bluuebunny/crossref_metadata_2025 huggingface dataset:
July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations
Authors: Kulidzanishvili V. , Georgobiani D.
Published: July 2016

The 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

The 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

The 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

The 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

Large 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

In 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

This 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

The 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

Transport 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.
Searches for Brown Dwarfs
Authors: Liebert James
Published: July 2016

This review attempts a brief summary of the numerous and diverse searches for the so-called brown dwarfs, substellar objects having masses between giant planets and the lowest mass M dwarf stars.
IRIS and GONG
Authors: Schmider F.-X.
Published: July 2016

After the first success of helioseismology, it has been shown than new results could only be obtained from long set of continuous observations. Therefore different groups intented to set-up worldwide networks in order to observe the Sun 24 hours a day. This is the case of GONG and IRIS. Both are six-stations networks. Figure 1 shows the different sites of the two networks. They have one common site in Izaña.
The Chandrasekhar Mass of A Gravitating Electron Crystal
Authors: Engelhardt D. , Bues I.
Published: July 2016

The 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

We 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

The 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).
On Variations in the Chandler Frequency
Authors: Abraham H.J.M. , Boots J.N.
Published: July 2016

This paper suggests that some of the reported changes in the Chandler frequency are associated with inelastic changes in the Earth. There has been controversy as to how much of the apparent secular polar drift is due to actual motion of the axis of rotation within the Earth, and how much it is merely the reflection of movements by certain observatories. Therefore, when more southern data are available it will be interesting to see whether similar results are obtained.
Rotation and Stellar Interiors (Review Paper)
Authors: Roxburgh Ian W.
Published: July 2016

Research into the effect of rotation on the internal structure of stars has a long and detailed history. The names of McLaurin, Jacobi, Kelvin and Jeans are associated with detailed work on the structure and stability of rotating liquid masses assuming uniform rotation. Much of this work is summarized in Jeans’ (1929) Astronomy and Cosmogony and more recent summaries are given in Lyttleton (1953) and Lebovitz (1967).
Evolution of A Rotating Star of Nine Solar Masses
Authors: Kippenhahn R. , Meyer-Hofmeister E. , Thomas H.-C.
Published: July 2016

To compute the evolution of a rotating star, the following approximations were used in order to obtain some of the main effects of rotation with simple models of spherical symmetry:
The Effects of Rotation on the Atmospheres of Early-Type Main-Sequence Stars (Review Paper)
Authors: Collins George W.
Published: July 2016

In discussing the status of the theory of rotating stellar atmospheres, it is necessary to draw upon the contributions of many well established aspects of astrophysics and to interconnect them in a cohesive pattern structured so as to provide insight into a rather specific problem – namely, the structure and characteristics of a surface of the star undergoing axial rotation. Many different connections are possible having varying degrees of emphasis and, of necessity, those given here represent only one such presentation. The discussion could be much simplified if it were not necessary to test the efficacy of the theoretical development by referring to observations. Unfortunately, such a comparison is necessary and the results are at the moment somewhat inconclusive. This unhappy situation arises from the retrospectively obvious fact that axial rotation does not play a dominant role in determining the directly observable properties of stars. Indeed, if rotation were a dominant factor, earlier attempts at describing stellar structure and evolution would have met with little success. However, it is becoming increasingly clear that the structure and final evolution of highly evolved stars are greatly influenced by the total angular momentum which they retain from their earlier history. In order to understand the angular momentum distribution present in the final state, it is necessary to understand the effects of stellar evolution on the total angular momentum and its distribution. But even before this step can be taken, one must first successfully describe the rotational structure of the main-sequence phase as it is this state which provides the initial conditions necessary for any further study. It is further appropriate that we attempt to describe this period of a star’s life as the largest body of observational material with which we must test our results exists for these stars. In addition, we should expect a study of the atmospheric structure to be the most fruitful as this is the region of the star which provides the final modification of the radiation we observe.
Sur La Validité De La Relation Masse-Luminosité Dans le Calcul Des Masses Des Étoiles
Authors: Couteau Paul
Published: July 2016

