bluuebunny/crossref_metadata_2025 huggingface dataset:
Wide-field Astronomy with Tech Pan Film - A Positive Outlook for Schmidt Photography
Authors: Parker Quentin A , Phillipps Steven , Morgan David
Published: July 2016

The introduction of film-based Kodak Technical Pan emulsion at the UKST has led to a new lease of life for deep, wide-field astrophotography. This is because the excellent imaging, resolution and low noise characteristics of Tech Pan typically yield a one magnitude depth gain over equivalent IIIa-F plates. Many new projects are underway to take advantage of the significant information gains. The cheap cost of film and ease of transportation gives direct economic benefits too. Tech Pan could also offer a medium term, competitive alternative to CCD mosaics for providing new, deep, wide-field surveys via stacking of several digitised exposures of the same field. A one magnitude gain could result from the stacking of just 6 Tech Pan films to yield an R ∼ 23.5–24. Even without digital co-addition the largest current CCDs cannot hope to match Tech Pan’s inherent ∼ 3 µm resolution and the 40 square degree area coverage of the UKST.
Faint Features of Galaxies revealed by the Digital Co-addition of Schmidt Plates
Authors: Kemp S. N. , Meaburn J.
Published: July 2016

We have digitally co-added eight IIIa-J/GG395 UKST plates centred on the IC 4296 cluster of galaxies. The factor of increase in S/N in the co-added array enables galaxy profiles to be followed, and filamentary and diffuse features to be detected, down to bj surface brightnesses of 28 mag arcsec−2. Examples of warped disks, shells, trails, diffuse IGM and extended haloes revealed by this technique are discussed and illustrated.
An Infrared Colour Discriminator for Giant and Supergiant Optical M Stars
Authors: Raharto Moedji
Published: July 2016

An infrared colour - MK spectral type diagram of optical M giants, M Miras and M supergiants is presented. The area in the diagram with m12 − m25 > 0.70 and MK spectral type earlier than M4 is occupied by early type optical M supergiants. The region of spectral type later than M4 is occupied by optical late M giants (Mira variables) and late M supergiants. The area in the diagram with a colour range of 0.15 < m12 − m25 < 0.70 is occupied by optical giants (Mira Variables) and supergiants (M supergiants with blue companions and probably some M supergiants in the evolutionary stage pre or post M supergiants with large infrared excesses). Finally, the area in the diagram with m12 − m25 < 0.15 is clearly occupied by M giants without circumstellar dust shells. The colour distribution of the M giants, M supergiants and M Miras in the colour - spectral type diagram suggests that we can use the colour properties as search criteria for (i) early M supergiants with colours of m12 − m25 > 0.70, (ii) late M supergiants with colours of m12 − m25 > 0.70, (iii) M giants with m12 − m25 < 0.15, (iv) Mira candidates using IRAS point sources which are also identified as optical M stars.
Detailed Studies of Trapezium-type Multiple Stellar Systems
Authors: Salukvadze Guram N. , Javakhishvili Giorgi Sh. , Kurtanidze Omar M.
Published: July 2016

A brief review of observational studies of Trapezia-type stellar systems is presented. The important role of such systems in investigating problems of star formation is discussed.
Nature of Emission-Line Stars in the Outer Orion Region
Authors: Nakano Makoto , McGregor Peter J.
Published: July 2016

Near-infrared photometry is reported for 76 emission-line stars in outer regions of the Orion molecular cloud complex. Most of our program stars are selected from the Hα emission-line star catalog of the large-scale Kiso Schmidt survey of the Orion region. We confirm that most of the emission-line stars with strong emission detected in the Kiso survey are typical T Tauri stars with masses in the range 0.5 to 2 M⊙. Low mass stars have therefore continued to form in the outer parts of the Orion region, away from present day massive molecular clouds, until at least as recently as a few million year ago.
CCD Observations of Gravitational Lenses and Extragalactic Supernovae with the Brorfelde Schmidt Telescope
Authors: Florentin-Nielsen Ralph , Joergensen Henning E.
Published: July 2016

The Brorfelde Schmidt telescope has been modified to use a 1024 × 1024 12 micron pixels CCD camera. The field is 27 × 27 arcmin. When required, the spatial sampling is improved by co-adding multiple exposures with small offsets. The telescope is operated in service mode, with one observer carrying out several different observing programmes in parallel. The telescope is particularly well suited for long term monitoring programmes, most notably photometric monitoring of gravitationally lensed QSOs and searches for extragalactic supernovae.
Quasar Spectroscopy with FLAIR
Authors: Parker Quentin A. , Clowes R.G. , Watson F.G.
Published: July 2016

