bluuebunny/crossref_metadata_2025 huggingface dataset:
Photometry and Variability of Double Stars
Authors: Walker R. L.
Published: July 2016

Selected topics of double star photometry are discussed together with current observational programs and new observing techniques. A revised catalog of visual binaries with one or more variable components is described.
White Dwarf Formation in Two-Body Systems: Sirius AB, Procyon AB, 40 Eri BC AND Stein 2051 AB
Authors: Roark Terry P.
Published: July 2016

The orbital histories of the systems Sirius AB, Procyon AB, 40 Eri BC and Stein 2051 AB are examined. It is assumed that the changes in the orbital elements are a direct result of mass loss from the white dwarf precursor component. This loss is considered to be isotropic and no exchange between the components is allowed. These histories, coupled with observed atmospheric abundances, theoretical ages and cooling times lead to the conclusion that stars as massive as 10M⊙ can be white dwarf progenitors. Indeed, in the case of Sirius B, there is evidence that the progenitor mass was not less than 8M⊙ and that the star did not lose mass in an explosive manner.
Review of the Dynamical Aspects of Triple Systems
Authors: Szebehely V.
Published: July 2016

A classification of possible motions of triple systems is presented emphasizing the transient phenomena occurring in addition to the final (asymptotic) outcome and clarifying the discrepancies between the astronomical and mathematical formulations. A conjectured possible instability is described and it is shown that systems with negative total energy and low angular momentum may lead to instability and to the formation of binaries. The ejected or escaping star may have high velocity if the triple close approach preceding the escape is sufficiently close. The computational results of several systematic series of such escapes are applied to various stellar configurations.

The present status of the fundamental problem of partitioning the phase-space into stable and unstable regions is reviewed and a recently developed technique, applicable to stellar dynamics is described. Recently discovered families of periodic orbits and previously established classical configurations are shown to weaken the general instability conjecture.

The possible existence of triple systems in states of dissolution offer intriguing observational challenges regarding the discovery of these projected temporary trapezium type systems.
Numerical Experiments on the Decay of Three-Body Systems
Authors: Valtonen M. J. , Aarseth S. J.
Published: July 2016

Numerical results are presented for calculations of stellar three-body systems. Among the triple systems with similar initial separations between each of the stars, the equal-mass systems are most stable with typical half-lives of about 40 crossing times. In the other extreme, systems with a very small total angular momentum or a large mass difference have half-lives of only about 10 crossing times. The escaping star is usually the lightest one, while the escape probability for the heaviest star approaches zero when its mass exceeds the combined mass of the other two stars by more than a factor of about 5. The final binary becomes very eccentric (ē ≳ 0.8) when the three stars are restricted to a plane and do not have a very high total angular momentum, or when the total angular momentum is very small.
Data Processing and Analysis for Space-Based Astronomy
Authors: Mistrik I.
Published: July 2016

The sensors on a spacecraft, the spacecraft data handling system, the mission support ground data system, the experimenter’s scientific data reduction and analysis system, the post-mission data storage and dissemination system all comprise elements of the data handling system for a space-based astronomy.

Primary treatement is given to the experimenter’s scientific data system where the following aspects of astronomy missions are discussed: increasingly close operational contact of the experimenters with the sensors calls for moving data processing operations to the earliest possible point of the system. On the other hand, potential need for subsequent reprocessing of data would favor the central ground-based facility for initial processing with the open-end system philosophy.

One approach, extant and planned implementation of the scientific data analysis system for the zodiacal light experiment of the solar probe Helios, is presented in detail, taking into consideration experience from the various astronomy missions, in particular Pioneer and Skylab.
The Use of Standardized Data Formats with the Westerbork Radio Telescope
Authors: Harten R.H. , Spoelstra T.A.Th.
Published: July 2016

Since 1970 the Westerbork Synthesis Radio Telescope has been collecting data on galactic and extragalactic fields. The data is stored and cataloged on magnetic tape using a standard format. This data is routinely reduced and analyzed at different observatories in Europe. A reduction program package allows manipulation and display of the data. After the initial reduction all tape output from the reduction programs uses the same tape format regardless of the program. Transportation of data between observatories is done via magnetic tape with the same standard format. For data transportation to observatories not normally using Westerbork information a common tape format has been developed. Suggestions to alleviate problems with this data transfer are discussed.
Work on the General Catalogue of Variable Stars
Authors: Kukarkin B.V. , Kholopov P.N. , Kireeva N.N.
Published: July 2016

The Variable Stars Bureau of the Astronomical Council of the USSR Academy of Sciences presents this paper in order to provide information on our work with the hope that it will be discussed and recommendations to it will be made. More rational co-operation of our Bureau and the Strasbourg Centre de Données Stellaires is highly desirable. It should be based on the exchange of information gained in these centres in order to make both centres free from duplicating work.
Catalogues of Spectroscopic Binaries
Authors: Batten Alan H.
Published: July 2016

