bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coronal Holes and the Locations of the LDE-Type Flares
Authors: Antalová A. 
Published: July 2016

AbstractA qualitative analysis is presented of a possible link between two physical processes on the Sun, namely the gradual magnetic reversal of the large-scale magnetic field of the Sun, and the increase of a flare activity in the solar sectors where the polarity reversal of the faint large-scale magnetic field is observed. The data in Table 1 (years 1976-1979) show that the LDE flare producting nests of the 21st cycle were located within and along the borders of reversed sectors. The flaring centers precede the formation of coronal holes.
Suppression of Solar Radio Noise Storms in Eruptive Flares
Authors: Kahler S. W. , Cliver E. W. , Chertok I. M. 
Published: July 2016

AbstractWe report four cases in which eruptive flares were accompanied by sharp decreases in pre-existing radio noise storm intensity observed by the IZMIRAN station at 169 and 204 MHz. The type IV/noise storm emission probably originated in similar eruptive flares occurring earlier in the same active region complexes. In several cases the flares were accompanied by coronal mass ejections (CMEs) observed by the Solwind or SMM coronagraphs. We suggest that a noise storm accompanying streamer reformation following an initial CME was interrupted by the disruption of the streamer in the second CME.
Faint Hα Emission in the Corona and Its Relation to the Prominences
Authors: Dermendjiev V. N. , Mouradian Z. , Leroy J.- L. , Duchlev P. 
Published: July 2016

AbstractThe relation between episodically observed in the solar corona faint Hαemission structures and the long lived prominences was studied. Particular consideration was given for cases in which the corresponding prominences had undergone DB process. An MHD interpretation of the phenomenon “emissions froides” (cool emission) is proposed in which an essential role plays the prominence supporting magnetic field.
Spectral Analysis of a Quiescent Filament
Authors: Kotrč P. , Heinzel P. , Gorshkov A. V. , Kononovich E. V. , Kupryakov Yu. A. , Smirnova O. B. 
Published: July 2016

AbstractWe have determined principal plasma parameters in a filament by applying the appropriate cloud model to several observed spectral lines. Then we compared them to prominence models from the recent numerical NLTE modelling of Gouttebrozeet al. (1993) (referred to as GHV). Some preliminary results of such an attempt are described and related problems are briefly discussed.
A Detwisting Prominence Event and Its Computer Representation
Authors: Ökten A. , Özişik T. 
Published: July 2016

Many active and short-lived dynamic structures in the solar atmosphere (such as sprays, surges and active prominences) are responsible for transportation of mass and energy into the solar corona, although the contribution of each event is not the same. At the same time, this kind of plasma ejections owe their existence to local magnetic fields. One of the above mentioned phenomena is eruptive prominence. According to Schmieder (1988), common characteristics of eruptive prominences are helical structures, the rotational motions and ‘twisting’ or ‘detwisting’ of the fine structural threads.In this paper, our aim is to show the evolution of a detwisting prominence event and to present to the readers a new data treatment method which can be used to study this kind of event more precisely and rapidly.
Dynamical Fine Structure of a Quiescent Filament
Authors: Mein N. , Mein P. , Wiik J. E. 
Published: July 2016

AbstractA quiescent filament was observed in Hαby the MSDP spectrograph of the Pic-du-Midi Observatory. The dynamical structure is characterized by the statistical moments of the Dopplershift and the intensity at +/− 0.256 Å versus the minimum intensity of the profile. The fitting by a numerical simulation provides the velocity distribution of the ”threads“, and the dynamical characteristics of the underlying chromosperic fine structures.
Diagnostics of the Coronal Plasma
Authors: Sylwester J. 
Published: July 2016

AbstractIn this review I intend to discuss selected aspects of the X and EUV diagnostics of the corona. Especially, I would like to stress on the publications which indicate that the assumptions commonly adopted in the interpretation of solar soft X-ray (SXR) spectra are not necessarily adequate.Multitude of prominent features from excited stages of many abundant ions of N, O, Ne, Na, Mg, Al, Si (K-shell transitions), Ar, Ca, Fe and Ni (K- and L-shell transitions) are contained in the 1-25 Å wavelength band. All these features are observed in emission on top of the continuum.A list of important space experiments performed by 1985 has been prepared by Doschek (R1985). Substantial experimental activity has been observed since that time. Japanese-UK-USAYohkohpayload is delivering thousands of SXR images and spectra each week. Theoretical considerations, reinterpretation of previous measurements and interpretation of incoming data stream indicate that number of assumptions characteristic for the ”classical approach“ have to be at least questioned.
Non-Steady, Plane, One-Dimensional and Isothermal Flows
Authors: Matsuura O. T. 
Published: July 2016

