bluuebunny/crossref_metadata_2025 huggingface dataset:
22. Meteors and Meteorites
Authors: Ceplecha Zdeněk , McCrosky R. E. , Babadžanov P. B. , Elford W. G. , Hemenway C. L. , Javne’ A. A. , Millman P. M.
Published: July 2016

The limited space made available for this report by recent regulations of the Executive Committee of our Union does not allow the traditional list of all published papers. Also, it omits the data on detection of cosmic dust, which are now published each year in surveys by the COSPAR Dust Panel. This report is mainly based on completely fresh information contained in numerous letters sent to me.

The accompanying report of our Meteorite Committee is done in the old style, but only a limited number of references are given. Evidence for a terrestrial origin of tektites is becoming stronger every year, and this subject is omitted in order to shorten the report.

Before starting the report, I mention with great regret the death of Prof. Dr Cuno Hoffmeister. His name remains connected forever with the famous period of naked-eye observations of meteors. Another great loss for meteor observers was the death of Mr Koiro Komaki, the President of the Nippon Meteor Society.
29b. Working Group on Line Intensity Standards
Authors: De Strobel G. Cayrel
Published: July 2016

Systematic equivalent width comparisons as initiated by K. O. Wright during the Seventh General Assembly of the IAU in 1948 and continued by G. Cayrel de Strobel since the Twelfth General Assembly in 1964 are meeting less and less response from the astronomical community. Griffin has stressed systematic errors in spectrographic results. For instance he claims in his paper (M.N.R.A.S., 143, 319) that owing to the light thrown in the wings of the instrumental profiles, the observed equivalent widths of absorption lines in late type stellar spectra are 5 to 10 % less than the true values. Furthermore Griffin pointed out the weakness of purely spectrographic comparisons which are all affected by the same type of errors. What is really needed is to know the true equivalent width of a few lines as they can be obtained from an accurate double pass photoelectric scanner. Pagel suggested that this can be done by comparing spectra of integrated sunlight from sky or minor planets with scans obtained by solar spectrometers. Griffin prefers that a bright star be used for this purpose. A complete change in the activity of this working group could very well be decided if the primary object is to have true standards of equivalent widths and if these cannot be obtained from conventional high dispersion spectrography.
31. Time
Authors: Zagar F. , Winkler G. M. R. , Belocerkovskij D. J. , Bonanomi J. , Enslin H. , Markowitz W. , Smith H.M. , Torao M.
Published: July 2016

The astronomical observatories which actively cooperate in the network of the system of the Bureau International de l’Heure, are, at present, about 70. Most of the astronomical time determinations are carried out by means of Danjon Astrolabes or transit instruments; 10 observatories dispose of a PZT and 5 others are installing or planning to have it. The results of their observations, ɸ(observed latitude) and Δ T (difference between local U.T.0 and U.T.C), are collected at the BIH and – contrary to the procedure used until 1967 – used to simultaneously obtain the instantaneous coordinates of the pole (x, y), referred to conventional international origin (CIO), and longitudes origin on the pole equator. As a consequence of the adoption of the above-mentioned conventional pole, the BIH had to change all conventional longitudes in order to keep the origin formerly defined (1967); they are now reported in BIH Annual Reports. A further change was operated on the constant of aberration which, at the beginning of 1968, from 20˝.47 was changed to 20˝.496. The BIH had therefore to operate a step of to U.T.1, at the beginning of January 1968, and so did the Greenwich Observatory, with a step of + 0.0069. Global corrections, due to these variations and to others occurred from 1955 to 1968 (in 1958, variation of the polar reference, from Cecchini’s to the mean pole of the date; in 1961, adoption of FK4 and of new longitudes), to the data of the past years (until 1968), are reported on Table 8 of the BIH Annual Report, 1968. The formula supplying the correction U.T.2 —U.T.1 remained unchanged, except for the variable t, which is expressed (since 1967) as a fraction of the Besselian year. Finally, stars coordinates in the catalogs used for time service were revised on the basis of observations made during the latest ten years (Neuchâtel, Greenwich and Mizusawa) and a catalog has been prepared, which includes 807 right ascensions for 1960, drawn from 20 catalogs, with more than 185000 observations of the U.S.S.R. (Pulkova) time service, which is also preparing a new catalog of proper motions. The unification of star positions and proper motions is recommended for the PZT.
34. Interstellar Matter and Planetary Nebulae
Authors: Osterbrock D. E. , Kahn F. D. , Aller L. H. , Davies R. D. , Greenberg J. M. , Pike’ner S. B. , Rosino L.
Published: July 2016

Although additional surveys with large Schmidt telescopes continue to yield small catches of additional planetaries (Kohoutek) one cannot escape the conclusion that most planetaries available to existing equipment have been detected. Much remains to be done with powerful Schmidt equipment in the southern hemisphere, especially in the Magellanic Clouds. A vast body of photometric and spectroscopic observation needs to be garnered for the numerous faint nebulae so far discovered.