There are two centres at which papers on spectroscopic binaries are filed and catalogues produced — Toulouse, France and Victoria, B.C., Canada. The aims of these two are somewhat different. At Toulouse a running file of all references to spectroscopic binaries is kept, and many workers have found the comprehensive series of Catalogues Complémentaires (e.g. Pedoussaut and Carquillat 1973) very useful. At Victoria, on the other hand, we concentrate more specifically on spectroscopic determinations of orbital elements, and our catalogue of them was a direct successor of the five such catalogues published by the Lick Observatory. While the Toulouse catalogues are comprehensive, we at Victoria try to make a critical assessment of each orbit we include, and we regard this as one of the most important aspects of our catalogues. Such a critical catalogue obviously cannot be published as frequently as are the Catalogues Complémentaires, which, just as their name implies, are complementary to the Victoria work. There is no fixed interval between the publication of successive Lick-Victoria catalogues. The five from Lick appeared at a mean interval of about a decade, but the transfer to Victoria delayed the appearance of the Sixth Catalogue (Batten 1967) to almost twenty years after that of the Fifth (Moore and Neubauer 1948). After another decade, the Sixth Catalogue is out of date and out of print, and we are well advanced on the preparation of a Seventh, which we hope will appear in 1977. The Sixth Catalogue contained orbital elements for 737 spectroscopic binary systems. About 200 (or 25 per cent) new systems have now to be added, and about one per cent of those already in should be deleted. In addition, new orbital information is available for over 100 of the systems already in the Sixth Catalogue.
The Princeton-Pennsylvania-Florida Card Catalogue of Eclipsing Variables
Authors: Wood Frank Bradshaw
Published: July 2016

For many years, the study of close double stars seemed somewhat remote from many astronomical problems. The specialists in the field pursued it with enthusiasm, regarding each light or velocity curve as a particular challenge and each system as unusual and interesting in its own right. However, the relation to most other branches of astrophysics sometimes seemed remote. In favorable cases, masses and radii (and hence mean densities) could be obtained and the mass-luminosity relation could be strengthened; even this advantage was partially negated when it was early realized that in many cases the fainter components were notorious violators of the relation established by visual binaries (i.e., systems well separated compared to those discussed here). Various complexities, connected chiefly with interaction effects between the close components, prevented their use for the extremely precise determinations of limb darkening which at one time seemed possible. Other difficulties have prevented the determination, with the precision once comtemplated, of details of internal structure from the apsidal rotation.
The Future Role of Data Centres in Astronomy
Authors: Wilkins G. A.
Published: July 2016

There are two main modes of data-centre operation – the passive and the active. In the passive mode the data are received, catalogued and stored, and some are later copied and distributed in response to specific requests. In the past the passive mode has been represented by the many printed volumes of observational data in astronomical libraries, but the techniques of data acquisition are now such that it is often no longer practicable, even if it were desirable, to print the very large amounts of observational data that are now produced by modern instruments. In the active mode of data-centre operation the centre collects data that it considers to be useful, then evaluates, combines and analyses them, and finally publishes the results of this work. In the past the active mode has been common in astronomy, and the general catalogues of stellar data are examples of this mode of operation, but each one has required many years of effort. Modern computer systems can, however, store large amounts of data and can display, manipulate and copy them very quickly; it is now possible to combine data of many different kinds and to analyse them together, with the prospect of giving new knowledge about the systems being studied.
Astronomical Data Coordination: A Perpetual Task
Authors: Heintz W. D.
Published: July 2016

The conference now about to be concluded has presented a wide spectrum of coordinate efforts, of accomplishments, projects, and viewpoints. As is only natural and even purposeful in a first colloquium of this scope, there are also some loose ends which we hope to tie together later. Many experienced scientists found it worth participating in the subject which is more organization rather than primary research, and this is a very encouraging feature. Most of us will have deplored, in one context or other, the lack of reliable data compilations; yet not much could be done before efficient computer and storage facilities were at hand, and we may also have nourished the hope that someone else would undertake the tedious and often thankless job of compilation. We are grateful that the invitation to convene the first Numerical Data conference came from the Strasbourg Observatory, where a large-scale and multi-purpose program has been successfully developing in recent years.
The distance scale beyond the Local Group – A progress report on work in the southern hemisphere
Authors: Smith Malcolm G.
Published: July 2016

Afin d’éviter la répétition du contenu de nombreuses revues récentes, cette contribution rapporte principalement les projets d’étude au-delà du groupe local, en cours de réalisation dans l’hémisphère Sud.

La majeure partie de ce travail n’ayant commencée que récemment, les résultats sont préliminaires. Divers sujets sont traités: le groupe du Sculpteur (§ II), des groupes proches de l’hémisphère Sud et des galaxies de champ (§ III), ainsi que les distances des amas denses les plus proches de l’hémisphère Sud. D’autres travaux seront cités dans certaines revues de la conférence: (i) les études sur les nuages de Magellan, et d’autres objets du groupe local, (ii) les problèmes d’anisotropie de l’expansion de Hubble, (iii) les estimations des distances des objets quasi stellai-res.
Spectroscopy and the Hubble diagram of faint radio galaxies
Authors: Spinrad Hyron , Smith Harding E.
Published: July 2016

L’ÉTUDE SPECTRALE ET LE DIAGRAMME DE HUBBLE DES RADIOGALAXIES

Nous discutons les identifications récentes et les observations des radiogalaxies faibles, au décalage spectrale z = 0.75, en les présentant dans des diagrammes Hubble.
A search for neutral hydrogen in primordial protoclusters
Authors: Davies R. D. , Pedlar A.
Published: July 2016

