bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Individual Normal Modes of Oscillation of the Sun in the Period Range from 2 Hr to 10 Min in Solar Diameter Studies
Authors: Bos Randall J. , Hill Henry A. 
Published: July 2016

AbstractNew observations of solar oscillations are reported. Power density spectra derived from these observations reveal narrow-band oscillations that are spatially global, have spatial symmetry properties that are either symmetric or antisymmetric for reflection about the center of the solar disk and also about the solar equator, and have coherence times ≿41 days. Large-scale differential refraction effects have been reduced by a factor of 105 over that found in previous solar diameter studies by the design of the experiment; thus, these effects are eliminated as a possible source of the oscillations. A discussion is presented of this reduction as well as other features of the observing and analysis program. It is concluded that the probability is very high that individual normal modes of oscillation of the Sun have been detected in the period range from 2 hr to 10 min.
On the Origin of Oscillations in a Solar Diameter Observed through the Earth's Atmosphere: A Terrestrial Atmospheric or a Solar Phenomenon
Authors: Hill Henry A. , Bos Randall J. , Caudell Thomas P. 
Published: July 2016

AbstractInterpretations of current and past results from ground-based solar diameter measurements, as well as the planning of scientific programs for the 1980’s, are strongly dependent on the perceived level of the degrading effects of the Earth’s atmosphere. One of the more effective approaches has been to design the observing program and the subsequent data analysis such that the solar diameter measurements themselves could provide an evaluation of atmospheric effects. Many important results have been obtained in studies of this type and these results are collected here to help in appraising the current situation. This evidence all points in one direction: the Earth’s atmosphere, while complicating the design of observational programs, is not the source of the oscillations observed in solar diameter measurements. Further, this same evidence indicates that the Earth’s atmosphere will not pose any serious limitations in ground-based solar diameter studies during the 1980’s.
Evidence for the Phi-Dependent Rotation-Oscillation of the Sun (and for the Driving Mechanism of the Asymmetric Dynamo)
Authors: Csada I.K. 
Published: July 2016

AbstractLongitude-dependent oscillations of the solar rotation are derived from the 27-day averages of the photospheric velocity data. Two pairs of prominent periods are obtained. Their harmonic means correspond to a semiannual variation and to the first harmonic of the latter. To explain the origin of the oscillation the corona and the interplanetary material are supposed to rotate parallel to the planetary plane with an inclination to the solar equator. The non-uniform shearing around the equator is assumed to result in oscillation with a period of half of a year.
Atmospheric Internal Gravity Waves as a Source of Quasiperiodic Variations of the Cosmic Ray Secondary Component and their Likely Solar Origin
Authors: Galper A.M. , Kirillov-Ugryumov V.G. , Leikov N.G. , Luchkov B.I. 
Published: July 2016

AbstractHard gamma-radiation fluctuations with the periods from 4 to 60 min were investigated in the
course of balloon flights at altitudes of 30–40 km. Quasiperiodic intensity variations (QPV) were observed with periods of 5 min, 12–15 min, and 23–26 min, those of 5 min predominating. QPV last no longer than several hours, their associated amplitudes ranging from 5 to 20%. QPV were observed both in mid-latitudes and in the tropics, their detection probability for 3h exposure being 0.3. In the total charged component QPV with comparable amplitudes were not registered. Synchronous atmospheric pressure variations were recorded practically with an amplitude 20 times less than that of gamma-radiation. This suggest short internal gravity waves (IGW) in the stratosphere in the range from 10 to 100 km as the most likable source of QPV. Since the temperature profile of the Earth atmosphere provides conditions for superdistant waveguiding propagation of short IGW with a period of ∼ 5 min at altitudes of 110 and 30 km, the source of waves can be well away from the point of their registration. The IGW generation in the stratosphere can be attributed to the resonance caused by global solar oscillations with low l modes. The resonance probability is likely to be due to the hard solar radiation variations which are absorbed in the ozone layer. The coincidence of the frequency oscillation range in the chromosphere and that of IGW in the stratosphere suggests an IGW resonant excitation mechanism in the Sun–Earth system.
Far-Ultraviolet and Visible Observations of Flares on dme Stars
Authors: Bromage G E , Patchett B E , Phillips K J H 
Published: July 2016