Spectroscopic and spectrophotometric studies have been carried out for most bright planetaries (λ < 5800) but much remains to be done in the red and near infrared. Important advances have been made in the far infrared (~10μ) (Gillett, Low, Stein, Woolf) where a number of planetaries seem to show abnormally strong continua. This abnormally intense radiation has been attributed to non-thermal emission, effects of many faint lines, and to thermal emission by dust grains (Krishna Swamy, O’Dell) with perhaps the bulk of the evidence favoring the last-mentioned hypothesis. An increasing number of radio observations from 9·5 mm to 73 cm (Thompson, Colvin, Stanley, LeMarne, Kaftan-Kassim, Babieri and Ficarra, Terzian, L. Aller and Milne, Hughes) all indicate that planetaries are thermal sources.
37. Star Clusters and Associations
Authors: Golay M. , Larsson-Leander G. , Barhatova K. A. , Gascoigne S. B. C. , King I. R. , Rosino L. , Ruprecht J. , Swope H. H. , Walker M. F.
Published: July 2016

The data contained in this report have been taken from two sources: (1) Information received from astronomers active in the field of Commission 37 in response to a circular letter mailed July 1969; (2) Surveys of special fields, prepared by W. Becker on “Open star clusters and spiral structure”, by G. Larsson-Leander on “Clusters and stellar evolution”, by M. Walker on “Young clusters’, and by P. -B. Bouvier on “Dynamical models and numerical computations’. It is a pleasure to thank them and all of those who have contributed to the preparation of this report.

G. Alter reports that after a long delay the second edition of the Catalogue of Star Clusters and Associations. (G. Alter, J. Ruprecht, V. Vanýsek), which was discussed at a meeting of our commission at the Congress in Hamburg (1964) (Trans, IAU, 12B, 1966, 336), will now be published by Publishing House of the Hungarian Academy of Sciences. It is considerably enlarged, since it includes the contents of the annual Supplements published in B.A.C. between 1959 and 1967.
25. Stellar Photometry and Polarimetry
Authors: Graham J.A.
Published: July 2016

Most astronomical observers at some time become involved in photometric techniques even if the participation may be limited to a rough check of the brightness of an object for measurement at the telescope. The field is in fact so broad that much of the current work is more appropriate to the reviews of other IAU Commissions and it has become accepted that Commission 25 deals mainly with those subjects which are of common practical interest to photometrists and polarimetrists around the world. We are now at the beginning of a new stage, that of observation with space telescopes and it will be important to ensure that the transition to the new techniques of measurement is a smooth one. In our review, we restrict our discussion to stellar work, leaving to other Commissions the consideration of photometry and polarimetry of stellar systems, solar system objects and gaseous nebulae. We consider recent work concerning detectors, photometric and polarimetric systems, standard stars and sequences, catalogues of new material and related items of interest to observers. The reference numbering system of Astronomy and Astrophysics Abstracts is used where possible. We shall draw attention to some important conference volumes and to some major observing projects completed during the last 3 years and finally shall look briefly towards probable developments and future prospects for the times ahead.
Commission 16: Physical Study of Planets & Satellites/Etude Physique des Planètes & Satellites
Authors: Marov M. Ya. , Cruikshank D. P.
Published: July 2016

This report includes a number of achievements in planetary science in the last approximately three years. Each section was contributed by the scientists identified at the end of that section.
21. Light of the Night Sky / Lumière du Ciel Nocturne
Authors: Leinert Christoph
Published: July 2016

The light of the night sky is a difficult to disentangle mixture of tropospherically scattered light, airglow, zodiacal light (including the thermal emission by interplanetary dust particles), unresolved stellar light, diffuse scattering and emission by interstellar dust and gas, and finally an extragalactic component. It has the reputation of being a very traditional field of astronomy, which certainly is true if we look at the long history of the subject. The recent renewed interest in this topic, which continued during this triennium, appears mainly to come from three sources: - first from the impressive results of the IRAS and COBE infrared satellites. They brought to general consciousness the fact that the infrared sky is characterised by strong emission from interplanetary and interstellar dust, and made clear that this emission may interfere with the study of faint interesting sources. - then from the development of sensitive detectors and arrays for essentially all of the wavelength range to be covered in this report, from the Lyman limit to ≈ 300 μm. Now the difficult measurements of the ultraviolet diffuse radiation and of the extragalactic background light in the infrared cosmological windows around 3 μm and 200 μm have become feasible and state of the art projects. - finally, the threat to astronomical observations arising from man-made development and lighting has become important enough to further studies of uncontaminated and contaminated night sky brightnesses. This report will refer mainly to those areas and is meant to highlight noteworthy developments. It was prepared with the help of Drs. Bowyer and Mattila.
7. Direct measurements of meteoritic dust using
rockets and satellites
Authors: Dubin Maurice
Published: July 2016