La prévision de Sunyaev et Zel’dovich que les proto-amas peuvent passer par une phase d’hydrogène neutre pendant leur formation a été testée par la recherche de leur émission de la raie d’hydrogène décalée vers le rouge. Des limites supérieures comprises entre 0. 07 et 0. 17 °K ont été obtenues dans une bande de 2. 5 MHz à 327 MHz ce qui correspond à un décalage vers le rouge de z = 3.33. Ces résultats indiquent qu’il ne peut pas exister plus de proto-amas d’hydrogène que la quantité calculée par ces auteurs.
The mass to light ratio of Markarian galaxies
Authors: Huchra John P.
Published: July 2016

Une estimation du rapport moyen masse sur luminosité des galaxies de Markarian est déterminée à partir de bonnes mesures de vitesses pour des paires serrées de galaxies de Markarian. Une comparaison avec les données rassemblées par Turner pour des galaxies de champ montre que les galaxies de Markarian et les galaxies de champ ont le même rapport moyen masse sur luminosité. Le degré de regroupement en amas ou en paire des galaxies de Markarian est comparé avec celui trouvé pour les galaxies de champ. Les galaxies de Markarian ne montrent pas une tendance plus grande que les autres galaxies à se regrouper en paires.
The “conventional” view of redshifts
Authors: Rees M. O.
Published: July 2016

Exposé du point de vue “conventionnel” sur les décalages vers le rouge.

In Peebles’ well-known textbook, one chapter is entitled “a child’s garden of cosmological models”. Maybe a “jungle” would better describe the lush diversity of theories expounded at this exceptionally interesting conference. If there is a dominant orthodoxy in cosmology, the proceedings here have successfully obscured it – a participant without prior exposure to the subject would not have gleaned from this week’s discussions what views were “conventional” and what were not. Anyway, I presume that my brief is to assess the status of the cosmological views that would commend themselves to Peebles and his like: that is to say, the package of ideas in which there was a “hot big bang”, galaxies and clusters condensed via gravitational instability, the quasar phenomenon is related to galactic nuclei, and all large redshifts (except perhaps quasar absorption lines) are due to the expansion of the universe. This, at least, is the framework within which we “conventional” people attempt to interpret the data – or (in the view of some “radicals”) the self-imposed blinkers by which our vision is confined.
Historical Introduction
Authors: Freeman K.C.
Published: July 2016

Our ideas about the surface brightness distribution of galaxies has changed greatly since 1970. I contrast the view at that time with our present view of the subject, and then briefly discuss some topics in the studies of Low Surface Brightness Galaxies (LSBG) that I think are particularly interesting: the Tully-Fisher relation, LSBG as systems of high angular momentum, LSBG in clusters of galaxies, and the potential impact of the HIPASS survey.
The Space Density of Spiral Galaxies as function of their Luminosity, Surface Brightness and Scalesize
Authors: de Jong Roelof S. , Lacey Cedric
Published: July 2016

The local space density of galaxies as a function of their basic structural parameters -like luminosity, surface brightness and scalesize-is still poorly known. Our poor knowledge is mainly the result of strong selection biases against low surface brightness and small scalesize galaxies in any optically selected sample. We show that in order to correct for selection biases one has to obtain accurate surface photometry and distance estimates for a large (≳ 1000) sample of galaxies. We derive bivariate space density distributions in the (scalesize, surface brightness)-plane and the (luminosity, scalesize)-plane for a sample of ~1000 local Sb-Sdm spiral galaxies. We present a parameterization of these bivariate distributions, based on a Schechter type luminosity function and a log-normal scalesize distribution at a given luminosity. We show how surface brightness limits and (1+z)4 cosmological redshift dimming can influence interpretation of luminosity function determinations and deep galaxy counts.
Low Surface Brightness Dwarf Galaxies in the Bristol – Anglo-Australian Observatory Virgo Cluster Survey
Authors: Jones J.B. , Phillipps S. , Schwartzenberg J.M. , Parker Q.A.
Published: July 2016

We describe a new, deep photographic survey of the Virgo Cluster which uses multiple exposures on Tech Pan film with the United Kingdom Schmidt Telescope to probe the dwarf population to fainter surface brightness limits than previous surveys. We have identified galaxies having sizes (≥ 3 arcsec scale length) and surface brightnesses (≤ 24.5 R mag arcsec−2) characteristic of those expected for dwarf spheroidal galaxies in the cluster. The survey is providing substantial samples of extremely low luminosity galaxies outside the environment of the Local Group and nearby groups for the first time. An initial study of two small areas has found dwarf spheroidal candidates in large numbers (500 deg−2) which indicate a steep, continuously rising luminosity function at low luminosities.
Counting the Ghosts: Optical Field Surveys for Low Surface Brightness Galaxies
Authors: Dalcanton Julianne J.
Published: July 2016

Given the difficulties in detecting even a single LSB, surveying statistically significant numbers of LSBs presents a daunting task. Large, systematic surveys with well understood selection criteria are necessary for assessing the full cosmological significance of the LSB population. Here I briefly review some of the progress which has been made in the last ten years, and suggest strategies which may prove fruitful in the future.
Environmental Effects on the Faint End of the Luminosity Function
Authors: Phillipps S. , Jones J.B. , Smith R.M. , Couch W.J. , Driver S.P.
Published: July 2016

