bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectrophotometric reductions with an IBM 1620
Authors: Eriksson P.-I.
Published: July 2016

Nowadays more and more of the reductions of astronomical data are made with electronic computers. As we in Uppsala have an IBM 1620 at the University, we have taken it to our help with reductions of spectrophotometric data. Here I will briefly explain how we use it now and how we want to use it in the near future.
Photoelectric spectrophotometry of G-type main-sequence stars
Authors: van den Bergh S.
Published: July 2016

Almost all our information about stars is ultimately derived from analysis of the wavelength dependence of stellar radiation. Traditionally the stellar energy distribution has been studied at very high resolution (spectroscopy) and very low resolution (photometry). Until quite recently the intermediate resolution range, involving investigations with a resolution (spectral purity) of between 10Å and 100Å, has been rather neglected. The intermediate resolution range may be studied using low dispersion objective-prism spectra, narrow-band filters or photo-electric spectrophotometers.
The search for faint-blue stars
Authors: Bok B. J.
Published: July 2016

Reflectors with Ritchey-Chrétien optics are especially suited for colour studies of stars too faint for discovery and study by objective-prism techniques. At the Cassegrain focus (f/8) of the 40-inch reflector at Siding Spring Observatory, we have a field of perfect definition with a diameter of one degree, and with a plate scale almost three times that of the 48-inch Palomar Schmidt. Even for multicolour photometry, there is no problem of overcrowding and the magnitude limit of the study is as faint as the available standard magnitudes permit one to go. Multicolour photography with Ritchey-Chrétien reflectors with apertures of 40 inches and greater offers unparalleled possibilities for the discovery of intrinsically blue stars.
Classification of K dwarfs according to metal abundance
Authors: Pagel B. E. J.
Published: July 2016

The work of Eggen, Lynden-Bell and Sandage (1) and of Eggen (2) on the correlation between space motion and ultraviolet excess on theUBVsystem among near-by dwarfs has brought out two very interesting effects (among others): first, the usefulness of the eccentricity of a star's galactic orbit as a kinematic parameter; and second, the sharp division into two main stellar populations. We may identify these as a disk population (Baade's Type I) with eccentricitye≤ 0·5 and ultraviolet excess δ (U — B) ≤ 0m15 and a halo population (Baade's Type II) with both parameters usually exceeding these limits; stars of the halo population have velocities symmetrically distributed about the valueV= − 250 km/sec relative to the local standard of rest, corresponding to zero galactic rotation.
Observations en six couleurs d'etoiles F, G et K analysees du point de vue des effets du rougissment interstellaire et de la composition chimique
Authors: Canavaggia R.
Published: July 2016

Je voudrais exposer quelques vues sur les renseignements que l'on peut tirer de la photométrie en six couleurs de l'Observatoire Lick, pour l'étude des étoiles de types avancés, aux points de vue du rougissement interstellaire et de la composition chimique. Mianes et moi avons déjà publié deux notes aux Comptes Rendus à ce sujet (1, 2). Généralisant une méthode exposée dans un mémoire déjà ancien (3), nous avons entrepris de déterminer le rougissement interstellaire des étoiles F, G, K, supergéantes, géantes ou naines, par comparaison avec les couleurs intrinsèques des céphéides de population I, supposées connues. En ce qui concerne les naines, nous avons abouti à ce qui paraît être, pour les étoiles F et G tout au moins, une excellente méthode pour la mise en évidence d'une déficience en métaux. En plus de cela, la comparaison avec les céphéides fait ressortir, chez les étoiles de types G avancés et K, un défaut de rayonnement dans le visible qui pourra être utile dans l'analyse difficile des étoiles K.
Far-infrared stellar astronomy
Authors: Wildey R. L.
Published: July 2016

The photometer with which I am presently observing stellar radiation responds in the wavelength band extending from 8 to 14 microns. I believe common usage places the boundary between the intermediate and far infrared at 10 microns. From the title of this paper one may therefore infer that what I say today is at least one-third wrong from the start.
Multicolor photometry of spiral arms
Authors: Baum W. A.
Published: July 2016

This paper describes the use of multicolor photometry to examine differences in stellar population across an arm of a spiral galaxy. We know that spiral arms are the loci of contemporary star formation, but we have no assurance that those loci are frozen in the rotating material of the galactic disk. In fact, they cannot be thus frozen unless they are individually short-lived. Otherwise, the difference in angular velocity between the inner and outer regions of spiral galaxies would have produced much more tightly wound-up arms than we now see.
Condensation of paper on the “Revision of the Calibration of Absolute magnitudes by Hγ absorption”
Authors: Petrie R. M.
Published: July 2016

1. The relation between the measured absorption at Hγand absolute magnitude was made for A stars (B8–A3) in 1950 and for B stars in 1953. The systems so obtained gave lower luminosities than the MK calibration and the more recently derived photometric-distance scale. Furthermore, the rise of photo-electric three-colour photometry has recently made available accurate magnitudes and colour excesses of a substantial number of early-type stars in the nearer open clusters. A reconsideration of the Hγ–Mrelation then appeared to be feasible and worth while.
Spectroscopic parallaxes of M-type supergiants
Authors: Sharpless S.
Published: July 2016

