bluuebunny/crossref_metadata_2025 huggingface dataset:
Radial Pressure in the Solar Nebula as Affecting the Motions of Planetesimals
Authors: Whipple Fred L.
Published: July 2016

In the classical rotating Laplacian-type nebula, pressure gradients can develop radially to the protosun because of central radiation, particle ejection, and magnetic-field expansion or because of radial temperature or total gas density gradients. Except for the last two effects, the acting central acceleration for the gas is reduced from the gravitational value; the pressure gradient in the gas caused by temperature or density gradients may either add to or subtract from the gravitational acceleration, depending on the sense of the pressure gradient. Planetesimals in the nebula may thus experience tangential accelerations (+ or —) with respect to the gas because of the differential radial accelerations acting on the particles and the gas. As a consequence, the planetesimals may spiral outward or inward with respect to the protosun. The present paper deals with growing planetesimals and a range of drag laws depending on the Reynolds number and on the ratio of particle size to mean free path.

Particles spiral in the direction of positive pressure gradient, thus being concentrated toward toroidal concentrations of gas. The effect increases with decreasing rates of particle growth, i.e., with increasing time scales of planet formation by accretion. In the outer regions, where evidence suggests that comets were formed and Uranus and Neptune were so accumulated, the effect of the pressure gradient is to clear the forming comets from those regions. The large mass of Neptune may have developed because of this effect, perhaps Neptune’s solar distance was reduced from Bode’s “law,” and perhaps no comet belt exists beyond Neptune. In the asteroid belt, on a slow time scale, the effect may have spiraled planetesimals toward Mars and Jupiter, thus contributing to the lack of planet formation in this region.
Possible Interaction of Interstellar Particles With the Solar and Terrestrial Environment
Authors: Greenberg J. Mayo
Published: July 2016

The possibility for detection of interstellar particles in the Earth’s environment is considered on the basis of the passage of the solar system through the interstellar medium. Among the forces which inhibit interstellar particle penetration, the deflection by the solar magnetic field and the repulsive force due to the radiation from the Sun are by far the most important.
Barred Galaxies: Scientific Overview
Authors: Freeman K. C.
Published: July 2016

In this scientific overview, I discuss some of the important features of barred galaxies, and attempt to identify some of the outstanding problems.
Infrared Emission from Barred Spiral Galaxies
Authors: Hawarden Tim G. , Huang J. H. , Gu Q. S.
Published: July 2016

Amongst relatively undisturbed spiral galaxies of type ≤ Sc barred morphology is unquestionably associated with powerful mid- and Far-IR emission. On the other hand, even amongst early type galaxies, those with LFIR/LB < 1/3 exhibit no association of high relative FIR luminosity with barred morphology, but some association of IR colors resembling those of star formation regions (SFRs). Amongst systems with LFIR/LB < 0.1 this ratio may be anti-correlated with barredness. It appears that enhanced IR emission from those galaxies whose star formation rate is currently elevated by the the bar translates them into the group with higher FIR-to-optical luminosity ratios. Depletion of extended nearnuclear gas and dust, once the bar has swept up the currently-available supplies, may reduce the fraction of the background stellar radiation field which can be converted to FIR radiation in the inner, most luminous parts of the galaxy. Thus, after the starburst has subsided, such galaxies may be less FIR-luminous than unbarred systems. Several uncertainties remain: it is still not clear whether barred morphology is a necessary condition for the generation of a starburst in an otherwise undisturbed galaxy, while evidence as to the effect of differing bar strengths is conflicting.
A Nuclear Ring in the Sa(r!) Galaxy NGC 7742
Authors: Wakamatsu K. , Hamabe M. , Nishida M. T. , Tomita A.
Published: July 2016

NGC 7742 is well known for its prominent blue nuclear ring around an EO-like core, and so appears as a Hoag-type galaxy, an elliptical galaxy with an outer ring (Schweizer et al. 1987). The galaxy is classified as Sa(r!) in the Revised Shapley-Ames Catalog (Sandage and Tammann 1987) with an exclamation mark to emphasize the prominence of the ring. Its photographs are published in Laustsen et al. (1987), Wray (1988), and Sandage & Bedke (1994).

The ring has a diameter of 19″ = 1.6 kpc at a distance of 17.1 Mpc (Buta & Crocker 1993), and so should be a nuclear ring of the galaxy. Nuclear rings and pseudorings are often detected in strongly barred (SB) galaxies, and interpreted to be linked to the inner Lindblad resonance (Buta & Crocker 1993). These nuclear features are, however, also found in some weakly-barred (SAB) and non-barred (SA) galaxies. NGC 7742 is a galaxy of the highest circular symmetry in its core, ring, and main body, and so the best object for a detailed study of formation mechanisms of nuclear rings in non-barred galaxies.
O/H Abundances in the Ringed Galaxy NGC 4736: Mixing Processes in the Interstellar Medium
Authors: Martin P. , Belley J.
Published: July 2016