Recent studies have demonstrated that many galaxy clusters have luminosity functions (LFs) which are steep at the faint end. However, it is equally clear that not all clusters have identical LFs. In this paper we explore whether the variation in LF shape correlates with other cluster or environmental properties.
An HI Survey of LSB galaxies selected from the APM Survey
Authors: Côté Stéphanie , Broadhurst Tom , Loveday Jon , Kolind Shannon
Published: July 2016

We present preliminary results of a neutral hydrogen (HI) redshift survey to find Low Surface Brightness (LSB) galaxies in the very nearby universe. Our sample consists of all galaxies in the APM catalog (Maddox et al. 1990) with a mean surface brightness of μ ≥ 24 mag/arcsec2, down to a magnitude limit of bj ≤ 17. With the Parkes 64m radiotelescope 35 objects were detected at v < 4300 km s−1. The resulting luminosity function, HI mass function, and for the first time total mass function are presented. It is found that LSBs make a negligible contribution to the overall integrated luminosity, HI mass, and total mass contained in galaxies.
Observational Properties of Triple Galaxies
Authors: Karachentsev I. D.
Published: July 2016

This report presents basic observational parameters for galaxy triplets selected by criterion of their isolation on the sky (=Catalog of Triple Galaxies, Karachentseva et al, 1979). The CTG sample is compared with a sample of wide triple systems from Nearby Galaxies Catalog (Tully, 1988) as well from a new whole-sky catalog of small galaxy groups in the Local Supercluster (Makarov & Karachentsev, 2000). For all the samples their medians of the virial mass-to-luminosity ratio lie in a narrow range, 31 <Mvir/L< 36 (M⊙/L⊙), while the medians of the crossing time occupy a wider range, 0.07 <Tcross< 0.37 (in 1/Hunits).
The effects of galaxy winds on small galaxy groups
Authors: Helsdon Stephen F. , Ponman Trevor J.
Published: July 2016

We present the largest survey to date of the X-ray properties of loose groups. We derive relations between X-ray luminosity, temperature and velocity dispersion, and also examine the surface brightness profiles of these systems. We find significant departures from the trends seen in galaxy clusters, which we interpret as arising from the effect of galaxy winds, and we briefly compare the properties of these loose groups with those of compact groups.
Collisional Ring Galaxies in Small Groups
Authors: Horellou C.
Published: July 2016

The probability of plunging orbits is enhanced in groups of galaxies and indeed, observations show that ring galaxies, which are believed to form when a galaxy passes through the center of a larger rotating disk, are often found in small groups. Numerical simulations combined with a knowledge of the large-scale H I distribution provide strong constraints on the dynamical history of these systems and on the identity of the intruder. Here we present a numerical model of the Cartwheel galaxy which supports the suggestion that the most distant companion is the intruder. We also present high-resolution H I observations of the more irregular system Arp 119 that reveal a possible connection to the most distant companion.
Galaxies in the M81 Group and IC342/Maffei Complex: The Structure and Stellar Populations
Authors: Drozdovsky Igor , Nikolay Tikhonov
Published: July 2016

We present optical V, R, and I-band observations on the structure and stellar populations of the M81 Group and IC342/Maffei Complex galaxies. The images have been obtained with the 6m BTA and 2.5m Nordic optical telescopes. Stellar photometry of several galaxies in these groups have been performed. The resulting colour-magnitude diagrams reveal the morphology of different stellar populations in these systems. Distances to the galaxies have been estimated from the tip of the red giant branch (TRGB), or from the brightest blue and red stars. For some galaxies the reddening, metallicity and surface profile parameters have been measured. We describe in more detail the results for four galaxies: IC 2574, Holmberg I, DDO 53 and IC 342. A more comprehensive project is underway.
Mass-to-Light Ratio Measurements of Galaxies, Groups, and Clusters using the Numerical Action Method
Authors: Shaya Ed , Peebles P. J. E. , Phelps Steven , Tully R. Brent
Published: July 2016

The numerical action variational method (NAM) is an elegant, non-chaotic technique for calculating the trajectories of gravitating systems in a cosmological context. It has been used extensively for establishing orbits of Local Group galaxies in a series of papers (Peebles 1989, 1990, 1994, 1995) and for the Local Supercluster (Shaya, Peebles, & Tully 1995).

Our repertoir of tools include code that holds present distances constant and predicts possible redshifts, one that holds present redshifts constant and predicts possible distances, and one that varies masses of each mass tracer and simultaneously satisfies both distance and redshift.

Our results indicate a Ω0 = 0.2, a mass-to-light ratio of field galaxies in the range of 100 M⊙/L⊙ in blue light (t0 = 11 Gyr with no cosmological constant), but for the Virgo Cluster, the value is 6 or 7 times higher. The higher values of Ω0 determined from using the IRAS galaxy distributions may be a result of under weighting this important mass component of the universe plus a poor correlation between cluster and field galaxy distributions.
Evidence for dark matter on different scales from the KLUN galaxy sample
Authors: Hanski M. O. , Teerikorpi P. , Ekholm T. , Theureau G. , Baryshev Yu. , Paturel G. , Lanoix P.
Published: July 2016

The KLUN (Kinematics of the Local UNiverse) sample of 6600 spiral galaxies is used in studying dark matter on different scales:

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The Morphological Type dependence of the zero-point of the Tully-Fisher relation indicates mass to light ratio M/L ≈ 9 − 16 on galactic scales.