M-type supergiants have certain advantages as distance indicators: high luminosity, high discovery probability, and extreme redness such that they can be observed efficiently in the infrared where the interstellar absorption is relatively low. It is known that these stars appear in an advanced stage of the evolution of an O-association, such as h/χPersei, in which the most massive members have moved to the right in the HR diagram. They, therefore, represent population I tracers which are somewhat older than, say, the O-type stars.
OAO-2 Observations of the Near Ultraviolet Extinction Feature
Authors: Savage Blair D.
Published: July 2016

OAO-2 near UV spectral scans of 75 early-type stars have been examined for evidence of the UV extinction bump. The bump has been detected in 40 of these stars. The position of the maximum of the bump is within ± 40 Å of 2175 Å in all cases. A color excess between the wavelengths 2175 Å and 3500 Å was determined for all 40 stars. This color excess, which is a measure of the bump strength, correlates very well with E(B – V) except for stars associated with nebulosity.
Dust Near the Nucleus of M 31
Authors: Johnson Hugh M.
Published: July 2016

Special photographic observations reveal silhouetted dust patterns as close as 6″ from the nucleus. The spatial distribution and kinematics of the dust are discussed.
Gas and Dust in Interstellar Clouds
Authors: Davies R. D.
Published: July 2016

Detailed measurements have been made of the H, OH and H2CO lines formed in the L1534 dense dust cloud; some H and H2CO observations have been made of the dust cloud lying behind the Orion cluster. These indicate a similar distribution of the 3 species throughout the dust clouds. Studies of H, OH and H2CO absorption features in clouds lying in front of bright radio sources provide estimates of the physical conditions in regions of molecule formation.
The Thermal Accommodation Coefficient of Graphite
Authors: Day Kenrick L.
Published: July 2016

An experiment has been performed to determine the thermal accommodation coefficients for the gases hydrogen, oxygen, methane, and carbon dioxide on graphite, in the temperature range 273–77 K. The experimental results are compared to those indirectly predicted in a theoretical paper by Hollenbach and Salpeter, and agreement is found to be satisfactory. A sticking coefficient for atomic hydrogen on a graphite grain is derived which would support the conclusion that recombination of hydrogen on grain surfaces could be a significant process. The very high measured thermal accommodation coefficients for the heavier gases supports the popular assumption that retention of such gases on grain surfaces should be considered extremely likely.
Photodesorption from Interstellar Dust Grains
Authors: Greenberg Lawrence T.
Published: July 2016

An experiment to measure the photodesorption of physisorbed gases from a cold fused quartz substrate by near UV photons is described. The observed yield (mol photon–1) is as large as 10–5, a higher yield is likely in the vacuum UV. Included is a discussion of the photodesorption process and some applications to the interstellar medium. The observed yield is enough to maintain molecular abundances in moderate density interstellar clouds in equilibrium.
Dust, Star, and Hydrogen Distributions in the Orion Association
Authors: Isobe Syuzo
Published: July 2016

From the star counts on the Palomar Sky Survey prints, dust and star distributions in the Orion Association are studied. The Hydrogen distribution in the same region is obtained from an Hα photograph. It is found that a considerable part of the interstellar absorption on the line of sight is due to the circumstellar dust grains in the Orion Association.
Dust Particles and Molecules in the Extended Atmospheres of Carbon Stars
Authors: Gilra Daya P.
Published: July 2016

It is shown that the absorption due to a circumstellar shell containing solid silicon carbide particles can very nicely explain the observed strong violet opacity in stars in which the carbon to oxygen ratio is > 1. It has been shown by Friedemann and Gilman that solid SiC particles can form in the cooler outer layers of such stars. Thermal re-emission from SiC particles is predicted to be in the 10–13 μ region and recent infrared observations by Hackwell show an emission band in this region, thereby strongly supporting the SiC suggestion. It is also shown that the opacity due to C3 pseudo-continuum is not adequate to explain the observed violet opacity.

It is suggested that the vibrational bands of C3 and SiC2 molecules should be among the major opacity sources in the infrared spectra of the late N-type carbon stars and some of the observed bands may be, at least in part, due to these molecules. The frequencies of their isotopic species have been calculated and attempts should be made to observe these bands.

Thus the atmosphere of a late N-star should be pictured as containing, probably on its outskirts, solid carbon particles. There is some kind of smoke veil around the star causing a reddening by absorption of the ultraviolet.

A veiling effect by smoke has been occasionally envisaged to interpret various astronomical phenomena, even in the case of novae. A late N-star would be a striking example. The smoke veil would vary in variable N-stars.

