bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of charged small particles
Authors: Grün E. 
Published: July 2016

ABSTRACTCollisions of dust particles with magnetospheric electrons cause dust particles to become negatively charcied if the electron flux exceeds the photo-electron flux (2.5 x 1010r-2cm-2s-1) at the distance r (A.U.) from the sun. These charged dust particles interact with a planetary magnetic field via the Lorentz force. Only for very small particles (e.g. ~ .1 µm in Jupiter's magneto-sphere) the Lorentz force exceeds the gravitational force of the planet. In most observationally relevant cases (Jupiter's and Saturn's ring systems) elec-tromagnetic forces cause only small perturbations of the Keplerian orbits. Local fluctuations of the plasma parameters change the charge of the particles and lead to spatial diffusion. Small changes in the plasma environment of a ring of particulates may release large quantities of dust grains by electro-static blow-off. Drag forces induced by the magnetospheric plasma compete with the radiation pressure drag outside the synchrous orbit. Effects of these dust-magnetospheric interactions are observed in the ring systems of Jupiter and Saturn.
On the role of mother-planet magnetic field in spiral structure explanation of formation of spokes
Authors: Song G.X. 
Published: July 2016

AbstractSome features about the spokes in B rings can be explained in terms of the electromagnetic effect. Due to the existence of the magnetic field in Saturn, plasma and micro-sized dust particles, the loosely spiral structure of magnetic field near Saturn, which is similar to that invoked to explain the sectoral structure of the interplanetary magnetic field in the solar system, may be induced.The spiral structure is rotating with mother-planet and will gradually form at corotation circle, but the wave amplitude will grow outside the corotation and will decay gradually inside the corotation. Using the characteristics of this spiral structure, we have tried to attack the mechanism of the formation of spokes.
A priority of space exploration: observation of Saturn's rings from a Saturn orbiter
Authors: Brahic André 
Published: July 2016

AbstractObservations of Saturn’s ring by Voyager spacecrafts have revealed a much more complex system than expected. So many basical physical meehanisms are involved that more data are required. The logical next step after Voyager is the launch of an orbiter around Saturn. Significant improvements of our knowledge about the ring system could be obtained with the highest possible resolution, with observations with a large variety otf phase angles, with multiple occultation experiments, with observations of the evolution of selected area with time, and with observations of small particles phenomena and electromagnetic properties of the spokes.
Recent X-ray Observations of Supernova Remnants and their Interpretation
Authors: Aschenbach B. 
Published: July 2016

AbstractA review is given of recent observations of the X-ray emission from supernova remnants carried out on the Einstein, Tenma and EXOSAT satellites as well as from a few sounding rocket experiments. Our current interpretation of the high resolution images, high resolution energy spectra and the first few spectrally resolved images is discussed.
X-ray Images of Supernova Remnants
Authors: Seward Frederick D. 
Published: July 2016

Einstein observations of supernova remnants have been reviewed and analyzed. Images of 44 galactic remnants have been reprocessed, merged when necessary, and collected into a catalog. Some bright remnants were viewed with both moderate and high resolution instruments (IPC with 1’ resolution and HRI with 4” resolution). Some IPC images of nearby remnants have been separated into 2 energy bands, 0.2–0.6 keV and 0.6–4.5 keV; whereas most images cover the band 0.2–4.5 keV. The catalog consists of 72 images of the 44 remnants.These images will be published in the form illustrated here. Contour levels are spaced geometrically as indicated below the figures and show the faintest observable features. The pictures are more linear and generally show only the brighter regions. Images are
available now, however, in FITS format, on magnetic tape and may be obtained by writing to the author.
A Hydrodynamical Model of Kepler’s Supernova Remnant Constrained by X-ray Spectra
Authors: Ballet J. , Arnaud M. , Chieze J.P. , Magne B. , Rothenflug R. 
Published: July 2016

AbstractWe present NEI hydrodynamical models of Kepler’s SNR compared with the EXOSAT and EINSTEIN X-ray spectra.
Plasma Diagnostics with X-ray Lines of Oxygen in Puppis A
Authors: Fischbach Kathryn F. , Canizares Claude R. , Markert Thomas H. , Coyne Joan M. 
Published: July 2016

AbstractHigh resolution X-ray spectral observations of Puppis A were performed with the FPCS on Einstein. We use plasma diagnostics of lines from OVII and OVIII to constrain the values of temperature, ionization timescale, and hydrogen column density.
X-ray Images of PKS1209-52 and its Central Compact X-ray Source
Authors: Matsui Yutaka , Long Knox S. , Tuohy Ian R. 
Published: July 2016