The space density and the mass distribution of meteoritic dust in the vicinity of the Earth may be directly measured using rocket and satellite vehicles. In comparison with optical and radio detection of meteors, rocket measurements are capable of detecting particles with diameters from 0.1 to 10μ. This range of particle sizes has been observed from photometric measurements of zodiacal light, by ground collections of deep-sea sediments and of the magnetic component of dust settling on flat surfaces, and collections from high-altitude aircraft. Direct measurements from rocket-launched vehicles appear the most reliable for identifying and detecting the meteoritic dust component: since meteor observations are not sensitive enough to detect this component, ground collections suffer from contamination of the terrestrial component of dust and variations resulting from hyper-velocity interactions with the atmosphere, while zodiacal light measurements are capable of determining the gross aspects of the cosmic dust in the ecliptic subject to assumptions of light scattering from solid particles.
9. Some results of outer ionospheric studies
based on radio observations of
the first sputnik
Authors: Alpert Y. L.
Published: July 2016

The method and results of the study of the outer ionosphere based on the ' rise' and ' set' of radio signals of the sputnik are given in full in the paper of which this is an abstract. Results of the theoretical calculations of the maximum horizontal distance rM of signalreception, which are needed for the treatment of experimental data, are also described. Calculations were carried out for a spherical Earth, and the resulting elliptic integral was tabulated by means of the high-speed electronic computer of the Academy of Sciences of the U.S.S.R. A parabolic model of the lower ionosphere and an exponential decline of electronic concentration in its outer part were accepted.
Celestial Reference Systems — An Overview
Authors: Kovalevsky J.
Published: July 2016

The paper starts with a short presentation of the conceptual foundations of celestial reference systems and of the IAU decisions taken in 1991. The necessity to define and use them in the framework of General Relativity induces some difficulties that are analyzed. In the case of kinematically defined reference systems, the origins of a possible residual rotation of the frames is analyzed. The same analysis holds also for an isolated dynamical reference system, for which further developments of the metric are necessary. Finally, a few topics concerning the non-isolated case of the barycentric reference system, the transformation between reference systems, and the significance of measurements are mentioned.
Optical Positions of Extragalactic Radio Sources Using the UCAC1
Authors: Assafin M. , Zacharias N. , Andrei A.H. , Martins R. Vieira
Published: July 2016

Extragalactic radio source positions referred to the first USNO CCD Astrograph Catalog (UCAC1) are presented. They were derived from CCD observations taken with the 1.6-meter Cassegrain telescope at the Laboratório Nacional de Astrofísica, Brazil (LNA). The observations started in 1997 and were carried out in a joint program between USNO, Observatório do Valongo/UFRJ, Brazil, and Observatório Nacional/CNPq, Brazil. They were planned to provide, together with CTIO observations, fiducial points to link the UCAC to the ICRF. The results presented here refer to 24 radio source targets distributed mainly between −30° and −70° declinations. Reduction techniques follow standard procedures. The results are compared with VLBI and with similar precise optical positions, in order to contribute to the evaluation of the UCAC astrometry.
Examination of the Hipparcos Proper Motion System from Lunar Occultation Analysis
Authors: Sôma Mitsuru
Published: July 2016

Lunar occultations were analyzed to detect errors in the proper motion system of the Hipparcos frame. The analysis suggests much larger errors in the rotation of the Hipparcos reference frame than those explained by the Hipparcos team, which were determined from the direct comparison between the Hipparcos and FK5 catalogs.
Global Astrometric Solutions with Sparse Matrix Techniques
Authors: Branham Richard L.
Published: July 2016

Modern astrometric techniques lead to large, linear systems solved by the precepts of least-squares. These systems are usually sparse, and one should take advantage of the sparsity to facilitate their solution. As long as the matrix A of the equations of condition possesses the weak Hall property, characteristic of linear systems derived from astrometric reductions, it is possible to find a sparse Cholesky factor. Before the equations of condition are accumulated, by use of the fast Givens transformation, a symbolic factorization of A using Tewarson’s length of intersection technique determines the ordering of the columns of A that result in low fill-in. The non-null elements are stored in a sparse, dynamic data structure by use of dynamic hashing. Numerical experimentation shows that this competes well with alternatives such as nested dissection, and large, but sparse, linear systems with several thousand unknowns can be solved in a reasonable amount of time, even on personal computers.
Diurnal and Sub-diurnal Terms of Nutation
Authors: Brzeziński Aleksander
Published: July 2016

This paper discusses the short-period terms of nutation which are included in the recent theories of nutation for a rigid Earth. We argue that these terms should be expressed as terrestrial perturbations, that is as polar motion, and describe how such a transformation can be accomplished in practice. Based on the available rigid-Earth amplitudes, we estimate this lunisolar effect in polar motion for an elastic Earth with liquid core, and compare it to the oceanic and atmospheric perturbations at similar frequencies.
Towards sub-microarsecond rigid Earth nutation series in the Hamiltonian theory
Authors: Souchay J. , Folgueira M.
Published: July 2016

The nonrigid Earth nutation series adopted by the IAU (International Astronomical Union) are based on the works of Kinoshita (1977) and Wahr (1979). In the first one, the rigid Earth nutation series were calculated by the application of the Hamiltonian canonical equations to the rotation of the rigid and elliptical Earth. In the second one, the transfer function for the nutations of an elliptical, elastic and oceanless Earth with fluid core and a solid inner core was obtained. The nonrigid Earth nutation coefficients were derived from the convolution between Wahr’s transfer function and Kinoshita’s rigid Earth nutation series.