B. Rosen and P. Swings (1953)
Common-Envelope Evolution, the Formation of CVs, LMXBs, and the Fate of HMXBs
Authors: Taam R.E.
Published: July 2016

Recent three-dimensional studies of the common-envelope phase of binary evolution have provided important insights into its theoretical description. The role of non-axisymmetric effects associated with gravitational torques is essential for understanding all aspects of the evolution. For successful ejection of the common envelope and survival of the remnant compact binary it is required that the orbital period of the progenitor system is long, so that one of the components of the system is in the red giant or red supergiant stage of evolution. Not only must there be sufficient energy released from the orbit to unbind the common envelope, but it is also necessary that a sufficiently steep density gradient exist above the evolved core of the giant. If these conditions are satisfied, the time scale for orbital decay in the region above the core exceeds the time scale for mass loss from the common envelope and merger is avoided. The implications of these results for the formation of cataclysmic variables (CVs), low-mass X-ray binaries (LMXBs), and the descendants of high-mass X-ray binaries (HMXBs) are discussed.
The Environments of Type Ib/c Supernovae
Authors: Van Dyk S. D. , Barth A. J. , Filippenko A. V.
Published: July 2016

Up to about 1985, supernovae (SNe) generally were placed into the two Minkowski classes, type I and type II, defined by the absence or presence, respectively, of hydrogen in their optical spectra. Around that time it was acknowledged that several type I SNe were systematically peculiar, both spectroscopically and photometrically (Elias et al. 1985; Wheeler & Levreault 1985; Uomoto & Kirshner 1985; Branch 1986; Filippenko 1986), by missing the characteristic Si II spectral feature near 6150 å, having distinct infrared light curves, being optically redder and subluminous, and showing radio emission (Sramek et al. 1984). These SNe were designated as type Ib (Elias et al. 1985; Branch 1986) to distinguish them from the classical type Ia. Harkness et al. (1987) identified He I lines in spectra of the SN Ib 1984L, but some subsequent examples showed no He in their spectra and were further subclassified as Type Ic (Wheeler & Harkness 1990). The two subtypes, however, are nearly indistinguishable at late times. In this Symposium the entire class has been referred to as type Ib/c SNe. A recent bright example is SN 1994I in M51 (Filippenko et al. 1994).
Models for the Formation of Binary and Millisecond Pulsars
Authors: Bhattacharya D.
Published: July 2016

Under the name “binary and millisecond pulsars” are grouped a number of radio pulsars, forming roughly 10% of the known pulsar population, which distinguish themselves on three counts:

— Short spin period

— Low magnetic-field strength

— Presence of an evolved binary companion
Low-Mass X-ray Binaries—Recent Developments
Authors: Van Der Klis M.
Published: July 2016

Recent developments in the field of low-mass X-ray binaries are briefly reviewed, with particular emphasis on a comparison between the systems that contain accreting low magnetic-field neutron stars and those that contain black-hole candidates. The possibility that inclination effects play a role in black-hole candidate phenomenology is explored.
ASCA Observations of White Dwarfs, Neutron Stars and Black Holes
Authors: Inoue H.
Published: July 2016

ASCA, the fourth Japanese X-ray astronomy satellite, was launched by the Institute of Space and Astronautical Science (ISAS) on 1993 February 20. ASCA is designed to be a high-capability X-ray observatory (Tanaka et al. 1994). It is equipped with nested thin-foil mirrors which provide a large effective area over a wide energy range from 0.5 to 10 keV. Two different types of detectors, CCD cameras (SIS) and imaging gas scintillation proportional counters (GIS) are employed as the focal plane instruments.
Propellers — A New Class of Interacting Binaries
Authors: Mikołajewski M. , Mikołajewska J. , Tomov T.
Published: July 2016

CH Cyg and MWC 560 are very peculiar symbiotic binaries consisting of an M giant and a white-dwarf companion. The systems have many features in common. In particular, both show occasional eruptions with sub-Eddington luminosity accompanied by flickering activity, and appearance of high-velocity jets. We present arguments that objects like CH Cyg and MWC 560 form a new subclass of interacting binaries distinguished by the presence of wind accreting magnetic white dwarfs.
First results from VIRGO on SoHO
Authors: Fröhlich C. , Andersen B.N. , Appourchaux T. , Berthomieu G. , Crommelynck D.A. , Domingo V. , Fichot A. , Finsterle W. , Gómez M.F. , Gough D. , Jiménez A. , Leifsen T. , Lombaerts M. , Pap J.M. , Provost J. , Cortés T. Roca , Romero J. , Roth H-J. , Sekii T. , Telljohann U. , Toutain T. , Wehrli C.
Published: July 2016

First results from the 4-6 months observations of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) on the ESA/NASA Mission SOHO (Solar and Heliospheric Observatory) are reported. The time series are evaluated in terms of solar irradiance variability, solar background noise characteristics and p-mode oscillations. The solar irradiance is modulated by the passage of active regions across the disk, but not all of the modulation is straightforwardly explained in terms of sunspot flux blocking and facular enhancement. The observed p-mode frequencies are more-or-less in agreement with earlier measurements, but it is interesting to note that systematic differences seem to exist between the observations in different colours. There is also evidence that magnetic activity plays a significant role in the dynamics of the oscillations beyond its modulation of the resonant frequencies. Moreover, by comparing the amplitudes of different components of p-mode multiplets, each of which are influenced differently by spatial inhomogeneity, we have found that activity enhances excitation.
Precision solar astrometry from SoHO/MDI
Authors: Kuhn J.R. , Bogart R. , Bush R. , Sá L. , Scherrer P. , Scheick X.
Published: July 2016