We demonstrate that the multi-object fibre-spectroscopy system ‘FLAIR’ on the UKST can be used to observe efficiently and effectively the brighter (B < 18.5) high-grade quasar candidates identified from UKST low-dispersion objective-prism plates. The quasar candidates were selected objectively by the application of AQD (automatic quasar detection) to prism plates that have been digitised using the COSMOS measuring machine. Thirteen high-grade quasar candidates with B ≤ 18.5 from a prism plate of ESO/SERC survey field 296 were observed with a 35-fibre version of FLAIR. From a total observing time of only 3 hours at a resolution of 8.4 Å/pixel six candidates were confirmed as quasars and four were identified as stars. The planned upgrade to a thinned, back-illuminated CCD in 1994 should yield a 3-fold increase in sensitivity and further enhance the capabilities of FLAIR for performing useful spectroscopic observations of quasars of moderate faintness over large areas of sky.
Basic principles in spectro-imaging Foreword on Marseilles Observatory - 3D spectroscopic methods
Authors: Courtès G.
Published: July 2016

Focal reducers provide efficient solutions to the drawbacks introduced by the large focal length of direct foci on large modern telescopes. They house a variety of spectroscopic devices, and lead to various families of spectroimagers. Rational filterings, BPM irmltisimultaneous bandwidths, extreme spectral resolution of the field scanner interferometers (Tully’s first design, Taurus, Cigale) and their image reconstruction, as well as the possibility to obtain the spectra of all image elements of the field owing to the new (Tiger and Silfid) integral field spectrographs sometimes combined with Fabry Perot Interferometers (Pytheas) are now within reach. In classical spectrography the focal reducer leads to the optimized size Baranne’s white pupil spectrograph.
A New Technique for Characterising Planetary Nebulae in External Galaxies
Authors: Taylor K. , Douglas N.G.
Published: July 2016

Planetary Nebulae are proving to be powerful tertiary distance indicators as well as sensitive probes of a galaxy’s velocity field and mass distribution. We present a new technique for determining the positions, luminosities and radial velocities of the PNe in an external galaxy which may enable a one-step measurement of all these parameters.
Fabry-Perot Imaging of the Seyfert 2 Galaxy NGC 2273: Preliminary Report
Authors: Golev V. , Bonev T. , Jockers K. , Yankulova I.
Published: July 2016

Narrow-band images of the ringed Seyfert 2 galaxy NGC 2273 = Mark 620 taken with tunable Fabry-Perot interferometer are presented. Some preliminary contusions are outlined.
Area Spectroscopy of the Extended Emission Line Region in the Seyfert Galaxy NGC 3516
Authors: Aoki K. , Ohtani H. , Kosugi G. , Yoshida M.
Published: July 2016

The researches into extended emission line region (EELR) give us the valuable informations about the nucleus. A recent study of the EELR in the Seyfert 1 galaxy NGC 4151 by Yoshida and Ohtani (1993) have revealed that a strongly asymmetric radiation field in this typical Seyfert 1. They have suggested the anisotropy may be caused inside the BLR. It is important to examine if any other Seyfert 1 galaxy has an anisotropic nuclear radiation.

The famous Seyfert 1 galaxy NGC 3516 has EELR which extends ∼ 10” on either side of the nucleus. The morphology of the EELR is Z-shape. This nearby (D=38.9Mpc) galaxy is of type SBO for which the object is expected to be free from contamination by HII regions and dust clouds.
The distant (z = 0.471) radiogalaxy 3C 435 A with the integral field spectrograph TIGER
Authors: Rocca-Volmerange B. , Adam G. , Ferruit P. , Bacon R.
Published: July 2016

The distant radiogalaxies recently discovered at the most remote distances (z≥3.5) are among the best cosmological targets. However so various features caracterize these galaxies (red stellar energy distribution, huge emission lines, high density of galaxy companions, alignment of ultraviolet and radio axes, large degree of polarisation) that their structures are not simple to understand. Stellar populations will only become the best indicators of evolution of galaxies if these structures are clearly understood from a two-dimension spectroscopy on each image point. The integral field spectrograph TIGER is a unique instrument at the CFHT to give details on the nature and velocities of the various components of distant radiogalaxies.We present the observations with TIGER of an intermediate-redshift galaxy 3C435A (z=0.471) (Rocca-Volmerange et al, 1994). The two nebular lines [OII], [OIII] and the largely extended stellar continua are observable, allowing to date galaxy with the help of our evolution model. The present and past star formation activities and the origin of alignment will be thus analysed in terms of galaxy evolution.
Search for Chemically Distinct Nuclei in Galaxies
Authors: Sil’chenko Olga K.
Published: July 2016

Using the multi-pupil spectrophotometer of the 6-m telescope, five new chemically distinct galactic nuclei are found.
Bidimensional Spectroscopy with the 6-meter Telescope in Time Resolving Mode
Authors: Afanasiev V. L. , Dodonov S. N. , Drabek S. V. , Vlasiouk V. V.
Published: July 2016

Degradation of images of astronomical objects during observations with large optical telescope may be described as combination of atmosphere turbulence on a time scale shorter than some tenths of a second and random fluctuation of object’s position due to telescope and observer’s guiding errors, bending of construction under external factors (wind, etc.). Special investigations on the 6-meter telescope (Balega, 1989) showed, that the peak frequency of such low-frequency fluctuations is located near 1 Hz.