AbstractUsing the Sedov’s (1959) method of self-similarity, non-steady solutions were obtained for a plane, one-dimensional and isothermal flow in presence of gravity. Although simple, such a flow seems to be suitable for describing, in a first approximation, the transient plasma ejections along thecoronal rays. The topology of the solutions shows that the ejections through such structures can be classified in two distinct types. The observable properties for each type are discussed in an attempt to establish a preliminary framework for the strategy of future observations, as well as for the analysis of the existing observational data.
Detection of Small-Scale Dynamics in the Emission Corona
Authors: Rušin V. , Minarovjech M. 
Published: July 2016

AbstractHigh-time records of green (530.3 ran) and red (637.4 nm) coronal line intensities display many occasional short-term variations of different types (oscillations in the range from 5 s to 5 min, non-periodic small or abrupt brightness observed in the line or both in the line and background). The distribution of these features around the Sun is non-uniform, and the amplitude of 5 min oscillations decreases rapidly with the height above the solar surface.
Energetic Protons Associated with Interplanetary Shocks
Authors: Slivka M. , Kudela K. , Borodkova M. , Zastenker G. 
Published: July 2016

AbstractDuring the period March - May 1981, nine interplanetary shocks passing through the position of the Prognoz-8 s/c influenced the flux of energetic protons (Ep≥ 12 keV). The temporal profiles of two of them agree with the model of diffusional acceleration. They have the greatest shock strength (among the nine observed), which corresponds to a maximum energy gain in the individual interactions of the protons with the shock front. Both are most probably associated with quasiparallel shocks initiated by the flares with the eastern heliolongitudes(&gt; 30° E).Two events with the profile expected for the drift acceleration are caused by the flares at the western longitudes(&gt; 30° W).The peak flux for the flares with the high importance (3B) is higher than that for low importance flares (IN) if all “intermediate” flares (position 30° E - 30° W) are combined. For those events the flux profile is more complicated and signatures of both acceleration mechanisms are apparent.
Abundance Modification by the Diamagnetic Effect
Authors: Steinitz R. , Kunoff E. 
Published: July 2016

AbstractIt is well established that there is a chemical abundance differentiation between material in the photosphere, and material in the corona or the solar wind. It appears that this effect is according to first ionization potential (FIP).We explore the possibility that this differentiation is the result of strong diamagnetic effects experienced by ions in the chromposphere-corona transition zone, in the presence of diverging magnetic structures.
Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: I. The Code and Test Cases
Authors: Erdélyi R. , Goossens M. , Poedts S. 
Published: July 2016

AbstractThe stationary state of resonant absorption of linear, MHD waves in cylindrical magnetic flux tubes is studied in viscous, compressible MHD with a numerical code using finite element discretization. The full viscosity tensor with the five viscosity coefficients as given by Braginskii is included in the analysis. Our computations reproduce the absorption rates obtained by Lou in scalar viscous MHD and Goossens and Poedts in resistive MHD, which guarantee the numerical accuracy of the tensorial viscous MHD code.
Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses
Authors: Ambrož P. , Sýkora J. 
Published: July 2016

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.
July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations
Authors: Kulidzanishvili V. , Georgobiani D. 
Published: July 2016

AbstractThe observational data of July 11, 1991 eclipse solar corona obtained by both electropolarimeter (EP) and CCD-matrix were processed. Using these data, the solar corona photometry was carried out. The results of EP data are compared with the ones of CCD data. It must be noted here that the CCD data give us only characteristics of the inner corona, while the EP data show the features of both the inner and middle corona up to 4R⊙. Standard flattening indexϵis evaluated from both data. The dependence of the flattening index on the distance from the solar limb is investigated. The isophotes in Na and Ca lines are plotted. Based on these data some ideas and conclusions on the type of the solar corona are presented.
On Filter Observations of Coronal Structures in the Light of FeX 6374 Å Emission Line
Authors: Guetman F. I. , Kim I. S. , Bücher A. , Druzhinin C. A. , Noëns J.-C. , Salakhutdinov R. T. , Semenikin A. A. , Skomorovsky V. I. 
Published: July 2016