The SoHO/MDI experiment generates a continous record of the solar limb brightness using 1.96″ pixels. Because there is no atmospheric blurring, these data allow measurements of solar limb brightness and shape changes with a precision that has not been achieved from the ground. The first results of a 1 month astrometric timeseries from the MDI solar structure program will be described here.
The seismic structure of the Sun from GONG
Authors: Anderson E. , Antia H.M. , Basu S. , Chaboyer B. , Chitre S.M. , Christensen-Dalsgaard J. , Eff-Darwich A. , Elliott J.R. , Giles P.M. , Gough D.O. , Guzik J.A. , Harvey J.W. , Hill F. , Leibacher J.W. , Kosovichev A.G. , Monteiro M.J.P.F.G. , Richard O. , Sekii T. , Shibahashi H. , Takata M. , Thompson M.J. , Toomre J. , Vauclair S. , Vorontsov S.V.
Published: July 2016

This paper is an interim report of our inferences about the hydrostatic structure of the Sun, following the first report of the GONG team in Science (Gough et al., 1996). That work confirms that the spherically averaged structure of the Sun is more or less in agreement with current standard solar models. However, there remain some significant deviations which we regard as important clues to the existence of dynamical phenomena which are not taken into account in standard solar modelling.
The scientific achievements of P. Delache
Authors: Bonnet R. M.
Published: July 2016

An overview of the multiple facets of Philippe Delache's scientific achievements is presented, from his early involvement in experimental work and space research, through his re-orientation towards radiative transfer, astrophysics, and then the study of the global Sun and its internal structure, and the study of the interior of Jupiter. The constant concern of P. Delache for a proper and correct mathematical analysis of the problems and for modelling, are outlined in this brief overview. The generous character, the profound and complex personality, as well as the human qualities of this very talented scientist, among which modesty is very prominent, are presented in this description of a remarkable career which ended much too early.
Apparent solar diameter and variability
Authors: Vigouroux A.
Published: July 2016

Philippe Delache brought me to solar physics in late June 1992. The first things he began with was the diameter of the Sun as it is measured at the “plateau de Calern”, and my first work was to analyze this time series in order to separate the “noise” from the pertinent information (section 2). Wet then applied the technique developed for this purpose to the study of the 11-year solar cycle as seen in the Wolf sunspot number (section 3) and I continued in collaboration with Judit Pap with the study of total irradiance and some other solar indicators which could help to understand its variations (section 4).
Solar activity and solar oscillations
Authors: Elsworth Y.
Published: July 2016

Helioseismology provides us with the tools to probe solar activity. So that we can consider how the solar oscillations are influenced by that activity, we first consider the phenomena that we associate with the active Sun. The surface of the Sun is not quiet but shows evidence of convection on a wide range of scales from a few hundred kilometres through to several tens-of-thousands of kilometres. The surface temperature shows signs of the convection structures with the temperature in the bright granules being some 100 K to 200 K hotter than the surrounding dark lanes. Sunspots, which are regions of high magnetic field that suppress convective flows, are clearly visible to even quite crude observations. They are several tens-of-thousands of kilometres in diameter and about 2000 K cooler than their surroundings. Ultraviolet and X-ray pictures from satellites show that the higher layers of the solar atmosphere are very non-uniform with bright regions of high activity. Contemporaneous magnetograms show that these regions are associated with sunspots. Flares - regions of magnetic reconnections - are seen at all wavelengths from X-ray through the visible to radio. They are the non-thermal component of the radio emission of the Sun. There are many other indicators of activity on the Sun.
Asteroseismology: ground based observational methods
Authors: Frandsen S.
Published: July 2016

The improvement in observational techniques to study pulsations in solarlike stars is discussed. For higher mass stars the problem is to allocate specific eigenmodes to a set of observed frequencies. Additional observables can be used to sort out the present ambiguities.
Observational asteroseismology of δ Scuti stars
Authors: Breger M. , Audard N.
Published: July 2016

Ground-based observational networks are now able to reliably detect more than 20 frequencies for individual δ Scuti stars. The ground-based Delta Scuti Network specializes in the intensive study of individual stars for several months with dedicated telescopes on different continents. With the new quantity and quality of data, the observational limit to extracting 50 or more frequencies in a single δ Scuti star is no longer determined only by the signal/noise ratio, but by the available frequency resolution.

Recent results on the δ Scuti stars FG Vir and 4CVn are presented. 4CVn exhibits some of the characteristics of δ Scuti stars: some close spacings are observed, pulsations occur in specific frequency regions with relatively sharp borders, and show large amplitude variations. This presents an important asteroseismological diagnostic, and can help us to improve our understanding of for example rotation and excitation mechanisms.