The method of Time Resolving Image Mode, developed by J.-L.Nieto et al (1987) for post-detection improvement of angular resolution at CFHT, showed that, even in places with excellent quality of atmosphere, the resolution of large telescope may be increased by 20-30% only, although powerful methods of image recentering and frames selection were performed. Moreover, such method of data processing may be applied to relatively bright objects only. For 6-meter telescope, resolution improvement would be useless at all due to smaller Fried parameter and larger main mirror.
Reduction of 3D Spectral Data, Obtained with the 6-meter Telescope
Authors: Vlasiouk V. V.
Published: July 2016

Development of 3D spectral methods on the 6-meter telescope prompted the necessity of creating specialized software for data reduction, adapted to personal computers IBM AT/386/486 class. We had to concentrate our efforts on preparing the software for bidimensional spectral data produced by Multi-Pupil Integral Field Spectrograph of the 6-meter telescope (MPFS) and analog of panoramic spectrophotometer with spectral channeling, using scanning Fabry-Perot interferometer (PYTHEAS-6).

MPFS - analog of spectrograph TIGER (Courtes et al., 1988), developed for the 6-meter telescope, provides bidimensional spectroscopy of extended sources, allowing the simultaneous detection of 99 individual spectra, produced by a lens raster from 9 by 11 microlenses. The main features of this instrument are described in (Afanasiev et al, 1994).
Tridimensional Spectroscopic Techniques: Conference Summary
Authors: Bland-Hawthorn J.
Published: July 2016

Over the last four days, we have enjoyed a wide range of talks on developments in three dimensional spectroscopic techniques. The conference organizing committee are to be congratulated for the artful manner in which instrumental presentations were interleaved with talks on the scientific results from these instruments. The general thrust of most talks was to advance the versatility of traditional instruments either through the Jacquinot (throughput) advantage or through the multiplex advantage, or both. A number of groups have attempted to utilize the full aperture of scanning Fabry-Perot and Fourier Transform interferometers. Arguably, Fabry-Perot interferometers have a wider application at present, although imaging Fourier Transform devices appear to have finally arrived, at least in the near infrared.
Expansion of HII Regions in Density Gradients
Authors: Franco José , Tenorio-Tagle Guillermo , Bodenheimer Peter
Published: July 2016

The main features of HII regions expanding in spherical and disk-like clouds with density gradients are reviewed. The spherical cases assume power-law density stratifications, r~w, and the disk-like cases include exponential, gaussian, and sech2 distributions. For power-law profiles, there is a critical exponent, wcrit = 3/2, above which the ionization front cannot be “trapped” and the cloud becomes fully ionized. For clouds with w < 3/2, the radius of the ionized region grows as t4/(7-2w) and drives a shock front into the ambient neutral medium. For w = wcrit = 3/2 the shock wave cannot detach from the ionization front and the two move together with a constant speed equal to about 2ci, where ci is the sound speed in the ionized gas. For w > 3/2 the expansion corresponds to the “champagne phase”, and two regimes, fast and slow, are apparent: between 3/2 < w ≤ 3, the slow regime, the inner region drives a weak shock moving with almost constant velocity through the cloud, and for w > 3, the fast regime, the shock becomes strong and accelerates with time.

For the case of disk-like clouds, which are assumed cylindrically symmetric, the dimensions of the initial HII regions along each azimuthal angle, θ, are described in terms of the Strömgren radius for the midplane density, Ro, and the disk scale height, H. For yo = Rosin(θ)/H ≤ α (where α is a constant dependent on the assumed density distribution) the whole HII region is contained within the disk, and for yo > α a conical section of the disk becomes totally ionized. The critical azimuthal angle above which the HII region becomes unbounded is defined by θcrit =sin-1(αH/Ro). The expansion of initially unbounded HII regions (i.e. with yo > α) proceeds along the z-axis and, if the disk column density remains constant during the evolution, the ionization front eventually recedes from infinity to become trapped within the expanding disk. For clouds threaded by a B-field oriented parallel to the symmetry axis, as expected in magnetically dominated clouds, this effect can be very prominent. The expanding gas overtaken by the receding ionization front maintains its linear momentum after recombination and is transformed into a high-velocity neutral outflow. In the absence of magnetic fields, the trapping has only a short duration.
Star Formation in the NGC 2071 Molecular Cloud
Authors: Evans N.J.
Published: July 2016

The NGC 2071 molecular cloud has been studied with a broad array of techniques, including a large scale study of CS emission, high resolution scans in the far-infrared, N H3 studies with the VLA, and near-infrarred imaging. The far-infrared emission constrains the density distribution to fall off approximately as r−1. The NH3 data strongly supports the presence of a disk oriented perpendicular to the molecular outflow, while the CS emission indicates the presence of dense gas in the region. The results will be combined into a coherent picture of this region of current star formation and molecular outflow.
Dense Clumps in NGC 2024 - Protostellar Condensations?
Authors: Schulz A. , Zylka R. , Güsten R.
Published: July 2016