AbstractA complete X-ray image of the SNR PKS1209-52 (= G296.5+10.0) was obtained with the IPC and HRI on the Einstein Observatory. The remnant has a shell-like X-ray morphology much like its appearance at radio wavelengths, while a compact X-ray source is clearly detected near the center of the remnant. The flux observed from the X-ray nebula F(0.1−4.5 keV) is 8 × 10−11 ergs cm−2 s−1, which corresponds to a luminosity L(0.1−4.5 keV) = 8 × 1035 ergs s−1 for a distance of 2 kpc. Applying a simple shell model to the X-ray emission distribution, we derived an ambient interstellar medium nO = 0.08 H atoms cm−3, total X-ray emitting plasma mass 150 M⊙, and thermal energy 1.2 × 1050 ergs. The flux from the compact X-ray source F(0.15−4.5 keV) is ~2 × 10−12 ergs cm−2 s−1. There are no obvious optical counterparts brighter than mv ~ 22 within the 3.3″ radius HRI error circle. If the object is a hot neutron star, the HRI/IPC count rate ratio implies a surface temperature of 1.6 × 106 K for NH = 3.2 × 1021 cm−2.
The Dominant Interactions Between SNR and the ISM
Authors: Braun Robert 
Published: July 2016

AbstractThe interactions of supernovae ejecta with the surrounding medium which have a dominant influence on the resulting SNR dynamics and brightness are considered for both young and evolved objects. The important roles of clumpy ejecta in determining the brightness of young SNR and of shock impingement on a pre-existing shell in influencing both the brightness and subsequent dynamics of evolved SNR are stressed.
A Model of SNR Evolution for an O-Star in a Cloudy ISM
Authors: Shull Peter , Dyson John , Kahn Franz 
Published: July 2016

AbstractWe present an analytical model of SNR evolution in a cloudy interstellar medium for a single progenitor star of spectral type 05 V. The model begins with the progenitor on the zero-age main sequence, includes the effects of the star’s wind and ionizing photons, and ends with the SNR’s assimilation by the ISM. We assume that the ISM consists of atomic clouds, molecular clouds, and a hot intercloud phase. The type of SNR that results bears a strong resemblance to N63A in the Large Magellanic Cloud.
Radio Emission from Young Supernova Remnants: Effects of an Inhomogeneous Circumstellar Medium
Authors: Dickel John R. , Eilek Jean A. , Jones Eric M. 
Published: July 2016

AbstractThe evolution of young supernova remnants has been modeled using a 1-dimensional hydrodynamic code. Turbulent dynamo amplification of magnetic fields and both turbulent and shock acceleration of relativistic electrons have been included macroscopically to produce synchotron radiation. The observed radio morphology cannot be reproduced by expansion into a homogeneous medium; it appears that many small cloudlets must be present in the circumstellar material.
A CO (J = 1-0) Survey of Five Supernova Remnants at ℓ = 70° - 110°
Authors: Fukui Y. , Tatematsu K. 
Published: July 2016

AbstractA program of CO observations of five selected supernova remnants is in progress on the 4-m radio telescope at Nagoya. Here, we report observations of two supernova remnants, G78.2+2.1 (the γ Cygni SNR) and HB21. In these two remnants we have obtained evidence for the interaction between the supernova remnants and molecular gas.
High Resolution Radio Observations of the SNR G160.9+2.6 (HB9)
Authors: Leahy D.A. , Roger R.S. 
Published: July 2016

AbstractG160.9+2.6 (HB9) is a supernova remnant of large angular diameter and low radio surface brightness. We report new observations of the continuum emission from HB9 at 408 MHz and 1420 MHz with angular resolutions of 3.5’ and 1.0#x2019;, respectively, which reveal significant filamentary structure not previously detected. The 1420 MHz field covers only the central and eastern parts of HB9. The 408-1420 MHz spectral index (S∝vα) of regions common to both maps is α=-0.68, with no significant spatial variation. The radio filamentary structure closely follows the optical structure. X-ray emission from HB9 is more centrally concentrated than the radio or optical emission. The radio, optical, and particularly, the X-ray surface brightness are all diminished in the northern and northwestern portions of the remnant, in directions approximately coincident with an extensive molecular cloud detected in CO.
A Shell SNR Associated with PSR1930+22?
Authors: Routledge D. , Vaneldik J.F. 
Published: July 2016

