bluuebunny/crossref_metadata_2025 huggingface dataset:
Stellar Surface Convection, Line Asymmetries, and Wavelength Shifts
Authors: Dravins Dainis
Published: July 2016

Wavelength positions of photospheric absorption lines may be affected by surface convection (stellar granulation). Asymmetries and wavelength shifts originate from correlated velocity and brightness patterns: rising (blueshifted) elements are hot (bright), and convective blueshifts result from a larger contribution of such blueshifted photons than of redshifted ones from the sinking and cooler (darker) gas. For the Sun, the effect is around 300 m s−1, expected to increase in F-type stars, and in giants. Magnetic fields affect convection and induce lineshift variations over stellar activity cycles. A sufficient measuring precision reveals also the temporal variability of line wavelengths (due to the evolution of granules on the stellar surface). A major future development to come from adaptive optics and optical interferometry will be the study of wavelength variations across spatially resolved stars, together with their spatially resolved time variability. Thus, precise radial velocities should soon open up new vistas in stellar atmospheric physics.
Upward Revision of the Individual Masses in Alpha Cen: Implications for the Evolutionary State of the System
Authors: Neuforge C. , Pourbaix D. , Noels A. , Scuflaire R.
Published: July 2016

A new calibration of the α Cen system is presented. It shows that a theoretical model consistent with the observations and with the higher masses determined by Pourbaix (1999) can be obtained. Our model of α Cen A has a convective core. This could serve as a discriminant in a future asteroseismological calibration of the system.
Spectroscopy of Project Fire I, April 14, 1964
Authors: Millman Peter M.
Published: July 2016

The Fire I test, April 14, 1964, was designed to study the heating of an Apollo-type reentry vehicle. The total reentry complex weighed approximately 230 kg and entered the upper atmosphere at a velocity of 11.5 km/s. The spectrum of the reentry complex has been studied in the wavelength range 8700 to 8800 Å, where 102 multiplets of 21 atoms and the band systems of 5 diatomic molecules have been identified. Comparisons with meteor spectra are made.
On the Influence of the Atmospheric Dust on the Zodiacal Light Polarization
Authors: Divari N. B. , Krylova S. N.
Published: July 2016

Three-color observations of the nightglow brightness and polarization were made at the Majaky Observatory in October 1969 to determine the brightness of zodiacal light at the ecliptic pole. On the assumption that the degree of polarization of zodiacal light is 0.20 at the ecliptic pole, the corresponding brightnesses are found to be 68, 70, and 96 G2 stars of the 10th magnitude per square deg. at 0.37, 0.53, and 0.58μ.

The large diurnal variations in observed intensity and direction of polarization are attributed to the effects of dust in the Earth’s atmosphere.
On the Manganese Content of Cosmic Flakes From Deep-Sea Sediments
Authors: Utech Karl
Published: July 2016

Cosmic flakes belong to the category of cosmic microparticles. They occur together with cosmic spherules in sediments (Utech, 1965). These flakes appear to represent ablation products of iron meteorites burnt away during the passage of a meteorite through the atmosphere by friction against air molecules. Microprobe analyses offtakes from deep-sea deposits proved the particles to consist of magnetite which in most cases had been altered into maghemite in the outer zones. This is in agreement with the assumption that they represent fragments of fusion crust of iron meteorites. Most of the flakes, however, contained a small percentage of manganese. This element is not a common constituent of iron meteorites. The author attempts to explain the presence of manganese in flakes and its absence in cosmic spherules.
The Cometary and Asteroidal Origins of Meteors
Authors: Kresák Lubor
Published: July 2016

A quantitative examination of the gravitational and nongravitational changes of orbits shows that for larger interplanetary bodies the perturbations by Jupiter strongly predominate over all other effects, which include perturbations by other planets, splitting of comet nuclei and jet effects of cometary ejections. In an approximation to the restricted three-body problem, Sun-Jupiter-comet/asteroid, the value of the Jacobian integral represents a parameter of conspicuous stability which can be applied to delineate the evolutionary paths of the potential parent bodies of the meteoroids in the system of conventional orbital elements. Earth-crossing orbits can be reached along three main paths by the comets, and along two by the asteroids.

The structure of meteor streams, however, indicates that the mutual compensation of the changes in individual elements entering the Jacobian integral, which is characteristic for the comets, does not work among the meteoroids. It appears that additional forces of a different kind must exert appreciable influence on the motion of interplanetary particles of meteoroid size. Nevertheless, the distribution of the Jacobian constant in various samples of meteor orbits, from those of faint Super-Schmidt meteors up to those of meteorite-dropping fireballs, furnishes some information on the type of their parent bodies and on the relative contribution of individual sources.
Cometary vs Asteroidal Origin of Chondritic Meteorites (Abstract)
Authors: Wetherill George W.
Published: July 2016

Monte Carlo calculations indicate excellent agreement between observed and predicted orbits of Prairie network fireballs, if it is assumed that fireballs are derived from remnants of short period comets of Jupiter’s family. No such satisfactory agreement has been found for any other proposed source. The distribution of radiants and time of fall observed for chondrites will also be reproduced by this source, provided that consideration is given to the fact that the Earth’s atmosphere will permit low velocity bodies to survive but will destroy high velocity bodies. Again, no other proposed source has been found to be adequate.