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Preliminary results from a study of selection effects influencing double galaxies give a larger value M/L ≈ 30 − 50.

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Study of the Perseus-Pisces supercluster, using Malmquist bias corrected TF distances and Tolman-Bondi solutions indicates M/L ≈ 200 − 600 for large clusters. Similar results were obtained in our previous work on Virgo galaxies.

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Application of a modified version of Sandage-Tammann-Hardy test of the linearity of Hubble law inside the observed hierarchical (fractal) galaxy distribution up to 200 Mpc suggests that either Ω0 is very small (0.01) or the major part of the matter is uniformly distributed dark matter.
Co-rotating Photospheric Clouds in μ Centauri
Authors: Balona L.A. , James D. , Lawson W.A. , Shobbrook R.R.
Published: July 2016

Several periods close to 0.5 d have been reported for μ Cen. We obtained over 300 echelle spectra and simultaneous multicolour photometry over a two-week period. We find that the period is 0.66 d and is, in fact, singly periodic. Greyscale images of many consecutive nights show moving features which do not repeat nightly, as may be expected for P = 0.5 d, but repeat approximately every alternate night. In spite of this, periodogram analysis of the radial velocity, as measured at the point of minimum intensity in the spectral line, does indeed show a 0.5-d period. The amplitude of this periodicity decreases during the course of the run. This seeming contradiction, as well as the apparent multiperiodicity, is due to the use of period finding techniques which exclude singly-periodic solutions of a complex nature. We interpret the variations as due to two, co-rotating, circumstellar clouds distributed around the star, such that they are separated by a time interval of 0.5 d. It appears that μ Cen is another example of the growing list of Be stars in which the periodicity is due to co-rotating photospheric clouds.
Non-radial Pulsation Modeling of ω (28) CMa
Authors: Maintz M. , Rivinius Th. , Tubbesing S. , Wolf B. , Štefl S. , Baade D.
Published: July 2016

Adopting non-radial pulsation (nrp) the line profile variability lpv of several absorption lines of different ions was modeled for ω (28) CMa. The parameters suggested by Baade (1982) to characterise the pulsation could be confirmed. The pulsation period in the inertial frame was found to be negative, i.e. an actually retrograde mode appears prograde due to the rapid stellar rotation. The line profiles could be reproduced in detail including structures like spikes and ramps. They were identified as velocity effect due to the latitudinal component of the nrp velocity field υϑ in combination with low inclination i. In spite of small photometric variations (Štefl et al. 1999) the lpv of the absorption lines can be explained by nrp entirely.
Far-infrared Excesses in Classical Be Stars
Authors: Miroshnichenko A.S. , Bjorkman K.S.
Published: July 2016

A sample of Be stars with large far-infrared excesses detected by IRAS is selected and their high-resolution IRAS images are examined. The far-infrared emission from most of them is marginally extended and is associated with the optical sources. Modeling of the stars’ spectral energy distributions allows us to rule out the infrared cirrus nature of the excesses. We suggest that the excesses are more likely due to circumstellar dust, possibly formed early in the evolution of the star.
B-type Emission-line Stars with Warm Circumstellar Dust
Authors: Sheikina T.A. , Miroshnichenko A.S. , Corporon P.
Published: July 2016

We selected a group of 11 B-type emission-line stars with large IR excesses, which show a steep flux decrease towards longer wavelengths. Analysis of their observational characteristics has been carried out on the basis of the data collected from literature, results of our recent photometric and high-resolution spectroscopic observations. Possible nature and evolutionary state of the group objects are discussed.
Optical and Near–Infrared Spectroscopy of the Emission Line Young Stellar Object Gy 2-18 (HHL 31)
Authors: Persi Paolo , Polcaro Vito Francesco , Bohigas Joaquin , Tapia Mauricio
Published: July 2016

We present the results of optical and near–IR spectroscopy of the massive young star associated with the extended reflection nebula Gy 2-18 (HHL31). The optical spectrum between 4000-5000 Å suggests a B0-B2 classification for this object. In addition the Hα line profile indicate the presence of a consistent stellar wind with a velocity of the order of 1200 km/s. The near-IR spectrum is dominated by the presence of the hydrogen recombination emission lines (Pfund and Bracket series). The measured line intensities of these lines are in agreement with the presence of a strong stellar wind in Gy2-18.
Be Stars in Roche-Lobe Interacting Binaries
Authors: Tarasov A.E.
Published: July 2016

Different types of massive interacting binaries with Be components are discussed. Due to mass exchange, Be stars in these systems have some peculiar characteristics. Often it is even difficult to find traces of the Be star and/or mass-losing star in the optical region of the spectrum. Using the value of the orbital period as a primary parameter, it is possible to divide all massive interacting binaries into two large groups: short-period or classical Algols and long-period binaries. The last group includes a number of very active mass transfer systems named as W Serpentis. There is also a small group of double systems whose stars do not fill their Roche lobes but have emission lines in the spectrum. Properties of their spectral variability are discussed. Analysis of each group lets us find different behaviours in mass exchange that depend on the size of their Roche lobes.
Evidence for Magnetic Field Decay in the Slowest Known Be/X-ray Pulsars X Per and RX J0146.9+5121
Authors: Li X.-D. , Wang Z.-R.
Published: July 2016