Les travaux sur les parallaxes dynamiques sont peu nombreux; les plus récents remontent déjà loin dans le passé (Russell et Moore, 1940; Barbier, 1936; Baize et Romani, 1946; et Strand, 1953). L’idée directrice est toujours la même: associer la troisième loi de Kepler et une relation masse-luminosité. Par l’intermédiaire de la loi de Pogson on en déduit aisément une parallaxe qualifiée de dynamique, puis la masse du système. Il serait judicieux de l’appeler masse dynamique afin de la différencier de la masse trigonométrique qui est la seule fondamentale.
Spectroscopic Observations of Visual Double Stars
Authors: West Frederick R.
Published: July 2016

There are certain visual double stars which, when close to a node of their relative orbit, should have enough radial velocity difference (10-20 km/s) that the spectra of the two component stars will appear resolved on high-dispersion spectrograms (5 Å/mm or less) obtainable by use of modern coudé and solar spectrographs on bright stars. Both star images are then recorded simultaneously on the spectrograph slit, so that two stellar components will appear on each spectrogram.
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.
Systematic Errors in the Photographic Positions of Double Stars at the Sproul Observatory
Authors: Lippincott Sarah Lee
Published: July 2016

The long range program of the Sproul Observatory initiated in 1937 by Peter van de Kamp has been primarily devoted to a detailed astrometric study of the positions of nearby stars from photographs taken with the 24-in. refractor. The accumulation of plates over a long time interval provides the opportunity for finding perturbations of small amplitude leading to the discovery of unseen companions. By now there are 30 yr of observation on most of the stars with parallaxes greater than +0.″10 and brighter than the 12th magnitude, which are observable at latitude +40°.
Knowledge of Masses and Radii of Eclipsing Binaries and their accuracy
Authors: Popper Daniel M.
Published: July 2016

My task this morning is to review the current situation on masses and radii as determined from eclipsing binaries, including a discussion of the reliability of results appearing in published catalogues and lists. The presentation is divided into six sections: problems in interpretation of light curves; catalogues of photometric elements; problems in interpretation of spectrograms; catalogues of spectrographic elements; lists of masses and radii; present status.
The Bruce and Palomar – Schmidt Proper Motion Surveys
Authors: Luyten Willem J.
Published: July 2016

The Proper Motion Survey on plates taken with the Bruce telescope of the Harvard Observatory was begun in 1928 with a fellowship from the Guggenheim Foundation. The plates used have a scale of 1 mm = 59”, generally go down to 16mpg though a few long exposure plates almost reach 18mpg and the survey is considered reasonably complete for the larger motions down to 14.5mpg.
Status of the Lowell Proper Motion Survey
Authors: Giclas H. L.
Published: July 2016

A proper motion survey of the northern hemisphere, utilizing first epoch plates made some thirty years ago with the 13 – inch Pluto search telescope of the Lowell Observatory, was begun in 1957. The relative proper motions of stars fainter than the eighth magnitude and with motions greater than 0.″26 per year are measured directly on the calibrated grid of the projection blink comparator.
A Determination of Secular Parallaxes of Reference Stars from Relative Proper Motions of Open Clusters
Authors: Deutsch A. N.
Published: July 2016

The determination of secular parallaxes of stars is usually based on meridian observations of proper motions of bright stars, this introducing known systematic errors. The mean parallaxes of stars can be obtained by means of radial velocities which are known for the bright stars. The more perspective method, the reference of stars to galaxies, is not applicable at low galactic latitudes.
Status and Problems of the International Reference Star Programs
Authors: Scott F. P. , Schombert J. L.
Published: July 2016

One of the major projects in positional astronomy now in progress is the cooperative effort of 18 transit circles throughout the world to relate the positions of 20,000 reference stars in each hemisphere of the sky to the fundamental system. It is intended that these reference stars will serve as intermediaries in concurrent photographic surveys to relate the positions of upwards of 300,000 stars to the 9th magnitude to the fundamental system.
Recent Observations Relevant to the Improvement of FK4
Authors: Gliese Wilhelm
Published: July 2016

Since the closing date for material included in the FK4 many new positions of fundamental stars have been published, most of them observed differentially. I think in these few minutes it is neither desirable nor necessary to present alist of all these catalogues. We are mainly interested in recent observations which allow us to improve the fundamental system of positions and even more the system of proper motions.
The Determination of the Proper Motions of X-Ray Sources
Authors: Eichhorn Heinrich , Gatewood George D. , Sofia Sabatino
Published: July 2016