It now appears likely that the mean lifetime of chondrites is limited to ˜107 yr by the high probability of complete fragmentation following impact by smaller bodies. This improves the agreement between the observed cosmic ray exposure ages and those predicted for a cometary source. This also requires some modification of the earlier discussions of alternative sources, but does not result in them becoming more satisfactory.
Bar Properties as a Function of Hubble Type
Authors: Elmegreen Debra Meloy
Published: July 2016

Previous optical surface photometry of barred spiral galaxies revealed that there are two distinct types of bars: large bars tend to have a nearly constant surface brightness (”flat“ bar), while smaller bars tend to have a decreasing surface brightness with a scale length similar to the disk (”exponential“ bar). Statistically, flat bars tend to occur in early Hubble types and exponential bars in later types. Studies of resonances in spirals indicate that flat bars end inside corotation, while exponential bars end between the inner Lindblad and 4:1 resonances. Near-infrared (JHK) surface photometry of bars is presented in order to compare the stellar distributions and bar potentials in flat and exponential barred galaxies. The presence of isophotal twists in some galaxies provides additional information on resonances. The grand design and fiocculent optical structures in the two types of barred galaxies will be compared and contrasted with their near-infrared light distributions.
The Far-Infrared Radiation in M83
Authors: Jones L. V. , Keel W. C.
Published: July 2016

The fact that a galaxy is barred may have an effect on the source of the far-infrared (FIR) radiation observed. Yet, to date, no one has addressed the effects that that might have on interpreting the global FIR signal. We hope to add to the existing data on FIR radiation in galactic bulges by comparing a barred galaxy, M83, to an unbarred galaxy, M74.

We use optical, Ha and UV images that are blurred to the same resolution as the IRAS HIRES images. Looking at the blurred UV images, bright "globs" were chosen and apertures were fit to them. The “globs” were then located on the optical, Hα and FIR images and fluxes were determined for each aperture used.
Molecular Gas in the Central Regions of Barred Galaxies
Authors: Kenney Jeffrey
Published: July 2016

The morphology and kinematics of molecular gas in the central regions of barred galaxies are described. The largest gas concentrations are often located near ILRs, although there is a range of morphologies. The gas motions associated with star-forming rings are predominantly circular, while motions just beyond the rings are often non-circular and in some cases show clear radial inflow. In barred galaxies with circumnuclear starbursts in early phases of evolution, the CO is centrally peaked, perhaps inside IILRs. The most intense star formation occurs where the gas motions are circular, and where the rotation curve rises steeply and is nearly solid body.
HI Absorption as a Tracer of Nuclear Rings in Galaxies
Authors: Koribalski Bärbel
Published: July 2016

H ɪ absorption measurements against strong continuum background sources are an excellent tool to study the cold ISM in the line of sight to the object (e.g. pulsars, galaxies, quasars). Here we present a brief overview of such studies against the nuclear region of starburst galaxies. The high angular resolution provided by synthesis telescopes allows us to resolve the central region of nearby galaxies and thus investigate the gas kinematics close to the nucleus. The detection of fast-rotating nuclear rings is related to the bars in these galaxies which in turn might have been triggered by tidal galaxy-galaxy interactions.
Non-Axisymmetrical Components in the Gravitational Potential of Isolated Spiral Galaxies and the Presence of Nuclear Activity
Authors: Márquez I.
Published: July 2016

From a detailed photometric analysis together with some kinematical information for a sample of isolated spirals, we conclude that most of them host rings or bars, features generally explained as originating from a non-axisymmetrical component of the gravitational potential. In a previous study, we have determined that all the isolated spirals hosting an active nucleus show these kinds of non-axisymmetrical components, the presence of which could be connected with the nuclear activity in the form that they can be very effective in transporting gas into the central parts. Therefore, as non-active spirals show a similar behavior, a detailed analysis of the possible differences between the central regions of active and non-active isolated spirals is motivated.
Modelling the Structure of the Ringed Spiral NGC 4736
Authors: van Driel Wim , Mulder Pieter , Combes Françoise
Published: July 2016

We studied the ringed RSab(r)-type spiral NGC 4736, which has a probably slightly oval disk and a very small bar. We mapped the galaxy in the HI and Hα spectral lines and we obtained long-slit optical spectra. These data were modeled using a 2-D gas dynamical code. The 2-D potential used is axisymmetric in the inner and outer regions and oval (b/a=0.8) at intermediate radii only. The oval component rotates at a pattern speed of 40 km s–1 kpc–1, close to the observed value. Inner and outer rings, like those observed, form at the inner and outer Lindblad resonances, though they co-exist only during a limited time interval in the simulations. The morphology and kinematics of the inner ring and spiral structure as observed in neutral and ionized hydrogen can be well understood in terms of gas dynamical simulations, given the form of the (stellar) potential. What remains to be explained is the origin of the nonaxisymmetric features in the mass distribution defining the potential.
Ring Formation in the Disk of Barred Galaxies
Authors: Guivarch B. , Athanassoula E.
Published: July 2016

