binary Stars
Authors: Heggie Douglas C.
Published: July 2016

The concept of the “lifetime” of a population of binaries is applicable only to those of low binding energy, i.e. wide pairs. Of several possible methods of estimating a lifetime, that based on the average change in binding energy due to non-disruptive encounters appears to be the best.
Planetary Systems and Stellar Multiplicity
Authors: Huang Su-Shu
Published: July 2016

In 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

The 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

An 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 Astronomical Data Systems Group in Japan
Authors: Terashita Yoichi
Published: July 2016

In spite of the relatively large size of the astronomical community in Japan, there have been rather few efforts to organize an astronomical data system(s) and to take advantage of such systems. As a matter of fact, it has been realized that astronomical data, as the volume grows, are in many cases easier to handle in computer readable form than in printed form, and there is a growing trend of recording observational data or large tables on magnetic tapes and the likes, and of acquiring such data from other investigators (notably from investigators in other lands). However, it has not always been realized that machine-readable data bring about various kinds of problems when they are to be used by a number of astronomers whose fields of interest are different from each other or who works at geometrically scattered insitutions.
High Resolution Observations of Solar Velocity Fields from Spacecraft and Rockets Using Spectroscopic Methods
Authors: White Oran R.
Published: July 2016

Progress in the development of rocket and satellite spectrometers has now given us the opportunity to study the solar UV spectrum for evidence of mass motions in the chromospheric-coronal transition region. It is my intent to discuss briefly the motivation behind such space experiments, to summarize the few existent observational results, and to suggest relevant programs to exploit the opportunities offered by space experiments in the future.
Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results
Authors: Stenflo J.O.
Published: July 2016

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.
Energy Balance in Coronal Holes and Solar Wind Streams
Authors: Zirker J.B.
Published: July 2016

Coronal holes are regions of depressed density and temperature in the inner corona that coincide with open magnetic field lines. They were recognized for many years on eclipse photographs, but real understanding of their importance began to emerge only after data from rocket and satellite observations were analyzed. Wilson (1976) has summarized the early history of research on coronal holes.
The Hubble constant and the local expansion field
Authors: Tammann G. A.
Published: July 2016

On 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.
21 - cm observations of redshifts and their implications for the distance scale
Authors: Tully R. Brent , Fisher J. Richard
Published: July 2016

Il existe une corrélation étroite entre la largeur de la raie d’hydrogène neutre à 21 cm et la luminosité des galaxies spirales ainsi qu’entre cette largeur et le diamètre des galaxies spirales. Elle existe pour un échantillon de spirales proches dont la distance est calibrée par les céphéides, ainsi que pour des spirales dans quelques amas. La comparaison entre ces deux relations nous donne la distance de l’amas et une valeur pour la constante de Hubble. Pour l’amas de Virgo la méthode nous donne une distance de 14, 5Mpc, donc Ho = 77 km/s/Mpc. Pour 1’ amas de la Grande Ourse, une distance de 12, 6 Mpc, donc Ho = 75 km/s/Mpc. Il faut signaler qu’on trouve ces résultats avec des galaxies vues plutôt par la tranche. Il existe une différence systématique: avec les galaxies vue de face on trouve des distances plus grandes. Pour les galaxies de champ la corrélation existe, bien que la dispersion augmente. Avec 74 galaxies des types Sc-Sd et d’inclinaison 45°-75° on trouve Ho = 80 km/s/Mpc, avec celles situées dans l’amas supergalactique on trouve Ho = 75, et avec celles hors de l’amas supergalactique on trouve Ho = 90 km/s/Mpc. Cette différence est significative à 2 sigma près.
Dynamical state of pairs of galaxies
Authors: Karachentsev I. D.
Published: July 2016

Les estimations de masses de galaxies doubles sont obtenues sur la base des observations récentes de 148 paires de galaxies pour lesquelles les vitesses radiales des deux composantes ont été mesurées.

On montre que le rapport masse orbitale moyenne sur luminosité dépend essentiellement du type morphologique des galaxies doubles et du type d’interaction entre les deux composantes de la paire. Les valeurs minimales de ce rapport sont obtenues pour les galaxies doubles dont les caractéristiques d’interaction sont linéaires, à savoir: ponts, queues, ainsi que pour les paires avec des composantes compactes et des galaxies de Markarian,

La relation empirique entre le rapport masse-luminosité et la séparation spatiale des composantes de paires ne montre pas de façon évidente l’existence de halos stellaires cachés autour des galaxies doubles,
Arguments and evidence concerning non-cosmological redshifts
Authors: Burbidge G.
Published: July 2016

Les arguments et les preuves en faveur des décalages non cosmologiques vers le rouge, sont résumés.

