bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Modelling of the Reflection Spectrum of Venus in the Visual and Near Infrared Ranges
Authors: Feigelson E. M. , Lukashevich N. L. , Krekov G. M. , Tytov G. A.
Published: July 2016

The influence of a dense molecular atmosphere under a cloud layer on spectral albedo of a planet is investigated. The lengths of paths of protons in the clouds are calculated. Experimental spectral transmission functions were used to calculate gas absorption. The results are compared with experimental data.
Water Vapor in Venus Determined by Airborne Observations of the 8200 Å Band
Authors: Gull Theodore R. , O'Dell C. R. , Parker R. A. R.
Published: July 2016

The region of the 8200 Å Band of H2O was studied in spectra of Venus obtained with an echelle grating spectrograph operated at an altitude of 14.6 km in the NASA Learjet research aircraft. Taking advantage of low foreground absorption, observing at a time of velocity quadrature, differential spectroscopy with respect to lunar spectra, and spectrum averaging, we establish a value of H2O of 3 ± 20 μ for the total path over the entire disk. This value differs from earlier studies of the integrated disk but supports the low values recently derived from infrared bands and by very high spectral resolution groundbased studies.

These results establish that the average value over the entire disk is quite low but allows that locally larger values may exist as reported by Barker. A more complete description of this work appeared in Icarus21 (1974), 213.
Optical Line Emission from IO
Authors: Brown Robert A.
Published: July 2016

In early summer of 1972, we discovered an anomalous brightness in the spectrum of Io near the sodium D-lines. This effect is revealed to be time-varying emission by free sodium atoms on Io.
On the structure of galaxies according to photometric studies
Authors: Shchegolev D. E.
Published: July 2016

The colours and brightnesses of various details about 12″ or larger in diameter were measured on photographs taken in the two wave-lengths 4360 Å and 6100 Å, of the spiral galaxies: NGC 224, 598, 3031, 3623, 3627, 3628, 4192, 4217, 4254, 4258, 4321, 4565, 4631, 5194, and 5457. The plates were taken with the 500 mm meniscus astrograph at the Kazakhstan High Altitude Observatory near Alma-Ata. Extra-focal stellar images taken with a ‘two storied plate holder’ were used for standardizing.
Radio Observations at 1.4 GHz of Abell Clusters
Authors: Fanti C. , Fanti R. , Feretti L. , Ficarra A. , Gioia I.M. , Giovannini G. , Gregorini L. , Mantovani F. , Marano B. , Padrielli L. , Parma P. , Tomasi P. , Vettolani G.
Published: July 2016

We have observed with the Westerbork Synthesis Radio Telescope (WSRT) at 1.4 GHz the Abell clusters included in the HEAO-2 satellite observing program, for which radio information was not available. In practice we excluded the clusters south of 15°, in order to ensure an adequate angular resolution in declination; moreover we did not observe distance class (d.c.) 6 clusters for which better resolution and sensitivity would be necessary. The final list includes 61 clusters. These have been observed to a limiting peak flux density of about 5 mJy, corresponding to average minimum radio powers ranging from ∼5×1021 to ∼2×1023 W/Hz for d.c. 1 to 5. By adding the present data to those already available in the literature, we have radio information about all the clusters of d.c. 1 and 2, north of 15°, except A1185. The sample of d.c. 3 clusters contains 60% of the clusters of this class, but seems unbiased both for richness criteria and for radio characteristics; therefore it is useful for statistical studies. The observed clusters of d.c. 4 and 5, instead, are richer than average. The list of the observed clusters is presented in table 1: the Abell name is given in column 1, the d.c. in column 2, the richness class in column 3, the number of radio detected cluster galaxies in column 4 (in parentheses the number of galaxies for which the membership of the cluster is doubtful or the radio identification is not certain is given). The identification of the radio sources with the cluster galaxies of d.c. 5 is still in progress. While a more complete discussion of the properties of radio sources in clusters will be performed later, using the data about all the clusters of the sample, here we summarize the results of the discussion on d.c. 1 and 2 clusters.
The Jets in 3C 449 Revisited
Authors: Cornwell T. J. , Perley R. A.
Published: July 2016

Bridle (this volume) has summarized the overall characteristics of the jets found in numerous low-luminosity and some high-luminosity radio sources. Previous observations made with the partially completed VLA at wavelengths of 6 and 20 cm indicated that 3C449 was an archetypal radio source obeying all the “rules” summarized by Bridle. New observations with the VLA of the polarization structure at 6 and 20 cm have destroyed this simple picture and identify 3C449 as a “rogue” jet source.
Hot-Spots and Radio Lobes of Quasars
Authors: Swarup G. , Sinha R.P. , Salter C.J.
Published: July 2016

A number of investigations have been made of the dependence of largest angular size (LAS) of quasars on their redshifts Z (Miley 1971; Wardle and Miley 1974; Hooley ET AL. 1978; Wills 1979; Masson 1980). The earlier workers found a relation LAS ∝ Z−1 indicating a decrease in linear size of quasars as (1+Z)−n, where 1 < n < 3. The latter workers have argued that the apparent decrease is perhaps caused by an inverse correlation between LAS and radio luminosity. It is also interesting to investigate the dependence of size of hot-spots on luminosity and Z.
A Method for Calibrating, in Absolute Flux Units, Ca II H Profiles of Late Type Stars Observed at ESO
Authors: Castelli F. , Gouttebroze P. , Beckman J. , Crivellari L. , Foing B.
Published: July 2016