We study the effects of different collision laws and of recycling on the results of simulations using sticky particles to describe the gas clouds in a disc galaxy.
Global Bar–Forming Instabilities
Authors: Christodoulou D. M. , Shlosman I. , Kazanas D. , Tohline J. E.
Published: July 2016

We have recently obtained some interesting results on the global stability characteristics of gaseous and stellar systems using a free–energy variational formulation and Ginzburg–Landau phase transition theory (Christodoulou et al. 1995a, b). For m = 2 nonaxisymmetric modes in particular, we have been able to formulate a new, robust, global stability criterion (Christodoulou, Shlosman, & Tohline 1995, hereafter CST) that avoids many of the problems that plagued the well–known Ostriker & Peebles (1973) criterion. In this article, we briefly summarize the conclusions from the above–cited investigations and we proceed to comment on the stability properties of some interesting stellar models that were discussed during this conference and that are not trivially understood in terms of the new stability criterion.
Counterrotation and Barred Galaxies
Authors: Galletta G.
Published: July 2016

In this review we discuss the phenomenon of counterrotation, observed in ~40 apparently normal galaxies where gas or stars are rotating in a direction opposite to the main stellar body. It appears in all morphological types, from ellipticals to spirals or irregulars.

The problem of the origin and the evolution of counterrotation is discussed, in the wider frame of the galaxies accreting matter from their environment (e.g., minor-axis dust-lane ellipticals or polar-ring S0s). Various sources of matter appear to be candidates for the production of the counterrotation.

Due to the tendency of the bar potential to populate particular families of orbits, some cases of counterrotation found in barred galaxies are interpreted as intrinsic to barred galaxies.
The Wavy-Pattern of Stellar Rotation Curves in SBO Galaxies
Authors: Wozniak H. , Pfenniger D.
Published: July 2016

We discuss the “rotation” curves of SB0 galaxies with self-consistent models constructed with Schwarzschild’s method. Their distribution functions are compared with that of N-body simulations.
A Tidal Trigger of Starburst or Seyfert Activity
Authors: Chatterjee Tapan K.
Published: July 2016

Some of the classical seyferts are observed to be prototypical ovals, e.g. NGC 1068 and 4151 (e.g., Bosma 1981; Kormendy 1982; Scoville et al. 1988). Such a non-axisymmetric potential corresponding to an oval disk can produce inward flow of gas and induce mild activity. To test the efficiency of this process, we study a collision between a face-on spiral with a high gaseous content and an equally massive compact elliptical, under marginally bound conditions, as such encounters are most frequent.

We model the spiral galaxy by an exponential model disk (of radius R) with a (static) thickness and scale length α = 4/R and a spherical polytropic bulge (n=0,3,4, equally weighted combination) containing 1/3 of the mass (cf. Chatterjee 1990); about 20% of the mass of the disk contains gas particles. The elliptical is modeled identically as the bulge. The gravitational potential is softened with softening constants of ∊ = r∘/5, r∘/3, and 0.8r∘, for the bulge of the spiral as well as the elliptical, stellar and gaseous components of the disk, respectively. Here r∘ is the radius containing 75% of the total mass of the galaxy in question, while the mutual gravitational interaction is softened with a softening constant of r∘/4.
Stellar Orbits in Barred Galaxies with Nuclear Rings
Authors: Heller Clayton H. , Shlosman Isaac
Published: July 2016

We investigate the dynamical response of stellar orbits in a rotating barred galaxy potential to the perturbation by a nuclear gaseous ring. The change in 3D periodic orbit families is examined as the gas accumulates near the inner Lindblad resonance. It is found that the x2/x3 loop extends to higher Jacobi energy and a vertical instability strip forms in each family. These strips are connected by a symmetric/anti-symmetric pair of 2:2:1 3D orbital families. A significant distortion of the x1 orbits is observed in the vicinity of the ring, which leads to the intersection between orbits over a large range of the Jacobi integral. We also find that a moderately elliptical ring oblique to the stellar bar produces significant phase shifts in the x1 orbital response.
Modelling the Galactic Bar using Red Clump Stars
Authors: Stanek K. Z. , Mateo M. , Udalski A. , Szymański M. , Kałuzny J. , Kubiak M. , Krzemiński W.
Published: July 2016

The color-magnitude diagrams of ~ 1 × 106 stars obtained for 19 fields towards the Galactic bulge with the OGLE project reveal a well-defined population of bulge red clump stars. We found that the distributions of the extinction-adjusted apparent magnitudes of red clump stars in fields lying at ι = ±5° in galactic longitude differ by ∼ 0.4 mag. A plausible explanation of this observed difference in the luminosity distribution is that the Galactic bulge is a triaxial structure, or a bar, which is inclined to the line of sight by no more than 45°. The part of the bar at the positive galactic longitude is closer to us. Work is now under way to model the Galactic bar by fitting the observed luminosity functions in the red clump region for various fields. Preliminary results indicate that the angle of the inclination of the bar to the line of sight can be as small as ∼ 20°. Gravitational microlensing can provide us with additional constraints on the structure of the Galactic bar.
A Gas Dynamical Approach to a Face-on View of Our Galaxy
Authors: Wada Keiichi , Taniguchi Yoshiaki , Habe Asao , Hasegawa Tetsuo
Published: July 2016