ABSTRACTFour large flare events – one on each of the dMe stars UV Cet, AT Mic, EV Lac and EQ Peg – have been witnessed during a total of 17½ hours of far-UV (λλ1150-1950) IUE exposures. Some observational characteristics of these four events are compared. Two showed strong
enhancements of chromospheric and transition-region line strengths. The other two did not, even though their visible flares were intense (ΔU ~ 2 mag). The brightest UV flare spectrum (EQ Peg) is contrasted with that of the largest solar flare seen from ‘Skylab’.
Empirical Models of Stellar Flares: Constraints on Flare Theories
Authors: Kodaira K. 
Published: July 2016

ABSTRACTA review is presented on empirical flare models of UV Cet type stars based upon optical,UV, X-ray, and radio observations. The observational constraints on the flare energetics, nature of radiation sources, and flare structures are discussed, with special attention to the geometrical dimension and the magnetic field of the flaring region. The hot-plasma model in the solar analogy is critically examined by comparing it with observations. Possible future observations are suggested to tighten the constraints on the stellar flare theories.
Steady State Number of the Extinct Comets in High-Inclination Orbits
Authors: Nakamura Tsuko 
Published: July 2016

AbstractSteady state number of the short-period(SP) comets captured from nearly parabolic(NP) orbits with 60°≤ i(inclination) ≤ 120° and 0.5≤q (perihelion distance) ≤1.5 AU is calculated. Due to smallness of the q and slowness of the capture process, almost all these SP comets become completely extinct. Combining annual flux of the observed NP comets of high inclination with the capture probability from NP to SP orbits and the ejection rate in SP orbits obtained by Monte Carlo simulations, we find that the steady state number of the extinct SP comets in high-inclination orbits is at least 1-2 hundred. If this number can be considered to correspond to the observed one of Apollo-type objects with i ≥ 60°, it is concluded that only less than a few percent of extinct comets leaves sizable non-volatile cores or shells. The number of asteroid-like bodies deduced from the extinct comets with small perihelion distance and high inclination has less ambiguity than that of low inclination, because contribution from asteroid belt is negligible and the source comets are visible(free from observational selection) through the whole course of orbital evolution.
Orbital Evolution of Trojan Asteroids
Authors: Érdi Bálint 
Published: July 2016

AbstractThe motion of the orbits of Trojan asteroids are investigated. Four asteroids around L5 are shown to have librating perihelion. A criterion for the libration of the perihelion is derived and expressed by the initial conditions. This criterion is solved for the initial conditions in two special cases. Thus regions in the configuration space of the initial conditions yielding libration of the orbits of Trojan asteroids are established.
Recent increase of the activity of the symbiotic star CH Cygni
Authors: Chochol Drahomir , Hric Ladislav 
Published: July 2016

CH Cyg has exhibited a great deal of activity in the recent times. We obtained two spectra with dispersion of 9 A/mm with the 2 m telescope of the Ondrejov Observatory on the nights of July 4/5 and August 6/7, 1981. The differences between these spectra are conspicuous. The description of the spectral changes during this period follows:The Balmer lines became broader, the R wing of the early Balmer shell lines being partly suppressed by absorption. The inverse P Cygni profiles became apparent from H8 to H30.
Observations of Local Interstellar Mg I and Mg II
Authors: Bruhweiler F. , Oegerle W. , Weiler E. , Stencel R. , Kondo Y. 
Published: July 2016

AbstractWe have combined Copernicus and IUE observations of 5 stars within 50 pc of the Sun to study the ionization of magnesium in the local interstellar medium (LISM). The high resolution Copernicus spectrometer was used to detect interstellar Mg I 2852 in the spectra of α Gru, α Eri, and α Lyr, while placing upper limits on Mg I in the spectra of α CMa and α PsA. Observations of Mg II 2795, 2802 for these stars were also obtained with IUE and Copernicus. The column densities of Mg I and Mg II are used to place constraints on the temperature of the LISM.
FeII and MgII in the nearby Interstellar Medium
Authors: de Boer Klaas S. , Lenhart Heinz 
Published: July 2016

AbstractUV spectra with 15 km s-1 resolution of bright stars have been searched for Fell and Mgll interstellar lines. We present equivalent widths of absorption for 8 stars and find average line-of-sight densities n(FeII)= 4 10-8 and n(MgII)= 2 10-7 cm-3 . This represents approximately n(H)= 0.03 cm-3.
Dark Cloud and Globule Distribution for Galactic Longitudes 230 to 360 Degrees
Authors: Feitzinger J.V. , Stuewe J.A. 
Published: July 2016