Martin Rees and I have an almost impossible task -- to summarize on both sides of the argument the state of affairs in this field, but we agreed to try and entertain you.
Constraints on the Unseen Galaxy Population from the Lyα Forest
Authors: M. Lanzetta Kenneth , Chen Hsiao-Wen , Webb John K. , Barcons Xavier
Published: July 2016

Here we describe results of our attempt to determine what types of galaxies are responsible for the Lyα forest absorption systems, based on our ongoing imaging and spectroscopic survey of faint galaxies in fields of HST spectroscopic target QSOs. Our primary conclusions are that the bulk of the Lyα forest arises in more or less normal galaxies (that span the normal range of luminosity and morphology) and that any “unseen” low surface brightness galaxies are unlikely to contribute significantly to the luminosity density of the universe.
Low Luminosity Galaxies in Large Surveys
Authors: Huchra John P.
Published: July 2016

The debate about the slope and amplitude of the galaxy luminosity function at the faint end is discussed w.r.t. faint galaxies in large surveys, in particular the second CfA (CfA2) and the Las Campanas (LCRS) redshift surveys. Large surveys are necessary to determine the statistics of rare objects or objects that can only be seen out to limited volumes. Both surveys show excesses of faint galaxies over Schechter function fits, but the parent sample for the LCRS survey generally does not contain large or low surface brightness galaxies which do appear in the CfA2 survey. The objects that comprise the relatively large excess of faint galaxies in the CfA2 survey are shown to be primarily of low surface brightness and late morphological type and are generally emission line galaxies. Galaxy samples constructed like the LCRS will generally always be deficient in low luminosity galaxies and thus are not useful for constraining the faint end of the galaxy luminosity function.
The Faint End of the Galaxy Luminosity Function in Rich Clusters
Authors: Smith R.M. , Phillips S. , Driver S.P. , Couch W.J.
Published: July 2016

Recent results on the determination of the shape of the faint end of the galaxy luminosity function in rich clusters are discussed. There is increasing evidence that in many cases the faint end of the function is steep, indicating a large population of dwarf, possibly low surface-brightness, galaxies. In addition, the magnitude at which the turn-up appears is approximately constant with richness and distance. However, it is clear that not all clusters show such a feature.
A Survey for Low Surface Brightness Dwarf Galaxies Around M31
Authors: Armandroff Taft E. , Davies James E. , Jacoby George H.
Published: July 2016

By applying a digital filtering technique to 1550 deg2 of the POSS-II in the vicinity of M31, we found two previously unidentified very low surface brightness dwarf galaxies which we designate And V and VI. Follow-up imaging with the KPNO 4-m telescope resolved these into stars easily. The V- and I- band images of And V indicate a distance similar to that of M31, and <[Fe/H]> ~ −1.5. All evidence strongly supports its classification as a dwarf spheroidal companion to M31. Data for And VI are being analyzed, but preliminary indications support a similar conclusion. Our search for more dwarfs, including follow-up observations of numerous candidates found via digital filtering, is incomplete; thus, further identifications may be forthcoming.
Dwarf Galaxies in Nearby Groups
Authors: Bremnes T. , Binggeli B. , Prugniel P.
Published: July 2016

We present preliminary results from two observing campaigns where global photometric data for most dwarf galaxies in the M81 and M101 groups as well as some field dwarfs were obtained. The galaxies in the denser M81 group are more often of dwarf elliptical type and are redder and fainter than those of the M101 group and surrounding field, which are mostly of the dwarf irregular types. But both types follow the same total magnitude - central surface brightness relation, so there might be an evolutionary connection between the two classes.
The Interstellar Medium in LSB Galaxies
Authors: de Blok W.J.G.
Published: July 2016

I describe the properties of the interstellar medium in LSB galaxies, and conclude that apart from low density the other important factor determining the slow evolution of LSB galaxies is the metallicity, and (due to inefficient cooling) the corresponding lack of large amounts of molecular gas.
The Extreme Outer Regions of Disk Galaxies: Star Formation and Metal Abundances
Authors: Ferguson Annette , Wyse Rosemary , Gallagher Jay
Published: July 2016

The extreme outer regions of disk galaxies, lying at or beyond the classical optical radius defined by R25, present an opportunity to study star formation and chemical evolution under unique physical conditions, possibly reminscent of those which existed during the early stages of disk evolution. We present here some of the first results from a large study to measure star formation rates and metallicities in the extreme outer limits of a sample of nearby spiral galaxies. Despite their low gas column densities, massive star formation is often observed in these outer parts, but at an azimuthally–averaged rate much lower than that seen in the inner disk. Gas-phase O/H abundances of roughly 10% solar characterize the gas at 1.5–2 R25. The implications of our results for star formation ‘laws’ and models of disk evolution are discussed.
The Low Surface Brightness Galaxy HIPASS1126-72
Authors: Kilborn Virginia , de Blok Erwin , Staveley-Smith Lister , Webster Rachel
Published: July 2016

The low surface brightness galaxy HIPASS1126-72 was detected in the HI Parkes All Sky Survey (HIPASS). The galaxy was previously listed in the Southern Galaxy Catalogue under the name SGC1124.87221. This galaxy represents a class of galaxies that we will readily detect in the HIPASS survey, which have low surface brightness in the optical, but are easily detectable in neutral hydrogen.