In this paper we have applied to the Sun a method for calibrating, in absolute flux units, Ca II H profiles of late-type stars. After comparing, in the region 3948-3882 A, an LTE synthetic spectrum with the data of the solar flux Atlas by Kurucz et al. (1984), we have defined the wavelength ranges where observations agree with computations, based on specific radiative equilibrium models and collisional broadening parameters. By fitting in these regions the spectrum of the moon observed at ESO with the corresponding synthetic spectrum, we derived a calibration factor that enables us to calibrate, in absolute flux units, the whole observed range.
Seismology of the Stellar Cores
Authors: Fossat Eric
Published: July 2016

The tremendous development of helioseismology in the last ten years has included extremely important results obtained through full disk measurements, both in Doppler shifts and broad band photometry. It was then looking very attractive to try to detect the same kind of small amplitude p-modes on other stars.
Lithium Abundances of Solar-Type Stars: A Critical Application of High Signal-to-Noise, High Resolution Spectroscopy
Authors: Soderblom David R.
Published: July 2016

The study of lithium depletion in solar-type stars should help elucidate essential properties of convection in those objects. Recent high-quality observations have revealed extensive flaws in our understanding of this phenomenon. The state of our knowledge of Li depletion is reviewed, with a brief possible explanation of it all.
Well Determined Atmospheric Parameters from High S/N Reticon Spectra of Four G and K Dwarfs Within 10 pc of the Sun
Authors: Perrin M.-N. , Cayrel de Strobel G. , Dennefeld M.
Published: July 2016

The detailed analysis of high resolution, high signal-to-noise spectra of four G and K dwarfs lying within 10 pc of the Sun is presented. This analysis is part of a project aiming at building up a homogeneous set of reliable atmospheric parameters for all F, G and K stars nearer than 10 pc according to the Gliese catalogue.
Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars
Authors: Gratton Raffaele G.
Published: July 2016

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.
The Chemical Composition of Giants in the Globular Cluster ω Cen
Authors: Smith Verne V.
Published: July 2016

High-resolution, high S/N spectra have been obtained for 22 giant stars in the globular cluster ω Cen. These stars span a wide range of temperature and position on the giant branch and include some of the S-type and Barium star members. Spectra were obtained on the CTIO 4m telescope with the echelle spectrograph and CCD detector. Initial abundance results for Iron, Calcium, and Oxygen are presented for three stars: one of the most luminous cluster red-giants, a giant on the blue edge of the ω Cen giant branch, and an extreme Barium star member.
The Stability of Continental Blocks in Seismically Active Regions
Authors: Shcheglov V. P.
Published: July 2016

In connection with the problem of continental drift some authors voice a supposition of the existence of progressive and rotational motion of continental blocks, particularly in seismically active regions. Azimuths of some terrestrial objects determined over long time intervals were used to investigate these motions. Naturally, the reliability of the result depends on the length of these intervals.

The axis of the meridian instrument of Uloug-Beg Observatory in Samarkand, installed 550 years ago (1420-30) is the most ancient meridian direction on the Earth. Using measurements made by the author in 1941, 1956, and present-day observations, it was found that the direction of the axis had moved through an angle of . Allowing for observational errors in the pre-optical period one can accept a change of 5′ or per year. To ascertain if the observed change is caused by rotation of the continental block or local deformation repeated measurements of azimuths of triangulation stations first measured forty years ago were made. The results show the absence of continental block rotation in the region of Middle Asia within a possible accidental error of .
Polarization of Herringbone Structure in Type II Bursts
Authors: Suzuki S. , Stewart R. T. , Magun A.
Published: July 2016

Herringbone Type II bursts were first described by Roberts (1959). These bursts are distinguished by their unusual structure - rib-like features (herringbones) extending on either side of a Type II backbone.
Polarimetry and Physics of Be Star Envelopes (Review paper)
Authors: Coyne George V. , McLean Ian S.
Published: July 2016

A review of the most recent developments in polarization studies of Be stars is presented. New polarization techniques for high-resolution spectropolarimetry and for near infrared polarimetry are described and a wide range of new observations are discussed. These include broadband, intermediate-band and multichannel observations of the continuum polarization of Be stars in the wavelenght interval 0.3–2.2 microns, high resolution (0.5 Å) line profile polarimetry of a few stars and surveys of many stars for the purposes of statistical analyses. The physical significance of the observational material is discussed in the light of recent theoretical models. Emphasis is placed on the physical and geometrical parameters of Be star envelopes which polarimetry helps to determine.
On the Problem of the Chemical Composition of β Lyrae
Authors: Bahýl V.
Published: July 2016