Recently the bar model for our Galaxy has been an emerging consensus. Here, we investigate how a rotating bar-like bulge affects the global gas dynamics in a disk and compare the longitude-velocity (LV) maps from self-gravitating hydrodynamical simulations, which is based on Wada and Habe (1992), with observed maps of neutral hydrogen and carbon monoxide in the Galaxy. We found that the features on the numerical LV maps depend strongly on four factors: the pattern speed of the bar, the position angle of the Sun, the strength of the bar potential and the ratio of the gas mass to total dynamical mass. We conclude that our Galaxy has a rotating, weak, bar-like bulge (a/b ∼ 0.7) observed from nearly end on (θp < 20°). The allowed range of pattern speed of the bar is surprisingly narrow (19±5 km s−1 kpc−1) and is consistent with recent observations of bulge stars. Self-gravity of the interstellar matter is needed to account for the observed molecular ring at a radius of ∼ 4 kpc even if the gas mass fraction to the dynamical mass is small (about 5%).
The Corotation Radius and Other Resonances in NGC 7479
Authors: Aguerri J. A. L. , Muñoz-Tuñón C. , Varela A. M. , Prieto M.
Published: July 2016

The luminosity profiles perpendicular to the bar of the galaxy NGC 7479 display “shoulders”, which are observationally identified as an increase in the brightness profile (see Figure 1, right). In the literature (see e.g. Buta 1986), the presence of these features in other barred spirals has been reported. The “shoulders” have been attributed to annular structures resulting from the presence of a bar (Schwarz 1981, 1984, 1985), appearing at the OLR. Their stability and the precise modelling depends on the structural parameters of the bar. We attempt to test the plausibility of this theoretical interpretation using 2D photometry of the barred galaxy NGC 7479. The key parameter is the corotation radius (CR), defined as the galactocentric distance at which the gas and the shock wave corotate. From the CR all other Lindblad resonances can be obtained. Some of the techniques used to derive the CR are:
Pole Coordinates by the IMPS Stations
Authors: Yumi S. , Yokoyama K. , Ishii H.
Published: July 2016

Pole coordinates derived from the latitude data of the IPMS stations during 1962.0 – 1974.3 are compared with thos’e by the 5 ILS stations. A systematic change in the difference is mainly attributed to a supposed change in a local effect at Ukiah and an annual variation in those at Kitab and Carlo-forte, noting that the results from a more numerous set of stations would give a more precise solution.
Hybrid Systems for Use in the Dynamics of Artificial Satellites
Authors: Kozai Y.
Published: July 2016

For observed positions ofi artificial satellites and their orbital elements, many kinds of reference coordinate systems have been available. Some are more convenient for reductions of observations, while others are more convenient for analyzing the orbital elements for geodesy. In this review paper, perturbations produced owing to the adoption of diffrent kinds of reference systems are discussed.
General Principles for the Realization of Reference Systems for Earth Dynamics
Authors: Veis G.
Published: July 2016

A reference system is useful to express conveniently the location of a point and to study kinematic and dynamic phenomena. Although the definition of a reference system is theoretically very simple, its realization becomes very fifficult since it must be achieved by measurements reduced and expressed in this system.

A referenoe system can be materialized by direct measurements of the coordinates or, more frequently, indirectly by measuring differential quantities and calculating the coordinates “de proche en proche.” The accuracy of the system definition cannot be better than the accuracy of the measurements themselves.

For Earth dynamics we need a reference system related to the Earth, but since observations of other bodies such as galaxies, stars, planets, and satellites also may be required, the reference systems in which the positions of these bodies are expressed must also be related to the selected terrestrial system.

To optimize the selection of a reference system one must consider both the phase of the operations for the establishment of the system and the phase of the utilization of the system, because the establishment of a reference system is not the final goal.
The Role of VLBI in the Establishment of Coordinate Systems
Authors: Zhongolovitch I.
Published: July 2016

Considering the future development and general solution of the problem under consideration and also the high precision attainable by astronomical observations, the following procedure may be the most rational approach:

1. On the main tectonic plates of the Earth’s crust, powerful movable radio telescopes should be mounted at the same points where standard optical instruments are installed. There should be two stations separated by a distance of about 6 to 8000 kilometers on each plate. Thus, we obtain a fundamental polyhedron embracing the whole Earth with about 10 to 12 apexes, and with its sides represented by VLBI.
The Determination of the Equator-Point for Observing Star Declinations
Authors: Mikhailov A. A.
Published: July 2016

