bluuebunny/crossref_metadata_2025 huggingface dataset:
Concluding Remarks
Authors: Kino Ivan R.
Published: July 2016

It is a great honor to be asked to summarize a conference such as this one, but it is also an impossible task. For a summary I refer you to the table of contents; what I will do here instead is to offer some personal impressions of what we have been doing.

My initial feeling was that of an outsider; I have never worked in the field of double and multiple stars, to which many of you have devoted your careers. Yet this meeting has impressed me with the interrelationship of our areas. In this room, are astronomers who represent and have discussed celestial mechanics, stellar dynamics, stellar spectroscopy, and the astrophysics of star formation. I have not counted heads, but we outsiders might even outnumber you hard-core binary-fanciers. And this is, in some sense, a measure of the value of this meeting, and, even more pointedly, of the value of your work: how much does it matter to the rest of us? Every astronomer should ask himself—particularly when the technicalities get thickest— “What am I doing this for?” The answer is emphatically not merely that this particular work is interesting to do. The appeal of astronomy is not in the bricks and mortar that each of us prepares, but rather in the architecture of the structure that we build with those materials. The questions that we really pursue are not the orbits of binaries, nor the structure of star clusters, but rather the basic problems of the universe: how and why are stars made, and why do they develop as they do?
The Visual Double Star Catalogues
Authors: Worley Charles E.
Published: July 2016

The historical development and current status of the two visual double star catalogues maintained at the Naval Observatory are discussed.
Existing Data Centers and their Future Role
Authors: Baum W. A.
Published: July 2016

Two IAU data centers, one at the Lowell Observatory and the other at Meudon, were organized in the early 1960s for the purpose of establishing a collection of planetary data and images accessible to all qualified scientists. These centers trace their origin to an IAU resolution sponsored by Commission 16 in 1961. Ours at the Lowell Observatory, known as the Planetary Research Center, was also recommended by the U. S. Lunar and Planetary Missions Board and by the U. S. Space Sciences Board Panel on Earth-Based Planetary Astronomy. Since its inception, our Center has been supported by a grant from NASA Headquarters.
Solar Motion with Respect to the Nearest Galaxies
Authors: Vaucouleurs G. de , Peters W.L. , Corwin H.G.
Published: July 2016

Solutions for solar motion with respect to 12 classical members of the restricted Local Group and 9 additional proposed members of an extended Local Group, all within 2 Mpc, suggest that the Local Group – both restricted and extended – is expanding at a rate, H* = 47 ± 12 ou 57 ± 11 km s-1 Mpc-1, which is significantly lower than its free-space (asymptotic) value Ho ≃, 90 km s-1 Mpc-1, as required by the rotating-expanding model of the Local supercluster. The differential rotation effects predicted by the model are detectable in the velocity residuals with correct phase L*o = 87° and amplitude A* = 30 to 40 km s-1 Mpc-1 in the first-order expansion.

V = H*r + V⊙ cos A + A* r sin 2(L-L*o) cos2B

The solar motion with respect to the velocity centroid of the Local Group is V⊙ = 340 ± 18 km s-1 toward the apex 1 = 105° ± 5°, b = -11° ± 3°. With the conventional values of the solar motion within the Galaxy the apex of the galactic center in the Local Group is at supergalactic coordinates L = 325° ± 11°, B = -12° ± 11° with a velocity VG = 140 + 25 km s-1.

The residual velocity dispersion σ = 40 to 50 km s-1 implies a virial theorem mass VT ≃ 9 x 1011⊙ not significantly in excess of that which can be accounted for by the member galaxies and intergalactic gas clouds.
Redshift -magnitude bands in clusters of galaxies
Authors: Tifft W. G.
Published: July 2016

This paper presents new material and analysis for three clusters of galaxies. We assume familiarity with the initial Coma work (Tifft 1972, 3). Redshifts and nuclear magnitudes are now available for 108 Perseus galaxies. The sample is nearly complete to radius and V(6)=16.8 (6″ scaled from in Coma). No field galaxies are seen, not surprising in view of field studies in the Coma region (Tifft and Gregory 1976). Table 1 shows average data. The central field has a mean redshift 700 km/s less than the outer part, a difference independent of magnitude and significant at the 99.9 confidence level. A redshift excess appears around N1275 and N1265. Excluding these radio regions the difference exceeds 1000 km/s.
Comment on photometric evolutionary corrections
Authors: Huchra John P.
Published: July 2016

De récentes études de galaxies très bleues montrent que la formation des étoiles a lieu avec une fonction initiale de masse plus riche en étoiles de masse élevée que la fonction de Salpeter.
Dynamical friction in clusters of galaxies
Authors: White Simon D.M.
Published: July 2016

La formule classique pour la friction dynamique prédit que l’évolution de l’orbite d’une galaxie qui est membre d’un amas sera trop rapide pour être en concordance avec les observations, si toute la masse de l’amas est concentrée dans les galaxies elles-mêmes. Quoique cette formule ait été prouvée sous des conditions très différentes, elle semble bien décrire les effets des rencontres gravitationelles dans un amas qui est stabilisé par sa propre gravitation. La friction dynamique mène à une concentration de galaxies massives au centre d’un amas, laquelle concentration doit avoir des effets importants sur la structure de la galaxie centrale. On ignore tout des détails de l’évolution dynamique de cette galaxie, mais il est probable que les effets soient assez grands pour interdire toute déduction cosmologique de la relation m-Z.
Westerbork 21-cm observations of the low and high velocity HI in Stephan’s quintet
Authors: Allen R.J. , Sullivan W.T.
Published: July 2016