AbstractObservations at 408 and 1420 MHz are reported which show a large (1.7 degree diameter) faint shell of nonthermal emission partially surrounding PSR1930+22. This may be the SNR associated with the pulsar, whose spin-down age is only 40000 years.
The Rotation Measure of Background Radio Sources Seen Through the Supernova Remnant OA184 (G166.2+2.5)
Authors: Kim K.-T. , Kronberg P.P. , Landecker T.L. 
Published: July 2016

AbstractRadio sources in the field of the extended SNR OA184 (G166.2+2.5) have been studied to determine the excess rotation measure (RM) arising from the SNR. Of a total of 32 radio sources observed with the VLA in the C configuration, eight are found to be polarized above 7σ The sources seen through the SNR show significantly high RM in comparison to background sources. The excess RM due to the Faraday active plasma in the SNR is estimated to be 150±20 rad m−2, which corresponds to . The sign of RMs of the sources within an area of about 2°×2° centred on the SNR shows a systematic longitudinal polarity change on either side of l ≈ 166°.2. Although a larger sample is needed to justify this, we tentatively interpret this “flip” as due to the reversal of an irregular component of the galactic magnetic field on a scale of order 100 pc.
Infrared Analysis of Supernova Remnants
Authors: Dwek Eli 
Published: July 2016

AbstractInfrared observations of supernova remnants obtained with the Infrared Astronomical Satellite provide new insights into the dynamics and energetics of the remnants, and into their interaction with the ambient interstellar medium. In most remnants the infrared emission arises from dust that is collisionally heated by the X-ray emitting gas. The infrared observations can therefore be used as a diagnostic for the physical conditions of the shocked gas. In particular, it is shown that all the prominent X-ray remnants in the Galaxy and in the LMC cool mainly by dust grain collisions instead of atomic processes.
New Observations of Non-Radiative Shocks in the Cygnus Loop
Authors: Hester J.J. , Raymond J.C. 
Published: July 2016

AbstractWe present deep Hα and [O III] images and echelle spectra of non-radiative shocks in the NE Cygnus Loop. The contrast between the smooth Hα structure and the clumpier [O III] indicates that portions of the sheet-like front are beginning to go radiative. The column depth through the shock seems to be ≼ 1017.5 cm−2 for the entire region – a remarkable constraint for such a large structure.
Absolute Energy Distributions for Selected Quiescent Symbiotic Stars
Authors: Slovak M.H. , Code A.D. 
Published: July 2016

AbstractAbsolute continuum energy distributions for 1200 A to 100μ have been derived for eight quiescent symbiotics. These data are a combination of contemporaneous satellite and ground-based observations, including low resolution IUE and optical spectrophotometry, broadband JKLM infrared photometry and IRAS Point Source Catalogue fluxes. The resulting multifrequency energy distributions represent a merged, uniformly calibrated set of observations and provide a unique opportunity for comparison with quiescent theoretical models.
Radio Imaging of Symbiotic Stars
Authors: Taylor A.R. 
Published: July 2016

AbstractA brief review of radio observations of individual symbiotic stars is presented, with emphasis on radio imaging of the circumstellar nebulae. The ionized nebulae are catagorized into two types: outburst ejecta and stellar winds. Among the ejecta-type there is a strong tendency for bipolar or jet morphology. In the case of the quiescent, stellar wind emitter, a few very wide binary systems (eg. Hl-36) offer the potential of directly viewing the effects of the binary interaction.
Optical Polarimetry of Symbiotic Stars
Authors: Magalhães Antonio Mârio 
Published: July 2016

AbstractA review of some physical mechanisms that may give rise to detectable optical polarization in symbiotic stars is presented, emphasizing the ability of polarimetry in studying the evolution of dust envelopes, the atmospheric structure of the cool component and the geometry of these systems. A brief summary of the techniques is also given. General polarimetric properties of symbiotics as well as data for a few specific systems are discussed. Proposed models for symbiotics that include the prediction of their polarimetric properties are highly encouraged. Specific suggestions for future work from the ultraviolet through the infrared and which explore the potential of the technique are advanced.
On the outburst of symbiotic stars
Authors: Nussbaumer H. , Vogel M. 
Published: July 2016

SummaryThe most commonly advocated models for explaining the outburst of symbiotic systems are thermonuclear runaways, modulated mass accretion through a disc, or accretion disc instabilities. We show that the onset of a strong stellar wind on the cool component can also produce the observed increase in luminosity.
Z Andromedae: Quiescence and Activity
Authors: Cassatella A. , Fernandez-Castro T. , Oliversen N. 
Published: July 2016