The improvement in the accuracy of the techniques as a Very Long Baseline (VLBI), Lunar Laser Ranging (LLR) and Global Positioning System (GPS) has led in this decade to the extension of Kinoshita’s theory and more precise determination of Wahr’s transfer function. In the present paper and starting from Kinoshita’s work (1977), we present the different steps carried out, during this last decade, to obtain the sub-microarcsecond rigid Earth nutation series REN 2000 from the Hamiltonian study of the rotation of a rigid Earth (Souchay et al., 1999).
Report of the BIPM/IAU Joint Committee on Relativity for Space-Time Reference Systems and Metrology
Authors: Petit G.
Published: July 2016

The BIPM/IAU Joint Committee on relativity for space-time reference systems and metrology (JCR) has worked in collaboration with the IAU Working Group on relativity for celestial mechanics and astrometry (RCMA) on the problems of astronomical relativistic space-time reference frames and the RCMA has proposed to the IAU a consistent framework for defining the barycentric and geocentric celestial reference systems at the first post-Newtonian level. Because new clock technology and space missions will necessitate the application of this framework for time and frequency measurements in the solar system, practical resolutions are proposed by the JCR to the IAU to allow a consistent treatment of these measurements. The paper outlines the conclusions of the work which resulted in the proposed IAU resolutions.
Report of Special Commission 3 of IAG
Authors: Groten Erwin
Published: July 2016

Since the last presentation of SC-3 on numerical values of fundamental geodetic parameters at the IAU General Assembly at Kyoto in 1997 there were some conceptual as well as fundamental numerical changes. The four basic parameters of geodetic (ellipsoidal) reference systems (GRS) can no longer be considered as constant with time:J2,a, ω, and GM have to be replaced by clearly (±10−8or better) specified mean values or have to be associated with a specific epoch or, in case of GM, with specific reference frames (a= semi-major axis of Earth ellipsoid,J2= second degree zonal harmonic of geopotential,ω= spin of Earth rotation). In case of (a, J2....) associated tidal reductions must be specifically defined in view of particular applications and significant differences between different tidal reduction types. Or we may replace “a” by a quantity which is independent of tides like the geopotential at the geoid, W0, where, however, also temporal changes are now discussed. The official geodetic reference systems such as GRS 80 and WGS 84 (revised in 97-form) are also no longer truly representing reality; a new system GRS 2000 is desired. We are, meanwhile, able to define and determine tidal and non-tidal (secular, periodic, aperiodic) variatipns of some fundamental geodetic parameters. Others are under investigation. New precession and/or nutation formulas to be adopted by IAU in 2000 or later would imply, again, changes in geodetic parameters such asH= hydrostatic flattening. Those and related other consequences are considered.
Radio Sources and Scintillation
Authors: Rickett Barney
Published: July 2016

A review is given of the interplay between studies of compact radio sources and the scattering and scintillations that occur as the signals travel through the irregular refractive index of the interstellar and interplanetary plasmas.
Radio Intra-Day Variability: Answers and Questions
Authors: Jauncey David L. , Kedziora-Chudczer Lucyna , Lovell James E.J. , MacQuart Jean-Pierre , Nicolson George D. , Perley Rick A. , Reynolds John E. , Tzioumis Anastasios K. , Wieringa Mark H. , Bignall Hayley E.
Published: July 2016

Intra-day variability (IDV) of active galactic nuclei (AGN) has been detected from gamma-ray energies to radio wavelengths. At high energies, such variability appears to be intrinsic to the sources themselves. However, at radio wavelengths, brightness temperatures as high as 1018 to 1021 K are encountered if the IDV is intrinsic to the source. We discuss here the accumulating evidence showing that, at radio wavelengths where the highest brightness temperatures are encountered, interstellar scintillation (ISS) is the principal mechanism causing IDV. While ISS reduces the implied brightness temperatures, they still remain uncomfortably high.
Monitoring the Microarcsecond Quasar J1819+3845
Authors: Dennett-Thorpe J. , de Bruyn A.G.
Published: July 2016

We present the results of a year-long monitoring campaign on J1819+3845. We interpret the results of this WSRT campaign to infer critical source parameters such as source lifetime and structure on tens of microarcseconds. The long lifetime of the source at such high brightness temperatures requires continuous energy injection or exotic emission processes. We have previously interpreted the extreme scintillation of Jl819+3845 as due to a relatively nearby (~ 20 pc) scattering screen. We show this screen has a velocity w.r.t. the LSR of ~ 25 km s−1, as measured by the changing scintillation properties throughout the year: the ‘velocity parallax’.
The Radio Luminosity of Pulsars and the Distribution of Interstellar Electron Density
Authors: Andreasyan R.R. , Arshakian T.G.
Published: July 2016

The radio luminosities of pulsars are given as functions of their period and the time variation of the period. The parameters of that dependence are calculated and independent distances are determined for pulsars. The average electron densities toward the pulsars are determined from the known dispersion measures. The results obtained are used to study the large-scale electron density distribution in the Galaxy. The distribution maximum lies in the vicinity of the Sagittarius spiral arm. The electron density falls off exponentially in the regions between spiral arms.
The Control System of the Active Main Reflector for FAST
Authors: Qiu Yuhai , Zhu Lichun
Published: July 2016