The deolinations of the stars are by definition reckoned from the celestial equator. However this great circle is not marked on the sky; therefore, instead of dejclinations, the polar distances of the stars are measured, as the position of the pole can be found by observing a star in upper and lower culmination and taking the mean zenith distance, corrected for changes in the position of the star and observer during the elapsed interval of time. Thus the zero point of the polar distance to be measured is established and it remains to determine the scale, which is given by the divisions of the circle. These divisions must be carefully investigated as to their strict equality and they must go around the circle without a gap or overlapping. In this way, the scale has only one fixed point in the pole, while the other end near the equator hangs loosely. This leads to a noticeable discrepancy near the celestial equator when the measurements starting from the north pole meet those from the south pole. It would be very valuable if we could determine the position of an intermediate point, say on the equator, for then the measurements would be established at both ends and would consist of an interpolation between two fixed points. This can be achieved by determining the exact absolute declinations of a number of stars situated close to the equator with different right ascensions. We shall explain how this can be done.
Practical Realization of a Reference System for Earth Dynamics by Satellite Methods
Authors: Anderle R. J. , Tanenbaum M. C.
Published: July 2016

Observations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.
Comparison of the Uccle-Brussels Coordinates in the BIH, NWL and EUR 50 Systems
Authors: Pâquet P. , Dejaiffe R. , Rop W. De , Verbeiren R.
Published: July 2016

The possibility exists at the Royal Observatory of Belgium (Uccle-Brussels) of comparing the coordinates of a well-defined point simultaneously obtainable in the BIH, NWL and EUR50 astronomical and geodetical systems.

The following differences between these reference systems have been obtained:

if the longitudes are positively measured westward.
Results of Latitude Observations with the Floating Zenith Telescope at Mizusawa: Comparisons between the Results Obtained from the Astronomical and Doppler Satellite Observations
Authors: Takagi S.
Published: July 2016

In this article, we intended to see whether we can obtain the same pole motion from two kinds of telescopes: the floating zenith telescope (PZT) and the ILS zenith telescope (VZT). The observations with the PZT have been pursued since 1967.0 with a star list whose star places are taken from the PK4 and its supplement. We revised the method of reduction of the observations with the PZT by adopting a variable scale value for the photographic plate (Takagi et al., 1974).
1.1.8 Photometry of the Zodiacal Light with the Balloon – Borne Telescope Thisbe
Authors: Frey A. , Hofmann W. , Lemke D. , Thum C.
Published: July 2016

We report on new measurements extending the spectral range of our earlier photometry (Frey et al. 1974) to the near ultraviolet. The residual extinction caused by atmospheric ozone was found to be 0.m25 ± 0.m13 (2950 Å) and 0m36 ± 0m13 (2150 Å) at 41.5 km float altitude. Within the errors of 10-30% arising from calibration and the reduction procedure our measurements at 5000, 3450, and 2950 Å are compatible to a colour of the zodiacal light not different from that of the sun. Our result obtained at 2150 Å is an upper limit, since no reduction of airglow and integrated starlight has been done yet at that wavelength. This upper limit is 30% above a solar-like spectrum. This result is not in contradiction to the 0A0-2 measurements (Lillie 1972). The strong intensity increase he found occurs at wavelengths below 2150 Å.
1.3.2 Discussion of the Rocket Photometry of the Zodiacal Light
Authors: Leinert C. , Link H. , Pitz E.
Published: July 2016

The measurements of the zodiacal light at elongations ε = 15° to 30° performed by the ESRO rocket experiment R – 214 mere discussed on the basis of model calculations.
1.3.3 Consequences of the Inclination of the Zodiacal Cloud on the Ecliptic
Authors: Robley R.
Published: July 2016

Assuming that the decrease in the density of the interplanetary dust follows an exponential distribution both in the transverse and radial direction, we can write n = no Exp(-(h/H)-(r-l/R)), where h is the distance from the ecliptic plane and r the heliocentric distance both expressed in astronomical units (a.u.); then we show that the modulation of the radiance B(90, 0) of the zodiacal light observed at the ecliptic pole defines the parameter H as a function of the inclination angle B between the zodiacal cloud and the ecliptic plane; moreover, the experimental value of the ratio B(90, 0)/B(90, 90) defines the parameter R. It can be deduced that the flatness of the zodiacal cloud, expressed by R/H, is < 5 and that the plane of symmetry of the zodiacal cloud is very close to that of the invariant plane of the solar system (B<2°).
2.3.3 Micrometeorite Impact Craters on Skylab Experiment S 149
Authors: Nagel K. , Fechtig H. , Schneider E. , Neukum G.
Published: July 2016

During the Skylab experiment S 149 three different sets of areas were exposed. 71.5 cm2 were facing the sun for 46 days, and 36 cm2 for 33 days, whereas 77.5 cm2 were exposed in anti-solar direction for 34 days. A fourth set is currently being exposed with the hope of future recovery. The exposed surfaces consisted of stainless steel, aluminium, platinum, glass, and pyroxene. The recovered targets have been investigated with a light microscope and a scanning electron microscope. We found two groups of possible impact structures:

1.) Five craters between 1 and 30 µm. These craters show clear signs of hypervelocity impact. Measurements yielded diameter to depth ratios between 2 and 3. Chemical investigations in the craters yielded an enhancement in aluminium in one case.

2.) 44 crater-like structures between 1 and 4 (µm in diameter. These features have been found on 4 cm2 of pyroxene exposed in solar direction. They show diameter to depth ratios between 5 and 8. Chemical measurements of the interior of these structures indicate the elements of the pyroxene composition.