AbstractThe red coronal line of Fe X (6374 Å) seems to be extremely suitable for filter observations due to reduced sky scattering in this spectral interval and absence of blending by Fraunhofer lines. Comparative analysis of location of Hαstructures in colour and black-white pictures of the solar corona of July 11, 1991 was carried out. A conclusion was made that care should be taken when interference filters are used for the red corona observations. Non-ideal monochromatization of present-day existing interference filters may be responsible for some ”false“ red and white coronal structures which belong to Hαprominence emission. Estimations of parameters of an interference filter for the reliable red coronal observations are presented.
On Possible CaII Emission in the Solar Corona
Authors: Kononovich E. V. , Smirnova O. B. , Schukin A. E. 
Published: July 2016

AbstractThe July 1981 solar eclipse corona was observed through aλ3933 Å birefringent filter to prove the existence of CaII emission in the low solar corona. A special method was elaborated to eliminate scattered light and to take into account the background radiation. The measured intensity is by 1 – 2 orders of magnitude larger then the continuum emission in the same wavelength interval. The corresponding gradient is also larger having a value about 3 × 10−10cm−1.
Spartan 201 Observations of the Ultraviolet Extended Solar Corona
Authors: Gardner L. D. , Hassler D. M. , Strachan L. , Kohl J. L. 
Published: July 2016

AbstractThe instruments on the Spartan 201 spacecraft are an Ultraviolet Coronal Spectrometer and a White Light Coronagraph. Spartan 201 was deployed by the Space Shuttle on 11 April 1993 and observed the extended solar corona for about 40 hours. The Ultraviolet Coronal Spectrometer measured the intensity and spectral line profile of HI Lyα and the intensities of O VI 103.2 and 103.7 nm. Observations were made at heliocentric heights between 1.39 and 3.5 R⊙. Four coronal targets were observed, a helmet streamer at heliographic position angle 135°, the north and south polar coronal holes, and an active region above the west limb. Measurements of the HI Lyα geocorona and the solar irradiance were also made. The instrument performed as expected. Straylight suppression, spectral focus, radiometric sensitivity and background levels all appear to be satisfactory. The UV observations are aimed at determining proton temperatures and outflow velocities of hydrogen, protons and oxygen ions.
Stellar Coronal Structures
Authors: Linsky J. L. 
Published: July 2016

AbstractLarge magnetic structures in the coronae of stars containing gas at a wide variety of temperatures are now being studied in X-rays, radio wavelengths, and Hα. Here I will summarize what we are learning about coronal structures in three types of stellar systems: the magnetic chemically peculiar stars, the RS CVn binary systems containing G- and K-type subgiants, and active solar-type dwarfs like V471 Tauri and AB Doradus.
Statistical Mechanics of Quantum Plasmas Path Integral Formalism
Authors: Alastuey A. 
Published: July 2016

AbstractIn this review, we consider a quantum Coulomb fluid made of charged point particles (typically electrons and nuclei). We describe various formalisms which start from the first principles of statistical mechanics. These methods allow systematic calculations of the equilibrium quantities in some particular limits. The effective-potential method is evocated first, as well as its application to the derivation of low-density expansions. We also sketch the basic outlines of the standard many-body perturbation theory. This approach is well suited for calculating expansions at high density (for Fermions) or at high temperature. Eventually, we present the Feynman-Kac path integral representation which leads to the introduction of an auxiliary classical system made of extended objects, i.e., filaments (also called “polymers”). The familiar Abe-Meeron diagrammatic series are then generalized in the framework of this representation. The truncations of the corresponding virial-like expansions provide equations of state which are asymptotically exact in the low-density limit at fixed temperature. The usefulness of such equations for describing the inner regions of the sun is briefly illustrated.
Crystallization of Dense Binary Ionic Mixtures Application to White Dwarf Cooling Theory
Authors: Mochkovitch R. , Segretain L. 
Published: July 2016