AbstractA catalogue of dark nebulae and globules has been compiled from a study of the ESO-B and SRC-J sky atlas for galactic longitudes 230°<1<360°. This catalogue closes the great southern gap open since the work of Lynds (1962), We have listed 489 dark nebulae and 311 globules. The catalogue contains positions, sizes, opacities and the van den Bergh classification (1972) on the filamentary morphology of dark clouds. We present statistics concerning the northern and southern distributions and sizes of the nebulae.
Polarization of Radio Molecular Lines and Mapping of Magnetic Field Direction
Authors: Deguchi Shuji , Watson William D. 
Published: July 2016

AbstractTwo level calculations by others for the linear polarizations expected for molecular emission lines from interstellar clouds are extended by considering a number of coupled rotational states of a diatomic molecule. Higher transitions commonly have strengths comparable with that of the J=1-0 transition so that depolarization due to coupling between the various J-states might be expected to reduce the predicted linear polarization. The significance of the null observational results obtained recently by Wannier, Scoville and Barvainis is assessed. The inclusion of additional states tends to decrease the maximum polarizations, though the calculated polarization is increased under conditions for which “superthermal” excitation occurs.
The Dao Radial Velocity Spectrometer and Recent Results
Authors: McClure Robert D. , Fletcher MJ.M. , Grundman W.A. , Richardson E.H. 
Published: July 2016

AbstractA photoelectric radial-velocity spectrometer has been in use at the coudé focus of the 1.2m DAO telescope for several years. New improvements, resulting in a lowering of background noise, have allowed observations of stars significantly fainter than previously possible. Recent observations with the instrument at the coudé focus of the CFH telescope in Hawaii have shown that velocity measurements to better than 1 km s−1 accuracy are possible at 19th B magnitude. Various observing programs being carried out at DAO and CFHT are discussed.
Radial Velocities from CCD Detectors
Authors: Willmarth Daryl W. , Abt Helmut A. 
Published: July 2016

The technique of measuring radial velocities by comparison of an object spectrum of unknown velocity to that of a template or mask spectrum of known velocity is well established. An analog device of this nature was developed by Griffin (1967), using a photomultiplier and mechanical mask to judge the degree of correlation between two spectra as a function of Doppler shift. This instrument was a large step forward in speed and efficiency, but suffered a low throughput due to a mask transmittance of about 10%.Digital cross-correlation techniques soon evolved using either digitized data from photographic plates (Simkin 1974) or data obtained directly in digital form (Da Costa et al. 1977, Tonry and Davis 1979). These methods have the advantage of preserving the actual spectrum of the object from which other quantities can be derived. The Fourier methods used in these studies are also used to derive the Doppler broadening of the source.
Coravel Radial Velocities of Supergiants in the Small Magellanic Cloud
Authors: Maurice E. , Martin N. , Prévot L. , Rebeirot E. 
Published: July 2016

Kinematical studies of the Magellanic Clouds began more than half a century ago, when Wilson, in 1918, first interpreted the gradient of the 17 radial velocities of gazeous nebulae in the Large Cloud in terms of rotation. In the case of the Small Magellanic Cloud, the first real attempt to understand the velocity field of this galaxy was performed by the Radcliffe astronomers (Feast et al., 1960, 1961). Their study was based on radial velocities of 40 stars and 13 HII regions.With the installation by ESO of an objective-prisme astrograph in South Africa, in 1961, and then of several larger telescopes in Chile in 1968, the number of measurements significantly increased for Magellanic objects, in particular in the SMC. In this galaxy, the objective-prism observations resulted in about 100 stellar radial velocities (Florsch, 1972a) of probable members. A compilation by Maurice (1979) of all then known slit-spectrograph radial velocities gave velocities for 80 supergiants, 35 HII regions and 12 planetary nebulae.
Bibliography of Radial Velocity Papers (1981 – 1984)
Authors: Philip A.G. Davis 
Published: July 2016