Imaging spectrophotometry in the main nebular lines has been performed on 65 H ɪɪ regions in the ringed galaxy NGC 4736. O/H abundances were derived using the line ratios [O ɪɪɪ]/Hβ and [N ɪɪ]/[O ɪɪɪ] calibrated by Edmunds & Pagel (1984). We show that the O/H scatter in the resonance ring of star forming regions is small, no greater than normally expected in the well-mixed ISM of disks of gas-rich galaxies. The global O/H gradient (−0.046 dex/kpc) in the disk of NGC 4736 is shallower than gradients of normal spirals but comparable to gradients observed in weakly barred spirals. This last result could indicate that radial mixing is or was present in NGC 4736. The oval distortion in the central regions can be responsible for this homogenization but it is also possible that a strong bar was present in the past.
H II Region Statistics in Barred and Non-Barred Galaxies
Authors: Rozas M. , Beckman J. E. , Knapen J. H.
Published: July 2016

We present new high quality Ha continuum-subtracted images of the grand design galaxies NGC 157, NGC 3631, NGC 6764, and NGC 6951, two of them barred and two non-barred, and describe the statistical properties of the HII regions. We have determined the positions, angular sizes and fluxes of individual HII regions, and construct luminosity functions and diameter and density distributions. We find no significant differences between arm and interarm HII region properties, or between the barred and non-barred galaxies. This paper summarizes work described in more detail by Rozas et al. (1995a,b)
A Search for Symmetries in the Star Formation Patterns of Spiral Disks: Barred Galaxies
Authors: Rozas M. , Beckman J. E. , Knapen J. H.
Published: July 2016

The Hα brightness distribution of a face-on galaxy is a classical representation of the massive star formation rate per unit surface area. Here, we present a test for the degree of symmetry in this distribution, aimed at deciding whether this parameter shows a significant difference between barred and non-barred galaxies. The test consists in deriving the cross-correlation function of the Hα brightness as a function of curvilinear distance along pairs of opposed arms. In order to use the test, we first apply a geometrical unfolding technique. Here we explain this technique, and present the initial results of applying the test to NGC 157 and NGC 6764.
Study of the Gas Kinematics in the Center of the Barred Spiral Galaxy NGC 4258.
Authors: Dodonov S. N.
Published: July 2016

Integral Field Spectrograph observations of southeast (SE) gas outflow in the center (11×13 arcsec) of NGC 4258 with spatial sampling 0.6 and 1.2 arcsec were made with the 6-m Telescope. Reconstructed spatial and kinematic structure of the SE outflow from 20-30 pc to 200-220 pc are presented.
CO Kinematics, Star Formation and Dynamical Evolution of the Lensed Starburst NGC 4102
Authors: Jogee Shardha , Kenney Jeffrey D. P.
Published: July 2016

The circumnuclear (inner kiloparsec) regions of spiral galaxies are time-dependent systems whose morphology and dynamics can change significantly over less than a Hubble time. To develop an insight into this evolution it is important to study the fate of gas driven towards the central parts of a galaxy especially near the dynamical resonances. The panoply of CO morphologies displayed by the circumnuclear regions of starburst and nonstarburst galaxies such as NGC 3504, NGC 3351, NGC 7479, NGC 6951, etc, (Kenney, these proceedings) is not yet clearly understood. Another unsettled issue concerns the criteria for star formation in the circumnuclear region where, in contrast to the outer disk, the rotation curve is nearly solid-body and rises rapidly. These issues need to be resolved; the gas mass fraction, the radial variation of SFR (star formation rate) and its interplay with the gas kinematics can shed light not only on the temporal evolution of the circumnuclear CO morphology but also on secular evolution through the destruction and creation of new stellar components. For instance, stellar bars can be destroyed by an increase in the central gas mass concentration of a few % of the total galaxy mass while mechanisms to build or enhance a bulge by vertical scattering of the stars in a compact circumnuclear stellar disk have been proposed (Sellwood 1994, Pfenniger & Norman 1990). We have carried out a study of the circumnuclear region of NGC 4102 with these important issues in mind. NGC 4102, a LINER/HII, SABb spiral galaxy at a distance of 17 Mpc with a bar and/or lens feature qualifies as one of the most luminous nearby starbursts (Devereux 1989) and seems to be in a very early phase of evolution. The outflow timescale of the central starburst wind in NGC 4102, determined from optical spectroscopy of the ionized swept-up gas, is 106 years (Boer 1994), suggesting it is at an earlier evolutionary phase than M82 and NGC 253 whose outflow timescales are significantly larger.
The Extent of The HI Halo in Five Isolated SB Galaxies
Authors: Kristen H. , Jörsäter S.
Published: July 2016

We investigate the extent of the HI halo in five isolated SB galaxies featuring strong bars. VLA1 observations of these objects are used to determine the diameter ratio between the HI and the optical distribution. The mean diameter ratios D1.82/D(0) and DHI/D(0), for the sample presented here, are 1.1±0.1 and 1.2±0.1 respectively (1σ r.m.s.). For samples of various types, Bosma (1981) and Broeils (1992) find D1.82/D(0) = 2.2±1.1 and DHI/D(0) = 1.8±0.4 respectively. Our result thus could indicate compactness of the HI halo in galaxies with strong bars.
Photometry and Kinematics of the Ringed Barred Galaxy NGC 3081
Authors: Purcell Guy B. , Buta R.
Published: July 2016

We present a preliminary analysis of B- and I-band CCD images and Rutgers imaging Fabry–Perot Hα interferometry of the galaxy NGC 3081. We find that the outer R1 and inner ring are both intrinsically oval. We derive a bar pattern speed from the velocity field.
Barred Galaxies in the Virgo Cluster
Authors: Andersen Victor
Published: July 2016