The five impacts of the first group correspond to a cumulative flux of the order of 10−4 (m−2s−l) for masses of about 10−12 g. The second group may indicate a fragmentation process at altitudes around 450 km. Considering these 44 crater-like structures having been produced by fragments of one projectile, the impact rate could be comparable to that calculated for the first group. If individual projectiles had produced these structures, the corresponding flux could be 2 orders of magnitude higher.
2.3.5 Magellan Collections of Large Cosmic Dust Particles
Authors: Hallgren D. S. , Hemenway C. L. , Wlochowicz R.
Published: July 2016

A new balloon collection technique, Magellan, for obtaining large cosmic dust particles > 50µ is described. The technique utilized a 40 m2 aperture funnel suspended 300 m below a balloon at an altitude of 25 km. First results indicate that the collected particles are diverse both chemically and physically.
2.3.6 Specific Sources of Extraterrestrial Particles
Authors: Rosinski J.
Published: July 2016

Sampling of magnetic particles in the 5 to 20 µm diameter size range on the earth’s surface at different latitudes was used to detect meteor streams composed of particles of masses too small to be detected by other means. Magnetic spheroid concentration peaks appeared simultaneously at different latitudes in the Northern and Southern Hemispheres, proving that the majority of spheroids is of extraterrestrial origin. Extraterrestrial particles consist of two major classes: (1) magnetic particles containing a high concentration of iron oxide in the form of magnetite; and (2) glassy particles containing a low concentration of iron and a large concentration of Si and Al; they contain Ni, Mn, Cr and Ti; the concentration of Ti is approximately one hundred times larger in glassy particles than in magnetic spheroids. Comparison of chemical composition of particles collected from different meteor streams must be very carefully evaluated; chemical composition of surfaces and interiors of magnetic particles is different due to selective fractionation of different chemical compounds between molten and solid phases and due to evaporation during entry of meteoritic particles into the atmosphere. The presence of H2O, CO2 and CnH2n+2 in internal cavities of a few spheroids was found to be difficult to explain; those gases were associated with meteoritic particles and consequently they existed in space. The yearly earth flux of extraterrestrial particles can only be determined by the summation of daily fluxes obtained at different latitudes; the daily flux changes from year to year. Fluxes of particles present in January and October were calculated. Particles collected in January seem to originate from sources present between November 6 and January 15; during this period of time S. and N. Taurid, Geminid, Ursid and Quadrantid meteor streams are active. Particles collected in October seem to originate from the unknown meteor stream or from the Giacobini-Zinner meteor stream providing it is preceded by micrometeoritic particles approximately two weeks prior to the visual display.
3.2 The Production Rate of Dust by Comets
Authors: Delsemme A. H.
Published: July 2016

The present set of short-period comets produces only 250 kg/sec of dust whereas the flux of long-period and “new” comets produces an average of 20 tons/sec.
3.6 Dust Emission from Comet Kohoutek (1973f) at Large Distances from the Sun
Authors: Grün E. , Kissel J. , Hoffmann H.-J.
Published: July 2016

During a period of 60 days around the time when the HEOS 2 satellite penetrated the orbital plane of Comet Kohoutek (1973f) the micro-meteoroid experiment on board registered an excessive particle flux. These particles are identified with those originated in Comet Kohoutek. Orbit calculations show that their emission occurred outside 3.8 AU from the sun. The ratio of the force of radiation pressure to that of gravity of these particles was determined to ß =1 ± 0.1, their mass has been measured from the satellite data (10−13g to 10−11g). The velocity and the rate of dust particles emitted from the comet is studied on the basis of the theory of dust comets formulated by Finson and Probstein. An emission rate of appr. 1.2 × 1018particles per second in the size range corresponding to 0.9 ≤ ß < 1.1 and an emission velocity of appr. 0.5 km/sec match best the observed data.
3.9 Condensation Processes in High Temperature Clouds
Authors: Donn Bertram
Published: July 2016

Neither thermodynamic calculations nor standard nucleation theory describe condensation processes in cosmic clouds, but rather are a first approximation. Condensation is an irreversible kinetic, not equilibrium, process. The nominal molecules of condensed minerals (e.g. Al2O3, CaTiO3, MgAl2O4) occur only in the bulk lattice not in cosmic gases. Reactions among gas molecules must be an intrinsic part of condensation. Molecules yielding a particular condensate are a small fraction, less than 10−3, of condensible and reactive (e.g. H, H2, H2O) molecules. No theoretical or experimental results are available for condensation under such conditions. There is no basis for expecting nearly pure, known minerals to form in cosmic clouds. A generalization of nucleation theory following Hirschfelder (JCP, 61, 2690, 1974 can be made, in principle. No thermodynamic data is known for most of the possible compositions of nucleating clusters and no calculations are possible. Grain compositions should fall between thermodynamic and kinetic calculations. An experimental study appears feasible and is planned. The following conclusions are drawn from the theoretical analysis. (1) An interpretation of interstellar grains may not be made using only terrestrial minerals. (2) Condensation temperatures and compositions of interstellar grains or primordial solar system condensates may not be deduced from equilibrium calculations.
4.2 Meteoroid Densities
Authors: Lindblad B.A.
Published: July 2016