It has been suggested that in NGC 2024 star forming processes are still going on, and dense cores found by 1.3 mm continuum observations are identified as possible protostellar condensations. To trace the molecular gas of high density, we observed the CS (J=7-6) line using the 30 m IRAM MRT for the first time at submillimetre frequencies (spat, resol. 8.5”). These and complementary observations of lower J CS/C34S transitions as well as the temperature probing NH3(1,1) and (2,2) non-metastable lines enable us to determine temperature and density of 3 selected cores, their kinematics and their masses. These parameters are compared with what is expected for protostellar condensations.
Stellar Winds in A-Type Supergiants
Authors: Talavera A. , Gomez de Castro A.I.
Published: July 2016

The contribution of A supergiant stars to the return of mass and energy to the interstellar medium is not very important. Abbott (1982) analised a sample of early stars and concluded that B and A supergiants provided less than 8 % of the mass input to the ISM by stellar winds. However, A-type supergiants are important in the framework of the stellar winds-mass loss phenomenology since they are located at the boundary between hot and cool stars, where radiative acceleration may not be sufficiently efficient to drive the wind.
Observations of the Progenitor Wind of SN 1987A
Authors: Wampler E.J. , Richichi A. , Baade D.
Published: July 2016

As part of a general ESO program to monitor the spectrum of SN 1987A, we are collecting intermediate high resolution (R = λ/Δλ ≈ 2x104) spectra of the supernova. By the end of the year 1987 it was possible to see narrow emission features due to [OIII] and hydrogen in spectra taken with the ESO Cassegrain echelle spectrograph (CASPEC) (Wampler and Richichi 1988, 1989). At that time, the velocities of these lines were about 286 km/sec and their widths were about 14 km/sec (FWHM). It is almost certain that these lines arise from a cloud of highly ionized gas that was first detected in ultraviolet spectra obtained by IUE in May 1987 (Fransson et al. 1989). This cloud is presumably a circumstellar shell that surrounded the progenitor of SN 1987A and was ionized by the initial UV flash from the supernova explosion. In the ideal case of an expanding spherical shell that is large enough for light travel times to be important, one would expect the intensity of an emission line to increase and then decrease again as the light from the front of the shell fades. At the same time the velocity of the line would increase as the integrated light became dominated by light from the back (receding) hemisphere. The IUE light curve (Fransson et al. 1989) for the ultraviolet [NV] line was consistent with the photometric behavior expected from a nebula about 400 light days in diameter. At the distance of the LMC, one light year is equal to a span of one arc-second, and the photometric behavior of [NV] is consistent with the extent of the nebula measured by Wampler and Richichi (1989).
Carbon Monoxide Emission from Young Planetary Nebulae
Authors: Bachiller R. , Bujarrabal V. , Martín-Pintado J. , Planesas P. , Gómez-González J.
Published: July 2016

We have mapped the CO J=2-l and J=l-0 emission with high angular resolution (about 10” and 20”, respectively) from the young planetary nebulae NGC2346, M2-9 and NGC6720 (the Ring nebula in Lyra). The observations were carried out by using the IRAM 30-m dish at Pico Veleta (near Granada, Spain).
The Trapezium Radio Cluster of the Orion Nebula
Authors: Garay Guido
Published: July 2016

We review the characteristics and discuss the nature of a dense group of compact radio sources found projected toward the Trapezium cluster of the Orion nebula. There are twenty-six radio sources, with flux densities greater than 2 mJy, clustered within a region of 35” radius around θ1C Orionis, the most luminous star of the Trapezium. The density of radio objects, of 1.4×104 pc-3, is extraordinarily high, about a thousand times greater than the density of stars in typical galactic clusters.
Collisions Between High Latitude Clouds: Theory Meets Observations
Authors: Lattanzio J.C. , Keto E.R.
Published: July 2016

We report on fully three-dimensional hydrodynamic and radiative transfer simulations of collisions between high latitude clouds. Our model uses the smoothed particle hydrodynamics code described by Lattanzio and Henriksen (1988) to compute the velocity, temperature, and density fields in the impacted clouds and a recently developed radiative transfer code to compute 13 CO line radiation from the simulated source. By including the instrumental effects involved in a particular observations we can make detailed comparisons with the observations. The model shows that: 1) The previously unexplained energy source for the broad CO line wings reported by Blitz, Magnani, and Wandel (1988) derives from the collisions. 2) Collisions can induce rapid gravitational collapse and star formation in these clouds which are otherwise supported against gravitational contraction via their internal energy content. 3) The external pressure due to intercloud HI, firts proposed for these objects by Keto and Myers (1986), plays a significant role in the stability and evolution of the high latitude clouds.
Large-Scale Irregularities in the Interstellar Medium
Authors: Vats Hari Om
Published: July 2016

The radio flux measurement of the compact extragalactic objects are known to show two types of variablity i.e. intrinsic and extrinsic. Some of the unusual minima in the flux measurement seem to involve large structures in the interstellar medium. In this article we outline a simple ray approach for simulation of these minima in the flux measurement. Simulation will help in estimating the physical parameters of these large scale irregularities or structures in the interstellar medium. Some preliminary results of the simulation will also be described.
Characteristics of Small-Scale Magnetic Fields in a Solar Coronal Hole
Authors: Lin Y.
Published: July 2016