At the University of South Florida Observatory, a program is under way to determine the proper motions of the star-like objects which are possibly or probably associated with X-Ray sources. The objects under study are Sco X-l, and objects believed to be identical with Cen X-2, Cyg X-2, and Co D -32° 1057. Since it has been speculated that these might be neutron stars, an effort was made to study not only their proper motions but also those of other stars in the neighborhood to ascertain membership of any moving cluster with known age and distance, whereby their own ages and distances might become known. These efforts were successful so far in the case of ScoX-1 (Sofia, Eichhorn and Gatewood, 1969), whose proper motion is virtually identical to that which a member of theScorpio-Centaurus Association would have at this position, so that the membership of Sco X-l in this association becomes highly probable. On the basis of this and other information, Gatewood and Sofia (1969) conclude that Sco X-l is quite likely a neutron star. The reduction was described in detail by Gatewood (1968). No definitive results are available yet for the other three objects.
The JPEC
Authors: Redman R.O.
Published: July 2016

In their Report for the year ending 1970 August 31 the Council of the Royal Society announced a decision to dissolve the Joint Permanent Eclipse Committee.
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.
Simultaneous Solution for the Masses of the Principal Planets from Analysis of Optical, Radar, and Radio Tracking Data
Authors: Lieske J. H. , Melbourne W.G. , O’Handley D. A. , Holdridge D. B. , Johnson D.E. , Sinclair W.S.
Published: July 2016

The Jet Propulsion Laboratory has developed a set of computer programs known as the Solar System Data Processing System (SSDPS) which is employed in improving the ephemerides of the major planets and for improving the values of several associated astronomical constants. A group of solutions for the masses of the major planets, together with the AU and radii of Mercury, Venus, and Mais, is presented. These solutions based upon optical, radar, and spacecraft radio tracking data are preliminary. The relative power of radar and radio tracking data vis-à-vis purely optical data in a solution is shown. The problems which could arise by adopting solutions based upon a single data type are demonstrated.
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 m

GM = 398603 × 109m3/s2

J2 = 0.0010827

These 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.
A Certain Discontinuous Markov Process in Stellar Dynamics
Authors: Tscharnuter Werner
Published: July 2016

The basic assumption in Chandrasekhar’s approach of statistical stellar dynamics (Chandrasekhar, 1942) is the postulate that a test star within a stellar system being stationary in the sense of collisionless continuum theory suffers random displacements in velocity space generated by the fluctuating part of the gravitational field in a manner that can be described in terms of a random walk. This is equivalent to the assertion that the increments of velocity are regarded as stochastically independent in disjoint time intervals. From this Chandrasekhar derived a diffusion process in velocity space.
Numerical Experiments on the N-Body Problem
Authors: Aarseth S. J.
Published: July 2016

This 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.
A Multi-Particle Regularisation Technique
Authors: Heggie D. C.
Published: July 2016

Certain features of a practical regularisation method, in which the potential or kinetic energy is used as a time-regularising function, are described. For two-body encounters the method is less powerful than Kustaanheimo-Stiefel regularisation, but it has wider applicability.
High Resolution Observations of Umbral Fine Structure
Authors: Sobotka M. , Bonet J A , Vazquez M
Published: July 2016

The main results of a photometric and spectroscopic study of umbral fine structures are presented. The observations were obtained at the SVST (La Palma) under conditions of very good seeing.
Plasma Motions around Sunspots
Authors: Lustig G. , Wöhl H.
Published: July 2016

Motions 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

The 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.
Active Region Evolution Through Coordinated Observations
Authors: Mein N. , Mein P. , Schmieder B. , Engvold O. , Molowny R. , Ai G.X.
Published: July 2016

On May 7, 1991, several ground-based instruments have been coordinated to observe AR 6615 (S10-W26), before and during the flight of the SERTS rocket experiment (Schmieder et al.,1992):

– Imaging spectroscopy (MSDP) at the VTT telescope of Tenerife (collaboration Paris-Meudon and KIS Freiburg). Hα and NaD1 are observed simultaneously in 2D fields, with 9 and 11 wavelengths respectively (Mein, 1991).

– High resolution “white light” pictures (around 4686Å) at the Swedish Vacuum Solar Telescope (SVST) of La Palma (Scharmer et al., 1985).