Z Andromedae, often considered as the prototype of symbiotic stars, experimented, after several years of quiescence, a small outburst in March-April 1984, followed by a larger one in September-October 1985. The imminence of a new activity phase was predicted by Viotti et al. (1982). Z And is, together with AG Draconis, the only symbiotic star observed both during quiescence and activity with the IUE satellite. The early photometric and spectroscopic history of Z And has been recently reviewed by Kenyon (1986).The behaviour of Z And in the ultraviolet during quiescence has been studied by Fernåndez-Castro et al. (1988), on the basis of data obtained by the International Ultraviolet Explorer from 1978 to 1982. In that period of time, the UV continuum and the emission line fluxes varied quasiperidically with a period of about two years, in phase with the Hα variability found by Altamore et al. (1979), with the UBV photometry by Belyakina (1985) and also in agreement with the ephemeris given by Kenyon and Webbink (1984). The electron density derived from Si III/C III] flux ratio, also varied in phase with the UV flux. In particular, a correlation was found between the electron density variations, and the UV continuum flux at 2900 A. This fact, together with the presence of a Balmer jump in emission, indicates that the principal contributor at those wavelengths is nebular emission, mainly free-bound transitions.
Spectroscopic Orbit of the Eclipsing Symbiotic Star CH Cyg
Authors: Mikołajewski M. , Szczerba R. , Tomov T. 
Published: July 2016

Mikołajewski et al.(1987) quoted convincing arguments that CH Cygni is eclipsing binary system:1.Photometric minima in U light were separated by 57004÷5780 days which is very close to the spectroscopic period (P=5750±250d) found by Yamashita and Maehara (1979).2.Variations of Hβ and Hγ profiles during both minima can be succesfully interpreted as an eclipse of a rotating disk or envelope from which these profiles originate (see also Fernie et al.,1986).3.The flickering activity was absent during the 1985 minimum while observed before and after the minimum.4.Only forbidden lines were unaffected by the minimum. Recently, additional arguments for the eclipsing nature of CH Cygni have been found:5.Deep minimum in the IUE integrated flux was coincided with the minimum detected in U light (Mikołajewska et al., 1987a).6.Changes of Balmer decrement and Balmer continuum emission measure suggest a presence of relatively small dense region occulted during the minimum and extended low density region coinciding with the radio jets (Mikołajewska et al., 1987b).7.Radial velocity of the jet spatially resolved by Solf (1987) in the [OIII]5007 line suggests the jet is practically perpendicular to the line of sight.
Polarization in CH Cygni During Quiet and Active Phases
Authors: Rodriguez M.H. 
Published: July 2016

Our wide-band polarimetric observations of CH Cyg began in 1974 and continued In 1976 and 1984. During the first two observational seasons the star was in quiet phase between two outbursts, in 1984 the latest outburst that began in 1977 was declining. Figure shows mean values of the degree of polarization P and the position angle θ for the different observational periods. Standard errors calculated by photon noise statistics are 0.02–0.04% for P and 1–5% for θ.In 1974 (October 12 - December 1) polarization parameters did not change significantly. Sharp increase of the degree of polarization in the shortwave region of the spectrum and change with wavelength of the degree of polarization are typical for many cool luminous stars and indicate existence of an asymmetric circumstellar envelope around CH Cyg. Interstellar polarization in the direction of CH Cyg should be quite small [1,2],as its distance is 330 pc and colour-excess EB-V does not exceed 0.07m.
Symbiotic Nova PU VUL (Kuwano-Honda Object): Some Results of Coordinated Investigations
Authors: Gershberg R.E. , Shakhovskoj N.M. 
Published: July 2016

Since 1979 a team consisting of T.S.Belyakina, N.I.Bondar’, K.K.Chuvaev, Yu.S.Efimov, R.E.Gershberg, V.I.Krasnobabtsev, E.P.Pavlenko, P.P.Petrov, I.S.Savanov, N.I.Shakhovskaya, N.M.Shakhovskoj, A.G.Shcherbakov and V.I.Shenavrin from the Crimea, Dr. V.Piirola from Finland and Drs D.Chochol, L.Hric and J.Grygar from Czechoslovakia are carrying out a coordinated study of pecular Kuwano-Honda (PU Vul) object, and this short report is made on behalf of the team.PU Vul flared up from 14m to 9m in 1978 and up to date maintains the high brightness. Our studies include the optical and IR photometry, spectroscopy, spectrophotometry, polarimetry and UV observations with the space station Astron. The general character of brightness variations and time distribution of our observations are given in Fig.1.
The Search for the Elusive Companion of EG Andromedae
Authors: Pesce Joseph E. , Stencel Robert E. , Oliversen Nancy A. 
Published: July 2016