Two determinations of helium abundance in the primary β Lyrae's component existed before 1975. According to Boyarchuk (1959) helium is 631 times overabundant relative to hydrogen and according to Hack and Job (1965) the ratio He/H varies from 1 to 2.25 depending on the effective temperature. We started to examine this probleme with the aim to decide between these extreme results. In the meantime there were published two papers by Leushin at al. (1977, 1979) in which there was found, that He/H = 1.5 for Teff = 12 000 °K and log g = 2.5. The earlier results were based on equivalent widths analysis with curve of growth method. The authors of newly published papers have started from convenient models of the atmosphere, calculated equivalent widths and compared them with observation. In our paper (Bahýl′ 1979) we started from models of the atmosphere, too. Then we calculated the theoretical profiles. We have found the best fit for the model Böhm-Vitense (1967), Teff = 12 900 °K, log g = 2 and He/H = 2.72, as shown in Fig. 1.
Rotational Velocity Versus Mass Loss in be Stars
Authors: Doazan V. , Franco M. L. , Stalio R. , Thomas R. N.
Published: July 2016

C IV and Si IV resonance line profiles of 21 Be, B-shell and normal stars are studied with the aim of detecting evidences for mass loss. We found that almost all our sampled stars are loosing mass. A relation between an estimated lower limit for the rate of mass loss and the observed rotational velocity was searched but not found.
“IUE Observations of 17 Lep”
Authors: Molaro P. , Selvelli P. L. , Stalio R.
Published: July 2016

The spectrum of 17 Lep is dominated by numerous and strong shell lines of once-ionized metals. The shell shows a composite radial velocity structure which indicates the presence of multiple components with a velocity range between −50 and −250 km s−1. Unlike in the visible, where these multiple components are present only during outburst, in the ultraviolet such components seem to be a permanent feature.
Internal Dynamics of Magellanic Cloud Clusters
Authors: Papenhausen Paul , Schommer R. A.
Published: July 2016

It is believed that stellar systems become mass-segregated on a time scale comparable to the two-body relaxation time (Tr). Globular clusters in the Magellanic Clouds have an extensive range in age and richness. Thus, in the clouds, there are candidate clusters with ratios of Tr to age both > 1 and < 1. Our objective is to study the radial density structure of clusters as a function of mass (magnitude) and compare with expectations based upon Tr. We report here preliminary results on two such clusters at the age extremes in our sample: NGC 458 (SMC) and 121SCO3 (LMC).
Abundances of Young LMC Clusters
Authors: Schommer R.A. , Geisler Doug
Published: July 2016

We present Washington system photoelectric photometry for stars in three young LMC clusters: NGC 1850, NGC 1866, and NGC 2164. We derive metal abundances [A/H] of −0.3, −0.4, and −0.6, respectively.
Mass Distributions of Galaxies by Globular Cluster Systems
Authors: Takayanagi Kazutomo
Published: July 2016

Density curves of polytrope index 5 were fitted to the surface density distributions of 26 globular cluster systems. Though we have shown only two of them in Fig. 1, the remaining systems resemble the above cases. No differences exist between elliptical and spiral galaxies.
A Search for Optical Couterparts of Globular Cluster X-Ray Sources
Authors: Aurière Michel , Chevalier Claude , Ilovaisky Sergio , Koch-Miramond Lydie , Cordoni Jean-Pierre
Published: July 2016

The identification of the optical counterpart of the M 15 (NGC 7078) X-ray source has been confirmed photometrically and spectro-scopically (Aurière et al. 1984, 1985, 1986; Ilovaisky and Chevalier: 1985; Charles et al. 1985, 1986). It is designated M15:AC211 from the Aurière and Cordoni catalogue (1981).
17. Optical investigations of radio sources: Introductory Lecture
Authors: Minkowski R.
Published: July 2016

Loose agreement of a radio position of low accuracy with that of some object listed in the NGC is not sufficient to provide the identification of a radio source. Even satisfactory coincidence of a precise position with that of an astronomical object requires supporting evidence. Agreement of the size of the source with that of the visible object, at least in order of magnitude, is an important argument in favour of an identification; exact agreement of sizes can be expected only where radio and optical emission are physically connected. The radio spectrum, the optical spectrum, and the physical characteristics of the visual object also have to be taken into account. Observations of the radio spectrum should be particularly useful to support the identification of sources with H 11 regions which can be recognized from their thermal emission even if they are obscured and optically inaccessible. If all data are available, satisfactory agreement exists between optical and radio observations. The best example of this kind at the moment is perhaps NGC 2237, the Rosette nebula, reported as a source by Ko and Krauss (1955) [1] and also observed by Mills, Little and Sheridan (1956 [11]; see also paper 18).
33. Hydrogen emission nebulae as radio sources
Authors: Haddock F. T.
Published: July 2016

This talk is based largely upon the centimetre-wave observations of hydrogen emission nebulae made with the Naval Research Laboratory 50-ft. paraboloidal reflector at 3·15 cm. [1], at 9·4 cm. [2], and at 21 cm. [3]. After the detection of the first individual bright galactic nebulae at 9·4 cm. a systematic search was made to detect other hydrogen emission nebulae, principally with the aid of the catalogue of emission nebulae obtained by Sharpless [4] from 48-inch Schmidt plates at Mount Wilson and Palomar Observatories. An interesting correlation between radio detectability and nebular classification by optical size and brightness was found, in spite of the fact that optical extinction was not taken into account. The Sharpless catalogue lists 140 classified emission nebulae, of which sixty-five of the brightest were scanned with the radio antenna beam. Of these, twelve nebulae were detected and measured. They can be grouped as follows.
A comparison between radioheliograms and optical observations of the solar corona
Authors: Waldmeier M.
Published: July 2016