A Bibliography of Radial Velocity Papers has been constructed from two sources; volumes 30 -34 and 37 of Astronomy and Astrophysics abstracts (covering the second half of 1981 through the first half of 1984) and the papers in IAU Colloquium No. 88 (held in October 1984). All the papers listed under Radial Velocity in the index of Astronomy and Astrophysics abstracts were listed with the subject classification assigned by AAA. In some cases papers were assigned to two or more classifications and these papers are listed once each for each classification.The bibliography is presented on pages 419 - 437 in the following format. The sheets presenting the information for each paper were too long to fit on one page in the book so each page has been broken up into three sections; А, B and C. Section A contains the abstract number, the names of the first three authors (and other authors if there are more than three) and the topic of the paper. Section B contains the title of the paper and repeats the abstract number. Section С contains the reference and repeats the abstract number. The entries are presented in groups of ten to aid the eye in following the entries across one page to another. There are seven sections to the Bibliography, I - VII.
Equations of State of Hydrogen-Helium and Carbon-Oxygen Mixtures
Authors: Godon P. , Shaviv G. , Ashkenazi J. , Kovetz A. 
Published: July 2016

The usual approach to the problem of the Equations Of State (EOS) for White Dwarfs and super giant Planets, under the conditions of high densities and low temperatures, faces two problems.The first has to do with Pressure Ionization : the energy levels of the electrons in the case of extreme pressure ionization cannot be treated in the same way as the energy levels in a single isolated atom. The simple treatment of pressure ionization, in which the level of the continuum is reduced by an amount equal to the electrostatic energy, leads to problem because the number of energy levels, entering the Saha equation (partition functions), is not conserved, also the usual approach may lead to absurd results in which ions recombine as the density increases.
The Time Dependence of the Phases of the Harmonics Relative to the 1490 sec Fundamental in PG1346+082
Authors: Provencal J. L. , Clemens J. C. , Henry G. , Hine B. P. , Nather R. E. , Winget D. E. , Wood M. A. , Kepler S. O. , Vauclair G. , Chevreton M. , O’Donoghue D. , Warner B. , Grauer A. D. , Ferrario Lilia 
Published: July 2016

White dwarf stars provide important boundary conditions for the understanding of stellar evolution. An adequate understanding of even these simple stars is impossible without detailed knowledge of their interiors. PG1346+082, an interacting binary white dwarf system, provides a unique opportunity to view the interior of one degenerate as it is brought to light in the accretion disk of the second star as the primary strips material from its less massive companion (see Wood et at. 1987).PG1346+082 is a photometric variable with a four magnitude variation over a four to five day quasi-period. A fast Fourier transform (FFT) of the light curve shows a complex, time-dependent structure of harmonics. PG1346+082 exhibits flickering – the signature of mass transfer. The optical spectra of the system contain weak emission features during minimum and broad absorption at all other times. This could be attributed to pressure broadening in the atmosphere of a compact object, or to a combination of pressure broadening and doppler broadening in a disk surrounding the compact accretor. No hydrogen lines are observed and the spectra are dominated by neutral helium. The spectra also display variable asymmetric line profiles.
Synthetic Spectra of Magnetic White Dwarfs
Authors: Jordan Stefan 
Published: July 2016

AbstractA new program for the calculation of theoretical spectra and wavelength dependend degrees of the linear and circular polarization for magnetic white dwarfs with hydrogen atmospheres has been developed. The main improvement compared to previous models is a more realistic treatment of the bound-free absorption and of the magnetooptical parameters arising from free electrons in the continuum. For the newly discovered magnetic white dwarf HS 1254+3430 a polar field strength of 18 MG was found. Calculations for the high field object Grw +70°8247 confirms the results of Wickramasinghe and Ferrario (320 MG) but gave a better fit to the spectrum at wavelengths larger than 6200 Å.
On the Separations of Common Proper Motion Binaries Containing White Dwarfs
Authors: Oswalt T.D. , Sion E.M. 
Published: July 2016