The composition and density of meteoroids has been the subject of a number of investigations in recent years. Analysis of photographic meteor data have been presented by Jacchia et al (1967). Verniani (1964, 1967, 1969), Benyuch (1968, 1973, 1974), McCrosky and Ceplecha (1969) and others. The density of radio meteors have been studied by Verniani and Hawkins (1965) and Verniani (1966). in the present paper the dependence of meteoroid density on the type of the orbit is discussed.
5.11 A Technique for Measuring the Interstellar Component of Cosmic Dust
Authors: Tomandl Daniel A.
Published: July 2016

That there is an interstellar (IS) component in cosmic dust has been demonstrated by Pioneers 8 and 9 (Wolf, Rhee, and Berg, 1975). The Pioneer spacecrafts distinguished the IS from interplanetary (IP) dust by measuring particle velocity and direction. Unfortunately, detectors that are capable of measuring a particle’s velocity and direction are so restricted in their sensitive area and/or solid angle that their event rate is very low. Pioneers 8 and 9, for example, detected 1-5 IS particles out of 20 events in 7 spacecraft-years of operation (Wolf, Rhee, and Berg, 1976). More events can be obtained, however, if one uses a detector that only measures the direction of travel. The direction alone can be sufficient to distinguish between IS and IP dust—at least on a statistical basis. For example, if most IP dust travels in directions near the ecliptic plane, then an IS flux from out of the plane should be detectable. This paper will examine the use of direction alone in detecting IS particles.
6.4 Meteors
Authors: Ceplecha Z.
Published: July 2016

After hearing so many technical descriptions of different high velocity particle experiments, one easily recognizes the paramount importance of sensors for gathering the experimental data on meteoric dust. In contrast the “classical” meteor astronomy and physics is using a less expensive “sensor”, the Earth’s atmosphere. The interaction of the meteor body with the air has to be recorded and thus our experimental data are just records of the natural phenomenon itself: integral light photographs, spectral photographs, recently also image intensifier photographs and videorecords. The only “active” method is the radar observation of the ionized trail. The close distance of the phenomenon to the observational sites enables one to determine the complete geometrical and dynamical data (heights, distances, velocities); the light recording gives the intensity of the emitted light at individual points of the trajectory, the radar recording gives the ionization intensity. A suitable physical theory is necessary to convert the basic observational data into meteor mass and other parameters. The drag equation yields the “dynamic” mass, the luminosity equation yields the “photometric” mass, and the ablation equation yields the “ablation” mass. Por a single meteor, these masses are dependent on parameters defined by the drag coefficient, shape, bulk density, ablation rate and luminous efficiency. Differences in the resulting masses of a meteoroid computed from the different methods at the same trajectory point are good relative measures of the structural and compositional differences. The absolute calibration may be a problem, but laboratory and rocket measurements of the luminous efficiency, calibrations by the Lost City and Pribram fireballs and several other direct and indirect methods can be used.
Techniques of Perturbation Analysis
Authors: Van De Kamp Peter
Published: July 2016

A historical summary of stellar-perturbation analyses is presented, followed by a discussion of the attainable accuracy and the sources of observational errors. A provisional value for the mass-density of astrometric companions is found to be 0.063±0.018 (p.e.) solar masses per cubic parsec.
The Detection of Stellar Systems by Lunar Occultations
Authors: White N. M.
Published: July 2016

A few examples of the resolution of very close multiple stars by the method of lunar occultation are described. In this way both the power and some of the limitations of this technique may be demonstrated.
Effets de Selection Dans La Decouverte De Systemes Multiples
Authors: Muller P.
Published: July 2016

En étudiant les systèmes multiples issus d’un couple de découverte ancienne grâce à l’emploi ultérieur d’un instrument plus puissant, on constate qu’un grand nombre d’étoiles doubles n’ont jamais été examinées avec un tel instrument; il en résulte que parmi ces couples plusieurs centaines sont des systèmes au moins triples que nous ignorons.
Sur La Masse D’une Binaire Spectroscopique Membre D’une Etoile Double Visuelle
Authors: Couteau P.
Published: July 2016

We describe a method which interposes a relation Mass-Luminosity in order to calculate the dynamic parallax and the masses of the components in a system of known orbit which involves a spectroscopic binary. We apply the method to a few cases.
UBVRI Photometry of Stars in Trapezium Type Systems
Authors: Warman Josef , Echevarría Juan
Published: July 2016

We present UBVRI photometric data for 50 stars forming 14 systems of the trapezium type. Color-magnitude and color-color diagrams indicate the presence of ultraviolet excess and anomalous behavior in the infrared part of the spectrum. This is consistent with the dynamical ages for stars in trapezia.
The Formation of Multiple Systems by Dynamical Interaction in Clusters
Authors: Aarseth S. J.
Published: July 2016

This review is mainly devoted to a discussion of binary formation and evolution in stellar systems, as described by N-body techniques. The simplest formation mechanisms consist of ejection from bound triple systems and capture arising from hyperbolic three-body encounters. However, the large number of astrophysically close binaries cannot be accounted for in this way unless most stars are formed in compact groups. Numerical calculations show that the evolution of clusters containing several hundred members is invariably dominated by one central binary which absorbs a large fraction of the total energy. It is suggested that a visual binary in the core of the Hyades cluster may have been associated with this process.
Desiderata for the Catalogue of Nearby Stars
Authors: Gliese W.
Published: July 2016