We argue that the slowest known Be/X-ray pulsars X Per and RX J0146.9+5121 currently possess relatively weak (≲ 1012 G) magnetic fields. Unless these pulsars were born rotating very slowly (initial periods longer than tens of seconds), in order to explain their long spin periods (~ 835 and ~ 1412 s, respectively), they must have had magnetic fields stronger than a few 1013 G; that is, their magnetic fields must have decayed.
Discovery of Eight Recycled Pulsars – The Swinburne Intermediate Latitude Pulsar Survey
Authors: Edwards Russell T.
Published: July 2016

We have conducted a pulsar survey of intermediate Galactic latitudes (5° < |b| < 15°) at 20 cm. The survey has been highly successful, discovering 58 new pulsars, eight of which are recycled, in only ∼14 days of integration time. One pulsar has a very narrow (2° FWHM) average profile for the pulsar’s period (278 ms). The six new recycled binary systems provide valuable information on the formation of white dwarf pulsar binaries. Two systems have massive white dwarf companions (> 0.57 M⊙and > 1.2 M⊙), while another has a low mass (∼ 0.2 M⊙) companion in a 23.3-d orbit, residing the well-known orbital period “gap”.
Timing the Parkes Multibeam Pulsars
Authors: Manchester R. N. , Lyne A. G. , Camilo F. , Kaspi V. M. , Stairs I. H. , Crawford F. , Morris D. J. , Bell J. F. , D’Amico N.
Published: July 2016

Measurement of accurate positions, pulse periods and period derivatives is an essential follow-up to any pulsar survey. The procedures being used to obtain timing parameters for the pulsars discovered in the Parkes multibeam pulsar survey are described. Completed solutions have been obtained so far for about 80 pulsars. They show that the survey is preferentially finding pulsars with higher than average surface dipole magnetic fields. Eight pulsars have been shown to be members of binary systems and some of the more interesting results relating to these are presented.
Phase locked Spectroscopic Imaging of the Crab Pulsar
Authors: Fordham J.L.A. , Robinson J.R. , Kawakami H. , Michel R. , Much R.
Published: July 2016

The MIC photon counting detector developed at UCL has been upgraded to allow time resolved spectroscopic optical data to be acquired on periodical sources such as pulsars. First observing trials have been carried out on the Crab pulsar. The detector was phase locked to the pulsar period and a temporal resolution of 41.4μs employed. The phase locking allowed the co-addition of time slices over a large number of pulsar periods building up quantifiable spectroscopic data when observing in a flux limited regime.
Constraints on Emission Mechanism from the Nulling and Drifting Pulsar PSR B0031 – 07
Authors: Joshi B. C. , Vivekanand M.
Published: July 2016

High sensitivity data were obtained on PSR B0031-07 using Ooty Radio Telescope (ORT), which has a single polarization. As this pulsar lies outside the range of other sensitive instruments, such observations are possible only with ORT. Some earlier results, such as the different drift modes, were verified. Our analysis suggests competition between the energies of pairs of drifting sub-pulses and a phase memory across short nulls. The constraints these results put on the theories of pulse emission are enumerated.
Pulsar radio emission beams
Authors: Kijak Jaroslaw
Published: July 2016

We study the structure of the pulsar beam using the analysis of beam radius. We indentify three emission cones in radio beams. The dependence of the beam radius on frequency is obtained.
Hollow Core?
Authors: Qiao G.J. , Liu J.F. , Wang Yang , Wu X.J. , Han J.L.
Published: July 2016

We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could beβ< 0.5°. The “hollow core” is in agreement with Inverse Compton Scattering model of radio pulsars.
A Search for Variable Interstellar Magnetic Fields and Neutron Star Precession in Four Years of Polarization Position Angle Measurements on 98 Pulsars
Authors: Weisberg J. M. , Morgan J. J. , Despotes J. T. , Everett J. E. , Cordes J. M.
Published: July 2016

We have studied the temporal behavior of linearly polarized position angle in a sample of 98 pulsars observed from Arecibo over a four–year period in a search for free precession and changes in interstellar magnetic fields along pulsar– earth lines of sight. We set upper limits on changes in position angle.
Pulsar optical observation with the Very Large Telescope
Authors: Ray A. , Lundqvist P. , Sollerman J. , Leibundgut B. , Sutaria F.
Published: July 2016

Optical data in the V-band gathered with the 8.2m ESO Very Large Telescope (VLT) at the radio interferometric position of PSR 1706-44 are presented. The pulsar is close to a bright star in projection and was not detected. The pulsar magnitude limit must be fainter than V=24.5 for a distance of ≤from the bright star. In the outer gap model for an aligned rotor the optical flux should scale with the gammaray flux. For pulsars which emit pulsed gamma-rays but are not detected in the optical bands, the synchrotron cutoff frequency for the tertiary photons must be well below the optical frequencies and the magnetic and spin axes may be misaligned.
Intensive X-ray Monitoring of the 16ms Crab-like Pulsar PSR J0537 – 6910
Authors: Marshall F. E. , Gotthelf E. V. , Middleditch J. , Wang Q. D. , Zhang W.
Published: July 2016