We also report a new Gamma Doradus variable with two excited g modes (HD 108100, F2V).
Spectroscopic Properties of Herbig-Haro Flows
Authors: Böhm Karl-Heinz , Goodson Anthony P.
Published: July 2016

While recent studies of Herbig-Haro (HH) objects have focused less on the details of their spectra than on the hydrodynamics of jets and their working surfaces, many open questions concerning these spectra remain. Attempts to quantitatively explain a wide range of lines for many HH objects point to discrepancies between theory and observation. Some lines (specifically [S II](6716+6731)) are much stronger than predicted by simple plane-shock and bow-shock models, while in general high ionization lines (e.g. lines of [O III], [Ne III] and [S III] in the optical and the [C IV] and [N V] in the ultra-violet) are much weaker than expected, pointing to difficulties with current models. On the other hand, examination of these lines has lent new insight into both the quality of our predictions and the nature of HH outflows. Examination of many Fe lines have demonstrated that our ability to estimate abundances from faint lines is surprisingly good (or surprisingly consistent). Position velocity diagrams have also been constructed (using forbidden emission lines), allowing outflows to be mapped to within 0.″3 arcseconds of the source star.
Magnetic Fields of T Tauri Stars
Authors: Guenther Eike W.
Published: July 2016

The magnetic field strengths of several T Tauri stars are derived by measuring the width of unblended Fe I lines of high and low values of geff·λ2 using the autocorrelation function. The T Tauri stars were selected for their low values of v · sin i, and large strengths of the Ca II emission component. The derived magnetic field strength are 2.0 ± 0.6 kG and 2.6 ± 0.8 kG for the classical T Tauri stars Lk Ca 15 and T Tau, respectively. An upper limit of 0.6 ± 0.8 kG is found for the weak-line T Tauri star Lk Ca 16. The method is tested by analysing two non-magnetic main sequence stars, and a late-type star that is known to have a strong magnetic field.
Two-Wind Interaction Models of the Proplyds in the Orion Nebula
Authors: Henney W. J. , Arthur S. J.
Published: July 2016

Many low-mass stars in the Orion nebula are associated with very compact (≃ 1 arcsec) emission knots, known variously as proplyds, PIGs or LV knots. Some of these knots are teardrop-shaped, with “tails” pointing away from the massive star θ1 Ori C, which is the principal exciting star of the nebula. We discuss models of such knots, which invoke the interaction of the fast stellar wind from θ1 Ori C with a transonic photoevaporated flow from the surface of an accretion disk around a young low-mass star. We review previous analytic work and compare the results of the model with the observed brightnesses, morphologies and emission line profiles of the knots, as well as presenting new results from numerical hydrodynamical simulations.
Polarimetry of Close Binary Systems; Observations and Interpretations
Authors: McLean Ian S.
Published: July 2016

Polarization caused by scattering of starlight on gaseous extrastellar material in close binary systems is reviewed. A simple physical derivation is given to illustrate how in principle, variations synchronous with the orbital period of the Stokes parameters of the linear polarization can yield the orbital inclination and other parameters. High resolution multichannel spectropolarimetry across the emission line profiles of binaries is discussed as a new technique in studying the physics and kinematics of gaseous streams and stellar winds. The methods have application to a range of binary objects including systems like Algol and Beta Lyrae, X-ray binaries, Of and Wolf-Rayet binaries, VV Cephei stars and symbiotic stars. Some new observational results are presented.
On the Onset of Contact in Early-Type Binaries
Authors: Webbink R. F.
Published: July 2016

A previously published model of a detached binary evolving into deep contact, under the assumption that both components fill the same equipotential surface, is tested for self-consistency. Hydrodynamic equations describing the flow between components at their interface indicate an enormous discrepancy in the magnitude and direction of the flow in the evolutionary calculation. This behavior strongly supports the view that binaries reaching contact in this way undergo a cyclic thermal instability as in many models of W Ursae Majoris systems, rather than overflowing an outer Lagrangian point.
Mass Loss and Mass Transfer in Algols
Authors: Giuricin G. , Mardirossian F. , Mezzetti M.
Published: July 2016

We have examined the observational data of 60 Algols in order to check some theoretical views on mass loss and mass transfer in Algols. Not negligible contradictions between some theoretical non-conservative attempts and the observational scenario have been emphasized.
IUE Observations of Long Period Eclipsing Binaries: A Study of Accretion onto Non-Degenerate Stars
Authors: Plavec Mirek J.
Published: July 2016

It has long been thought that β Lyrae is a unique system, by virtue of its UV spectrum and its nature. I will argue that a whole class of interacting long-period binaries exists, similar to β Lyrae. According to IUE observations made in 1978-79 by myself and R. H. Koch, this group comprises: RX Cas, SX Cas, V 367 Cyg, W Cru, β Lyr, and W Ser. AR Pav is a transition case linking them with the symbiotics. I also suggest that HD 218393 (KX And), HD 72754, and HD 51480 are their non-eclipsing counterparts. I will call the whole group the W Serpentis stars.

These systems are mass-transfering binaries (case B) in which the mass transfer rate is relatively high, probably on the order 10−6 to 10−4 M⊙/year. They display an ultraviolet continuum with a color temperature definitely higher than the one observed in the optical region. Even more characteristical is the presence of strong emission lines of N V, C IV, Si IV, Fe III, Al III, and lower ions of C and Si. I will attempt to discuss these phenomena on the assumption that they are due to accretion onto non-degenerate stars.
Are Most of X-Ray Binaries Recurrent Transients?
Authors: Ziółkowski Janusz
Published: July 2016

The aim of this paper is to argue that some day in the not-too-distant future one of the well-known X-ray pulsars, say, Cen X-3 (although better examples would be probably GX 301-2 or GX 1+4), will disappear from the X-ray sky. It will reappear again after some, say, tens of years and its pulse period will be then longer than it is now.
Optical and Ultraviolet Observations of HZ Her
Authors: Kippenhahn R. , Ritter H. , Schmidt H. U. , Thomas H.-C.
Published: July 2016