Spiral galaxies in the Virgo cluster appear to be barred more frequently than galaxies in less dense environments. Tidal forces due to the cluster mass concentration seem to be the most likely mechanism for inducing these bars.
Dumbbell Bars and Spirals: Structures of Interacting Galaxies (with a Video-Movie)
Authors: Anosova J. , Tanikawa K.
Published: July 2016

We study the dynamics of spherical systems which consist of extended shells of relatively low-mass particles around and inside the orbit of two heavy centers of gravity (a binary with point-mass components) by computer simulations.
Bar Destruction Mechanism by External Interactions
Authors: Nishida M. T. , Wakamatsu K.
Published: July 2016

To investigate bar destruction by a vertical head-on galaxy encounter, the dynamical evolution after the instantaneous momentum change of the impulsive approximation of a vertical head-on galaxy encounter, and the instability of finite amplitude one-armed perturbations to barred structure, are investigated by 2-dimensional N-body simulations.

Preliminary results show that off-center vertical head-on collisions induce bar destruction but collisions in which the colliding galaxy passes through the very center of the target galaxy do not induce bar destruction.
Multiple Gas Rings in SA Galaxies
Authors: Palouš J. , Jungwiert B.
Published: July 2016

Rings are frequently observed in barred galaxies (e.g. Buta & Crocker 1993). Their origin is attributed to gas accumulation near resonances, which is due to a combination of the gravitational torques of a bar component acting on inelastically colliding clouds: outer rings are presumably associated with the Outer Lindblad Resonance (OLR), inner rings with the 4/1 resonance, and nuclear rings with the Inner Lindblad Resonance (ILR).

However, multiple rings are also observed in normal non-barred, or not obviously barred galaxies (e.g. NGC 7217, Verdes-Montenegro et al. 1995) so that we may ask what is the mechanism of their formation. We argue in this contribution that even a very weak bar or a triaxial distortion in the galaxy center, which would hardly be identified from observations, leads to long-lasting ring-like distributions of gaseous clouds. The formation time-scales of rings associated with different resonances are similar in our model so that all types of rings can coexist in galaxies with a high degree of axial symmetry in their central parts, such as SA galaxies.
Secondary Bars and Triaxial Bulges within Primary Bars
Authors: Friedli Daniel
Published: July 2016

Numerous galaxies clearly show two misaligned nested stellar bars or one bar plus one structure with twisted isophotes. Some galaxies seem even to have three distinct triaxial structures. Recent optical and near-infrared multi-band observations show that the angle between the primary and secondary bars does not take any peculiar value. The best way to reconcile such observations with theory certainly consists in postulating that the secondary bar rotates faster than the primary one. Numerical simulations have demonstrated the viability of such systems, and both direct and counterrotating models with bars within bars can be computed. Bar-within-bar systems could play a significant role in fueling AGN’s and/or circumnuclear starbursts, since AGN’s and/or blue or Hα nuclear rings are frequently hosted by such galaxies.
A Survey of Orbits in 2D N-body Bars
Authors: Sundin M.
Published: July 2016

A barred galaxy is mainly built of billions of stars moving on different orbits. Understanding of the orbital structure is essential for the interpretation of observations. The orbital structure can be investigated using analytical models and N-body simulations. This paper presents a method to classify orbits found in N-body simulations, i.e. orbits in a time-dependent potential. I present some results about mass loss and mass gain of bars and the influence of a bulge.
Observational Evidence for a Bar in the Milky Way
Authors: Kuijken Konrad
Published: July 2016

Evidence from a variety of sources points towards the existence of a bar in the central few kpc of the Galaxy. The measurements roughly agree on the direction of the bar major axis, but other parameters (axis ratio, size, pattern speed) are still poorly determined. Current dynamical models are limited by the quality of hydro simulations, the degeneracy of stellar orbit models, stellar-kinematic data and the significant lopsidedness of the central kpc. Microlensing promises new constraints on the mass distribution in the bulge/bar region.
Theoretical Summary
Authors: Miller R. H.
Published: July 2016

Why do so many galaxies have bars? Why are bars so rugged? These questions, vital to understanding barred galaxies, have not been addressed in this Conference.

Numerical studies seem to have replaced analytic theory. But the bars in numerical studies may not be good models of real galaxies.
Gravimetric and Astrogeodetic Reference Systems in Space and Time
Authors: Moritz H.
Published: July 2016

This paper is concerned with conceptual aspects of terrestrial reference systems to be used in connection with gravimetric and astrogeodetic methods. Two principal kinds of reference systems are discussed: natural coordinates, based on the gravity field (geoid and plumb lines), and geodetic coordinates, which numerically approximate the natural coordinates but are based on a reference ellipsoid instead of the geoid and are, therefore, directly related to spatial rectangular coordinates.