We present below some data from both instruments. Magnetic field maps are also available from the Huairou magnetograph (China), and from the GCT telescope (KIS/Tenerife).
Physical Features in the AR5395
Authors: Zhang Heng , Kong Yongjin , Luan Di , Cao Ying
Published: July 2016

The active region Boulder # 5395 (N34, L257), which appeared on the disk in March 1989, is one of the biggest active regions in fifty years. Study on the structure and dynamical characteristics of the region can help to understand the physics of solar flares. Many authors have studied morphology and sunspot motion of the region (e.g. Wang et al. 1991, and Zhao 1990); the magnetic emergence and shear; the relationship between the extrusion and the flares and the characteristics of the magnetic and velocity fields in the flare sites (Chen 1990; Li et al. 1990; Zhang et al. 1990). It comes into question that most of the regions display the features mentioned above but only a few of them produce such a high activity as AR5395 does. In other word, AR5395 must possess some particular features that are probably related to its high activity. Our attempt is to find what the special features are.
Avalanches of Magnetic Reconnection
Authors: Lu Edward T.
Published: July 2016

Active region coronal magnetic fields are expected to be in a twisted tangled state due to photospheric convective motions. These motions can drive the magnetic field to a statistically steady state where energy is released impulsively (Lu and Hamilton 1991). These relaxation events in the magnetic field can be interpreted as avalanches of many small reconnection events. We argue that the frequency distribution of these magnetic reconnection avalanches must be a power law. Furthermore, we calculate the expected distributions in a simple model of magnetic energy release events in a 3-dimensional complex magnetized plasma, and compare these to the distributions of solar flares. These distributions are found to match the observed power law distributions of solar flare energies, peak fluxes, and durations. This model implies that the energy-release process is fundamentally the same for flares of all sizes. Observational predictions of this model are discussed.
Magnetic Field Observation with the Solar Flare Telescope
Authors: Ichimoto K. , Sakurai T. , Nishino Y. , Shinoda K. , Noguchi M. , Kumagai K. , Imai H. , Irie M. , Miyashita M. , Tanaka N. , Sano I. , Suematsu Y. , Hiei E.
Published: July 2016

The Solar Flare Telescope was constructed at Mitaka in 1989. This instrument comprises four telescopes which respectively observe (a) Hα images, (b) continuum images, (c) vector magnetic fields, and (d) velocity fields in the photosphere. The instrument aims at the study of energy build-up and energy release in solar flares, in cooperation with the Solar-A satellite. The whole system has been in regular operation since 1992 July. The methods of measuring the magnetic and velocity fields are described.
New Calibration Parameter for Observations of Transverse Solar Magnetic Fields in the Fe I 5324.19 Å Line
Authors: Song Weihong , Ai Guoxiang
Published: July 2016

Adopting the computational model of papers I and II (Song et al. 1990, 1992) we have found that for a better fit of the center of the Fe I 5324.19 Å line, the effect of turbulent Doppler broadening has to be taken into account. Through theoretical and numerical analysis we conclude that the square root of the modulus of Stokes Q and U is an appropiate observational parameter to represent the transverse magnetic field, since it is approximately linearly proportional to the strength of the transverse magnetic field for suitable positions of the filter passband.
Lifetimes of the Magnetic Network Elements
Authors: Liu Yang , Zhang Hongqi , Wang Haimin
Published: July 2016

Using the 155 hours of coordinated observing data of Huairou and Big Bear Solar Observatories, the lifetimes of network elements have been determined by different ways. The sample of network elements has been chosen on a strict criterion in order to reduce the bias. Two statistical methods with different considerations show a mean lifetime of elements of 49.20 hours and 54.92 hours, respectively. The least-square fit method provides an average lifetime of 55.84 hours.
Solar Flares as an Ongoing Magnetic Reconnection Process
Authors: Tsuneta Saku
Published: July 2016

The soft X-ray images taken by theYohkohSoft X-ray Telescope (SXT) provide a powerful new tool to solve the mechanism of solar flares. In particular, a limb flare that occurred on 1991, December 2 gives us convincing evidence that magnetic reconnection of a neutral sheet formed at the loop top participates in the flare energy release. The neutral sheet appears to be associated with a destabilized rising loop system (filament) sheared with respect to the flaring loop. Similar formations of X-ray arcades are seen in the quiet Sun associated with filament eruptions on much larger spatial dimension and with a much smaller energy scale.
Coronal Magnetic Fields from the Effect of the Double Inversion of Circular Polarization of Radio Emission
Authors: Bogod V.M. , Gelfreikh G.B. , Ryabov B.I. , Hafizov S.R.
Published: July 2016