Des cartes à haute résolution d’hydrogène neutre à basse et haute vitesses dans le quintet de Stephan sont présentées. L’émission à basse vitesse a lieu comme attendue, dans la galaxie NGC 7320, et n’apparait pas inhabituelle dans ses caractéristiques. De nombreuses évidences conduisent à une distance de 15 Mpc pour cette galaxie. L’hydrogène neutre à haute vitesse, s’il est situé à 120 Mpc, a une masse de 1.6 x 1010 M⊙ et provient d’un grand nuage d’une taille de ~ 150 kpc décalé de ~ 100 kpc (3’E) par rapport à la position du quintet. Les galaxies spirales à haute vitesse du quintet étant extrêmement pauvres en hydrogène, nous suggérons que le nuage H I est le résultat d’une collision de type Spitzer-Baade de deux galaxies auparavant riches en gaz.
Size limits for expanding light sources
Authors: Terrell James
Published: July 2016

Les fluctuations rapides des brillances optiques et radio observées dans les quasars, ainsi que dans les objets BL Lac, imposent des limites supérieures sévères sur les dimensions possibles de ces sources; contrairement à l’opinion répandue, ces limites ne sont pas notablement modifiées par l’hypothèse d’une source lumineuse en expansion rapide. Le conflit entre les limites de variation des dimensions des quasars et la surface minimale pouvant émettre une énergie suffisante, en supposant des distances cosmologiques, n’est pas résolu par une expansion relativiste.
Anomalous Hubble expansion in inhomogeneous cosmological models
Authors: Mavrides Stamatia
Published: July 2016

Les amas ou superamas de galaxies sont assimilés à des condensations en expansion, plongées dans l’univers cosmologique. L’application des résultats déduits de modèles non homogènes en Relativité Générale au cas particulier du Superamas Local permet de rendre compte des observations. Elle montre aussi l’existence de modèles d’amas tels que la lumière qui les traverse présente (pour un observateur extérieur a l’amas) un décalage vers le rouge supplémentaire.
Multi-Wavelength Surveys for Galaxies Hidden by the Milky Way
Authors: Kraan-Korteweg Renée C.
Published: July 2016

The systematic mapping of obscured and optically invisible galaxies behind the Milky Way through complementary surveys are important in arriving at the whole-sky distribution of complete galaxy samples and therewith for our understanding of the dynamics in the local Universe. In this paper, a status report is given of the various deep optical, near infrared (NIR), and systematic blind H I-surveys in the Zone of Avoidance, including a discussion on the limitations and selection effects inherent to the different multi-wavelength surveys and first results.
The Fornax Spectroscopic Survey — Low Surface Brightness Galaxies in Fornax
Authors: Drinkwater M.J. , Phillipps S. , Jones J.B.
Published: July 2016

The Fornax Spectroscopic Survey is a large optical spectroscopic survey of all 14 000 objects with 16.5 < BJ < 19.7 in a 12 deg2 area of sky centered on the Fornax Cluster. We are using the 400-fibre Two Degree Field spectrograph on the Anglo-Australian Telescope: the multiplex advantage of this system allows us to observe objects conventionally classified as “stars” as well as “galaxies”. This is the only way to minimise selection effects caused by image classification or assessing cluster membership.

In this paper we present the first measurements of low surface brightness (LSB) galaxies we have detected both in the Fornax Cluster and among the background field galaxies. The new cluster members include some very low luminosity (MB ≈ −11.5 mag) dwarf ellipticals, whereas the background LSB galaxies are luminous (−19.6 < MB < −17.0 mag) disk-like galaxies.
Galaxy Pairs and Triplets at Medium Redshifts from the Sloan Digital Sky Survey (SDSS)
Authors: Infante L. , Strauss M. A. , Bahcall N. , Knapp G. R. ,   For the SDSS Collaboration
Published: July 2016

We have identified close pairs and triplets of galaxies in SDSS commissioning imaging data. The data set is from one of the SDSS equatorial scans covering an area close to 100 square degrees. We have estimated the angular correlation function of these galaxy systems and show that they appear to be appreciably more strongly clustered than are single galaxies.
Kinematics of early-type galaxies in compact groups: HCG 67, HCG 74 and HCG 79
Authors: Bonfanti P. , Simien F. , Rampazzo R. , Prugniel Ph.
Published: July 2016

We present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74 and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be associated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.
NGC 4622 versus NGC 3081 Disks: Encounter versus Intrinsic Rings
Authors: Freeman Tarsh , Byrd Gene , Ousley Derrick
Published: July 2016

Star formation processes in galaxies are far from being understood. Resonance rings of star formation are a common phenomenon of early-type barred spiral galaxies. Most rings are regions of enhanced star formation via gas cloud collisions near resonances, under the action of a gravitational bar perturbation. A small number of rings may form in response to a mild tidal interaction with a nearby companion. In either case, resonance rings are natural dynamical experiments in star formation stellar association time evolution. We study star formation in two galaxies where resonance rings probably have these two different modes of origin. NGC 3081 has four bi-symmetric star-forming rings that are probably connected to bar-driven gas dynamics, while NGC 4622 is a non-barred spiral where a strong one-sided ring may be connected to a past tidal interaction. We model the young clusters in the rings as two-fold and one-fold periodic orbits, respectively. We show that age indicators, Hα emission and the color index B – I, vary with position angle around the rings in a two-fold and one-fold sense as predicted by our models. The success of these models shows that future high resolution observations can be used to separate the individual associations from the underlying disk light so as to study their evolution and luminosity function.
Parameters of the Dark Halo distribution around M 31
Authors: Tenjes P. , Einasto J.
Published: July 2016