Beginning in summer 1957, W. N. Christiansen and D. S. Mathewson [1] have regularly obtained two-dimensional radioheliograms at λ = 21 cm with a resolving power of 3 minutes of arc. The authors have already noticed the close connection between the regions of radio emission on the one side and the fields of spots and faculae on the other side. Considering, however, that the radio emission at the wavelength involved emerges from heights of 20,000 to 50,000, or even up to 100,000 km above the photosphere, i.e. from the inner corona, it seems to be more suitable to compare the radioheliograms with the optical emission of the corona than with the photospheric and chromospheric phenomena. Yet, as the coronal observations can be carried out at the solar limb only, it is difficult to get optical pictures of the corona in front of the sun's disk. Such a picture has to be built up from the daily limb-observations covering the period from 7 days before to 7 days after the date in question; e.g. the coronal intensities shown along the central meridian are measured 7 days before at the E-limb or 7 days later at the W-limb. Since the corona may change greatly within a few days—especially during the present high solar activity—the reliability of an optical corona-picture diminishes from the limb to the central meridian. In addition, a further uncertainty has to be considered in constructing coronal maps, in so far as no station possesses complete coronal observations; therefore, observations of different stations have to be used, which are very difficult to reduce to each other. The main difficulty of such a reduction arises from the fact that the single stations carry out their observations at different distances from the sun's limb ranging from 20,000 to 45,000 km. The coronagrams discussed in the following are based on the intensities of the green coronal line 5303 Å as published in the Quarterly Bulletin on Solar Activity [2].
Solar observations by the large pulkovo radio telescope at 3.2-cm wavelength
Authors: Ikhsanova V.
Published: July 2016

The observations of the sun by the large Pulkovo radio telescope [1] began in 1956 December. In accordance with the antenna dimensions, a fan-beam diagram about one minute of arc in width and one degree in height was expected (at λ = 3.2 cm).
Optical observations of nonthermal galactic radio sources
Authors: Minkowski R.
Published: July 2016

A total of 9 nonthermal sources near the plane of the Galaxy have now been definitely identified with nebulosities. The identifications are well established; positions and sizes of the nebulosities and of the sources are in satisfactory agreement. At least three types of objects can be recognized:

1. Remnants of supernovae of type I.

2. The Cassiopeia A source, a remnant of a supernova of type II.

3. The Cygnus loop and several other large nebulosities which are most likely of similar origin. They also may be remnants of supernovae type II.

The large size and the low surface brightness of these objects render their detailed investigation a difficult and time-consuming task. The true picture may emerge slowly, and conclusions drawn at an early stage of the work may have to be discarded as the investigation progresses.
Flash stars in stellar aggregates
Authors: Haro Guillermo
Published: July 2016

In the past 10 years numerous extremely rapid variables have been found in different stellar associations. The spectrophotometric characteristics of some of these explosive variables are so similar to those of the UV Ceti stars that we propose the term “flash stars” for this variety, in order to provisionally distinguish them from the classical flare stars.
Preliminary results from spectroscopic observations of faint B stars
Authors: Petrie R. M.
Published: July 2016

Radial velocities of 570 B stars, mostly fainter than apparent magnitude 7 · 5 of spectral types between O8 and B5, have recently been determined at Victoria (Petrie and Pearce 1962). Spectroscopic absolute magnitudes based upon the measured strength of Hγ absorption have been determined for these stars. In addition to this totally new material, spectroscopic absolute magnitudes have been measured for an additional 180 stars. From the two lists 490 stars are available for a study of their distributions and radial velocities, since for this number magnitudes and colours have been measured with sufficient precision to allow reliable estimates of the interstellar extinction and the true distance moduli. The results given here are preliminary in the sense that approximately 200 additional stars will be added to the study when the program to determine photoelectric magnitudes and colours is completed. The radial velocities and absolute magnitudes of all the stars have already been measured.
Faint southern B star velocities
Authors: Thackeray A. D.
Published: July 2016

At the Radcliffe Observatory, Dr. Feast and I have recently compiled a third list of radial velocities of O and B stars which was designed primarily to push our optical knowledge of the dynamics of the Galaxy to great distances from the Sun (Feast and Thackeray 1963). This program was preceded by the determination of distance moduli of 248 O and B stars in cooperation with Dr. Stoy of the Royal Observatory, Cape, and Dr. Wesselink at the Radcliffe Observatory (Feast et al. 1961). As a result of this work we now have radial velocities for a very considerable number of southern stars at distances greater than 2 and even 3 kpc. It is quite possible that many of these distances are overestimated and it is highly desirable that the distances should be improved by the Walraven multicolour method or by some other technique. In the meantime it can certainly be claimed that our knowledge of radial velocities of these distant stars is considerably better in the southern than in the northern hemisphere.
Hydrogen motions in the central region of the Galaxy
Authors: Burke B. F. , Tuve M. A.
Published: July 2016