We present preliminary results of radio observations of the Sun with the Panoramic Analyzer of the Spectrum (21 channels in 1.8 – 8.2 cm wavelength range) of the radio telescope RATAN-600. Observations on 1992 January 9 – 10 have shown double inversion of the sign of a local source through the microwave wavelength range with fine spectral structure. This phenomenon can be treated as a result of mode coupling when the electromagnetic wave crosses two regions of quasi-transverse propagation (QT-region). Using this treatment we have found the strength of the coronal magnetic field at a number of points in the corona above an active region. The results also imply that trans-equatorial coronal arches affect the structure of magnetic fields at heights of about 3 . 1010 cm with B ~ 5 – 10 G.
The Evolutional Characteristics of Magnetic and Velocity Fields of Large Flares in AR 6659
Authors: Baorong Luo , Shuming Hou , Ti Luan , Ying Cao
Published: July 2016

The evolutional characteristics of magnetic and velocity fields of four large flares in AR 6659 are analysed in this paper.
Solar Microwave Spike Emission and Change of Magnetic Topology
Authors: Qijun Fu , Yuanfang Gong , Qiongzhen Shang , Songquan Lu , Hanming Hu , Chunsheng Li , Wei Li , Bing Zhao
Published: July 2016

Electron cyclotron maser (ECM) instability is today’s most favoured process for microwave spike emission. Although ECM looks attractive, the emission mechanism is still unclear due to the imperfection of present theories, inadequacy of observational data, and uncertainty as to conditions in the source region. To find solar active phenomena, both statistically and individually coincident with radio spike events, is essential for understanding the ambient conditions needed for generating spike emission, locating sites where spike emission is produced, and providing clues for particle acceleration and energy release in flares.

In this paper, evidence for an association between spike emission at 21 cm and fast variation of the magnetic configuration in post-flare loops is presented. Such associations may be helpful for solving the questions mentioned above.
The Statistical Relationship of Mass Motions Magnetic Fields and Flares in AR 5395
Authors: Yuhua Tang , Zunxiang Huan , Qing Lin , Aoao Xu
Published: July 2016

AR 5395 was the super-active region in Solar cycle 22. In this active region, there was rapid relative motion of magnetic elements, growth and decay of umbrae, frequent newly emerging magnetic flux and various mass motions.

Data include daily vector magnetograms (Huairou Observing Station, Beijing Observatory, Hα filtergrams and photographs of sunspot group with fine structures (Yunnan Obs. and Purple Mountain Obs.) on March 9 - 15, 1989. In this period 42 flares have been observed by Yunnan and Purple Mountain Obs. (table 1). Observational data showed that all the 42 flares occurred in four segments (marked as A,B,C,D) of U-shaped neutral line in this active region (Fig. 1).
Variation of Magnetic Fields and Electric Currents Associated with a Solar Flare
Authors: Yuanzhang Lin , Xiaolei Wei , Hongqi Zhang
Published: July 2016

It is well accepted that the source of energy for flares arises in the non-potential magnetic field from the dynamic evolution of active regions above the photosphere. So far, however, contradictory results have been suggested for the question of whether the occurrence of flares results in detectable changes of the magnetic fields and electric currents in the regions (Svestka, 1976)

The early researches of Severny’s group showed that the longitudinal and transverse magnetic fields in active regions change evidently after flares, which are characterized by the simplification of magnetic configuration as well as the decrease of magnetic strength and gradient (Severny, 1962, 1969). Then, after studying the magnetograms of two active regions measured by the Kitt Peak’s magnetograph, Harvey suggested that there were changes in longitudinal magnetic fields with a time scale of hours, but they could be attributed to the global evolution of active regions and not directly related to the occurrence of flares (Harvey et al., 1970). Moreover, from the analyses of the Kitt Peak’s magnetograms for the big flare of 3B importance on 4 August 1972, Livingston indicated that the longitudinal magnetic fields before and after the flare remained unchanged (Livingston, 1973). On the other hand, from the study of the magnetograms obtained by the Big Bear Observatory’s video magnetograph before and after a 2B flare in the region McMath 13225 on 10 September 1970, Tanaka reached the conclusion that in weak field areas of less than 100G, the longitudinal field changed about 30–100% at the onset of the flare, and this change was associated with the flare (Tanaka, 1978). In recent years, some authors have investigated in detail the magnetograms of the well known region AR2372 on 6 April 1980 obtained with the video magnetograph of the Marshall Space Flight Center (Krall et al., 1982; Hagyard, 1984; Ding et al., 1985; Lin and Gaizauskas, 1987). Their results showed that the change of the magnetic fields occurred before a 1B/X2 flare. Therefore we have a rather confused picture about the variation of magnetic fields associated with flares.
Atomic Orientation in Chromospheric Lines
Authors: Bueno J. Trujillo , Pillet V. Martínez , Almeida J. SáNchez , Degl’innocenti E. Landi
Published: July 2016