Available observational data allow us to discriminate between the visible matter and the dark matter in M 31 and thus to determine the most important parameters of the dark halo (the mass, the radius and the outer extent).
Interpretation of Rotation Curves of Giant Galaxies in the Local Group with the Truncated Disk Model: the Milky Way
Authors: Nikiforov I. I. , Petrovskaya I. V. , Ninković S.
Published: July 2016

In some external edge-on spiral galaxies, such as NGC 891, 4244, 4565 and 5907, the observed light distribution exhibits a sharp truncation in the outer parts (e.g., Casertano 1983, hereafter C83). As a rule, such galaxies are known to be warped in their gas disk, the deformation starting at about their optical cut-off radius. These facts suggest a truncation in the disk density distribution. Moreover, the rotation velocity of these galaxies starts decreasing at about the same radius, which can also be considered as the "signature" of truncation (see C83).

Both giant spiral galaxies in the Local Group, the Milky Way and M31, have a dip in the average rotation velocity which can be produced by a truncation of the galactic disk. Ninković & Petrovskaya (1992) constructed from Haud’s (1981) rotation curve for M31 a model including, like C83’s for NGC 5907, a truncated exponential disk and a halo. The truncation distance was found to be close to the radius beyond which warping of the hydrogen layer of M31 begins.
The Be Phenomenon
Authors: Balona L.A.
Published: July 2016

An overview of the Be phenomenon is given with particular emphasis on the problem of the mass loss mechanism. We assume that the principal mechanism of mass loss in these stars is magneto-centrifugal acceleration (MCA). Within this framework, we discuss how particular features of Be stars which distinguish them from normal B stars can be understood. The frequency distribution of Be stars relative to normal B stars in the Galaxy and Magellanic Clouds is discussed. The distribution of equatorial velocities, activity in the visual and X-ray regions and photospheric activity all point towards a magnetic model and seem to be qualitatively consistent with the MCA hypothesis. Periodic variations in light and line profiles offer particularly important clues. In this respect, the recent discovery of co-rotating photospheric clouds in several Be stars strongly suggests gas trapped in closed field lines. We investigate the dynamics of an outburst and suggest that the localized nature of these events imply magnetic flaring and acceleration of mass due to connection and disconnection of field lines. Finally, suggestions for further progress are presented.
Physical Properties and Evolutionary Stage of Be Stars
Authors: Harmanec P.
Published: July 2016

The determination of accurate and reliable basic physical properties of Be stars is a very complicated task which, among other things, requires a good knowledge of the variability pattern of each particular object. Possible confusion between a rotationally distorted photosphere and a pseudophotosphere – an inner optically thick part of a gradually formed envelope which temporarily mimics a photosphere – is discussed in some detail in relation to the stellar effective temperature, brightness and rate of rotation. It is shown that the currently available data allow us to set relatively stringent limits on possible radii of at least some brighter Be stars, but very few direct determinations of mass have been made. The only exceptions are the Be stars in eclipsing binaries. The trouble is, however, that all of them are interacting binaries for which reliable orbital solutions are seriously hampered by the presence of gas streams and by strong interactions between the binary components. Moreover, their masses need not be representative for the whole population of Be stars.

An answer to the question about the evolutionary stage of Be stars is even more uncertain since it is closely related to the principal, as yet unanswered question about the origin of the Be phenomenon itself.
A Spectroscopic Study of Be stars in the SMC Cluster NGC 330
Authors: Hummel W. , Gässler W. , Muschielok B. , Szeifert T. , Seifert W. , Appenzeller I. , Rupprecht G.
Published: July 2016

We present low resolution spectroscopy of about 20 Be stars in the SMC cluster NGC 330 to confirm the high contents of Be stars in this cluster.
The ST3 Mission, and its Capabilities for Be Star Observations
Authors: Linfield R. P.
Published: July 2016

The ST3 mission will launch a space optical interferometer into heliocentric orbit, for observation of 50–100 sources on baselines of 40–200 m, during a time span of 3–4.5 months. The angular resolution in the 450–900 nm passband will be ≈ 500 microarcseconds. For Be stars, a velocity resolution of 50–100 km/s can be achieved by operating the interferometer in a Fourier Transform Spectrometer mode. This should allow spectrally resolved measurements of the brightness distribution in circumstellar disks, but will be limited to stars brighter than a visual magnitude of ≈ 5.
ISO Observations of Be Stars
Authors: Waters L.B.F.M. , Trams N.R. , Hony S. , de Koter A. , Morris P.W. , Zaal P.A. , Marlborough J.M. , Millar C.E. , Vandenbussche B.
Published: July 2016

We discuss the infrared spectral energy distribution of Be stars, focusing on new results obtained with the Infrared Space Observatory. The 60-160 μm flux of some Be stars is higher than expected, which may be due to cold dust or an outer disk component with enhanced densities. The infrared spectrum of Be stars is dominated by numerous HI recombination lines, whose line strengths show a complex behaviour. The electron temperature in the disk of ϒ Cas was found to be about 9500 K, and evidence for an elevated temperature near the upper part of the disk is presented. Be stars may be recognized from their infrared spectrum on the basis of HI line flux ratios.
Observed Periodic Phenomena
Authors: Baade D.
Published: July 2016