The 21-cm hydrogen radiation near the galactic plane exhibits strong deviation from circular motion over longitudes within 30° or so of the galactic centre. In order to extend the observations first made by Rougoor and Oort,* the Carnegie multichannel H-line spectrograph was used with our 60-foot radio telescope at Derwood, Maryland, in order to confirm the Leiden work and extend observations to more southern longitudes. Cross-sections extending ±2° in latitude were taken every 2° in longitude from lII=−26°8 to lII=+2°2 and a series of points along the galactic equator were taken every 1° over the same range. Effort has been concentrated on the southern extension of the observations, which agree well with the Leiden observations over the section in common, but which carry the observations nearly 20° farther south in longitude.
Luminosity classification for G-type stars
Authors: Buscombe W. , Dickens C. R.
Published: July 2016

As an aid in classifying spectra of 40 stars from which radial velocities were measured at 36 Å/mm, two numerical indices were formed, which depend respectively on average differences in central absorption of eight pairs of lines sensitive to pressure, and of nine pairs sensitive to temperature in the atmosphere.
Objective-prism techniques in use by the Vatican Schmidt
Authors: McCarthy M. F. , Treanor P. J. , Bertiau F. C.
Published: July 2016

For the past 2 years during which the Vatican Schmidt camera (1) has been in regular operation a large proportion of the plate material has been obtained with one of three large objective prisms (2°5, 4°0 and 8°0); more recently the combination 12° (4° + 8°) prism has been found to be a most effective tool for classification studies (2) for the detection and measurement of the 4430Å interstellar band (3), for investigations of variable stars and for examining differences noted in the 3890Å region in spectra or G8 main-sequence stars.
Interstellar Grains in Museums?
Authors: Cameron A. G. W.
Published: July 2016

It is argued that carbonaceous chondrites, particularly of type I, are probably collections of interstellar grains which have been mildly transformed through exposure to higher than normal temperatures, resulting in a loss of volatile materials.
Dust and Star Formation
Authors: McNally D.
Published: July 2016

The view that dust is essential to star formation is challenged on the ground that other interstellar constituents can provide more rapid cooling. From the evidence of stellar minimum masses it is suggested that self absorption of the radiation emitted by the coolant H2 is the dominant mechanism leading to the heating of a collapsing fragment. It is however shown that extensive dust and molecule formation may take place during star formation and that a natural explanation for the 4 terrestrial planets in the neighbourhood of the Sun is then provided.
Pulsar Velocities
Authors: Bailes Matthew
Published: July 2016

Lyne & Lorimer (1994) recently demonstrated that revisions to the pulsar distance scale, coupled with new interferometric measurements of pulsar proper motions and a better treatment of selection effects, indicate that typical pulsar velocities are of the order 450 km s−1. This is between a factor of 2–4 greater than most estimates made over the last decade. This paper looks at the implications of these higher velocities for the various theories about their origin. An extremely simple argument is used to place a fairly rigid upper limit for the rate at which neutron star pairs merge of 10−5 yr−1 in the Galaxy. It appears inevitable that an extremely large fraction of binaries containing neutron stars coalesce during the common-envelope stage of massive binary evolution.
Pulsar/Supernova Remnant Associations
Authors: Frail D. A.
Published: July 2016

If one is interested in issues related to the birth and evolution of neutron stars, a promising avenue of research begins with the study of the byproducts of a Type II supernova event, namely a pulsar (PSR) and its supernova remnant (SNR). However, it has long been a matter of some embarrassment that out of the more than 600 known PSRs and the 175 catalogued SNRs there are few associations. In fact, for nearly 15 years following the discovery of PSRs only the Crab and Vela PSRs had an associated remnant. This failure has spawned something of a cottage industry to “explain away” the low incidence of PSR/SNR associations. Beaming (Frail & Moffett 1993; Narayan & Schaudt 1988), injection (Narayan 1987), field growth (Blandford, Applegate & Hernquist 1983) and black-hole formation (Chevalier 1994) have been invoked in this context at one time or another.
Internal rotation and dynamics of the Sun from GONG data
Authors: Korzennik S. G. , Thompson M. J. , Toomre J. ,   The GONG Internal Rotation Team
Published: July 2016

We report inferences for the Sun's internal rotation from GONG months 4-10 averaged power spectra. In keeping with the international collaborative nature of the GONG project, the results presented here are based on the work of several groups around the world inverting the GONG data and sharing their results via the world-wide web. These groups are at the Observatoire de la Côte d'Azur, Nice (T. Corbard, G. Berthomieu, J. Provost); Theoretical Astrophysics Center, Aarhus (J. Christensen-Dalsgaard, F. Pijpers); Center for Astrophysics, Cambridge MA (A. Eff-Darwich, S. Korzennik); QMW, London (R. Howe, M. Thompson, in collaboration with J. Schou, Stanford); Institute of Astronomy, Cambridge (T. Sekii, D. Gough); University of Sydney (D. Burtonclay, Li Yan, P. Wilson); and Tata Institute of Fundamental Research, Bombay (H. Antia, S. Chitre).
Herbig-Haro Objects in the Orion Nebula Region
Authors: O'Dell C. R.
Published: July 2016