Luyten [1,2] and Giclas et al. [3,4] list over 500 known common proper motion binaries (CPMBs) which, on the basis of proper motion and estimated colors, are expected to contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. Preliminary assessments of the CPMBs suggest that nearly all are physical pairs [5,6]. In this paper we address the issue of whether significant orbital expansion has occurred as a consequence of the post-MS mass loss expected to accompany the formation of the WDs in CPMBs.Though the CPMB sample remains largely unobserved, a spectroscopic survey of over three dozen CPMBs by Oswalt [5] found that nearly all faint components of Luyten and Giclas color class “a-f” and “+1”, respectively, or bluer were a WD. This tendency was also evident in a smaller sample studied by Greenstein [7]. Conversely, nearly all CPMBs having two components of color class “g-k” and “+3” or redder were MS+MS pairs. With the caveat that such criteria discriminate against CPMBs containing cool (but rare) WDs, they nonetheless provide a crude means of obtaining statistically significant samples for the comparison of orbital separations: 209 highly probable WD+MS pairs and 109 MS+MS pairs.
Structure and Evolution of SV Centauri
Authors: Drechsel H. , Rahe J. , Wargau W. , Wolf B. 
Published: July 2016

AbstractOptical photometric and spectroscopic observations of the eclipsing binary SV Cen were used to derive orbital elements and absolute dimensions of the peculiar early-type contact system. UV spectroscopic observations obtained with the IUE satellite yielded the detection of mass loss from the system forming an expanding circumbinary envelope. SV Cen exhibits a non-uniform rate of period decrease, with major variations on a time scale of a few years. The period changes are explained in terms of loss of angular momentum carried away by the ejected matter. Short-term fluctuations of the stellar wind on a time scale of a few hours were found from an analysis of the envelope line profiles of UV resonance lines. A model of the system is derived, and the evolutionary stage and interaction processes are discussed.
The Time Change of the AW UMa System
Authors: Kurpińska M. , Otmianowska K. 
Published: July 2016

AbstractIn connection with the period change of the AW UMa system, an A-type contact binary, as it was indicated by Woodward (1980) and elaborated by Kurpifiska (1980), we try to analyse with the Wilson-Devinney code all accessible light curves of this star before and after the observed shortening of the period.
Saturn’s E ring
Authors: Baum W.A. , Kreidl T.J. , Wasserman L.H. 
Published: July 2016

ABSTRACTThe spatial distribution of material in Saturn’s E ring has been derived from ground-based CCD observations obtained at the time of the 1980 edge-on presentation. The ring commences abruptly near 3 RS, peaks at the orbit of Enceladus (3.94 RS), and has tenuous outskirts to more than 8 Rs. On reasonable assumptions, we calculate the attenuation factor to be 5xl0-11km-1in the equatorial plane near Enceladus, and the physical thickness of the ring there to be 7500 km (FWHM). The attenuation factor in the equatorial plane is lower by a factor of 8 at Tethys, 76 at Dione, and roughly 1000 at Rhea, while the physical thickness increases by factors of 1.7, 2.9, and 5.5, respectively. This distribution of ring material appears to call for interactions with charged particles and fields. If the E-ring particles are predominantly icy and small, the total mass of the ring is probably less than 106tons.
Structure of Saturn's rings from Voyager radio occultation measurements
Authors: Tyler G.L. , Marouf E.A. , Eshleman V.R. 
Published: July 2016

ABSTRACTRadio occultation observations of Saturn's rings with Voyager 1 provided measurements of the collective microwave opacity and the near-forward scattering characteristics of the ring particles at 3.6 and 13 cm wavelengths. These measurements were obtained at a ring opening of 6.1°. Experimentally, the three classical rings and the Cassini division comprise four distinct structural regimes whose characteristics are as follows: Ring C exhibits a background of gently undulating (~ 1000 km radial scale) structure of normal opacity τ(3.6cm) ≲0.25, [τ = sin(6.1 °)1 n(I/Io)], imbedded in which are several narrow ringlets of less than few hundred km in width and of microwave opacity in the range 0.5 to 1.0. The opacity ratio ρ = τ(3.6cm)/τ(13cm) falls in the range 1.4 to 1.6 for most of ring C, indicating that a substantial fraction of the crosssectional area is due to particles in the 1 to 4 cm diameter range. Three gaps are clearly evident in ring C, two of them encompass imbedded ringlets of extremely sharp edges. The dual-wavelength opacity of several imbedded ringlets is consistent with models in which particles smaller than a few centimeters pile-up near the edges. In the Cassini division, several gaps of extremely sharp edges separate regions of opacity in the range 0.08 to 0.25; the opacity is nearly independent of the wavelength, precluding the existance of a substantial fraction of particles less than about 4 cm in size.