The recently discovered pulsar PSR J0537-6910 is the most rapidly rotating young pulsar known. This latest example of a Crab-like pulsar, located in the supernova remnant N157B in the Large Magellanic Cloud, is rotating twice as fast as the Crab pulsar. With a characteristic age of 5000 years, it is also the oldest known example of a Crab-like pulsar and was likely rotating close to the maximum rate for a neutron star when it was born. Here we report preliminary results from an intensive monitoring campaign of X-ray observations acquired with the Rossi X-ray Timing Explorer that began in January 1999. These observation have revealed a large glitch event in the pulse timing during the first six month of our campaign, consistent with those suggested by sparse observations dating back to 1993. The current evolution of the rotation rate of PSR J0537-6910 provides a unique probe of the internal structure of neutron stars and constraints on possible pulsar emission mechanisms.
Non-Dipolar Magnetic Fields in Pulsars
Authors: Eilek Jean A. , Hankins Timothy H.
Published: July 2016

Several bright pulsars have position angle sweeps which are not consistent with a simple dipole field in the radio emission region. The data are now good enough to justify modelling of deviations in the field structure in these stars, and the effect of these deviations on the radio emission. As a first step, we consider the effect of quadrupoles, and of polar currents, on the observed polarization and emission signatures.
Thermal X-Ray Pulses Resulting From Pulsar Glitches
Authors: Tang Anisia P.S. , Cheng K.S.
Published: July 2016

The non-spherical symmetric and exact thermal evolution model is used to calculate the transient thermal response to pulsar glitches. The three ways of energy release originated from glitches, namely the ‘shell’, ‘ring’ and ‘spot’ cases are compared. The ‘ring’ case is always the middle one in terms of the response time, the response duration and the intensity of the response. Taking the relativistic light bending effect and the rotational effect into consideration, the X-ray light curves resulting from the thermal response to the glitches are calculated. Only the ‘spot’ case produces modulative X-rays. Different sets of parameters result in different evolution patterns of light curves. This is thus a good method to determine the equations of state for pulsars.
The Pair Cascade in Strong and Weak Field Pulsars
Authors: Arendt, Paul N. , Eilek Jean A.
Published: July 2016

We have simulated the development of the pair cascade in a range of magnetic field strengths. We determined the efficiencies of lepton and secondary photon production, as well as the distribution functions of the pair plasma and of the escaping photons. We find the magnetic field has the most important effect on the cascade; primary beam energies and seed photon emissivities are of less importance.
Puzzling Pulsars and Supernova Remnants
Authors: Lorimer D.R. , Ramachandran R.
Published: July 2016

The fact that the majority of the youngest radio pulsars are surrounded by expanding supernova remnants is strong evidence that neutron stars are produced in the supernovae of massive stars. In many cases, the pulsar appears significantly offset from the geometric centre of the supernova remnant, indicating that the neutron star has moved away from the site of the explosion with a substantial space velocity since birth. Here we show that the these offsets show an overwhelming preference for one sign in terms of Galactic longitude, a result that has important implications for the number of genuine associations. The origin of this statistically significant effect may lie in a differential Galactic rotational velocity between stars and gas in the interstellar medium.
Time-variability of the Crab Nebula wisps
Authors: Spitkovsky Anatoly , Arons Jonathan
Published: July 2016

We present results of time-dependent numerical modeling of the internal structure of the collisionless shock terminating the pulsar wind in Crab Nebula. We treat the equatorial relativistic wind as composed of ions and electron-positron plasma with an embedded toroidal magnetic field. Relativistic cyclotron instability of the ion ring downstream from the shock is found to launch outward propagating magnetosonic waves. Due to the fresh supply of ions crossing the shock, the time-dependent process achieves a limit-cycle pattern, in which the waves are launched with periodicity on the order of the ion Larmor time. Compressions in magnetic field and pair density associated with these waves as well as their propagation speed qualitatively reproduce the features observed in the wisps.
The interaction of pulsar winds with old supernova remnants
Authors: van der Swaluw Eric , Achterberg Abraham , Gallant Yves A.
Published: July 2016

Shock waves in young supernova remnants (SNR) are generally considered to be the places where production and acceleration of charged particles (relativistic electrons and cosmic rays) take place. Older remnants can be re-energised if an active pulsar catches up with the shell of the remnant (Shull, Fesen, & Saken 1989). In that case a pulsar-driven wind can inject energetic particles into the shell, resulting into a rejuvenation of the radio emission of the old remnant due to the presence of additional relativistic electrons.

Radio observations of CTB80 (Angerhofer et al. 1981) and G5.4-1.2 (Frail & Kulkarni 1991) give evidence for the importance of the presence of an active pulsar close to the old shell of the remnants. In the first case the pulsar is believed to be inside the SNR. In the second case the pulsar is thought to have penetrated the shell of the SNR, and resides in the interstellar medium (ISM). We intend to investigate the physics which are connected with these kind of systems. One expects new effects resulting from the interaction of the three different shocks; the SNR shock, the bowshock bounding the pulsar wind nebula (PWN) and the (pulsar) wind termination shock. The dynamics of the system is described by a hydrodynamics code. We use the results from the hydrodynamics code to investigate the process of acceleration and transport of particles which are advected by the flow and diffuse with respect to the flow. We have applied the latter to a simple problem, the case of a spherically expanding SNR.
The Remarkable Binary Pulsar PSR B1259–63
Authors: Johnston Simon
Published: July 2016