The photospheric longitudinal magnetograms of a coronal hole are used to study the small-scale magnetic fields in the coronal hole. The research is concentrated on the characteristics of the network and the ephemeral region fields, and the results are compared with those in the ordinary quiet regions with mixed magnetic polarities.
Numerical Simulation of CME Propagation in a Helmet Streamer: Emerging Magnetic Flux Mechanism
Authors: Zhang J. H. , Wu S. T. , Dryer M. , Wei F. S.
Published: July 2016

We examine a limited parametric study of time-dependent, numerical MHD simulations of coronal mass ejectsion (CMEs). The physical initiating mechanims (at the base of a helmet-streamer magnetic configuration) is assumed to be magnetic flux that emerges from below the photosphere. The peak flux is taken to be viariable in both magnitude and polarity as well as with/without additional physical mechanisms that include emerging mass and momentum flux. We find that magnetic flux of sufficient magnitude and with polarity opposite to that of the overlying helmet’s magnetic field can be a distinct, physically- viable mechanism. We also find: (i) with an appropriate magnetic driver, it is not necesssary to add an arbitrary heating function to a pre-event helmet-streamer, as suggested by Steinolfson and Hundhausen (1988) to produce observed CME features; nor (ii) is it necessary to introduce anad hocaccelerating mechanism to a plasmoid as sugested by Linkeret al. (1990). However, we agree with the latter workers that the CME driving mechanism has the same importance as the configuration of the initial ambient corona in the determination of the mass ejection’s evolution as detected by coronagraphs.
The Free Energies of Partially Open Magnetic Fields and Coronal Mass Ejections
Authors: Smith D. F. , Low B. C.
Published: July 2016

The results of Low and Smith (1993) on how to circumvent Aly’s limitation on the energy of force-free magnetic fields are briefly reviewed. Two non-force-free configurations with energies in excess of the energy of the corresponding completely open field are discussed: 1. A magnetic bubble configuration with completely detached field lines. 2. A combined configuration consisting of closed field lines with plasma compressed against the star and a superimposed helmet streamer with all field lines tied to the surface. The results of Low and Smith are extended by considering the stability of these two-dimensional equilibria. It is shown that the bubble configuration is unstable. The stability of the combined configuration can only be answered by a numerical analysis because of the stabilizing effect of line-tying.
Masked Coronal Mass Ejections: An Attempt to Demask Them
Authors: Filippov M. , Golbraikh E. , Steinitz R.
Published: July 2016

We unify the elaborated classification system applied to Coronal Mass Ejections (CME). The unification is possible due to the fact that one and the same phenomenon – i.e., mass ejection – is projected on the plane of the sky. We conclude that it is not necessary to keep ten different morphological classes of CME’s, when they represent only one and the same phenomenon, seen in different aspects. Simpler future model of CME origin can be based on the suggested approach.
Phenomenological Pattern of the Outer Solar Corona Structure
Authors: Gulyaev R. A.
Published: July 2016

Topology of the outer solar corona has been analysed. In doing so the outer corona is treated as a visible manifestation of the heliospheric current sheet base. Generalization of the recent conception of the flat (galaxy-like) solar corona has been suggested. It is shown that 3D structure of the outer corona is well fitted by a second-degree surface of a hyperbolic paraboloid.
Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare
Authors: Karlický M. , Hénoux J. C.
Published: July 2016

Using a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.
Contrast of Filament Bright Rims
Authors: Kononovich E. V. , Smirnova O. B. , Heinzel P. , Kotrč P.
Published: July 2016

The Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.
Modelling the Electron Density Distribution in the July 1991 Solar Corona
Authors: Clette F. , Cugnon P. , Gabryl J.-R.
Published: July 2016

Using intensity and polarization maps computed from white-light observations of the July 11, 1991 solar eclipse, we present axisymmetrical models of the large-scale electron density distribution in the corona. These models are based on an expansion in Legendre polynomials, and are flexible enough to fit individual features, like streamers and holes. Furthermore, as the symmetry axis of our models can take any orientation, we consider two plausible configurations, aligned on the rotation axis or the mean bipolar magnetic field axis. Their respective abilities to reproduce a strongly non-spherical global magnetic structure are then compared.
The White-Light and Emission Coronae at the July 22, 1990 Eclipse
Authors: Rušin V. , Marková E.
Published: July 2016

Various instruments were used to study the solar corona at the July 22, 1990 eclipse. The white-light corona of July 22, 1990 is of maximum type (the Ludendorff index of the corona’s shape turns out to be a+b = 0.04). There are many streamers nearly equally distributed around the whole Sun, except of the southwest region where large coronal hole was located. The green (530.3 nm) and red (637.4 nm) coronal line intensities display many rapid changes in active regions around the eclipse day. Huge prominences were located above the E-limb. The estimated total brightness of the white-light corona (WLC) reached its value ofJK= 1.32 × 10−6.
SOHO Science Opportunities
Authors: Fleck B. , Domingo V. , Poland A. I.
Published: July 2016