Results of five nights of photoelectric UBV photometry of HZ Her and of simultaneous ultraviolet spectroscopy with IUE are presented.
A Starspot Model for the RS CVn Stars
Authors: Shore Steven N. , Hall Douglas S.
Published: July 2016

We employ a simplified dynamo model to describe the long term photometric spectroscopic behavior of the RS CVn stars. The essential feature of the model is that the stars are in nearly synchronous rotation, with the differential rotation slower and the rotational velocity higher than for a single evolved 1 to 2 solar mass star. The spot groups are formed by eruption of enhanced toroidal fields, which have areas at the photosphere of several tenths of the surface area; the sizes of these regions are shear limited. Estimates of the lifetimes of active regions and of flare energetics are presented. The RS CVn phenomenon is then related to both the evolutionary status and the orbital parameters of the binary system.
Spectrophotometry of the Hα Region in HR 5110.
Authors: Fraquelli Dorothy A.
Published: July 2016

Spectrophotometry of the bright RS CVn binary HR 5110 is presented. The data consist of 42 red spectrograms obtained with the DDO 74″ telescope. All spectrograms were scanned using the PDS microdensitometer system at the DDO and rectified intensity tracings were produced.
Observational Evidence for Large-Scale Spot Activity on the Primary Component of XY Ursae Majoris
Authors: Geyer Edward H.
Published: July 2016

Extensive pe- and spectroscopic observations of the short period eclipsing binary XY UMa within the last four years confirm the star spot and stellar activity model, which was presented in 1975.
Theories of Contact Binary Stars
Authors: Shu Frank H.
Published: July 2016

We review and contrast two current theories for the structure of contact binary stars: discontinuity theory and thermal relaxation oscillation theory. We find that the two theories are complementary with the crucial theoretical issue to be resolved being the secular stability of the temperature inversion layer. Critical observational tests remain to be performed.
The Physical Status of VW Cephei
Authors: Linnell Albert P.
Published: July 2016

The decreasing period of VW Cep, interpreted on conservative case mass transfer, implies mass flow from primary to secondary. The TRO theory then predicts semi-detached status. The system b-v color is the same at the two minima, to within observational error. This is in marginal disagreement with a hot secondary. It also implies close thermal contact, in disagreement with the postulated semi-detached status.
A Binary Model for the Symbiotic Star V 1329 Cygni
Authors: Chochol D. , Grygar J. , Hric L.
Published: July 2016

This emission-line object was discovered by Kohoutek in 1969. Its light curve was subsequently reconstructed since 1891. Before 1964, the object fluctuated at around 15m, with occasional deep minima as deep as 2.3m. Its spectrum was late M. In 1964 the object brightened up to 14m and then it reached 11.5m in the middle of the year 1966. Since 1966 the object has been slowly decreasing in brightness. Stienon et al. (1974) suggested that the photometric behaviour prior to the outburst could be explained in terms of an eclipsing binary with a period of 960 days. This is now confirmed by the analysis of the post-outburst photometric data and independently by the investigation of the radial velocities of the emission-line component. We have derived the following spectroscopic elements: Period = 950.07d; γ = 37 ± 6 km/s; K1 = 62 ± 8 km/s; f(M) = 23 M⊙; aisin i = 1160 R⊙. We propose a binary model for the symbiotic object consisting of a bright red giant M5 II with a mass of 25 M⊙, and of a very hot compact star of 1 M⊙. Line profiles of the nebular lines as well as Balmer lines suggest the existence of ejected “polar caps” and an equatorial ring around the hot component, much like in novae. It seems that the hot component accretes the material from the giant via strong stellar wind. Changes in the accretion rate can cause the observed optical fluctuations. The major outburst in 1964-1966 was probably caused by a shell flash which also ionized the expanding nebula surrounding the hot component.
Concluding Remarks
Authors: Smak J.
Published: July 2016

During the last four days we have seen a number of interesting and important results concerning problems which will certainly attract our attention in the years to come. To give examples, I would mention: formation of binaries, structure of contact systems, evolution with a common envelope, planetary nebulae with CBS nuclei, starspots and magnetic fields. As for individual objects, SS 433 would be obviously No. 1 on our list of highlights.
Use of meteorological measurements for computing refractional effects - a review
Authors: Angus-Leppan P.V.
Published: July 2016

Corrections which are dependent on the atmosphere include the first and second velocity corrections and the curvature correction in EDM, and the refraction correction for trigonometric heighting. Generalised correction formulae have been developed to make use of variable values of the refractivity N and the coefficient of refraction k. There are no universally applicable values of these parameters, so atmospheric models of the temperature gradient and, for microwaves, the humidity gradient, are needed to represent the very significant variations. The models should take into account variations due to meteorological factors, surface conditions and the height above the surface. Many models for the vertical gradients have been produced. That of Brocks (1948) is very important and has been widely used and developed by researchers. More recently Monin and Obukhov, basing their work on the physics of the lower atmosphere and dimensional analysis, have included equations for the vertical gradients in their turbulence theory. The Turbulent Transfer Model, which embodies later results in this theory, is currently being refined and developed for geodetic applications.
Computing parallactic refraction for stellar triangulation
Authors: Kakkuri Juhani , Ojanen Ossi
Published: July 2016

The parallactic refraction correction should be applied to the photographic observations of the light signals carried either by artificial satellites or by meteorological balloons. The correction to the right ascension and declination are made with the equations

where ϕ is the latitude of the observation station, z the zenith distance, α the right ascension, δ the declination and h the hour angle of the light signal. Parallactic refraction is denoted by Δζ.
The direct experimental detection of the systematic error of precise levelling
Authors: Remmer O.
Published: July 2016

A method is described for determining one and only one parameter governing the refraction effect of levelling. The central idea is that this parameter is determined not by (temperature) measurements during the observation but by adding one more element in the Least Squares Adjustment of the levelling network.