The Orion Nebula Region has two different systems of objects classified as HH objects. The North System is associated with the H2 fingers seen in the infrared and is probably the result of Rayleigh-Taylor instabilities in shocked material moving into the near side of the giant molecular cloud OMC-1. The South System is associated with source(s) within the Trapezium cluster, with the shocked HH objects occuring where jets from pre-main sequence stars impinge on the neutral lid of material that lies across the front of the Orion Nebula. Such jets are different from those driving other HH objects in that these are passing through photoionized material and two of the Orion jets may have been detected.
HD 192641 and HD 193077: Two Single, Hydrogen-Rich Wolf-Rayets?
Authors: Massey Philip
Published: July 2016

As recently as six years ago it was generally agreed that all Wolf-Rayet (WR) stars were the product of mass loss induced by Roche lobe over-flow (RLOF), and that thus they were all members of binary systems. In particular, the presence of absorption lines in the spectrum of a WR star was taken as a definitive indicator that the star was a binary, as it was well known that emission alone (other than the absorption present in P Cygni profiles) was a WR characteristic. However, Niemela (1973) showed that in the WN 7 binary HD 92740 that the absorption and emission lines move in phase, proving that in at least one case the absorption spectrum originates in the WR star itself. Conti (1976) has meanwhile suggested that WR stars could form by mass loss due to a stellar wind rather than RLOF. Obviously it is well worth examining the belief that all (or even most) WR stars are binaries. The currently popular feeling is that the late WN stars (WN 7, 8, and 9) are the only possible exceptions to the traditional picture, while the members of the other subclasses are all hydrogen-poor and probably members of binaries. I hope to convince you today that this is not the complete story.
Plans for the Improvement and Extension of the FK4
Authors: Fricke Walter
Published: July 2016

Recent absolute and differential observations of fundamental stars have indicated the need for a revision of the fundamental reference system represented by the positions and proper motions of the FK4. The revision of the FK4 will be based on modern fundamental and differential observations of high accuracy which allow (a) the extension of the FK4 to fainter stars, (b) the improvement of the system, (c) the derivation of individual corrections to positions and proper motions, and (d) the determination of the equinox and its motion. The completion of the programme, resulting in the FK5 and a Supplement giving data in the system of FK5 for bright stars and faint objects (including optical counterparts of radio sources), may be expected about 1980.
Preliminary Results of Relative Declination Observations Made with the Repsold Meridian Circle at Cerro Calán
Authors: Carrasco G.
Published: July 2016

Preliminary results obtained from 6 years of declination observations are presented. Some instrumental details are discussed, and the observed declination system is compared with FK4 in Δδδ.
Remarks on the Definition and Determination of Proper Motions
Authors: Dieckvoss W.
Published: July 2016

Classical methods of compiling catalogues of proper motions from catalogues of positions at different epochs and reduction to a rigorously defined homogeneous coordinate-system are reviewed, and the determination of proper motions of numerous stars by photographic differential methods, partly with assumptions on behaviour of faint reference stars, and partly by attachment to reference frames of stars with proper motions known from catalogues is discussed.
Prospects of Space Astrometry
Authors: Bacchus P. , Lacroute P.
Published: July 2016

The advantages of making astrometric observations from space are reviewed, and a project for measuring angular separations between stars along great circle arcs of the order of 90°, by means of a telescope mounted on a TD 1 satellite is described. Positions with accuracy of the order of ±0″.01, parallaxes to ±0″.007 and proper motions to ±0″.005 yr-1 for some 40000 stars brighter than 9m.5 would be obtainable in a two year programme.
On the Original Distribution of the Asteroids
Authors: Lecar M. , Franklin F. A.
Published: July 2016

The depletion of an initially uniform distribution of asteroids extending from Mars to Saturn, caused by the gravitational perturbations of Jupiter and Saturn, is calculated by numerical integration of the asteroid orbits. Almost all (about 85%) the asteroids between Jupiter and Saturn are ejected in the first 6000 years. Most of the asteroids between the 2/3 Jupiter resonance (4.0 AU) and Jupiter are ejected in the first 2400 years with the exception of the stable librators (e.g., the Hilda group). Interior to the 2/3 resonance the depletion was small, and interior to the 1/2 resonance (3.3 AU), no asteroids were ejected in the first 2400 years.
Molecular Formation in Hot Diffuse Clouds
Authors: Dalgarno A.
Published: July 2016

A description is given of the processes of molecular formation and destruction in diffuse interstellar clouds and detailed models of the clouds lying towards ζ Ophiuchi, ζ Persei and o Persei are used to assess the validity of gas phase chemistry. Modifications that may arise from shock-heated regions are discussed.
Interstellar Sulfur Chemistry
Authors: Prasad Sheo S. , Huntress Wesley T.
Published: July 2016

This paper summarizes results of a chemical model of SO, CS, and OCS chemistry in dense clouds.
Molecule Formation in the Seyfert Galaxy NGC 1068
Authors: Carlson Wayne J. , Foltz Craig B.
Published: July 2016

We have constructed models of relatively high-density radiation-bounded filaments near the nucleus of a Seyfert 2 galaxy. The amount of molecular hydrogen predicted by the models for reasonable values of the physical parameters is consistent with observations of the infrared continuum and the quadrupole rotation-vibration lines of H2 in NGC 1068.
The Charge and Isotopic Composition of Z ≥ 10 Nuclei in the Cosmic Ray Source
Authors: Webber W. R.
Published: July 2016