The wide range of periodic and cyclic variabilities commonly observed in Be stars and their circumstellar disks is reviewed. Many of them are related to the basic nonradial pulsation, the effects of which may range from the photosphere to the disk. Through pulsation-triggered outbursts, some stars may owe their Be characteristics largely to their intrinsic variability. However, because late-type Be stars do not normally show detectable short-periodic variability, this is probably not true of all Be stars. Comparisons are made with other variable early-type stars.
Short-period Variations of 28 CMa during 1998/9
Authors: Balona L.A. , James D.
Published: July 2016

The Be star 28 CMa was one of the first periodic Be stars to be discovered and shows very large line profile variations with a period of 1.37 d. Recently, it has been shown that the line profile and light variations can be modeled by a patch of gas suspended above the photosphere. We present echelle observations of the Hβ and Hϒ line and several helium and metal absorption lines. We show that the radial velocity variations of these lines are unchanged since they were first observed two decades ago. We also examined several emission lines of Fe II and show that they do not partake of the periodic variation. We attribute the periodic variations of the lines formed close to the photosphere to a co-rotating cloud, whereas the Fe II emission lines are formed in the circumstellar disk outside the co-rotating radius.
Doppler Imaging of Non-radially Pulsating Stars
Authors: Jankov S. , Janot-Pacheco E. , Leister N.V.
Published: July 2016

In addition to the common applications (temperature, magnetic field, abundance distributions) the Doppler Imaging technique can also be applied to non-radial stellar pulsations (NRP). Due to their rapid rotation, the Be stars are ideal candidates for Doppler Imaging. However, for the stars for which the periodic temporal line profile variability is produced by multiple mode NRP, the classical Doppler image in not an appropriate representation. When the corotating frequencies of existing pulsation modes are non-zero, the reference frame in which the resulting NRP is quasi-stationary cannot be defined. The technique can be applied “mode-by-mode”, which is illustrated in time-wavelength and Fourier frequency domain, using the time-resolved sequence of high resolution, high signal-to-noise ratio spectra of the Be star ζ Oph.
Multi-frequency Variations in the Be star ζ Ophiuchi
Authors: de Souza A.D. , Janot-Pacheco E. , Leister N.V. , Jankov S. , Hubert A.M. , Floquet M.
Published: July 2016

In this work we have adopted the non radial pulsation (NRP) model in order to explain the rapid spectroscopic time variations observed in the Be star ζ Ophiuchi. Time series analysis were performed with CLEAN and Sequential CLEANEST techniques. We have also applied a different version of the Local CLEANEST that is optimized for multiperiodic signals observed in monosite campaigns. The frequencies of 7.19 and 11.89 cycles/day have been identified. These frequencies were found in previous papers about the star.
The magnetic field of β Cep and the Be phenomenon
Authors: Henrichs H.F. , de Jong J.A. , Donati J.-F. , Catala C. , Wade G.A. , Shorlin S.L.S. , Veen P.M. , Nichols J.S. , Kaper L.
Published: July 2016

New circular spectropolarimetric observations of the B1 IIIe star β Cep (υsini = 25 km s−1) show a sinusoidally varying weak longitudinal magnetic field (~ 200 G peak-to-peak). The period corresponds to the 12 day period in the stellar wind variations observed in ultraviolet spectral lines. Maximum field occurs at maximum emission in the UV wind lines. This gives compelling evidence for a magnetic-rotator model for this star, with an unambiguous rotation period of 12 days.

The similarity between the Hα emission phases in β Cep and in Be stars suggests that the origin of the Be phenomenon does not have to be rapid rotation: we propose that in β Cep the velocity to bring material in (Keplerian) orbit is provided by the high corotation velocity at the Alfvén radius (~10 R*), whereas in Be stars this is done by the rapid rotation of the surface. In both cases the cause of the emission phases has still to be found. Weak temporary magnetic fields remain the strongest candidate.

A full paper, with results including additional measurements in June and July 1999, will appear in A & A.
HEROS Be Star Campaigns
Authors: Štefl S. , Rivinius T.
Published: July 2016

Systematic Be star observations with the HEROS spectrograph have been carried out in several long observing runs and seasons, mainly at the ESO La Silla Observatory. The HEROS data represents one of the most extended spectroscopic data sets for the Be star research. More complete and efficient diagnostics and a higher frequency resolution in analyses of periodic spectral variations were achieved, thanks to a combination of relatively high spectral resolution, a large sample of monitored spectral lines of different formation properties, long observing runs, and a relatively high frequency of observations of main targets.