Furthermore is described an experiment where it was found that this parameter differed significantly from zero and a tentative first value is suggested.
Removal of refraction errors in geodetic leveling
Authors: Holdahl Sandford R.
Published: July 2016

Refraction error is often regarded as the most serious problem with geodetic leveling. Its accumulation depends on the slope of the terrain being leveled, length of sight, and the vertical temperature gradient. Refraction error can be minimized by limiting and balancing sight lengths, and by not reading the portion of the level rod which is within 0.5 meter of the ground where air density changes most rapidly. The remaining refraction error should be removed by application of a correction to leveling data, otherwise heights and crustal motion may be determined so weakly that meaningful conclusions or interpretations cannot be inferred from the data by geophysicists.
The use of multi- or single wave methods to eliminate terrestrial refraction from geodetic measurements
Authors: De Munck J. C.
Published: July 2016

Refraction is a very important aspect of geodesy and astronomy: it is one of the main sources for troubles, papers and dissertations, at least in geodesy. Particular important is the vertical refraction because of the up- and down-asymmetry in the atmosphere. However, we must not forget that gravity does not only cause the asymmetry of the atmosphere, also the asymmetry of the mechanical parts of the instrument (bending of the tube, deformation and excentricity of the axis, etc.) and even an asymmetry of the mind of the observer. See figure 1. If it becomes possible to measure the refraction these effects will often become limiting factors for the accuracy.
The International Solar Polar Mission: Zodiacal Light/Background Starlight Experiment (ISPM-ZLE)
Authors: Schwehm G. H.
Published: July 2016

The International Solar Polar 1983 Mission will for the first time provide the opportunity to perform measurements out of the ecliptic and above the solar poles. The Zodiacal Light/Background Starlight Experiment of the Ruhr-University Bochum, FRG, (in collaboration with the State University of New York at Albany) which was selected for the NASA-S/C is a scanning photometer which is based on the HELIOS 1, 2 - Zodiacal Light Experiment.
Zodiacal Light Models with a Bimodal Population
Authors: Lamy P.L. , Perrin J.M.
Published: July 2016

The compatibility of the observed properties of the zodiacal light with a model made of two populations is investigated. It is shown that a population of submicron grains may play a non-negligible role.
Meteors and Atmospheres
Authors: Baggaley W. J.
Published: July 2016

Meteoroid ablation in an atmosphere produces a weak plasma column. The processes important in governing the state of the meteoric species subsequent to column formation are reviewed. The actions of transport and of chemical reactions in controlling the life of the various species in the column are described. It is found that the interaction of meteoric ions with atmospheric gases leads to the dissipation of ionization and is the source of anomalous radio-meteor echo characteristics: recognition of these effects is important in permitting meaningful interpretations of radio-meteor data. Several modes of interaction between meteoric species and an atmosphere can yield enduring emissions. The fate of the various species is discussed.
The Influence of the Atmosphere on Radar Meteor Rates
Authors: Elford. W.G.
Published: July 2016

The majority of radio studies of meteors have been carried out at frequencies higher than 17MHz and most of the rate observation at frequencies above 30MHz. At these frequencies a severe height selection of meteors occurs. In Figure 1(a) are shown the normalized height distributions of sporadic meteors observed at Adelaide on frequencies of 27MHz and 2MHz (Brown, 1976). The sharp cutoff of the latter distribution below 87 km is instrumental. The difference in the height distributions is due to the effect of the finite diameter of a meteor trail on its radar detectability. If the trail diameter is ≪ λ signals from the near and far edges reinforce but as the trail expands due to diffusion and the diameter becomes ≃ λ/4, interference reduces the amplitude. A meteor trail, produced by a particle with a velocity of 30 km s−1, has an initial diameter of 0.4m at 80 km, 2.0m at 104 km and 4.0m at 116 km.
One Hundred and Fifteen Years of Meteor Spectroscopy
Authors: Millman Peter M.
Published: July 2016

Early visual observations of meteor spectra were instigated by A.S. Herschel and, in the period 1866-1880, resulted in the recording of several hundred spectra and the correct identification of the lines of neutral sodium and magnesium. Some 60 meteor spectra were photographed from 1897 to 1940, which resulted in the identification of 9 neutral and 4 singly ionized atoms. Improved cameras and techniques after World War II, and in particular the use of closed-circuit television equipment recording on video tape, increased the data-bank of meteor spectra to several thousand and made possible the identification in these spectra of between 15 and 20 neutral atoms, 9 singly ionized atoms and 6 diatomic molecules. Reliable luminous efficiencies of the atoms and molecules radiating in the observed light of meteors are available in only a few cases. Where relative abundances of the elements have been calculated, these agree in general with those found by other techniques for interplanetary dust, and with abundances for the solar system as a whole.
Interaction of Large Bodies with the Earth's Atmosphere
Authors: ReVelle Douglas O.
Published: July 2016