The space-based Solar and Heliospheric Observatory (SOHO) is a joint venture of ESA and NASA within the frame of the Solar Terrestrial Science Programme (STSP), the first ”Cornerstone“ of ESA’s long-term programme ”Space Science — Horizon 2000“. The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun’s corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here.
SOHO Operations
Authors: Fleck B. , Domingo V. , Poland A. I.
Published: July 2016

SOHO, the Solar and Heliospheric Observatory, is currently scheduled for launch in 1995. After launch SOHO will be operated from the Experiment Operations Facility (EOF) at Goddard Space Flight Center (GSFC). The EOF will consist of facilities for instrument commanding, data reception, data reduction and data analysis. This paper briefly describes the operations concepts.
‘Sumer’ – Solar Ultraviolet Measurements of Emitted Radiation
Authors: Wilhelm K. , Curdt W. , Gabriel A. H. , Grewing M. , Huber M. C. E. , Jordan S. D. , Kühne M. , Lemaire P. , Marsch E. , Poland A. I. , Schühle U. , Thomas R. J. , Timothy J. G. , Vial J.-C.
Published: July 2016

The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of extreme ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy; provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature range from 104to more than 1.8 x 106K. The spatial and spectral resolution capabilities of the instrument will be considered in this contribution in some detail, and a new detector concept will be introduced.
Equation of state of dense Hydrogen and the plasma phase transition; A microscopic calculational model for complex fluids
Authors: Perrot F. , Dharma-Wardana C.
Published: July 2016

We discuss problems related to the electronic and ionic structure of fluid Hydrogen, for equation of state calculations in the domain where a ”plasma phase transition” (PPT) may occur. It is argued that the ionization of an electron bound to a particular nucleus proceeds through a progressive derealization involving ”hopping” electron states (i.e. cluster states). A description of the plasma containing pseudoatoms, pseudomolecules and free electrons is proposed. The PPT, if it exists, might be a mobility edge transition across a percolation threshold. It is shown how the effect of electron density, field-particle distributions and temperature on the binding energy of these pseudoatoms and pseudomolecules, can be included. Finally the abundances of these objects is determined by a minimization which allows the self-consistent optimization of ionic as well as electronic parameters contributing to the total free energy.
Jovian seismology
Authors: Mosser Benoît
Published: July 2016

This paper reviews a new astrophysical subject: seismology of the giant planets. Seismology is dedicated to the sounding of the interior structure of any object; on the other hand, the interiors of the Jovian planets need to be constrained, in order to improve our knowledge of their structure and of their evolution, as well as the thermodynamical laws involved at high pressures and low temperatures. The relationship between Jovian seismology and, first, Jovian internal structure, and second, high pressure physics, is examined, in order to determine the task of “dioseismology”† in the next years. We present then the seismological theoretical approaches developped since the pionnering work of Vorontsov et al. (1976), who calculated the frequencies of the Jovian eigenmodes. We report the first observational attempts for the detection of the oscillations of Jupiter. We discuss the observational results and examine what can be done in the future.
Hipparcos
Authors: Baglin A. , Fernandes J.
Published: July 2016

The HIPPARCOS mission will permit a decisive step forward in the comparison between observed and predicted global properties of stars, in producing distances and apparent magitudes with accuracies more than one order of magnitude higher than before. Nearby stars of intermediate and low mass will allow for statistical tests on the validity of the equation of state, like for instance the steepness of the main sequence.
On Radiative Transfer Near the Plasma Frequency at Strong Coupling
Authors: Kurilenkov Yu. K. , Van Horn H.M.
Published: July 2016

The effects of strong coupling on the frequency-averaged optical characteristics of plasmas, such as the Rosseland mean-free-path, are considered. The general expression for the Rosseland mean opacity has been analyzed in terms of the transverse dielectric function of a dense plasma and the frequency-dependent effective collision frequency. The corresponding values of the absorption coefficient and the refractive index for a dense plasma are presented at ω ≤ ωp up in obvious forms.
New Model Sequences from the White Dwarf Evolution Code
Authors: Wood M.
Published: July 2016

Model sequences computed with the recently-published OPAL radiative opacities, Itoh et al. conductive opacities, and Itoh et al. neutrino rates are presented. Cooling times for DA model sequences are found to be independent of metallicity for Z ≤ 0.001.
Non-Polar Variation of Latitude
Authors: Yumi S.
Published: July 2016

Analysing the residual latitude of the station, local trend in latitude variation other than by the polar motion was found.

Residual latitude was calculated for each of 26 stations which gave the continuous records of observation during 6 years comprising — 1962 — 1967 as a difference between observed variation of latitude and – normal variation calculated by the polar coordinates Iderived from all the results of 26 stations.

As far as the results during these six years are concerned, local trend at any station it seemed to be expressed in terms of 3λ.