AbstractThis paper is organized in two parts. First, phase diagrams for dense binary mixtures are computed with the density functional theory (DFT). The method of calculation is reviewed and the different approximations which are used are clearly stated. The DFT is then applied to several mixtures of astrophysical interest. A comparison is made between several existing phase diagrams and the origin of some discrepancies among them is discussed. In a second part, the consequences of these phase diagrams on the cooling of white dwarfs are presented in a pedagogical way starting from the simple Mestel theory. The importance of the partial separation of carbon and oxygen at crystallisation is emphasized and the possible effect of minor species such as 22Ne or Fe is also considered. The separation of carbon and oxygen adds 1 – 2 Gyr to age of the galactic disk estimated from the white dwarf luminosity function while the delay resulting from the presence of minor species is probably negligible when the chemical evolution of the Galaxy is properly taken into account.
White Dwarf Crystallization
Authors: Garcia-Berro Enrique , Hernanz Margarida 
Published: July 2016

AbstractThe inclusion of a detailed treatment of solidification processes in the cooling theory of carbon–oxygen white dwarfs is of crucial importance for the determination of their luminosity function. Carbon–oxygen separation at crystallization yields delays larger than 2 Gyr to cool down to luminosities corresponding to the observed cut–off. This leads to estimates of the age of the galactic disk 1.5 to 2 Gyr older than the ones obtained in previous studies (about 9 Gyr). Furthermore, the presence of minor chemical species, in particular 22Ne, alters significantly the crystallization process, and produces extra delays of 2 to 3 gigayears. However, the detailed computation of the theoretical white dwarf luminosity function, taking into account a reasonable model of galactic chemical evolution, and including the effect of these species, shows that the location of the cut–off, and then the estimated age of the disk, is not modified significantly.
Transport Processes in Dense Stellar Plasmas
Authors: Itoh Naoki 
Published: July 2016

AbstractTransport processes in dense stellar plasmas which are relevant to the interiors of white dwarfs and neutron stars are reviewed. The emphasis is placed on the accuracy of the numerical results. In this review we report on the electrical conductivity and the thermal conductivity of dense matter. The methods of the calculations are different for the liquid metal phase and the crystalline lattice phase. We will broadly review the current status of the calculations of the transport properties of dense matter, and try to give the best instructions available at the present time to the readers.
The Chandrasekhar Mass of A Gravitating Electron Crystal
Authors: Engelhardt D. , Bues I. 
Published: July 2016

AbstractThe internal structure of a white dwarf may be changed by a strong magnetic field. A local model of the electrons is constructed within a thermal density matrix formalism, essentially a Heisenberg magnetism model. This results in a matrix Fermi function which is used to construct an isothermal model of the electron crystal. The central density of the crystal is 108kg/m3 independent of the magnetic field within the plasma and therefore lower than the relativistic density, whereas this density is constant until the Fermi momentum x f = 0.3 * me * c. Chandrasekhar masses up to 1.44 * 1.4M0 are possible for polarizations of the plasma zone lower than 0.5, if the temperature is close to the Curie point, whereas the crystal itself destabilizes the white dwarf dependent on temperature.
Analysis of the Screening Formalisms in Solar and Stellar Conditions
Authors: Dzitko H. , Turck-Chieze S. , Delbourgo-Salvador P. , Lagrange Ch. 
Published: July 2016

AbstractWe discuss the quality of the electronic screening prescriptions usable in stellar evolution codes during hydrogen burning. The assumption log f = H(0)/kT is compared to a precise formalism where the radial dependence of the screened potential of the 2 ions is introduced.
The Canadian PZT’s
Authors: Tanner R. W. 
Published: July 2016

SUMMARYThe location of Ottawa PZT’s at various times was explained.PZT N° 1, modelled after the Washington PZT was located – from 1952-1960 in main observatory building, Ottawa 1960-1967.3 in special hut before observatory building 1967.4, near Calgary, Alberta, on the same parallel as Herstmonceux (within a few seconds of arc).
Les erreurs affectant les périodes, les demi-grands axes et les masses totales des couples visuels orbitaux
Authors: Dommanget J. 
Published: July 2016