During the last decade much work has proceeded on the problem of understanding the complex physiochemical processes associated with the entry of large meteoroids into the atmosphere. In this paper the respective areas of ablation, luminosity and infrasonic wave generation are surveyed from the viewpoint of the physics of fluids. Related work on meteorite cratering processes is not considered in this brief survey. Companion papers by Baggaley and by Ceplecha consider additional areas of current interest in meteor and fireball research.
On the Probability of Collision with Earth, and Orbital Life-Time of Bodies of Asteroidal and Cometary Origin
Authors: Kramer E.N. , Musiy V.I. , Timchenko-Ostroverkhova E.A. , Shestaka I.S.
Published: July 2016

The radius for gravitational capture of meteoroids by the Earth is

where R is the Earth's radius, h is the height where marked deceleration of meteor bodies begins, α0 is the average distance of the Earth from the Sun, v∞ and vg are preatmospheric and geocentric (undisturbed) velocities of the body.
On the Dust Production Rates of Comets
Authors: Hellmich R. , Keller H. U.
Published: July 2016

The dust production rates of comets on various orbits with perihelia between 0.1 and 0.5 a.u. and semimajor axes between 5 and 40 a.u. are calculated. A new model is used taking into account the screening of solar radiation by the dust and the multiple scattering of the photons. Screening and multiple scattering effects tend to compensate each other over a range of moderate optical thicknesses.
Experiments on Dust Collection for a Cometary Mission
Authors: Kissel J. , Clark B. C. , Clair D.
Published: July 2016

Experiments presently conducted at the Martin Marietta Denver facility to collect cometary dust during a Tempel 2 flyby are reviewed. It is shown that a number of viscid materials are quite suitable to collect particles up to 50 μm diameter at speeds up to 50 m/s. First results are presented for the more complicated setups using nonviscid metal surfaces for the collection of dust. These targets allow the use of surface analysis techniques for a more elaborate chemical analysis of the collected dust particles.
Poynting-Robertson Effect and Collisions in the Interplanetary Dust Cloud
Authors: Trulsen Jan , Wikan Arild
Published: July 2016

A simulation model has been developed to study the results of the Poynting-Robertson (PR) effect and collisions on the dynamical evolution of an interplanetary dust cloud. Fragmentational and accretional effects are neglected. With a mean free collision time of the order of the PR lifetime collisional effects become of importance. As the individual grains still spiral inwards collisions act to make the mean eccentricity and inclination of the grain orbits both decrease at comparable rates, giving rise to an expanding fan shaped dust cloud.
Orbital Elements of Micrometeoroids Detected by the Helios 1 Space Probe in the Inner Solar System
Authors: Schmidt K. D. , Grün E.
Published: July 2016

The Helios Spacecraft is able to detect micrometeoroids along its orbit in the inner Solar System between 0.3 AU and 1 AU distance from the sun (Grün et al. 1977, Grün et al. 1979). Data of the first 6 orbits are presented here. 168 particles have been identified in such a way that their osculating orbital elements (here especially semimajor axis a, eccentricity e and inclination i) can be calculated. Detailed information on impact speed is available only up to about 50 km s−1 which corresponds to a lower mass limit of 10−11g (Dietzel et al. 1973). So the detected micrometeoroids are divided into two groups below and above 10−11g for each sensor. Table 1 gives the absolute number of dust particles in the different mass intervals.
Evidence for Ice Meteoroids Beyond 2 AU
Authors: Zook H.
Published: July 2016

Humes et al. (1974) deduced from the P-10 (Pioneer 10) meteoroid penetration data that the spatial density of 2 × 10−9 g and larger meteoroids was nearly constant (or possibly increasing) with increasing heliocentric distances between 2 and 5 AU from the sun. With an assumed mass density of 0.5 g/cm3, P-10 particles (particles whose mass is ⪞ 2 × 10−9 g) would have a particle radius in excess of about 10 μm. The observation of a constant, or increasing, spatial density leads to some interesting conclusions regarding the processes that control the population of P-10 particles between 2 and 5 AU from the sun. We shall explore some of these processes below and shall obtain the result that the P-10 meteoroid data can be best understood if many of the penetrating meteoroids are made of ice.
Planetary Rings
Authors: Cook A. F.
Published: July 2016

Observations of the Rings of Saturn from the Pioneer spacecraft, discovery of the Ring of Jupiter, ground based polarimetry of the Rings of Saturn and some theoretical studies may be combined to markedly advance our understanding of the Rings of Jupiter, Saturn and Uranus. In particular, narrow rings can be self-gravitatingly stable inside Roche's limit and outside another closer limit. They can be created from a satellite which evolves across its Roche limit either by inward tidal drift or by growth of the planet by accretion.

These considerations suggest that Neptune may well be surrounded by one or more narrow rings like those of Uranus.