Important results concerning different parts of the extended atmospheres of Be stars and having strong impact on our understanding of these objects have been achieved.
Long-term Variability in Be-Star disks
Authors: Telting J.H.
Published: July 2016

Be stars can switch between non-disk, gradual disk growth, disk-loss events, and shell-line phases. Many aspects of this Be phenomenon are still not understood. In this paper I review recent work on variability in Be-star disks, divided in four different topics: disk growth (Section 1), long-term V/R variations and global disk oscillations (Section 2), spectacular variations (Section 3), and, concisely, the disk variability in Be/X-ray binaries (Section 4).
A Connection Between V/R and Polarization in Be Stars
Authors: McDavid David , Bjorkman K.S. , Bjorkman J.E. , Okazaki A.T.
Published: July 2016

Okazaki (1991) and Papaloizou, Savonije, & Henrichs (1992) suggested that the quasi-cyclic V/R variability observed in the emission line profiles of many Be stars is caused by a precessing one-armed density wave in the circumstellar disk. It seems likely that the changing aspect of such a non-axisymmetric density pattern might also lead to a related variation of the continuum polarization. We have searched for such an effect in two well-studied Be shell stars, ζ Tau and 48 Lib, based on data compiled from several groups of observers from 1984 to 1998. Using the Monte Carlo radiation transfer code of Wood, Bjorkman, Whitney, & Code (1996), we have calculated the polarization due to electron scattering in Be disks in the presence of one-armed density perturbations. Although the notorious long and short term deviations from strict periodicity present in Be stars make it difficult to rigorously demonstrate the connection between the V/R variability and the polarization variations, we have been able to find specific modes that are consistent with the observed V/R line profile variations together with the suspected polarization cycles.
Near Infrared Spectroscopic Observations of Early-type Be Stars
Authors: Ashok N. M. , Banerjee D. P. K.
Published: July 2016

The medium resolution (R=1000) near infrared spectra of 30 early type Be stars obtained during the period October 1998-April 1999 are presented. The Paschen β and Brackett γ lines are seen in emission in majority of these stars. The higher order Brackett series lines from m=10 to 19 are detected in emission with significant strength compared to the Brackett γ emission line flux indicating the effect of optical depth. The Fe II line at 1.6873μm is detected in a small number of stars indicating existence of higher density and lower temperature emission zone.
Mid-Infrared Spectra of Be Stars
Authors: Rinehart S.A. , Houck J.R.
Published: July 2016

We present medium-resolution (R ~ 600) mid-infrared (8-13.3μm) spectra of γ Cas and a coadded spectrum of nine Be stars. A large number of lines have been observed and identified in these spectra, including 39 hydrogen recombination lines in the spectrum of γ Cas. In the majority of our spectra, all of the observed lines are attributable to hydrogen recombination. Two additional sources, β Lyr and MWC 349, show [Ne II] emission and β Lyr also displays [He I] emission. We tabulate the effective line strength and line widths for the observed lines, and briefly discuss the physical implications of the observed line series. We also use a simple model of free-free emission to characterize the disks around these sources.
A Spectroscopic and Photometric Study of the Shell Star EW Lac
Authors: Cao Huilai , Li Zhongwei , Huang Lin , Guo Yulian
Published: July 2016

We report on combined spectroscopic and photometric observations of EW Lac during its outburst of 1983. At this time the star’s Hα and Hβ lines showed strong doubled-peaked emission profiles which were variable with time. UBV photometry exhibited a long-term and frequent erratic short-term variations. The amplitude of U, B and V variations reached about 0.3 magnitude on October 15, 1983. Both Hβ emission and the structure of the shell absorption lines of the star also displayed anomalous behavior in 1983. It is evident that this star was in a strong active phase at that time.
The Be Phenomenon in Pleione
Authors: Hirata Ryuko , Shimada Michihiro R. , Masuda Seiji , Katahira Jun-ichi
Published: July 2016

The spectral change of Pleione in the present Be phase (1988-1999) is briefly described. The Hα emission reached its maximum in 1995-1999. The V/R values of Hγ and metallic lines changed from V/R < 1 in 1995 to V/R > 1 in 1998-1999. The broad component of Mg II λ4481 line further weakened in Be phase.

The long-term variation in 1968-1999 is shown for several observational quantities. These quantities which reflect various levels from the photosphere up to the outer envelope did not change in a parallel way. The basic unsolved problems are pointed out.
Spectral and Photometric Evolution of V725 Tau (1996-1999): Towards a Shell Phase?
Authors: Piccioni A. , Bartolini C. , Bernabei S. , Galleti S. , Giovannelli F. , Guarnieri A. , Sabau-Graziati L. , Valentini G. , Villada M.
Published: July 2016

HDE 245770 = V725 Tau, the optical counterpart of A0535+26, presented in the last three years a period of uncommon optical faintness and of exceptionally low spectral activity. Photometric data obtained in 1997 and 1998 show a fading in all color, followed in 1999 by a nearly constant phase in which the star attained the lowest level of the last 23 years. In 1998 the emission lines became much fainter than in 1997, changing slowly from emission to absorption. In November 1998 only Hα was still showing a weak emission with an absorption core; this behaviour suggests the occurrence of a shell phase.
Search for Evidence of Radiative Equilibrium Departures in Extended Atmospheres
Authors: Venero Roberto , Cidale Lydia , Ringuelet Adela
Published: July 2016

Through the analysis of line profiles of atoms in different ionization stages, we study the source function behavior of those elements that allow us to outline temperature structures in moving extended atmospheres. The radiative transfer equation is solved in the comoving frame and NLTE for multilevel atoms.
Pulsar Searches at Effelsberg — Past, Present & Future
Authors: Lorimer D.R. , Kramer M.
Published: July 2016

It is fair to say that pulsar searches with the 100-m Effelsberg telescope have had something of a checkered history — after all, for many years, this was the largest radio telescope in the world never to have found a pulsar! This situation has, happily, changed. In this review we summarize recent discoveries of weak pulsars along the Galactic plane, give a progress report on a survey for highly dispersed pulsars in the Galactic centre and, in the spirit of this meeting, speculate on what should be a bright future for pulsar searches with this instrument.
Slow pulsars from the STScI/NAIC drift scan search
Authors: Xilouris K. M. , Fruchter A. , Lorimer D.R. , Eder J. , Vazquez A.
Published: July 2016