The main reflector of FAST consists of about 1800 elementary units. Each unit has three adjustable supports to fix its position, and its position is adjusted by means of mechanical actuators. According to the radio source position at any given time, all the actuators are continuously adjusted to form a proper paraboloid in real time during the course of the observation. The basic requirements of such a control system are discussed. A fieldbus control system based on LonWorks technology is suggested to control all 1800 actuators. The main advantages of this distributed control system are its reliability, flexibility, efficiency and economics.
GAIA Survey of Galactic Eclipsing Binaries
Authors: Zwitter Tomaž
Published: July 2016

The general importance and capabilities of observations of eclipsing binaries by the forthcoming ESA mission GAIA are discussed. Availability of spectroscopic observations and a large number of photometric bands on board will make it possible to reliably determine physical parameters for ∼ 105 binary stars. It is stressed that current methods of object by object analysis will have to be modified and included in an automatic analysis pipeline.
The Strange Story of BI Lyncis: an Extremely Helium-Rich Subdwarf with a Cool Companion
Authors: Jeffery C. Simon , Cuadrado R. Aznar
Published: July 2016

The star BI Lyn = PG 0900+400 was previously classified as an evolved binary system containing either a hot subdwarf or white dwarf and a thick accretion disk. We have analyzed new intermediate dispersion spectra and demonstrated that both views are wrong. BI Lyn is a highly-evolved system containing a luminous low-mass helium star and a rapidly rotating G-type giant. It may be closely related to the evolved sdO+G binary HD 128220.
The Stellar Wind Geometry of η Carinae
Authors: Smith Nathan , Davidson Kris , Gull Theodore R. , Ishibashi Kazunori
Published: July 2016

The Homunculus reflection nebula around η Carinae provides a rare opportunity to observe a star from more than one direction. For η Car, the nebula’s geometry is known well enough to infer how wind profiles vary with latitude. STIS spectra of the Homunculus show directly that η Car has an aspherical stellar wind. P Cygni absorption in Balmer lines depends on latitude, with relatively high velocities and strong absorption near the polar axis. Stronger absorption at high latitudes is surprising, and it suggests higher mass flux toward the poles, perhaps resulting from equatorial gravity darkening on a rotating star. Reflected profiles of He I lines are more puzzling, and offer clues to η Car’s circumstellar structure. The bipolar wind geometry may imply that intrinsically asymmetric ejection helped form the Homunculus. It is also critical for understanding this star’s variability and evolution.
Binaries with Invisible Massive Components
Authors: Chochol Drahomír , Mayer Pavel
Published: July 2016

V505 Mon is an early type eclipsing binary (usually classified as B5 Ib), in which only spectral lines of the primary component are visible. The radial velocity curve provides f(m) = 4.6 M⊙, suggesting that the secondary, invisible component is more massive. We have found evidence that this star is hidden from view by the disk detected during the primary eclipse. The structure of the disk can be characterized by a central ionization zone surrounded by the neutral outer parts. The profiles of the CII 1335/6 doublet lines were used to derive the rotational velocity of the disk as well as the velocity of the stream from the primary component to the disk. The masses of the components, deduced from the fractional size of the disk, are M1 = 1 M⊙ and M2 = 6.1 M⊙. Due to the low mass of the primary component its supergiant nature can be ruled out. Additional matter of a cloudy nature is present in the system and both components are embedded in an extended atmosphere. V505 Mon seems to be a prototype of the whole group of similar early-type binaries, in which the more massive component is hidden by a circumstellar medium, most likely a disk. Probable members are V742 Cas, V1362 Cyg, V2174 Cyg, V447 Sct and FY Vel with orbital periods between 33 and 225 days. Emission in Ha is always present, but there are no emissions in IUE spectra, so these binaries are distinct from the W Ser type. The evolutionary state of the members of this group is not yet understood.
V471 Tauri and SuWt 2: The Exotic Descendants of Triple Systems?
Authors: Bond Howard E. , O’Brien M. Sean , Sion Edward M. , Mullan Dermott J. , Exter Katrina , Pollacco Don L. , Webbink Ronald F.
Published: July 2016

V471 Tauri is a short-period eclipsing binary, and a member of the Hyades. It is composed of a hot DA white dwarf (WD) and a cool main-sequence dK2 companion. HST radial velocities of the WD, in combination with the ground-based spectroscopic orbit of the K star, yield dynamical masses of MWD = 0.84 and MdK = 0.93 M⊙. During the UV observations we serendipitously detected coronal mass ejections from the K star, passing in front of the WD and appearing as sudden, transient metallic absorption. Eclipse timings show that the active dK star is 18% larger than a main-sequence star of the same mass, an apparent consequence of its extensive starspot coverage. The high Teff and high mass of the WD are paradoxical: the WD is the most massive in the Hyades, but also the youngest. A plausible scenario is that the progenitor system was a triple, with a close inner pair that merged after several × 108 yr to produce a single blue straggler. When this star evolved to the AGB phase, it underwent a common-envelope interaction with a distant dK companion, which spiraled down to its present separation and ejected the envelope. The common-envelope efficiency parameter, αCE, was of order 0.3–1.0, in good agreement with recent hydrodynamical simulations.