AbstractWe report observations at opposite quadratures of the interacting symbiotic binary EG Andromedae (HD 4174, Period = 470d). Correcting for absolute motion at the system, it appears that many of the nebular lines arise from material that moves with the red giant star. The He II feature appears to track the hot component. It may be possible to use this feature in other, similar systems in order to “pin-down” the mass ratio.
Effects of Eccentric Orbit of BF Cygni on IUE and Optical Spectra
Authors: Mikolajewska J. , Mikolajewski M. 
Published: July 2016

A recent analysis of all available photometric data has resulted in a new ephemeris for BF Cyg: MIN=JD 2415058 + 756.8E. Simultaneously, optical spectra collected in 1979–1986 showed periodic changes of all emission lines (Mikolajewska 1987; Mikolajewska & lijima 1987). It is interesting that the forbidden lines of [OIII] varied in antiphase to the permitted emission lines and optical brightness.IUE spectra taken in 1979–1981 showed a strong hot continuum and high ionization resonance emission lines of NV, SilV CIV, intercombination lines of NIV], NIII], SiIII], CIII] and OIII] as well as Hell emission. The observed λ2200Å interstellar absorption band suggests E(B-V)≃0.3. Taking into account the interstellar reddening distribution in the vicinity of BF Cyg (Lucke 1978; Mikolajewska & Mikolajewski 1980), the observed extinction implies a distance d≲1.5kpc. This distance is in good agreement with the observed low value of the systemic radial velocity (∼15 km/s, Fig.1) of BF Cyg and the standard galactic rotation law. The standard extinction curve with E(B-V)=0.3 (Seaton 1979) was used for reddening correction of the spectra. The UV continuum of BF Cyg can be interpreted as a combination of a hot subdwarf (Teff≃60000K, L≃2500L⊙ for d=1.5kpc) and hydrogen bf+ff emission (Te≃10000K). The emission measure of the nebular (bf+ff) continuum varied from ∼4×1059cm−3 at maximum to ∼1059cm−3 at minimum. Assuming cosmic abundance of Si/C the observed SiIII]/CIII] line ratio implies ne≃2×l010cm−3 at the photometric maximum and ne≃3×109cm−3 at the minimum. We assume that these values are representative of the region where the bulk of the HI Balmer and intercombination line emission is produced. The ratio of NV(1240)/NIV(1720) gives Te(NV)≃11500K close to the value derived for the Balmer emission region from the UV continuum fit.
Spectral Morphology in Southern open Clusters and Associations at La Plata Observatory
Authors: Levato H. , Malaroda S. 
Published: July 2016

AbstractOur purpose is to describe the program on spectral classification of members of open clusters and associations started in January 1977 at La Plata Observatory. The program is essentially a continuation of the Abt and Levato studies made from Kitt Peak so, many details of it have been already described in Dr. Abt’s paper in this volume. We have a list of 40 clusters and associations included in the program which consists in obtaining two sets of spectra in two dispersions, 39 Å/mm and 125 Vmm, both sets 1.2 wide. These spectra, as has already been mentioned, are very useful for deriving accurate MK types and for discovering peculiar stars.
Spectea of Of and Be Stabs in the near Infrared Region up to 1.1μ
Authors: Andrillat Yvette 
Published: July 2016

AbstractThe classification of Of stars presents a number of problems, in part due to the small interval of the spectrum explored up to now. With J.M. Vreux an extended study has been made in the infrared region, up to 1.1μ. Be stars have been studied with L. Houziaux, The hydrogen Paschen lines and lines of helium I and II can be studied in the region and used to determine temperature class and luminosity.
Medium Resolution Spectroscopy at 1-2 Microns
Authors: Mould J. R. 
Published: July 2016

AbstractThe need for establishing classification criteria at long wavelengths is stressed. The usefulness of doing this is illustrated with a discussion of the composite spectra of FU Orionis stars. Spectra of these pre-main-sequence stars from 1.5-2.5μ were obtained with a Fourier Transform Spectrometer. Luminosity criteria in the l-2μ range are also discussed with application to M stars.
Spectral Classification from Low Dispersion Objective Prism spectra taken with the UK 1.2m Schmidt Telescope
Authors: Nandy K. 
Published: July 2016

AbstractA thin prism (with a dispersion of 2480 Å/mm at Hγ and Hβ) is now available for the UK 1.2m Schmidt telescope. Å 60-min. unwidened exposure on a Ilia-J (hypersensitized) emulsion reaches fainter than 20 mag. The spectra are measured and digitised with the fast measuring machine COSMOS. A method to determine the red shift of faint galaxies and the spectral classes of faint stars and galaxies from the digitised spectra will be described.