Assumed effect of local trend on the coordinates values of the instantaneous pole is also discussed.
Uniformity of the System in Latitude Observation
Authors: Yumi S.
Published: July 2016

Declination correction of an observed star or a star pair is usually obtained by the chain method. Chain method gives a consistent declination system for a certain programmed combination of stars or star pairs, but gives another system which is consistent for another combination.
Observed Rotational Velocities of Single Stars(Review Paper)
Authors: Slettebak Arne
Published: July 2016

Mean observed rotational velocities for single, normal, main-sequence stars are reviewed and compared with the mean observedvsini’s for giant and supergiant stars, Be stars, peculiar A-type and metallic-line stars, and Population II objects.
Rotational Perturbation of A Radial Oscillation in A Gaseous Star
Authors: Simon R.
Published: July 2016

The perturbation method has been applied to the problem of the oscillations of a gaseous star rotating around a fixed z-axis according to a general law of the type
Rotation and Macroturbulence in Supergiant Stars
Authors: Rosendhal Jeffrey D.
Published: July 2016

A statistical investigation has been made of rotation and macroturbulence in early type la and lab supergiants. The principal results are: (1) At all spectral types in the range B0-A5 both rotation and macroturbulence contribute to the observed line broadening. In the early B stars rotation is as important a broadening agent as large-scale mass motion. In the middle B and A stars turbulence dominates but there still is an appreciable contribution from rotation. (2) In spite of the fact that the stars observed seem to be losing mass, there is no strong evidence for significant angular momentum loss.
Astrometry of Double Stars. (Introductory Lecture)
Authors: Strand K.Aa.
Published: July 2016

Progress in the study of visual binaries depends upon the existence of a series of astrometric observations in addition to observations of their relative motions. The present paper discusses the proper motions, parallaxes and mass-ratios of visual binaries, the detection of astrometric binaries and the photographic astrometry of faint binaries.
The Light Variation and the Orbital Elements of AM Leonis = ADS 8024 A
Authors: Binnendijk L.
Published: July 2016

The star was followed photoelectrically in two colors through five consecutive nights in 1968 at Kitt Peak National Observatory. The light of the fainter visual component (a physical companion) was excluded. At primary minimum the system undergoes a total eclipse lasting 25 min. New internally consistent elements have been derived. A subluminous region on the larger star can be located. The previous light curve by Abrami leads to the same geometrical elements but to different photometric elements even when freed from the light of the distant companion.

The paper appeared inAstron. J.74, 1031 (1969).
The Luyten – Control Data Stellar Proper Motion Measuring Machine
Authors: Newcomb James
Published: July 2016

The discovery and measurement of stellar proper motions has always been associated with machines: for proper motion measurements involve four activities: observation, recording, comparison and measurement. Participation by the astronomer in these activities has step by step been replaced partically or wholly by machines. First the observation and recording functions changed from visual to photographic – with the fine guiding done by the astronomer; then the comparison by the blink microscope and the measurement by visually operated measuring machines. On a comparative time scale, the next step – automation of the comparison and measurement function – has been much money, time, and effort away from the previous steps, but as this presentation and other presentations at this conference will show, machines of varying degrees of automation and astronomer participation are now in operation.
Automated Proper Motion Survey: Data Reduction and Initial System Performance
Authors: Bonte A. E. La
Published: July 2016

The Automated Proper Motion Survey (APMS) has three broad goals-accuracy, completeness, and efficiency in the discovery and measurement of stellar proper motions on pairs of red-sensitive photographic star plates taken with the forty-eight inch Schmidt telescope. The specific range of motions sought is from 0.1 to 2.5 seconds-of-arc per year. The lower limit of 0.1 arc sec/year is consistent with the inherent uncertainties in the photographic emulsion and the typical epoch difference between plate exposures. At the opposite end of the scale, extension of the search radius beyond that corresponding to 2.5 arc sec/year would result in a prohibitively large number of spurious matches and a significant increase in processing time while yielding extremely few (though individually interesting) additional stellar motions. The specific range of stellar magnitudes sought is from 12 to 19 red. Significant motions for stars brighter than the limit mred = 12 are already fairly well documented and the corresponding bright Schmidt images begin to show extensive contamination from diffraction spikes, “blazes” radially away from the plate center, and photographic “bloom”. At the other limit, although images of stars fainter than mred = 19 are visually discernible on the plates (the plate limit is typically mred= 20), inspection of the faintest images reveals that they are amorphous and often quite asymmetric clusters of photographic grain. Thus, both the motion limits and the magnitude limits for the survey have been selected to cover the range of reliable and largely unexplored data on the plate material. The implementation of APMS, then, is tailored to these goals and ranges.
The Initial Performance of the Galaxy Machine
Authors: Stoy R.H.
Published: July 2016

The GALAXY (General Automatic Luminosity and X, Y) measuring machine of the Royal Observatory, Edinburgh was completed in 1969 and has been in continuous use since October. It scans a plate, notes the position of all images between preassigned limits and measures some, or all, of these for magnitude and position. The machine was conceived as an attempt to answer the “Schmidt Problem”: how best to handle the immense amount of data that plates taken with Schmidt cameras contain. The general concept of the present machine is due to Professor P. B. Fellgett but the credit for actually bringing the concept to fruition belongs to Dr. V. C. Reddish of the Royal Observatory, Edinburgh and a small design team of what is now Faul Coradi Scotland Ltd.
Some Results on A.G.K. 2 – A.G.K. 3
Authors: Lacroute P. , Valbousquet A.
Published: July 2016

Thanks to W. Dieckvoss’s great obligingness who communicated to us all his results, we could apply the overlap method to the A.G.K. 2 -A.G.K. 3.