SuWt 2 is a southern-hemisphere planetary nebula (PN) with an unusual ring-shaped morphology. The central star is an eclipsing binary with a period of 4.9 days. Surprisingly, the binary is composed of two main-sequence A-type stars with similar masses of ~ 2.5 M⊙. We discuss scenarios involving a third companion which ejected and ionizes the PN.

WeBo 1 is a northern PN with a ring morphology remarkably similar to that of SuWt 2. Although we hoped that its central star would shed light on the nature of SuWt 2, it has proven instead to be a late-type barium star!
The Slow Merger of Massive Stars: Merger Types and Post-Merger Evolution
Authors: Ivanova N. , Podsiadlowski Ph.
Published: July 2016

We study the slow merger of two massive stars inside a common envelope. The initial close binary system consists of a massive red supergiant and a main-sequence companion of a few solar masses. The merger product is a massive supergiant with an interior structure (core mass and composition profile) which is significantly different from that of a single supergiant that has evolved in isolation. Using a parameterized approach for the stream–core interaction, we modelled the merger phase and have identified three qualitatively different merger types: quiet, moderate and explosive mergers, where the differences are caused by the different response of the He burning shell. In the last two scenarios, the post-merger He abundance in the envelope is found to be substantially increased, but significant s-processing is mainly expected in the case of an explosive merger scenario. The subsequent evolution of the merger product up to the supernova stage is also discussed.
CW Leonis, IRC+10216
Authors: Knapp G.R.
Published: July 2016

CW Leo is the nearest and brightest example of a highly evolved carbon Mira variable red giant, and is surrounded by an extensive dusty, molecular circumstellar shell produced by mass loss. Since the shell heavily obscures the star, most of the information about CW Leo comes from observations of its shell, whose radial properties encode a history of the star as well as of the interaction between the outflowing gas and the interstellar radiation field. The shell of CW Leo contains a rich variety of molecules, from salts to cyanide, whose isotopic composition shows the effect of nuclear processing in the stellar interior and give information about the formation and composition of the circumstellar dust. This nearby star allows us a detailed look at one of the most eventful and interesting phases in a star’s evolution.
The Formation of Subdwarf B Stars
Authors: Han Zhanwen , Podsiadlowski Philipp , Maxted Pierre F.L. , Marsh Tom R. , Ivanova Natasha
Published: July 2016

We performed full binary evolution calculations and carried out binary population synthesis studies in order to investigate the formation of subdwarf B (sdB) stars via the channels of stable Roche lobe overflow (RLOF), common envelope ejection and helium white dwarf mergers. Our model is successful in the explanation of observational properties of sdB stars, e.g. we explained the orbital period – minimum companion mass (log P – Mcomp) diagram, the effective temperature – surface gravity (Teff – log g) diagram, the orbital period distribution, the log(gθ4) (θ = 5040/Teff) distribution, the mass function distribution, the binary fraction of sdB stars, the fraction of sdB binaries with WD companions, the birth rates, the space number densities, etc. We conclude that (a) the first RLOF needs to be more stabilized than commonly assumed, (b) the first stable RLOF is not conservative, (c) common envelope ejection is very efficient.
The Unusual Evolutionary State of Nova Scorpii 1994
Authors: Tout Christopher A. , Regős Enikő , Wickramasinghe Dayal
Published: July 2016

We have investigated possible models for the evolutionary status of the black-hole soft X-ray transient Nova Scorpii. We propose that it is a main-sequence star in which convective overshooting, or some equivalent mixing, occurs at the core-envelope boundary. Recent detections of chemical pollution on the surface of the secondary suggest that the black hole formed in a supernova whose ejecta left and fell back at a sufficiently low velocity to accrete on to the secondary. We examine the effects of increased opacity, increased metallicity and reduced hydrogen abundance on the evolution of the secondary in the hope that these might lead to an alternative scenario. All these only exacerbate the problem.
Exotic Stars as Challenges to Evolution: an Evaluation
Authors: Jeffery C. Simon
Published: July 2016

A star is exotic because, in some way, it extends our knowledge of how stars behave. As we make new observations we discover new phenomena that we do not understand. As we approach an understanding, those phenomena seem less exotic. That is nature. IAU Colloquium 187 set out to discover how far our knowledge of stars now reaches. This is a personal commentary on the proceedings.
Thermal-timescale mass transfer and magnetic CVs
Authors: Schenker Klaus , Wynn Graham A. , Speith Roland
Published: July 2016

We investigate the spin evolution of the unusual magnetic CV AE Aqr. As a prototype for a potentially large population of CVs subject to a thermally unstable phase of mass transfer, understanding its future is crucial. We present a new definition of the magnetospheric radius in terms of the white dwarf’s spin period, and use this along with numerical simulations to follow the spin evolution of AE Aqr. We also present preliminary SPH results suggesting the existence of a stable propeller state. These results highlight the complexity of MCVs and may provide an improved understanding of the evolution of all types of CVs.
Polarized Emission and the Discovery of New Magnetic CVs
Authors: Schmidt Gary D.
Published: July 2016