Observations of the Stokes I and V profiles of the Ca II H and K lines in solar magnetic regions are presented. Least-squares fits of dI/dλ to V are obtained and the wavelength variation of the residuals, i. e. V-kdI/dλ, calculated. We find significant symmetric residuals in umbrae, which are in agreement with the effect on the V profiles due to atomic orientation, i.e. with the existence of an unequal population of the Zeeman sublevels with M>0 with respect to those with M<0.
Wound Magnetostatics and Flaring
Authors: Boily C.M. , Lynden-Bell D.
Published: July 2016

We discuss the winding of a force-free axisymmetric magnetic field rooted on a heavy conductor on z = 0. In quadrupolar symmetry the field expands in the half-space z > 0 and the toroidal flux concentrates on a conical surface. After a mean twist of 208°, the conical layer hosts large toroidal current loops with reversal of the magnetic flux on either side. The evolution of the field structure is described by scale-free static solutions B ~ r−(p+2), with p taking values between 0 and 2. The large expansion factor of the field structure is suggestive of flaring originating on the solar photosphere.
Recent Development in Solar Wind Modelling
Authors: Esser Ruth
Published: July 2016

An improved knowledge of the physical conditions in the low corona and solar wind can only be obtained through careful comparisons between theoretical descriptions of the solar wind expansion and plasma parameters derived from observations. In this review we will present a summary of recent approaches in solar wind modeling. The plasma parameters characterizing the solar wind models will be compared to constraints inferred from in-situ and remote observations. We will then discuss the implications of the results obtained from this study for future model studies and observations. Emphasis will be placed on high-speed solar wind streams originating from large coronal holes.
Coronal and Heliospheric Observations of Solar Particle Events
Authors: Pick Monique
Published: July 2016

Observations of accelerated particle beams are used to probe the coronal and interplanetary magnetic field structures over large distances from the Sun on the order of a few AU and for various heliolatitudes. It is shown that the propagation of low energy particles is very much controled by discrete interplanetary magnetic field structures. These discrete magnetic structures are sometimes embedded within interplanetary solar wind plasma disturbances, commonly called CMEs. The connection between the corona and the interplanetary medium is discussed. These observations lead to new insights on the origin of accelerated particles detected in association with CMEs.
Type II Bursts of Different Subclasses Associated to Transients and Mass Ejection in the Higher Corona
Authors: Urbarz H.W.
Published: July 2016

The list of mass ejections published in Solar Geophysical Data during the period of Jan. 1981 to Oct. 1987 contains about 1300 Surges, Sprays and Type II bursts. The relationship between the mass ejection events and the shock front events is investigated by means of correlation of time and position. The result shows that type II bursts start as frequently after the mass ejections as prior to them.
Transient Phenomena in the Energetic Behind-the-Limb Solar Flare of September 29, 1989
Authors: Bhatnagar A. , Jain R.M. , Burkepile J.T. , Chertok I.M. , Magun A. , Urbarz H. , Zlobec P.
Published: July 2016

The powerful cosmic ray flare of Sept. 29, 1989 occurred behind the limb and was observed over a wide spectral range. The analysis of optical, radio, and other relevant data suggest two phases of energy release. After an impulsive phase a prolonged post eruption energy release occurred in an extended region of the corona following the eruption of a large coronal mass ejection (CME). This phase is responsible for numerous coronal and interplanetary phenomena including the ground-level increase of cosmic rays.
Study of Interplanetary Disturbances Using IPS
Authors: Ananthakrishnan S.
Published: July 2016