The discussion includes temporal variations due to Earth tides, and problems posed by the definition of the origin because of polar motion and by the change of station position due to plate motion, etc., as well as questions raised by the definition of reference ellipsoids, including effects of the atmosphere. A final section deals briefly with references for gravity observations.
Coordinates Used in Range or Range-Rate Systems and Their Extension to a Dynamic Earth
Authors: Newton R. R.
Published: July 2016

This paper describes briefly the coordinates that have been used with satellite systems that measure range or range-rate, and it shows that the methods previously used to define them lead naturally to the coordinate system needed for a dynamic Earth. This is one in which the Earth has no linear momentum and no angular momentum, and it is the only system that allows the motion of the Earth to be separated into a translation, a rotation, and an internal motion, and that preserves the usual forms of the equations of motion. The observations needed to define this system are outlined.
Geodetic and Astrometric Results of Very Long-Baseline Interferometric Measurements of Natural Radio Sources
Authors: Moran J. M.
Published: July 2016

The technique of very long-baseline interferometry, initially developed in 1967 to study the angular structure of compact radio sources on the order of a thousandth of a second of arc, has been used to measure to great accuracy geometric quantities of geodetic and geophysical importance. The baseline vector between various radio telescopes has been measured to an accuracy of about 1 m (the accuracy of the measurement of the length of the baseline vector is better than 50 cm). Variations in UT1 have been measured to an accuracy of 1 msec, polar motion to 500 cm, and the coordinates of radio sources to about 0.1 ardsec. Improvement of about 1 order of magnitude is expected in the next 5 years. The major work has been done by three groups: the Massachusetts Institute of Technology/National Aeronautics and Space Administration group; the Jet Propulsion Laboratory group; and the National Radio Astronomy Observatory/California Institute of Technology group. The results available in June 1974, the factors limiting their accuracy, and the prospects for the future are discussed in this paper.
Prospects for Rapid Realization of a Quasi-Earth-Fixed Coordinate System
Authors: Bender P. L.
Published: July 2016

It appears that a combination of VLBI, lunar ranging, and satellite ranging can provide a quasi-Eiarth-fixed coordinate system with high accuracy and good coverage more rapidly than any one technique alone. In considering this possibility, the conceptual separation of the job into two parts seems useful. There are: 1) establishment of a global network of at least three fundamental reference points on major plates, and 2) the determination of a larger number of regional reference points of geodynamic interest. The example of lunar ranging plus satellite ranging is used to illustrate one way in which an accurate realization of an initial terrestrial system could be achieved quickly.
Latitude Star System of the ILS and the Conventional International Origin
Authors: Sato K. , Wako Y.
Published: July 2016

The essential characteristics of the methods of finding declination corrections for the observed latitudes of the International Latitude Service (ILS) are discussed in the paper.

As the z term always includes the errors in the adopted mean latitudes of the stations, the declination system corrected by the z term method is not an absolute one but is internally consistent as it is in the case of the chain method. This method, however, can exclude the proper motion errors which introduce an error in the secular motion of the mean pole.

The adopted mean latitudes of the ILS stations which define the CIO should equally be corrected by an amount of(for the epoch of 1961.0), which was inferred from declination errors in the preliminary AG catalogue with reference to the Melchior-Dejaiffe catalogue.
Review of the Classical Methods for the Determination of Geodetic Datums
Authors: Mueller I.I.
Published: July 2016

In conventional geodetic systems, locations of points on the surface of the Earth may be defined either by means of natural (astronomic) or geometric gepdetic cooprdinates. The natural coordinates, the astronomic latitude (Φ), longitude (λ), and the orthometric (mean sea level) height (H), being gravity dependent, are conventionally referenced, to the geoid and are determined from “natural” observations (astronomic, gravimetric observations and spirit leveling). The geometric coordinates, the geodetic latitude (φ), longitude (λ) and height (h) are referenced to a (generally) rotational ellipsoid of arbitrary size, shape and orientation, and are determined from geometric (length and/or direction) observations.
1.1.2 Helios Zodiacal Light Experiment
Authors: Pitz E. , Leinert C. , Link H. , Salm N.
Published: July 2016

The Z.L. experiment consists of 3 photometers which are mounted rigidly into the s/c with orientations of about 15°, 30° and 90° south of the s/c – XY-plane, which coincides in orbit with the ecliptic plane (see Fig.1). Helios is spinning uith 1 Hz, and the integration time of the experiment is 513 revolutions. The 90° – photometer always looks to the south ecliptic pole and one revolution of the s/c is divided into 8 sectors to get information on the polarization of Z.L. The polarization is measured by a fixed polaroid foil within the photometer which is rotated by the s/c. In the other two photometers one revolution is split into 32 sectors with different angular resolution. Near the antisun where the gradient in Z.L. intensity is small, the sector length is 4 times the length near the sun (see Fig.2). In these 2 photometers the polarization is obtained by 3 differently oriented polarization foils moved by stepping motors. Intensity and polarization of Z.L. is measured in 3 different colors, which are near the international UBV – system (Ažusienis and Straižs 1969), the effective wavelength shifted by about 100 Å to the blue end.
1.1.5 Star Counts in the Background Sky Observed from Pioneer 10
Authors: Tanabe H. , Mori K.
Published: July 2016

Star counts in the sky region observed by Pioneer 10 at 4.64AU from the sun, where the contribution of zodiacal light is negligible, were made using the Palomar Sky Survey Atlas. Brightness of the integrated starlight derived from our star counts agrees, in general, with the Pioneer 10’s observation.
1.1.15 The Thermal Emission of the Dust Corona During the Eclipse of June 30, 1975
Authors: Léna P. , Viala Y. , Hall D. , Soufflot A.
Published: July 2016