The unique sensitivity of the Arecibo telescope at 430 MHz motivated a drift scan search of the visible sky divided up into eight declination strips. Based on an analysis of the data collected in the region assigned to us, eight new long-period pulsars have so far been discovered.
A Fast Search Technique for Binary Pulsars
Authors: Ransom Scott M.
Published: July 2016

I describe a computationally simple, efficient, and sensitive method to search long observations for pulsars in binary systems. The technique looks for orbitally induced sidebands in the power spectrum around a nominal spin frequency, enabling it to detect pulsars in high- or low-mass binaries with short orbital periods (Porb≲ 5 h).
Pulsar timing at Kalyazin (Russia)
Authors: Doroshenko O.V. , Ilyasov Yu.P. , Oreshko V.V.
Published: July 2016

Regular timing observations of millisecond and binary pulsars are made with the 64-m radio telescope at Kalyazin (Russia). Filterbank 160-channel receiver is used for observations at 0.6 GHz in two circular orthogonal polarization. Precise local time service (based upon a rubidium standards and hydrogen maser) is used for measurements of Times-of-Arrival (TOA) from radio pulsars. A local time scale is compared by GPS and TV-systems with the basic AT-scales (UTC(USNO) and UTC(SU)) within an accuracy about 50nsper day. Recently the second 1.4 GHz receiver (250 kHz × 64 channels) was constructed and installed at Kalyazin radio telescope. There is a possibility to combine a part of the 1.4 GHz back-end with the 2.2 GHz front-end to produce timing observations at three frequencies simultaneously. We present a results of precise timing observations conducted by the Kalyazin pulsar system. Most of data were obtained at 0.6 GHz in 1997–1999. The data will be used for valuable applications in fundamental metrology, interstellar medium, general relativity and pulsar physics itself.
High Time Resolution Observations of the Crab Pulsar with the UCL MIC Detector
Authors: Much R. , Carramiñana A. , Fordham J.L.A. , Kawakami H. , Michel R.
Published: July 2016

High time resolution (41.4μs) observations of the Crab Pulsar have been undertaken on the 2.1m telescopes at San Pedro Martir and the Observatorio Astrofisico Guillermo Haro (MX) in January/February 1999. In our prelimenary analysis of the Crab Pulsar’s light curve we obtained a slightly narrow widths on the seondary pulse than that reported by Percival et al. Our data indicate the presence of substructures in the pulsar’s main pulse, though not statistically convincing.
Small-eccentricity binary pulsars and relativistic gravity
Authors: Wex Norbert
Published: July 2016

Small-eccentricity binary pulsars with white dwarf companions provide excellent test laboratories for various effects predicted by alternative theories of gravity, in particular tests for the emission of gravitational dipole radiation and the existence of gravitational Stark effects. We will present new limits to these effects. The statistical analysis presented here, for the first time, takes appropriately care of selection effects.
Pulsar Position, Proper Motion, and Parallax via VLBI
Authors: Campbell R.M.
Published: July 2016

I briefly review the means by which VLBI observations can determine the position, proper motion, and parallax of a pulsar, and consider a small subset of the applications of such results.
The Proper Motions of Young Pulsars
Authors: McKay N. P. F. , Anderson B. , Lyne A. G. , Horlock J. L.
Published: July 2016

We report on a project to determine the proper motions of a sample of 13 young pulsars. Sky positions are measured with phase referencing using two elements of the MERLIN array, giving a baseline of 198km. This technique involves the concurrent observation of each pulsar with one or more extra-galactic reference sources located in the same primary beam. At an observing wavelength of 21 cm, this allows the measurement of pulsar positions to an accuracy greater than 1 mas.
Pulsar Profiles and Structure of the Emission Region
Authors: Kuzmin Arkady
Published: July 2016

Recent radio observations of pulsar profiles and the present knowledge about structure of the emission region based on this profiles data are reviewed.

Observations and component structure analysis revealed that there are pulsars profiles having more than 5 components. It call into question that the commonly adopted model of emission region as the double hollow cones and a central core is applicable. Mosaic model of an emission region fit observed profiles with complex more than 5 component structure.

The height (radius) for the emission region evaluated from a dependence of a width of integrated profiles from the pulsar period is estimated asrem≅ 1.5 × l07P0.1cm.

A comparative analysis of the frequency dependence of the profile widths of millisecond and normal pulsars in 0.1 to 1.4 GHz frequency range indicates that the frequency dependence of a width of their profiles, is much weaker than what is typically observed for normal pulsars. This suggests that the geometry of the emission region of millisecond pulsars is unlike that of normal ones.
Orthogonal Polarization Modes and Emission Regions of PSR B1133+16
Authors: Gupta Y. , Gangadhara R.T. , Rathnashree N.
Published: July 2016

Results from an analysis of polarization data, at three different frequencies, for PSR B1133+16, show a clear systematic phase shift between the mode separated profiles for the two orthogonal modes. It is found that the shift has opposite signs for the two components of the profile. Further, the shift shows a tendency to increase at lower frequencies. The implications of these results for the origin of orthogonal modes and the location of pulsar emission regions are discussed.
Polarization Characteristics of Pulsar Profiles
Authors: Han J.L. , Manchester R.N. , Qiao G.J.
Published: July 2016