Interstellar fragmentation provides the greatest contribution to the abundance of cosmic ray nuclei with Z = 17–25 observed at earth. The usual procedure to estimate the source abundance of these nuclei is to correct for this interstellar fragmentation using a propagation model and a set of fragmentation parameters for Fe nuclei and its products. Only a fraction of these fragmentation parameters have actually been measured and the accuracy of these as well as the semi empirical parameters used for the unmeasured cross sections is no better than ± 10–15%. As a result the actual source abundances of these nuclei can only be deduced to an accuracy of ± 2–3% of the Fe abundance.
Very High Energy Cosmic Rays
Authors: Linsley John
Published: July 2016

Results from ground level and underground experiments on cosmic rays with energy 1012 to 1020eV are reviewed. They show that the energy spectrum has two significant features, a ‘knee’ and an ‘ankle’. The arrival directions of these cosmic rays at the solar system are anisotropic, features of the anisotropy appearing to be correlated with features of the spectrum. Detailed interpretation of this information awaits conclusive evidence regarding the composition of these cosmic rays. New results and prospective new results on the composition are described and discussed.
5 GHz EVN Polarization of 3C286
Authors: Dallacasa D. , Schilizzi R.T. , Sanghera H.S. , Jiang D.R. , Lüdke E. , Cotton W.D.
Published: July 2016

3C286 (1328+307) is a powerful radio source identified with a quasar at z=0.849. There is a foreground galaxy responsible for an H I absorption line system at z=0.6922 (Brown & Roberts 1973), centered approximately 2.″5 to the southeast of 3C286. The radio source has a steep spectrum (α = −0.61, Sv ∝ vα between 1.4 and 15 GHz) which turns over at about 100 MHz. Subarcsecond resolution radio images show a misaligned triple structure, dominated by the central component (Spencer et al. 1989) which accounts for at least 95% of the total flux density at all frequencies. 3C286 is one of the strongest extragalactic sources in polarized emission (0.84 Jy at 5 GHz and 1.41 Jy at 1.4 GHz) and with a rotation measure close to 0 rad m–2 (Rudnick and Jones 1983). Hence the observed orientation of the electric field vector is essentially independent of frequency.
A Simple Method to Analyze Radio Frequency Outbursts of Quasars
Authors: Teräsranta H. , Valtaoja E. , Lainela M.
Published: July 2016

Quasars have been monitored with the Metsähovi Radio Telescope since 1980 at 22 GHz and 37 GHz. During these years we have recorded numerous outbursts in our sample. Some of the outbursts are simple in nature, while others also seem to have fine structure. Can the outbursts be modelled in a simple way?
Diffuse Cluster Radio Sources
Authors: Feretti L. , Giovannini G.
Published: July 2016

Diffuse radio sources in clusters remain a poorly understood phenomenon. They are very extended sources (0.4-0.6 Mpc), of low surface brightness and steep spectrum, which cannot be identified with any active radio galaxy. They are a rare phenomenon, as they have been found so far in few clusters of galaxies. This paper reviews the current findings about this kind of sources, and the suggestions about their formation and evolution.
Analytical Modelling of Linear Size Evolution of Powerful Radio Sources
Authors: Chyży Krzysztof T.
Published: July 2016

We assume that two continuous, supersonic jets of plasma advance into a uniform surrounding medium of constant density and pressure. In terms of fluid dynamics their propagation is described by the kinetic model suitable for high Mach number flows, which likely occur in edge-brightened powerful radio sources. In this approximation the jet flowing energy is dominated by the bulk energy of thermal material. The end of the jet enters the undisturbed ambient medium and forms a front shock, where the supplied bulk energy is in situ transferred to relativistic particles and magnetic field.
The Westerbork Northern Sky Survey
Authors: DE BRUYN A.G.
Published: July 2016

The WEsterbork Northern Sky Survey (WENSS) is a large–sky survey being carried out at 92 and 49 cm with the Westerbork Synthesis Radio Telescope (WSRT). At 92 cm WENSS will cover the sky north of declination +30° (an area of 10,000 square degrees) to a limiting (5σ) flux density of about 15-20 mJy. Both linear and circular polarization data is obtained. The polarization images have a noise level of about 2 mJy (lσ). The spatial resolution at 92 cm is about 1′. At 49 cm about one fifth of this area will be covered to somewhat lower flux density and with twice the resolution. The resulting catalogue will contain about 250,000 sources at 92 cm and 30,000 sources at 49 cm.
Summary of IAU Symposium 176
Authors: Linsky Jeffrey L.
Published: July 2016

This IAU Symposium 176 on the topic “Stellar Surface Structure” provided a much needed opportunity for instrumentalists, observers, and theoreticians to present their exciting new results and to preview the even more exciting future for high-resolution imaging of stellar surfaces. I will attempt a critical summary of this symposium by calling attention to those areas that will likely be very productive in the future and by discussing some important topics that have not been addressed adequately to date, such as the roles of systematic and random errors, the true nature of the solar-stellar connection, and the physical processes responsible for stellar surface structure.