Observations of the F-corona have been made in the 10 µ region of the infrared during the eclipse of June 30, 1973. Use of the supersonic aircraft “Concorde 001” permitted 74 min of observation during totality and greatly reduced problems due to sky noise. The plane of the ecliptic was scanned over heliocentric distances of from 3 to 19 solar radii off the east limb. Bright features previously observed at shorter wavelengths, notably emission at 4 solar radii are evident on the 10 µ scans, strongly indicating that the radiation is due to thermal emission by dust. The specific intensity in the 4 R⊙ feature is 5 µ W cm−2 sterad−1 µ−1; higher than the intensity 22 arcmin above the ecliptic. Spectra were taken at one region in the ecliptic and tentatively attributed to silicate-type material. Complete details may be found in Astron. & Astrophys. 37, 75-79 and 81-86, 1974.
1.1.16 The Color Characteristics of the Earth-Moon Libration Clouds
Authors: Roach J. R.
Published: July 2016

The 0S0-6 Zodiacal Light experiment has provided evidence for the backscatter of light from the Earth-Moon libration regions at 5000 A. Additional measured data at 4000 A and 6100 A show similar characteristics. The combined three-color data lead to libration region color indices slightly bluer than the average surrounding sky background. The differential b-v for the L4 region is approximately −0.05.
1.1.18 Presentation of Zodiacal Light Instrument Aboard the D2B Astronomical Satellite
Authors: Maucherat M. , Cruvellier P.
Published: July 2016

The french astronomical satellite D2B is to be launched on September 1975. During the dial of the orbit, one axis of the satellite points to the Sun, with an accuracy of ± 30 arcmin; during the night of the orbit, the satellite keeps this stabilization by gyroscopic effect. The perpendicular axes -one of them is the optical axis of the Z.L. (Zodiacal Light) instrument- roll around the Earth-Sun direction, once every 4 minutes. Because of the Earth’s motion around the Sun, the celestrial sphere will be scanned along ecliptic meridians, every orbits; the complete exploration of the sky will be achieved after six months. The Z.L. instrument is a photometer analyzing galactic and zodiacal fluxes, in the range λλ 3100-750, in five spectral intervals 200-500 wide, with a field of 2.8°□. For a single scan, the limit of detection by the instrument will be the 6th visual magnitude for early-type stars (0-B).
1.2.3 Scattering in the Earth’S Atmosphere: Calculations for Milky Way and Zodiacal Light as Extended Sources
Authors: Staude H.J.
Published: July 2016

The results of detailed calculations on first order Rayleigh- and Mie-scattering in the Earth’s atmosphere illuminated by the Milky Way and the Zodiacal Light are presented. The influence of various independent parameters, as optical depth of the Rayleigh- and Mie-component and position of Milky Way and Zodiacal Light, is discussed. Linear and circular polarization of the scattered light are considered. The results are compared uith the procedures commonly applied in reducing photometric observations of extended sources of the night sky. It is shown that a substantial part of the discrepancies between the brightness distributions of Zodiacal Light resp. Milky Way given by different authors is due to an inaccurate treatment of the atmospheric scattered light.
1.3.4 Method for the Determination of the Intensity of Scattered Sunlight Per Unit-Volume of the Interplanetary Medium
Authors: Mujica A. , Sánchez F.
Published: July 2016

The knowledge of the functions which give the intensity of the scattered sunlight is important in order to establish the models of the zodiacal cloud.
1.3.5 On the Visibility of the Libration Clouds
Authors: Röser S.
Published: July 2016

In recent years satellite observations of the region of the Earth-Moon libration points L4 and L5 became available, which showed different results. Roach (1975) has measured perturbations of the Zodiacal Light intensity near the libration points L4 and L5 with a photometer on board the OSO-6 satellite. He interpreted the results as counterglow of a cloud of particles, having an angular diameter of 6 degrees and an average brightness of 20 S10v, whereas observations by Burnett et al. (1974) set an upper limit of 10 S10 blue. Earth bound observations made by Bruman (1969) with the 48-inch Palomar Schmidt telescope gave no indication for discrete objects nor for clouds.
2.1.4 Orbital Elements of Dust Particles Intercepted by Pioneers 8 and 9
Authors: Wolf Henry , Rhee John , Berg Otto E.
Published: July 2016

The instrument measuring particle impacts on PIONEERS 8 and 9 has been extensively described in the literature (Reference 1) and will not be repeated here. This paper concerns itself with the analysis of the data obtained.
3.3 Can Short Period Comets Maintain the Zodiacal Cloud?
Authors: Röser S.
Published: July 2016

The combined effects of the Poynting-Robertson drag, collisions and sputtering are destroying the interplanetary dust cloud. The mass-losses estimated by different authors reveal great discrepancies. The estimations range from 1 t sec−1 (purely Poynting-Robertson loss) over some 10 t sec−1 given by Whipple (1967) to a value of 100 t sec−1 which is propagated by Bandermann (1967). The latter derives this high value from the assumption that the main mass loss is due to self-collisions.
3.10 Mariner Mission to Encke 1980
Authors: Yeates C. M. , Nock K. T. , Newburn R. L.
Published: July 2016