Polarization profiles of several hundred pulsars have been published recently (eg. Gould & Lyne 1998, GL98; Weisberg et al. 1999). In this report, we summarize the characteristics of circular and high linear polarizations of pulsar profiles, based on all previously published data.
Pulsar Research with the GMRT: A Status Report
Authors: Gupta Y. , Gothoskar P. , Joshi B.C. , Vivekanand M. , Swain R. , Sirothia S. , Bhat N.D.R.
Published: July 2016

The Giant Metrewave Radio Telescope (GMRT) coming up near Pune, India will be one of the important instruments for pulsar research work at metre wavelengths. Here we describe the capabilities of the GMRT for pulsar work and give the current status of the telescope in this context. Results from recent test observations are also summarised.
Coherent De-dispersion Observations at Jodrell Bank
Authors: Ord S. M. , Stairs I. H. , Camilo F.
Published: July 2016

Coherent de-dispersion removes the dispersive effect of the interstellar medium by convolving the digitally sampled telescope output voltages with an inverse filter function, derived from the tenuous plasma dispersion law. The time resolution obtainable by this method is limited only by the bandwidth that can be sampled sufficiently fast as to avoid aliasing. This allows high time resolution, therefore high precision, timing and polarimetry observations of millisecond pulsars. We present here the first results from the Jodrell Bank coherent de-dispersion system.
Pulsar Applications of the Caltech Parkes Swinburne Baseband Processing System
Authors: van Straten Willem , Britton Matthew , Bailes Matthew , Anderson Stuart , Kulkarni Shri
Published: July 2016

The Caltech-Parkes-Swinburne Recorder (CPSR) was installed at the Parkes Radio-telescope in August of 1998. It is capable of continuously two-bit quadrature-sampling a 20 MHz bandpass in two polarizations, though other configurations are possible. Since its successful installation, over 17 Terabytes of observational data have been recorded. These data were processed using the Swinburne Baseband Processing System (SBPS), a suite of data management and reduction software executed using a Beowulf-style cluster of high-performance workstations. A description of CPSR and SBPS is presented herein, followed by a brief presentation of some results from the past year of observations, and an outline of possible future uses of the system.
NTT and VLT Observations of two young pulsars
Authors: Mignani Roberto
Published: July 2016

The two young pulsars PSR J0537-6910 and PSR B1706-44 have been recently observed with the NTT and the VLT. Although both pulsars turned out to be undetected (V≥ 23.4 andV≥ 27.5 respectively) the observations provided interesting constraints on the evolution of the optical luminosity of young pulsars.
Implications of the Optical Observations of Isolated Neutron Stars
Authors: Shearer Andy , Golden Aaron , Beskin Gregory
Published: July 2016

Observations of the 5 confirmed optical pulsars indicate that the peak emission scales according to the outer field strength. We show that this gives gives further confirmation that a simple phenomenological models such as Pacini and Salvati (1987) still have validity. Furthermore we show that the Crab pulsar exhibits unpulsed emission which further complicate any studies of the thermal emission from Isolated Neutron Stars.
PSR J0218+4232 in the energy band 1–10 keV observed with BeppoSAX
Authors: Nicastro Luciano
Published: July 2016

On behalf of a large collaboration (see Mineo et al. (1999) for details) I present the results of a BSAX observation of PSR J0218+4232 which, for the first time, provides detailed information on the pulsar temporal and spectral emission properties in the broad energy band 1–10 keV.
Testing the two-stream instability in a pulsar magnetosphere
Authors: Asseo Estelle
Published: July 2016

Conditions for the development of a two-stream instability in a pulsar magnetosphere are deduced from specific dispersion relations for plane wave perturbations, that depend on the distribution functions of the involved particles. Three different approaches are investigated.

Firstly, using relativistic one-dimensional Juttner Synge distribution functions appropriate to describe pulsar pair plasmas flows, we analytically derive the dispersion relation anew, precisely determining the dependence of its coefficients on the temperature, fluid velocity and associated Lorentz factor. We obtain modified frequencies for quasi-longitudinal waves and specific conditions for a two-stream instability to develop.

Secondly, the importance of two-stream instabilities is tested numerically on two different timescales, that concern stationary and non-stationary properties of pair plasma flows. The linear analysis involves Gaussian distribution functions of the momentum, factorized with functions that depend on the localisation of the different groups of particles, and shows results that agree with observed luminosities.

Finally as derived from fluid equations, the nonlinear evolution of such an instability process allows to associate the high level of radio radiation observed from pulsars with the existence of a lattice of radiating ‘Langmuir‘ soliton-like structures in a pulsar emission region. Actually, pair plasma particles follow the bundle of diverging magnetic field lines in the open magnetosphere and ‘Langmuir‘ soliton-like solutions, modified by magnetic field and density gradients, imply additional radiation.
Pulsar Electrodynamics
Authors: Shibata Shinpei
Published: July 2016

First 1 emphasize the magnetospheric loop current system induced by the wind activity. Next, I address the formation of the field-aligned electric field. An interesting aspect is the reaction of the inner magnetosphere to an induced current. In the traditional outer gap, the current running through the gap is all carried by the particles created in the gap. However, if external current-carrying particles are added, the gap moves inward or outward; it can even appear near the star. It is suggested that the gaps appear at various altitudes, depending on the current distribution on field lines, the field line geometry, and the source of the current-carrying particles.