Some studies are given in (1) and (2) on the use of overlapping in A.G.K. 2 – A.G.K. 3; here only qualities of the results are studied from the pole to +40° of declination. Moreover some results will be improved by new measures. The details of the method will be published later.
Experience with a Simple Plate Overlap Reduction Method in a Field Around Alpha Persei
Authors: Dieckvoss W.
Published: July 2016

Some years ago at Bergedorf we studied the field around Alpha Persei (Heckmann, O. et alt., 1956). In an area of 5° x 5° more than 100 cluster members were found from an analysis of proper motions (p.m.) of 1453 stars. Meanwhile the field was studied photo metric ally (e.g. Mitchell, R. I., 1960). The age of the group seems to be comparable to that of the Pleiades (cp. e.g. Dachs, J., 1970), of the order of magnitude 108 years.
The Planetary Masses and the Orbits of the First Four Minor Planets
Authors: Schubart J.
Published: July 2016

Numerical tests are the basis of a study about the effects caused in the orbits of the planets (l)-(4) by possible errors in the system of planetary masses. The masses of five major and three minor planets are considered. Especially, the effects caused by (1) Ceres in the orbit of (2) Pallas since the time of discovery are found to be large enough for a determination of the mass of Ceres. A first result for this mass is (6.7 ±0.4) x 10-10 solar masses.
Corrections to the Lunisolar Precession and the Motion of the Equinox from Proper Motions of Cepheids
Authors: Sinzi A.M.
Published: July 2016

Corrections to Newcomb’s lunisolar precession and to motion of the equinox are evaluated from proper motions of 77 Cepheids, employing recently determined values of their distances. Results are diverse, depending on the weighting method. If the effect of the cosmic dispersion is neglected and ω0 is imposed to be 25 km/s/kpc, then Δp1 = 1.″1 ±0.″2 and Δλ′ + Δe = 1.″0 ±0.″1 per century in the FK4 system.
Relaxation Times in Strictly Disk Systems
Authors: Rybicki George B.
Published: July 2016

It is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.
Area-Weighting of Sunspot Group Positions and Proper Motion Artifacts
Authors: Petrovay K.
Published: July 2016

Two simple examples are presented to show that concepts about the physical nature of sunspot groups may significantly influence the statistical data analysis process. In particular, the second example shows that the well-known difference in the decay rates of preceding (p-) and following (f-) polarity parts of sunspot groups may lead to a fake proper motion effect when area-weighted group positions are used. This effect may be responsible for some recent contradictory findings concerning the motions of sunspot groups. It is therefore argued that while area-weighting is adequate when calculating the mean positions of p- and f-parts of a sunspot group separately, defining the position of the group as a whole by the unweighted average of the mean positions of the p- and f-parts is more satisfactory from the theoretical point of view (whenever it is possible to distinguish between spots of different polarities). Similarly, it is best not to “correct” sunspot proper motions for internal differential rotation within groups.
The Application of Boundary Element Method to 3-D Solar Linear Force-Free Magnetic Fields
Authors: Yan Yihua , Yu Qing , Kang Feng
Published: July 2016

In this paper a 3-d formulation is applied to extrapolate the solar magnetic field from the measured magnetogram directly, and no additional data treatment is needed. The validity of the proposed formulation is demonstrated by comparison between calculated and analytical or observed results of some magnetic force-free field problems.
Early Results from the HAO/NSO Advanced Stokes Polarimeter
Authors: Lites B. W. , Elmore D. F. , Tomczyk S. , Seagraves P. , Skumanich A. , Streander K. V.
Published: July 2016

The Advanced Stokes Polarimeter is a new instrument dedicated to quantitative measurement of vector magnetic fields in lines formed at several heights in the solar atmosphere at high angular resolution. We present results for a small, symmetric sunspot observed under good seeing conditions near disk center on 25 March 1992. The narrow penumbral “spines” of more vertical field reported by Degenhardt and Wiehr (1991) and Title et al. (1992) are clearly seen in these observations. These spines are characterized by higher field strength than the surrounding penumbra. The inferred field azimuth indicates that these spines flare out with height, as would be expected of stronger field intrusions within the background penumbral field. The observations indicate the penumbral field “canopy” extends well beyond the outer edge of the penumbra. Outside of the sunspot, the small flux elements of mixed polarity are nearly vertical in orientation.