The planetary program has always been conducted with the hope that the results would reveal great insight into the early period of solar system history and perhaps into the actual formation processes themselves. However, little knowledge has been gained of this very early stage for several reasons: The intense surface bombardment of all larger bodies, particularly in the inner solar system during that period; the subsequent differentiation of large bodies; and atmospheric effects and continued bombardment of the surface. The most promising approach to acquisition of knowledge pertaining to the early state of the solar system, its origin and evolution, therefore seems to be in the study of small bodies, e. g., comets and asteroids.
4.7 Meteor Radar Rates and the Solar Cycle
Authors: Lindblad B.A.
Published: July 2016

Long-term variations in meteor radar rates, echo amplitudes, and meteor end-point heights have been observed. These variations appear to be controlled to a large extent by the solar cycle of activity. Exceptionally high echo rates in 1953, 1963 and 1972 coincide approximately with solar cycle minima. The long-term variations are explained in terms of a solar controlled change in the atmospheric density gradient at the meteor ablation level.
5.1 Sources of Interplanetary Dust
Authors: Whipple Fred L.
Published: July 2016

Attention is centered on cosmic dust measures made by sensors on Pioneers 8 and 9 in Earth-like orbits. The conclusion follows Zook and Berg that the particles are largely “β-meteoroids,” interplanetary impact debris expelled by solar radiation pressure. An analysis of periodic comet orbits and comets observed during the missions failed to yield correlations, except possibly for debris from Comet Encke. A treatment of β-meteoroids from this stream is presented.
5.4 Orbital Evolution of Circum-Solar Dust Grains
Authors: Lamy Ph.
Published: July 2016

The orbital evolution of circum-solar dust grains is obtained by numerical integration of the equations of motion which includes the grains’ interactions with the solar radiation field and the solar wind. Our past solution (Lamy, 1974) is improved by avoiding a classical approximation for the Poynting-Robertson term and leads to an important revision of the orbital behaviour. Results are presented for obsidian grains whose inward spiraling is stopped by the effect of sublimation.
Multiplicity of Solar-Type Stars
Authors: Abt Helmut A.
Published: July 2016

A systematic search for binaries in a sample of 123 bright field stars of types F3-G2 IV or V is described. Combination of the results for 25 newly discovered spectroscopic binaries with those of 21 spectroscopic, 23 visual, and 25 common-proper-motion pairs previously known brings to 88 the total number of companions identified in the sample. The distribution of the 88 periods shows a single maximum; the median period is 14 years.

The frequencies of singles: doubles: triples: quadruples are found to be 42: 46: 9: 2. Less than half of the stars are thus observed to be single. Estimates of the completeness of this search lead to a determination of the number of systems missed and to a determination of their secondary masses.

Analysis of the secondary-mass distributions, observed and predicted from completeness estimates, indicates the existence of two types of binaries.

For systems with periods less than about 100 years, the distribution of secondaries varies with the cube-root of the secondary mass. These systems must be the result of fission. Two-thirds of their primaries have companions of stellar mass. Extrapolation of the cube-root relation implies that the remaining one-third of the primaries have non-stellar secondaries, i.e., close companions whose masses are less than 0.07 solar masses.

For systems with periods larger than roughly 100 years the distribution of secondaries follows that given by the van Rhijn function. They must be the result of condensations that contracted separately but are bound gravitationally. Roughly three-fourths of all primaries in the sample have such distant companions, all of which are likely to be themselves close fission-systems. Evidently single stars are rare among solar-type dwarfs.
Etoiles Multiples Et Amas Ouverts
Authors: Dommanget J.
Published: July 2016

It is generally suspected that multiple systems and galactic clusters are objects of different kinds. Their frequency distribution as a function of the number of components, n, as well as their sizes and their masses, show important differences between both categories and also the probable existence of a limit lying between n = 10 and n = 20 components. The basic difference between these objects seems to be that the multiple systems finally appear to be components of the stellar medium in th same way as single and double stars, whereas the galactic clusters are groups of components of a particularly dense part of this medium.
The Stein 2051 System
Authors: Strand K. Aa.
Published: July 2016

An investigation is currently being made of the parallax, proper motion, orbital motion, and mass ratio of the nearby binary star Stein 2051 [04h 11m.4, + 58°49’; (1900); mv = 11.08 and 12.44] based upon photographs taken with the Sproul Observatory 61-cm refractor, the 155-cm astrometric reflector of the U.S. Naval Observatory, and the 33-cm Vatican Carte du Ciel astrograph.

A parallax of 0”185 reduced to absolute has been obtained from the material of the Sproul and Naval Observatories which covers the period 1965 to 1975.

Since an arc of only 64° in the orbital motion of the visible components has been described from the 1908 epoch of the earliest Vatican plate, and since the separation has increased from 6.” 3 at that time to 7.“ 3 at present and still on the increase, the period of the orbit can only be roughly estimated to be in excess of 300 years.

With all plates measured in the same reference frame it has been possible to determine the individual motions of the two components and the mass ratio between them. Preliminary results indicate a perturbation in the orbital motion of the red component with a period of 20 years and a semi-major axis of 0’.’065. The mass ratio between the red dwarf system and the white dwarf is 0.5.