For definiteness of sign of charge and current direction,Ω ·μ> 0 is assumed throughout.
Pulsar Death at an Advanced Age
Authors: Arons Jonathan
Published: July 2016

I summarize the theory of acceleration of non-neutral particle beams by starvation electric fields along the polar magnetic field lines of rotation powered pulsars, including the effect of dragging of inertial frames which dominates the acceleration of a space charge limited beam. I apply these results to a new calculation of the radio pulsar death line, under the hypotheses that pulsar “death” corresponds to cessation of pair creation over the magnetic polesandthat the magnetic field has a locally dipolar topology. The frame dragging effect in star centered dipole geometry does improve comparison of the theory with observation, but an unacceptably large conflict between obsrvation and theory still persists. Offsetting the dipole improves the comparison, but a fully satisfactory theory requires incorporating magnetic conversion of inverse Compton gamma rays, created by scattering thermal photons from the surface of old neutron stars (t> 108years) kept warm (T≥ 105K) by friction between the rotating core and the crust. The result is a “death valley” for pulsars; offsets of the dipole center from the stellar center in the oldest stars ~ (0.7 − 0.8)R*suffice. The resulting theory predicted the existence of rotation powered pulsars with these advanced ages, a prediction confirmed by the recent discovery that PSR J2144-3933 actually has a rotation period of 8.5 seconds.
ICS as a Limiting Factor for Electron Energies in Pulsar Magnetospheres
Authors: Supper Rodrigo
Published: July 2016

Based on the polar cap model, we investigated in the energy loss of accelerated electrons in a neutron star magnetosphere by inverse Compton scattering of thermal photospheric radiation. An analytical treatment is presented, which turns out ranges in the magnetic field strength and thermal temperature where ultrarelativistic electrons can not survive.
1997 October Event(s) in the Crab Pulsar
Authors: Backer D. C.
Published: July 2016

In October 1997 daily monitoring observations of the Crab pulsar at 327 MHz and 610 MHz with an 85ft telescope in Green Bank, WV showed a jump in the dispersion by 0.12 cm−3pc. Pulses were seen simultaneously at both old and new dispersions for a period of days. In the months before this event faint ghost emission, a replica of the pulse, was detected with a nearly frequency independent delay that quadratically diminished to zero. There was also a curious shift in the phase, a slowdown, at all frequencies at the time of the dispersion jump. I attribute most of these phenomena to the perturbing optics of a plasma prism that is located in the filamentary interface between the synchrotron nebula and the supernova ejecta and which crosses the line of sight over a period of months. The required density, scale length and velocity are reasonable given detailed HST and previous observations of these filaments.
Infrared Observations of the Crab Nebula
Authors: Gallant Yves A. , Tuffs Richard J.
Published: July 2016

We obtained narrow-band continuum images of the Crab Nebula at 16, 6.4 and 2.2µm. From these we derive spectral index maps, extending the optical work of Véron-Cetty & Woltjer (1993). In the central parts of the Nebula the IR spectral index is close to the radio one, indicating the region where the radio-emitting electrons are accelerated.
Plasma Theory of Two Synchrotron Knots’ formation Discovered in the Crab Nebula
Authors: Shapakidze David , Machabeli George
Published: July 2016

The plasma mechanism of synchrotron knots’ formation discovered in the Crab Nebula at the distances 0″.65 (1016cm) and 3″.8 (6 × 1016cm) from the Crab pulsar is presented. The mechanism is based on exitation of cyclotron and Cherenkov-drift instabilities in the relativist s electron-positron plasma of the nebula. The higher luminosity of the knots is supposed due to the orientation of the direction of motion of the synchrotron radiation sources (Larmor circles) relative to the observer.
Supernova Remnant CTB 80 and PSR 1951+32
Authors: Strom R. G. , Stappers B. W.
Published: July 2016

The 39.5 ms pulsar PSR 1951+32 and the remnant with which it is associated, CTB 80, have both been observed with the recently upgraded Westerbork synthesis array (WSRT). Parts of CTB 80 have been observed over the frequency coverage from 0.3 to 8 GHz, while PSR 1951+32 has been observed from 0.3 to 1.6 GHz. The results are described and discussed in the context of the pulsar-remnant association.
Pulsars and Interstellar Scintillations
Authors: Gupta Y.
Published: July 2016

In this paper, I review our current understanding of interstellar scintillations (ISS) of pulsars. The emphasis is on new results that have appeared during the last five years. The topics covered include (i) review of the understanding of refractive ISS (ii) the shape of the spectrum of electron density fluctuations in the interstellar medium (iii) the distribution of scattering plasma in the Galaxy (iv) resolving pulsar emission regions using ISS and (v) ISS and pulsar velocities.
Observations of the interstellar scintillation of nearby pulsars at 1.7 GHz with the 32-m Toruń radiotelescope
Authors: Redmerska Malgorzata , Konacki Maciej , Lewandowski Wojciech , Wolszczan Alex
Published: July 2016

Preliminary results of 1.7 GHz monitoring of the interstellar scintillation of low-DM pulsars with the TCfA 32-m radiotelescope are presented. The dynamic spectra of pulsar intensity variations have been measured with the PSPM-2 which is a 2 × 64 × 3 MHz - channel spectrometer. The 192 MHz total bandwidth of this device provides an adequate frequency coverage to fully parametrize the observed scintillation. A distinct multiple imaging event has been identified in the dynamic spectra of PSR B1133+16.