Recent quasar surveys have identified several new magnetic cataclysmic variables accreting at remarkably low rates, ~10−13M⊙ yr−1. The new discoveries raise questions regarding selection effects that may influence the current sample and the traditional evolutionary conclusions that have been drawn. This paper reviews the techniques that have been used to identify polars, including a summary of the optical polarization as a function of accretion rate and magnetic field strength. The new, low-ṁ systems accrete without a shock and cooling is dominated by optical cyclotron emission in very well-defined harmonics. These binaries, which have been found to accrete at far below the rate corresponding to angular momentum loss by gravitational radiation, also appear to contain unusually cool white dwarfs, suggesting that they are either at an advanced age or in unusual evolutionary states.
Multi-Epoch spectroscopy and XMM-Newton observations of RX J2115–58
Authors: Cropper Mark , Ramsay Gavin , Marsh Tom
Published: July 2016

We present here phase-resolved optical spectroscopy and X-ray light curves of the asynchronous polar RX J2115–58 as they change on the beat period.
Hα Doppler Tomography of AM Her: Evidence for Bipolar Accretion
Authors: Papadimitriou Christos , Harlaftis Emilios
Published: July 2016

We present Doppler maps of Halpha emission lines of AM Her from four differents epochs. The tomography shows a strong velocity “spot” emission at (−100,−100) km s−1 and a weaker “spot” emission at (−100,−400) km s−1 which is suggestive of bi-polar accretion onto the white dwarf with stronger emission from the main pole at phase φ=0.0.
AE Aquarii continuum emissions from Radio low frequencies to Infra-Red
Authors: Abada-Simon Meil
Published: July 2016

AE Aquarii radio flares are attributed to synchrotron optically thick emission from expanding plasma clouds, and the turnover frequency and the optically thin part of the synchrotron spectrum seem to be between the sub-millimetre and infra-red wavelengths. We present the various processes which may affect the synchrotron radiation at both very low (radio) frequencies and at higher energies, and what they infer on the properties of the radio flare source and its surroundings. We also envisage that both thermal and non-thermal emission processes may explain the puzzling spectrum of AE Aqr.
Session 6: Discussion on Propeller Systems
Authors: de Martino Domitilla
Published: July 2016

I summarize some aspects which have been raised for discussion during Session 6, devoted to magnetic propeller systems.
The Pole Position in October 1980 as Determined from Lageos Laser Data
Authors: Reigber Ch. , Mueller H. , Wende W.
Published: July 2016

On the basis of 223 passes of Lageos Laser Tracking data taken in October 1980 during the MERIT short arc campaign from 13 tracking sites, the pole position was determined in the orbit correction program MGM along with the initial state vector. This analysis was done for a varying time resolution (5-1 days).

Basis of our computation is the GRIM3P gravity model and a station position set derived by UTEX and partly by the DGF1. The formal sigma of the 5 and 2.5 mean values for the pole coordinates is generally about 0.005 arc-seconds.
Progress Report on Project Merit
Authors: Wilkins George A
Published: July 2016

The origin, objectives and programme of Project MERIT, which is a special programme of international collaboration to Monitor Earth-Rotation and Intercompare the Techniques of observation and analysis, were described briefly at IAU Colloquium No. 56 (Wilkins, 1981). Further details of the project and reviews of the techniques to be used were published in a special report (Wilkins, 1980). The MERIT Short Campaign of observations was held during the period 1980 August 1 to 1980 October 31 and the preliminary results obtained will be published by the Bureau International de l’Heure in its Annual Report for 1980. The main objective of the campaign was to provide a realistic test of the operational arrangements that will be required during the MERIT Main Campaign in 1983/4. The first MERIT Workshop was held at Grasse on 1980 May 19-21 to review the operational aspects of the short campaign and to continue the planning for the main campaign. Some of the results obtained during the short campaign were presented on the following day at IAU Colloquium No. 63, and are reported in this volume. The proceedings of the Workshop will be published by the Working Group in a report that will also contain the principal results of the short campaign and information about the availability of the observational data.
Atmospheric Angular Momentum and the Length of Day
Authors: Langley R. B. , King R. W. , Shapiro I. I. , Rosen R. D. , Salstein D. A.
Published: July 2016

We have used lunar laser ranging (LLR) observations from the McDonald Observatory in conjunction with pole positions from the Bureau International de l’Heure (BIH) to determine the length of day (l.o.d.) at five-day intervals over the period 1971 through 1979. We compared the changes in these l.o.d. values to those inferred from determinations of the angular momentum of the global atmosphere, for the years 1976-1979, computed from twice-daily analyses of the zonal wind. These latter analyses were carried out by the National Meteorological Center, Camp Springs, MD. In both the observed (LLR) and the inferred (meteorological) values of changes in l.o.d., we have identified the near 50-day oscillation recently noted by Feissel and Gambis at the BIH. For the period of overlapping dates, the two oscillations agree closely in both amplitude and phase. The typical amplitude is about 0.2 milliseconds or approximately half the amplitude of the annual and semiannual variations in l.o.d.
Dissipation in the Moon: A Review of the Experimental Evidence and Physical Implications
Authors: King R. W.
Published: July 2016