A mass of 0.22 M⊙ of the red component has been determined based upon comparison of its luminosity (Mv = 12.42) with the red dwarfs Krüger 60 A (Mv = 11.82), o2 Eri C (Mv = 12.73) and Krüger 60 B (Mv = 13.48) which have the same spectral type (M4) and known masses of 0.26, 0.19, and 0.16 respectively in units of solar masses. Its dark compainion has a mass of 0.02 M⊙ The white dwarf of spectral type DC and Mv = 13.78 has a mass of 0.48 M⊙ as determined from the mass ratio of 0.5 mentioned above.
A Review of the Dynamics of Classical Triple Stars
Authors: Harrington R. S.
Published: July 2016

Four ways of studying the dynamics of triple systems are outlined, namely the analytical, the qualitative, the numerical, and the observational approach. A discussion of the stability of classical (revolutional, hierarchical) triples summarizes the results of analytical developments, based on the application of von Zeipel’s method to the general three-body problem, and of numerical experimentation. Finally, a summary is given of recent investigations concerning the dynamics of triples other than the revolutional systems.
Standards, Management and Security of Astronomical Data Sets
Authors: Davis M. S.
Published: July 2016

Astronomers have historically been among the first to apply or develop, at times, new technologies in the furtherance of their science. This has been especially true in the use of computers from their archaic, antediluvian beginnings to the present highly-developed, time-sharing, multiprocessing, teleprocessing systems. Thus, among the earliest applications in the last half century was the use by L. J. Comrie at the Greenwich Observatory of Hollerith machines for the construction of tables (Comrie, 1928). In 1940 Eckert described punched card methods for numerical integration, computation of a numerical lunar theory, computation of planetary perturbations, as well as applications in photometry and construction of star catalogues (Eckert, 1940). Indeed, one of the earliest collections of files for general use was available at the Watson Astronomical Bureau and included Boss’ General Catalogue of 33,342 stars, A. G. Catalogues, Yale Zone Catalogues, and Kohlschütter’s Catalogue.
Thoughts on the Form of Presentation of Star Catalogue Data
Authors: Eichhorn H.
Published: July 2016

The reductions of the direct measurements necessary for obtaining the published positions and proper motions of stars are rather involved. The transformation from equatorial coordinates to galactic coordinates – and proper motion components – is rather simple, and due to the exact definition of the galactic system, galactic coordinates and proper motion components can be given with the same accuracy as equatorial ones. Since it is data in the galactic system which are primarily of interest for the galactic astronomer, it is proposed that much data be henceforth published in catalogues of star positions and proper motions. One may assume that the minority of astronomers who need the data in the equatorial system will be least likely to make mistakes in transforming them back to the more direct form in which they were observed.

It is further suggested that the SAOC could be used as a base for continuous improvement and updating of a comprehensive catalogue of star positions, to be updated by the incorporation of newly available material every other year or so. Procedures by which this would be accomplished are indicated.
The Catalogue of Stellar Identifications
Authors: Ochsenbein F. , Egret D. , Bischoff M.
Published: July 2016

Collecting all the data and references for a given star is generally a very time-consuming task, because the star may have many identifications. It is therefore a very first need to know the various identifications which may be used in the primary literature concerning a given star, in order to retrieve the whole set of information about the star.

The Catalogue of Stellar Identifications (CSI), which tries to solve this problem of cross-identifications, is therefore the fundamental file of the Stellar Data Center. It was created five years ago by J. Jung (1971), who was the first Director of the Center, with the help of Madame Bischoff and Madame Morin. The CSI was first a merging of some fundamental catalogues: SAO, HD, AGK2, CPC (Cape Photographic Catalogue for 1950), YZ (Yale Zone Catalogue), and GC. For each star, the information was the following:
The Influence of Acquisition Techniques on the Compilation of Astronomical Data
Authors: Westerhout Gart
Published: July 2016

With the increasing use of electronic rather than photographic data collection, and on-line minicomputers at the telescope, two factors will necessitate a reconsideration of the way in which data are stored at the telescope.

1) Many of the electronic data collecting methods produce data in a final or semifinal (digital) form and usually with a large dynamic range; high-data-rate digital recording devices at the telescope are increasingly necessary.

2) Minicomputers allow quality control of data and often complete data reduction either in real time or with a very short time delay. We shall consider both these factors in some detail, emphasizing some of the many possibilities inherent in the increasing availability of one- and two-dimensional array detectors and mass storage devices. But let us first briefly examine the “classical” data gathering techniques. As in the later discussion, we shall subdivide the field into high-resolution spectroscopy, low-resolution spectroscopy (including multicolor photometry), surface photometry of extended objects, and positional astronomy.
Data Storage Requirements in Relation to Radio Interferometry Observations
Authors: Walter H. G.
Published: July 2016

Preliminary results of a search for observational data of radio sources are presented. Emphasis is put on those items which are imperative to make such a data collection amenable to astrometrical exploitation with a view to the identification of optical and radio positions, and the selection of suitable radio stars as reference points for other galactic and extragalactic objects.
The Critical Evaluation of Stellar Data
Authors: Underhill Anne B. , Mead Jaylee M.
Published: July 2016

Many catalogues of astronomical data appear in book form as well as in a machine-readable format. The latter form is popular because of the convenience of handling large bodies of data by machine and because it is an efficient way in which to transmit and make accessible data in books which are now out of print or very difficult to obtain. Some new catalogues are prepared entirely in a machine-readable form and the book form, if it exists at all, is of secondary importance for the preservation of the data.