SoitΔt, l’intervalle de temps couvert par les observations ayant permis le calcul des éléments orbitaux d’une étoile double visuelle. SoientP, sa période eta″, son demi-grand axe.Ces éléments sont affectés d’erreurs dépendant essentiellement de la précision générale du matériel d’observation, de l’importance relativeΔt/Pde l’arc couvert par les mesures, de la forme et de la situation de cet arc dans l’orbite apparente. Mais on négligera ici ces deux derniers facteurs car leur considération entraîne des difficultés qu’il n’est peut-être pas nécessaire de vouloir surmonter dans une première étude.
Détermination des masses des planètes (Invited Review Paper)
Authors: Kovalevsky Jean 
Published: July 2016

La présente revue ne donne pas une liste complète des déterminations des masses planétaires. La liste la plus complète récemment publiée est due à Kozlovskaya (1963); elle contient toutes les déterminations effectuées entre 1826 (masse de Jupiter par Encke)et 1961.Depuis, quelques autres listes ont été publiées. Elles sont incomplètes, car elles ont surtout pour but de proposer de valueurs des masses qui apparaissaient comme étant les plus probables à ces auteurs. Signalons ainsi les listes de Böhme et Fricke (1965) et de Kulikov (1965), préparées pour le colloque sur les constantes fondamentales de Paris (Symposium UAI N° 21). Une liste analogue a été préparée par Clemence (1966) pour l’UAI. Citons encore les revues préparées par le Jet Propulsion Laboratory (Mulholland, 1967) et une autre liste, rassemblée il y a deux ans, qui vient d’ère publiée par l’auteur (Kovalevsky, 1970). La présente synthèse est une suite de ce premier travail, compte-tenu des nombreuses nouvelles déterminations qui ont été effectuées depuis deux ans.
The 1964 IAU System and the Geodetic Reference System 1967
Authors: Kovalevsky J. 
Published: July 2016

In 1964, the IAU adopted, among the primary constants of its system, the following three constants especially related to the shape, dimensions and gravitational field of the Earth:a = 6378160 mGM = 398603 × 109m3/s2J2 = 0.0010827These values were discussed in 1967 by the IAG and adopted by the IUGG as the basis of a ‘Geodetic Reference System 1967’. Although at that time better values of these constants were available, IUGG decided to adopt the values of the IAU system in order to keep consistency with the values agreed upon by the astronomers.
Numerical Experiments on the N-Body Problem
Authors: Aarseth S. J. 
Published: July 2016

AbstractThis review first discusses the different types of numerical methods available for integrating the equations of motion of N-body systems. It is desirable to supplement ordinary integration schemes with special treatments of close encounters using a two-body perturbation description or introducing regularizing transformations of the co-ordinates and time. Direct methods are at present limited to the study of a few hundred particles but larger systems may be investigated using Monte Carlo techniques or the Boltzmann moment equations.N-body computations have been performed for a whole range of initial conditions and the general results are summarized. Numerical investigations have already clarified a number of important aspects of cluster evolution and the qualitative behaviour of small stellar systems is now quite well understood. Recent theoretical modifications have reduced the disagreement with experiments but further improvements are still needed.
Plasma Motions around Sunspots
Authors: Lustig G. , Wöhl H. 
Published: July 2016

AbstractMotions of large, stable sunspots – which are in some cases even recurrent – are determined using the Vacuum Tower Telescope (VTT) at Tenerife and sunspot drawings taken at the Kanzelhöhe Observatory in Austria. Around the sunspots fields of about 100 by 100 arcseconds are covered by a scanning spectrograph entrance slit in steps of one arcsecond every 15 seconds to determine the plasma velocities. The main aim is a determination of plasma and sunspot velocities within larger fields of activity and a search for special patterns of plasma flows, which reflect the well-known braking of the sunspot rotation velocity during aging.
The Continuum Intensity Magnetic Field Relation in Sunspot Umbrae
Authors: Pillet V. Martínez , Vázquez M. 
Published: July 2016

AbstractThe local relation between the temperature and the magnetic field in sunspot umbrae is studied. Sunspots with different sizes have been studied and we found a linear relation between temperature and the square of the magnetic field. We have found also a dependence between the minimum continuum intensity and the size of the spot.