The usefulness of Interplanetary Scintillation (IPS) data, which provide solar wind velocities (V) and relative scintillation indices (g), for predicting interplanetary disturbances is examined. Analysis of two years of g-map data from Cambridge shows that atleast two IPS stations are required for more definitive identification of events. Campaigns were made in April-May 1992 to map predicted solar wind disturbances simultaneously from two widely separated telescopes at Cambridge and Ooty. These show that apriori knowledge of strong flare activity helps in detecting scintillation enhancement. On the other hand, other events have been observed at Ooty, which show that both flares and coronal holes may be responsible for producing interplanetary disturbances, and hence it is premature to identify any one type of solar event as the sole cause of the disturbances.
Markarian’s First Survey (FBS) - Some Most Interesting Objects
Authors: Khachikian E.Ye.
Published: July 2016

In this review I try to show the important role of the Byurakan Observatory in the discovery and detailed investigations of ultlaviolet excess (UV) galaxies, which are now the center of attention of many observatories. Most new Seyfert (Sy) galaxies by the end of the 1960s, when no more than ten of this type of galaxy were known, were discovered among UV galaxies. In addition, many unusual and interesting galaxies were also discovered among UV galaxies: double and multiple nucleus galaxies, double nucleus Sy galaxies, galaxies with jets, galaxies consisting only of Superassociations (giant HII regions), Sargent-Searle objects, BL Lacs and QSOs possessing a different type of activity according to Ambartsumian. The material presented here overlaps considerably that of some other talks delivered by the author in IAU Symposia Nos. 121 and 194.
Spectral Variability of Quasars in the Optical Band
Authors: Trèvese Dario , Vagnetti Fausto
Published: July 2016

We performed a new analysis of the В and R light curves of a sample of PG QSOs. We confirm a variability-redshift correlation and its interpretation in terms of spectral variability. We find an intra-QSO and an inter-QSO α;-L correlation. The former can be explained neither by presence of the host galaxy nor by changes of the accretion rate. Hot spots due to accretion disk instabilities could explain the observations.
The New BL Lac Candidates from the FBS
Authors: Torosyan O. Kh.
Published: July 2016

Six new possible BL Lac candidates from the FBS are presented.
The Optical, Infrared and Radio Properties of Extragalactic Sources Observed by SDSS, 2MASS and FIRST Surveys
Authors: Ivezić Ž. , Becker R.H. , Blanton M. , Fan X. , Finlator K. , Gunn J.E. , Hall P. , Kim R.S.J. , Knapp G.R. , Loveday J. , Lupton R.H. , Menou K. , Narayanan V. , Richards G.R. , Rockosi C.M. , Schlegel D. , Schneider D.P. , Strateva I. , Strauss M.A. , Berk D.Vanden , Voges W. , Yanny B. ,   for the SDSS Collaboration
Published: July 2016

We positionally match sources observed by the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), and the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey. Practically all 2MASS sources are matched to an SDSS source within 2 arcsec; ~11% of them are optically resolved galaxies and the rest are dominated by stars. About 1/3 of FIRST sources are matched to an SDSS source within 2 arcsec; ~80% of these are galaxies and the rest are dominated by quasars. Based on these results, we project that by the completion of these surveys the matched samples will include about 107stars and 106galaxies observed by both SDSS and 2MASS, and about 250,000 galaxies and 50,000 quasars observed by both SDSS and FIRST. Here we present a preliminary analysis of the optical, infrared and radio properties for the extragalactic sources from the matched samples. In particular, we find that the fraction of quasars with stellar colors missed by the SDSS spectroscopic survey is probably not larger than ~10%, and that the optical colors of radio-loud quasars are ~0.05 mag. redder (with 4σ significance) than the colors of radio-quiet quasars.
Testing the Unified Model with an Infrared Selected Sample of Seyferts
Authors: Schmitt H. R. , Ulvestad J. S. , Antonucci R. R. J. , Clarke C. J. , Pringle J. E. , Kinney A. L.
Published: July 2016

We present a series of statistical tests using homogeneous data and measurements for a sample of Seyfert galaxies. These galaxies were selected from mostly isotropic properties, their far infrared fluxes and warm infrared colors, which provide a considerable advantage over the criteria used by most investigators in the past, like ultraviolet excess. Our results provide strong support for a Unified Model in which Seyferts 2’s contain a torus seen more edge-on than in Seyferts l’s and show that previous results showing the opposite were most likely due to selection effects.