In this paper comments are given about the importance of prefaces for transmitting the results of a critical evaluation of a body of data and it is noted that it is essential that this type of documentation be transferred with any machine-readable catalogue. The types of error sometimes encountered in handling machine-readable catalogues are noted. The procedures followed in developing the Goddard Cross Index of eleven star catalogues are outlined as one example of how star catalogues can be compared using computers. The classical approach to evaluating data critically is reviewed and the types of question one should ask and answer for particular types of data are listed. Finally, a specific application of these precepts to the problem of line identifications is given.
Main Features of The Stellar Bibliographic File
Authors: Ochsenbein F. , Spite F.
Published: July 2016

Due to the increasing amount of the literature about stellar studies, the gathering of the published information about a given star becomes a tedious and time consuming task. For enabling an automatic retrieval of information, a bibliographic file has been built in machine readable form through collaboration between Paris and Strasbourg Observatories. The file begins with the year 1950, and is kept up to date. Knowing the name of a star, a program prints the titles of the papers quoting this star. However, only the main journals were covered at first, and some other limitations have been imposed. The first part of this file will be very soon published on microfiches. Meanwhile the information can be obtained from the Strasbourg Stellar Data Center, (Centre de Données Stellaires).
Astronomical Data Files at the U. S. Naval Observatory: Star Catalogues, Ephemerides, and Observations
Authors: Fiala A. D. , Seidelmann P. K.
Published: July 2016

The history, contents, and method of distribution of the astronomical data files of the Naval Observatory are described. Some of the cooperative efforts to deal with the “data explosion” are discussed.
The influence of Magnetic Fields in the Solar Atmosphere Theoretical Aspects
Authors: Meyer F.
Published: July 2016

Since their first discovery in sunspots by Hale (1908), magnetic fields have been found connected with practically every structure of the solar atmosphere. Their omnipresence is due to the high electrical conductivity of the solar plasma and their dynamical importance is to a large degree due to the rapid outward decrease of gas pressure at the solar surface. In the following we will discuss some of the physical aspects of magnetic fields in the solar atmosphere.
Mass and Energy Flow in the Solar Atmosphere Implications of Skylab Observations
Authors: Wlthbroe George L.
Published: July 2016

The Skylab experiments acquired a wealth of observations applicable to investigating problems associated with the mass and energy flow in the solar atmosphere. In this review we discuss some of the observations of quiet regions, coronal holes and active regions and Illustrate the fundamental role that magnetic fields play in defining the structure and the mass and energy flow in these regions. Figure 1 (Altschuler et al., 1976) illustrates three major classes of structure: (1) strong field, magnetically closed areas typified by active regions, (2) weak field, open regions which, according to present evidence, appear to be associated primarily with coronal holes, and (3) weak field regions which appear to be magnetically closed on a large scale and appear to be associated primarily with normal quiet areas. Some of these latter structures can be seen in the X-ray photograph presented in Figure 2 (Vaiana et al., 1973a). Also evident in this figure are large coronal holes near the east limb at the north pole.
Surface brightness, standard candles and qo
Authors: Petrosian Vahé
Published: July 2016

Nous décrivons les effets de l’évolution ou de la variation de la brillance superficielle et des échelles de taille des galaxies, sur la relation magnitude-décalage vers le rouge. Nous discutons une méthode pour évaluer l’évolution de l’échelle de brillance superficielle. Elle permet de déterminer le paramètre de décélération et de faire une distinction entre le modèle cosmologique en expansion et le modèle du type lumière fatiguée.
Galactic evolution and the interpretation of cosmological tests
Authors: Tinsley Beatrice M.
Published: July 2016

Resume:

L’évolution galactique influence l’interprétation des tests cosmologiques en modifiant les relations entre la magnitude apparente, le diamètre angulaire, le décalage spectral, etc…, prédits par divers modèles. On considère plusieurs tests. Il se peut: (l) que l’évolution stellaire et dynamique dans les galaxies elliptiques rendent ensemble le diagramme de Hubble peu sensible au modèle cosmologique; (2) que la relation éclat-décalage dépende non seulement de l’évolution de luminosité mais aussi de la cosmologie; (3) que les dénombrements de galaxies à magnitude limite démontrent l’évolution galactique et renseignent sur le décalage au moment de la formation des galaxies. En général, les galaxies lointaines renseignent plus sur leur propre évolution que sur le modèle cosmologique.
Anomalous redshifts in groups of galaxies
Authors: Heidmann J.
Published: July 2016

Nous passons en revue les données d’observation sur les décalages spectraux anormaux dans les groupes de galaxies, incluant les paires, mais laissant de côté les aspects traités par d’autres: associations galaxie-quasar, amas de galaxies et théories.

La premiére partie traite des études individuelles sur les paires: paires connectées, compagnons en bout de bras spiral, paires serrées, paires superposées, puis des multiplets et des chaines.

La deuxeéime partie traite des études statistiques sur les compagnons des galaxies principales, les paires et les groupes.
21-cm observations of 3 C 286
Authors: Wolfe A. M.
Published: July 2016

Les observations VLB de la raie 21 cm en absorption décalée vers le rouge dans le QSO 3C 286 montre que le gaz s’étend, dans une zone ≥ 0.01” avec une variation de vitesse de 3kms-1. Ces observations rejettent l’hypothèse d’une enveloppe de gaz poussée par les photons émis, mais ne sont pas inconsistantes avec une absorption par une galaxie sur la ligne de visée.