Lesser artists borrow, great artists steal. Igor Stravinsky

You never can tell. George Bernard Shaw
The FK5: Present Status and Some Derived Results
Authors: Schwan Heiner
Published: July 2016

Work on all parts of the FK5 is near to completion. The Basic FK5 has been published in the course of 1989 so that this catalogue is now officially released; the data have been made available to the various data centres. Work on the bright part of the FK5 Extension is finished since the end of 1988 and a tape version was sent to various institutions on request. Work on the Faint Extension is also nearly finished and the complete FK5 Extension will presumably be available on magnetic tape in a few months.

Some results obtained from new observations of FK5 stars are presented. Comparisons of the FK5 with FC, NFK, FK3, FK4, GC, N30 were performed and are discussed with respect to systematic and individual accuracy. The parameters of galactic rotation and precession, and the distance to the Hyades cluster have been derived using proper motions which were obtained within the work on the FK5.
The Construction of 4 Dense Astrometric Standard Areas With the Carlsberg Automatic Meridian Circle
Authors: Chiumiento G. , Fabricius C. , Lattanzi M. G. , Massone G.
Published: July 2016

High precision work in photographic astrometry requires accurate monitoring of the telescope+filter+emulsion system being used.
PPM: A Tool for Astronomers
Authors: Bastian U.
Published: July 2016

The new catalogue of Positions and Proper Motions (“PPM”) was compiled to replace the AGK3 and SAO catalogues as an astrometric reference on the northern celestial hemisphere. It provides more than 180 000 reference stars, is on the system of FK5 (J2000.0) and has a higher accuracy than the two older catalogues.

Some properties of PPM and its High-Precision Subset are presented.
Magnetic Braking
Authors: Mestel L
Published: July 2016

The theory of angular momentum transport by magneto-thermo-centrifugal winds is reviewed, with special reference to recent observations of rapidly-rotating young solar-type stars.
Comparative Study of Young Open Clusters: Age Determination and Stellar Content
Authors: Mermilliod J. C.
Published: July 2016

75 young open clusters have been divided into 14 age groups on the basis of their MV/U-B diagrams. Composite HR diagrams have been constructed and empirical isochronous curves estimated (Figure 1). The left envelope defines a ZAMS. The mean position of the red giants in the HR diagram has been investigated, as well as the occurrence and location of Ap, Am and Be stars and of blue stragglers. Red giants appear mainly in clumps (shaded area).
Structure of the Pulsar Magnetosphere
Authors: Mestel L.
Published: July 2016

Motivation for the study of the pulsar magnetosphere is multifold. First of all, energy-wise the magnetosphere is the dominant problem, for the energy emitted in the radio pulses is at most one per-cent of the energy loss inferred from the secular increase in the rotation period of the central neutron star. With the possible exception of gamma-ray emission in a few cases, the pulsing observed in all wavelengths can be regarded as a diagnostic of a more basic phenomenon. A successful model should in fact tell us the total rate of energy loss from the star and its distribution between a low-frequency wave, a possible wind, and emission in the radio, optical, X-ray and gamma-ray bands. As a necessary preliminary, the model should predict the strength of the currents leaving and returning to the star, the location of relativistic particles, and the conditions for transition to a quantum magnetosphere via pair production (Sturrock 1971). But even if magnetospheric theory did not offer such hopes of ultimate links with observation, the problem is so well-defined that it is a challenge to the theorist: it is just intolerable that we should not know how a rotating magnetized neutron star comes to terms with its environment.
Pulsar Microstructure Quasi-Periodicity
Authors: Boriakoff Valentin , Ferguson Dale C. , Slater Gregory
Published: July 2016

Microstructure in pulsars occasionally has a quasi-periodic character with an average period of around 0.9 ms. A survey of this little known phenomenon (time characteristics, polarization, frequency behaviour, etc.) together with some new results are presented. Some physical interpretations (e.g. vibration of the neutron star, polar cap periodical sparking, standing wave pattern in the velocity of light cylinder model) are also presented.
The Present State of a Spectral Survey of the Southern Milky Way for Stars Earlier than A5
Authors: Geyer E. H.
Published: July 2016

The present state of a spectral survey of the southern Milky Way for stars earlier than A5 is described.
Microphotometry-Computer Classification of Objective-Prism Spectra
Authors: Yoss K. M.
Published: July 2016

Three-dimensional classification of late-type stars is obtained through computer-processed digitized microphotometer data. Plate transmissions are converted to relative intensity through spot-sensitometer calibration data. A pseudo-continuum consisting of several straight-line segments is formed by connecting high points in the spectrum. Absorption-line strengths and line ratios are then measured. The temperature-and-luminosity-sensitive ratios are relatively insensitive to seeing effects. For plates with a dispersion of 108 Å mm-1, preliminary results indicate an accuracy in derived absolute magnitude comparable to, and possibly better than, that of MK classification.

The CN anomaly serves as the abundance index. The CN index was defined in a manner to give the largest figure of merit (the ratio of total range of the index to the mean error). The adopted method is the same as that of Yoss and Lutz (1971) and has a figure of merit over twice that of the index similar to that of Griffin and Redman (1960).

For field stars, plate X and Y positions are converted to equatorial coordinates and printed out in order of increasing right ascension, making quick and easy identification of the Henry Draper numbers.