PSR B1259–63 is a unique system consisting of a young radio pulsar in orbit about a 10 M⊙Be star. Its orbital period is 3.4 yr and the eccentricity close to 0.9. Around periastron, the system is a radio and X-ray transient and shows changes in flux density, dispersion measure, rotation measure and scattering parameters on very short timescales. Timing observations show the equatorial plane of the Be star and the plane of the orbit are not aligned and the orbit precesses as a result. I briefly summarise 10 years of radio observations of PSR B1259–63 and the implications of these observations. Future work includes the determination of the orbital size through VLBI and observations at TeV energies.
A Model for the Binary Pulsar Radio Eclipse
Authors: Khechinashvili D. , Melikidze G. , Gil J.
Published: July 2016

We suggest that companions of two binary eclipsing pulsars, B1957+20 and J2051-0827, are degenerate magnetic dwarfs. The magnetospheres of the white dwarfs are infused with relativistic particles supplied by the pulsar wind. We demonstrate that the radio waves emitted by the pulsars are strongly damped due to cyclotron resonance with the plasma particles, in the magnetospheres of companions. Large stable continuos and frequency-dependent radio eclipses should occur as a result of this process. This agrees well with observations.
Neutron Star Atmospheres
Authors: Pavlov George G. , Zavlin V. E.
Published: July 2016

Properties of the thermal radiation emitted by neutron stars (NSs) are determined by thin plasma layers (atmospheres) at their surfaces. The NS atmospheres are very different from those of usual stars due to the immense gravity and huge magnetic fields. Current models of hydrogen NS atmospheres show that the spectra deviate substantially from blackbody spectra of the same temperatures. Comparison of the model spectra with recent observations of soft X-ray and UV-optical radiation of NSs yields the surface temperatures considerably lower than those obtained from the blackbody fits. This conclusion have important implications for theories of NS cooling and for understanding fundamental properties of the superdense matter in the NS interiors.
Rapidly rotating strange stars
Authors: Gondek-Rosińska D. , Haensel P. , Zdunik J. L. , Gourgoulhon E.
Published: July 2016

We study effects of the strange quark mass,ms, and of the QCD interactions, calculated to lowest order inαc, on the rapid rotation of strange stars (SS). The influence of rotation on global parameters of SS is greater than in the case of the neutron stars (NS). We show that independently ofmsandαcthe ratio of the rotational kinetic energy to the absolute value of the gravitational potential energyT/Wfor a rotating SS is significantly higher than for an ordinary NS. This might indicate that rapidly rotating SS could be important sources of gravitational waves.
Theories of Polar Motion from Tisserand to Poincaré (1890 – 1910)
Authors: Melchior P.
Published: July 2016

The discovery by Seth C. Chandler (1891) that the motion of the pole (the reality of which had been established by K.F. Küstner and by the simultaneous latitude observations at Honolulu and Berlin by German astronomers) resulted from two componentsi.e.a free circular motion with a period of 427 days and a forced elliptical motion with a period of 365.25 days, raised considerable interest in the scientific community of astronomers and geophysicists.

The celebratedMécanique Célesteof Tisserand (1890) had been published just one year before at a time when doubts still persisted and arguments could be presented in favor of the fixed pole. Starting with Tisserand’s arguments, we describe in this paper the impact of the successive contributions by A. Greenhill, S. Newcomb, Th. Sloudsky, S. Hough, G. Herglotz, A. Love, J. Larmor and H. Poincaré to the solution of the problems raised by the Chandler period.

The lines of reasoning taken by these eminent scientists were rigorously correct so that, after about one hundred years, contemporary researchers, who benefit from a far better knowledge of the inner structure of the Earth and are able to take advantage of modern computing power, do not contradict any of their conclusions and instead refine them with an accuracy which was not imaginable one century ago.
Early Observational Evidence of Polar Motion
Authors: Verdun Andreas , Beutler Gerhard
Published: July 2016

Bessel was not able to detect significant latitude variations in his observation series made between May 1820 and June 1821 at Königsberg Observatory. He left the topic until July 22, 1843, when he suspected that the latitude might have changed since 1820. Between March 1842 and April 1843 Peters, one of Bessel’s students, performed an observation series of the pole’s zenith distance at the Pulkovo Observatory using new observation techniques and reduction methods first developed by Bessel. From this series he deduced a significant value of 0″.079 ± 0″.017 for the amplitude of polar motion, but he was not able to separate the expected 10 month Eulerian period from an annual signal possibly caused (as he supposed) by seasonal temperature variations. Peters’ successors at Pulkovo, Gyldén and Nyrén, continued to observe latitude. Using these observation series Nyrén derived in 1873 significant values for the amplitude of polar motion, but he was not able to determine the phase angles because he assumed the period of polar motion being known. We conclude that Peters probably was the first one to have observed a variation of the latitude, but that he and Nyrén were misled by the Eulerian period when modeling polar motion.
Latitude Observations at Paris Observatory Prior to the ILS
Authors: Débarbat Suzanne
Published: July 2016

Latitude observations performed at the Paris Observatory from its beginning in 1667 are recalled together with the results mentionned in archives and publications of the time.