In 1969 the second edition of the “Catalogue of Nearby Stars” was published. It contains 1529 single stars and systems with a total of 1890 components. The catalogue lists all stars with parallaxes equal to or larger than 0.”045. Only 1049 of these objects are nearer than 20 pc. The “Catalogue of Stars within 25 pc of the Sun”, published 1970 in the Royal Observatory Annals No. 5 consists of 1744 systems of which 1566 trigonometric parallaxes.
The University of Texas Catalog of Ultraviolet and Optical Stellar Data
Authors: Parsons Sidney B. , Wray James D.
Published: July 2016

At the University of Texas we are working on the reduction and analysis of ultraviolet stellar spectra obtained with the S-019 experiment on Skylab (Karl Henize, principal investigator). Our objective prism photographs recorded nearly 10,000 stars at wavelengths shortward of 3000Å, many of them of 9th or 10th visual mag., and for proper analysis we need to assemble ground-based data into a workable master catalog. The most immediate application of this catalog will be computer simulation of the ultraviolet photographs in order to point out significant anomalies with respect to previous knowledge. We need to have a catalog, then, which is as complete as possible in terms of the existence of early-type stars to at least 10th mag., their spectral types, photometry, known peculiarities, duplicity, and so forth. Also the master catalog must contain only a single value for each magnitude and for the spectral type, rather than a listing of various determinations, in order to be useful for the simulation. This means that auxiliary data files are needed for recording data in more detail so that the master catalog may be kept at a workable size, while at the same time the basic data are readily available.
Critical Evaluation of Photometric Data
Authors: Nicolet B. , Hauck B.
Published: July 2016

Some problems encountered in the homogenization of photometric data (especially for the uvby$ and UBV systems) are presented: sources of inhomogeneity, method to obtain a homogeneous photometric value, establishment of a reference list, etc.

In many cases a homogeneous photometric value is necessary, but cannot be simply an arithmetical mean, and for this purpose it is necessary to make a critical evaluation of the data.
Some Thoughts on Astronomical Data Files
Authors: Bidelman William P.
Published: July 2016

Several astronomers were relaxing after a hard day at the I.A.U. when the talk got around to their research activities. One said, “There is a red star found in the Lowell proper-motion survey that seems rather interesting – it is G232-75, which has a proper motion of almost a second of arc per year. Since Giclas1 catalogue doesn’t give any spectral type I’m planning to go to Kitt Peak to observe it. The trip only costs about 300 dollars, and besides it’s fun to visit Arizona.”
A Catalogue of Photometric Sequences Supplement No.2
Authors: Argue A.N. , Miller E.W.
Published: July 2016

Photometric observers have from time to time expressed the need for a convenient way of finding in the literature the photometric sequences they require. This need is particularly felt in photographic photometry, and the increasing use of the Palomar Sky Survey in recent years, and more recently the ESO and SRC surveys, have given a new impetus to the subject. In addition, the use of image tubes has led to a further demand for suitable calibration sequences.
Proposal for A Data Centre on Galactic Non-Stellar Objects
Authors: Lortet M. C.
Published: July 2016

Bibliographic work was begun in 1969 on Interstellar Matter and Galactic Non-Stellar Objects, mainly those found in regions suspected to be favourable to star formation.

We are contemplating the systematization and automatization of this work, taking advantage of the tools now worked out for stellar data at the Centre de Données Stellaires de Strasbourg.
Third General Catalogue of MK Spectral Classifications
Authors: Buscombe William
Published: July 2016

For the convenience of astronomers who need information concerning certain stars but prefer not to search through hundreds of research articles in the hope of finding it, a file of MK spectral types and UBV photoelectric photometry is maintained at Dearborn Observatory. A generous donor made possible the publication in 1974 of a listing of approximately 17,000 IBM cards of data compiled by Pamela M. Kennedy and William Buscombe during 1963-1973.
Concluding Remarks
Authors: Garstang R. H.
Published: July 2016

When listening to the papers which have been presented I was struck by the feeling that much more effort is being devoted to the problems of the acquisition and handling of vast quantities of data than to the evaluation and presentation of the data, a situation which has in the past applied to spectroscopic data as well. The list of Data Centers which Dr. Jaschek presented attests to the efforts now underway to collect data. I would therefore urge strenuous attempts to critically evaluate collections of data whenever such evaluation is meaningful and feasible. I believe that many of our colleagues expect us to tell them a ‘best’ value for any particular datum, with, if possible, an indication of whether it is considered trustworthy (by a probable error or a quality index). I believe that this principle of giving the best representative values underlies much of the success of C. W. Allen’s book Astrophysical Quantities as well as of compilations such as the National Bureau of Standards spectroscopic publications. I would also emphasize the continuing value of bibliographies, at least in cases when the original data are published in widely scattered articles and until the publication of a comprehensive compilation. I believe that good bibliographies on topics of special interest could go far to meeting the casual needs of many users of our data.