Recent analyses of lunar ranging observations have revealed strong evidence of dissipation in the moon’s rotation (Ferrari et al. 1980; Cappallo et al. 1981). If interpreted as solid body friction, these results imply a tidal Q of about 25 (±5) at a frequency of one cycle per month. There is little evidence from other studies of the interior structure of the moon to support such a low solid-body Q. Yoder (1981) finds that turbulent fluid friction between the mantle and a core of radius ~300 km is a plausible mechanism to explain the observed dissipation. An iron or iron-sulfide core of this size is consistent with moment-of-inertia (Blackshear and Gapcynski 1977, Ferrari et al. 1980) and seismic (Goins et al. 1979) data, and is not excluded by conductivity data (Goldstein 1979). Stevenson and Yoder (1980) have proposed a model for formation of a solid iron inner core surrounded by a fluid iron sulfide layer of thickness 65 − 180 km.
Relations Between Celestial and Selenocentric Reference Frames
Authors: Kovalevsky J.
Published: July 2016

The very great accuracy with which the motions of the Moon can now be monitored by laser ranging, differential VLBI and occultation observations, implies that the interpretation of the measurements is conditioned by the choice and the accurate knowledge of a selenocentric, a terrestrial and a celestial frames. Two different types of selenocentric reference frames can be envisioned. The present selenographic frames are discussed but the author proposes that one should introduce a system defined by a purely geometric means. Some consequences of such a choice are discussed. One feature of the future conventional terrestrial frame is very important for Earth-Moon dynamics. Its origin should coincide with the center of mass of the Earth as determined by lunar laser ranging. As far as the quasi-inertial reference systems are concerned, the liaisons between a purely lunar dynamical system, subject to some hardly modelable effects, and purely celestial systems are analysed. The reduction of observations made with various techniques implies the use of different systems, and several problems are stated that should be solved before a unique system for Earth-Moon dynamics might be used.
Biases in Pole Position Computed from Data from Different Navy Navigation Satellites
Authors: Anderle R. J. , Colquitt E.S. , Tanenbaum M. , Malyevac C. A.
Published: July 2016

Biases have been noted in pole positions computed from Doppler observations of different Navy Navigation Satellites. Studies show that the differences in the orbits of the Navy Navigation Satellites, although small, are large enough so that uncertainties in knowledge of the earth’s gravity field could produce the biases noted.
Difficulties for Western Nations in Obtaining Publications from Other Nations
Authors: Weigel Jack W.
Published: July 2016

For science librarians in the developed nations of the West, the difficulties of obtaining publications from other parts of the world seem to center around two interconnected factors: the number of copies printed of each publication and the availability of timely information about publication plans. For example, as quite a few people in today’s audience are aware, many advanced research publications from the Soviet Union are issued in relatively small quantities. As a result, libraries in the West must often order Soviet books in advance of publication in order to have a reasonable chance of obtaining them. By the time a specific title from the Soviet Union gets listed in the national bibliography, Knizhnaia letopis’, copies are no longer available for purchase. With respect to periodicals, the limited number of copies has an effect both on new orders and on claims. An order to initiate a subscription must be submitted several months in advance of the first issue of the volume which is to start fulfillment of the subscription. Otherwise one or more issues will be missed; only those issues actually published after the subscription has taken effect will be received by the subscribing library. After a subscription is firmly established, there is always a possibility that a particular issue may not be received by the subscriber. Libraries in the West are accustomed to sending in a claim for each missing issue, but this is seldom effective in the instance of Soviet periodicals, since few (if any) extra copies are printed.
Astronomical Directories
Authors: Heck A. , Halbwachs J.L.
Published: July 2016

Astronomical directories are available as CDS Special Publications. They provide practical data that one seeks to have always at one’s disposal on astronomical organizations and related items of interest.

Over the years, these directories have proved to be very effective tools not only for improving national and international relationships in amateur and professional astronomy, but also for helping amateur astronomers, laypersons and public bodies to easily contact astronomical organizations as the need arises.

IDPAI 1989 (CDS Special Publication 12 - about 500 pages) will be the second edition of the International Directory of Professional Astronomical Institutions. It will gather more than 2600 entries from about 80 countries: professional astronomical observatories and institutions; organizations, universities, departments, groups or companies employing astronomers or researchers in astronomy; related entries of general interest: IAU adhering organizations, professional associations, funding organizations, academies, as well as bibliographical services, software producers, journals, publishers, manufacturers, dealers, etc.
Electronic Mail
Authors: Benn Chris
Published: July 2016

Astronomers have always had a special need for rapid communication over large distances, partly because of their interest in experiments requiring long baselines. Examples: Eratosthenes’ measurement of the circumference of the Earth; determination of longitude at sea; solar-eclipse tests of general relativity; very-long-baseline interferometry. Of these, at least the second has prompted innovations in communications techniques (beginning with the Greenwich time ball).

More recently, the pressing need to travel widely for clean air and aether, and the international flavour of the resulting collaborations, has given astronomers particular incentive to explore the latest communications innovation: electronic mail.