bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine Structures of the Inner Corona Observed at the 1991 Total Solar Eclipse
Authors: Takeda A. , Kurokawa H. , Kitai R. , Ishiura K. 
Published: July 2016

Extended AbstractThe Kwasan and Hida Observatories team (three of the authors but A. T.) observed the total solar eclipse of 11 July, 1991 with the multi-channel telescope at UABCS (Universidad Autonoma de Baja California Sur) campus in La Paz, Baja California Sur, Mexico. The primary purpose of our obsevation is to get high-resolution images of the inner corona at the wavelength of coronal emission lines and continuum shown in Table 1. Thanks to the clear sky and good seeing condition, we successfully got many images of high spatial resolution with photographic cameras and video recorders. Details of the observation have already been published by Kurokawaet al. (1992). In this paper, we present the results obtained from the photographic data reduction on fine structures of the inner corona. The procedure of photometrical measurement and image processing are fully described in another paper (Takeda, 1993).There have been published several observational works on the temperature structure of the coronal loops. Some authors proposed that hot coronal loops have cool cores (Foukal, 1975; Hanaokaet al., 1988), but others denied such coaxial models (Chenget al., 1980; Dere, 1982). Our high-resolution images obtained at the eclipse enables us to compare the positions of the loops seen in different emission lines of different ionization temperatures more precisely than any other previous observations. Main results are summarized as follows.
Hα Limb Evolution around the 1990 and 1991 Total Solar Eclipses
Authors: Bücher A. , Noëns J.-C. 
Published: July 2016

AbstractAt the periods of the total solar eclipses of July 1990 and 1991 a survey in the Hαlight was performed at Pic-du-Midi. Maps of the limb evolution are described and discussed.
Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid
Authors: Bouchard O. , Koutchmy S. , November L. , Vial J.-C. , Zirker J. B. 
Published: July 2016

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.
Colour Photometry of the Solar Corona of July 11, 1991
Authors: Alexeyeva I. V. , Kroussanova N. L. , Streltsova M. V. 
Published: July 2016

AbstractThe results of photometry of colour positives of the solar corona of July 11, 1991 are presented. Observations of the white corona were made without radial niters in Jojutla (Mexico). Dependences of coronal brightness on distance in the red (640 nm) and blue (420 nm) wavelength intervals are deduced for different coronal structures up to 3.0-3.5R⊙. The effect of ”reddening“ is noted. The excess of the red emission to the blue one (I640nm/I420nm) is found to be 1.20 and 1.17 at distance of 2.2R⊙for the N-E helmet streamer (P ≃ 37°) and the N-W region of low brightness (P ≃ 339°), respectively.
Equation of State of Stellar Plasmas
Authors: Rogers Forrest J. 
Published: July 2016

AbstractThe equation of state (EOS) of astrophysical plasmas is, for a wide range of stars, nearly ideal; with only small non-ideal Coulomb corrections. Calculating the EOS of an ionizing plasma from a ground state ion, ideal gas model is easy, whereas, fundamental methods to include the small Coulomb corrections are difficult. Attempts to include excited bound states are also complicated by plasma screening and microfield phenomena that weaken and broaden these states. Nevertheless, the high quality of current observational data, particularly seismic, dictates that the best possible models should be used. The present article discusses these issues and describes how they are resolved by fundamental many-body quantum statistical methods. Particular emphasis is placed on the activity expansion method that is the basis of the OPAL opacity code. Some comparisons with standard methods are given.
A Comparative Study of Hydrogen Equations of State
Authors: Saumon D. 
Published: July 2016

AbstractThe numerous complexities underlying large tables of thermodynamic quantities act as a deterrent to a careful evaluation of their reliability. As a consequence, equations of state are often used as black boxes. To clarify this situation, some of the more critical issues of equation of state physics are discussed from the point of view of the user. They are illustrated by a comparison of four equations of state for hydrogen. The flaws and disagreements thus brought into light are explained and evaluated with simple physical arguments.
Strongly Coupled Ionic Mixtures and the H/He EOS
Authors: DcWitt Hugh E. 
Published: July 2016

AbstractThis paper summarizes recent work on the strongly coupled OCP and Binary Ionic Mixture equation of state and other thermodynamic quantities in white dwarf interior conditions for both fluid and solid phases with the assumption of a uniform background. Conditions for phase separation of different elements in fluid or solid phases is strongly dependent on deviations from the linear mixing rule which gives the equation of state as an additive function of the OCP equation of state. These deviations turn out to be small (a few parts in 105) and always positive including the case where the fraction of the higher Z component approaches 0. Also the equation of state of strongly coupled light elements (H and He particularly) obtained from simulations with a linear response description of the electrons is given for conditions appropriate to brown dwarf star interiors. Recent Livermore work on a band structure calculation of the enthalpy of H and He mixtures under jovian conditions is discussed. This work leads to a prediction of a high temperature (15000 °K) for miscibility of He in ionized H at 10 Mb.
Towards A Helioseismic Calibration of The Equation of State of The Plasma in The Solar Convective Envelope
Authors: Vorontsov S. V. , Baturin V. A. , Gough D. O. , Däppen W. 
Published: July 2016

AbstractWe report the results of a nonlinear inversion of solar oscillation data that enable us to detect nonideal Coulomb interactions between particles, including pressure ionization, in the solar convection zone.
Thermal Cyclotron and Annihilation Radiation in Strong Magnetic Fields
Authors: Bezchastnov V.G. , Kaminker A.D. 
Published: July 2016

AbstractThe cyclotron and the one-photon annihilation emissions are investigated for a strongly magnetized thermal electron-positron plasmas. The annihilation spectral component is significant when the particle number density N exceeds some critical value, Ncr(T,B). For T ~ 108 − 109 K and B ~ 1012 − 1013 G, this condition can be fulfilled at N < 1022 cm−3, which is realistic for neutron star magnetospheres.
Time and Latitude Results of the Danjon Astrolabe Program at Santiago
Authors: Angulta C. , Noël F. 
Published: July 2016

ABSTRACTA brief report is given of the Danjon astrolabe program of Santiago de Chile, a description of the observation method, the reduction system and the Instrumental equipment. By means of the latitude and time determination a study of the variation of the latitude and earth rotation during the period 1966-1967, is made.
The Interaction of Rotation with Convection
Authors: Durney Bernard R. 
Published: July 2016

AbstractThe equations for a rotating convective spherical shell are solved in the Herring approximation as an initial value problem. The main results are
(1)The most unstable modes (those that maximize the heat flux) correspond to convective cells stretching from pole to pole.(2)The calculations of the Reynolds stresses show transport of angular momentum towards the equator. That is, differential rotation sets in with equatorial acceleration.(3)The convective heat transport is maximum at the equator. This would give rise to an equator-pole flux difference.(4)If convection is non-axisymmetric (as in the most unstable modes) there are no time independent solutions. The time dependence is oscillatory and of the form ωt + mφ.
Use of the Overlap Method for the Connexion of Proper Motions to Galaxies Problems of the Zone Without Nebulae
Authors: Lacroute P. 
Published: July 2016

There are two methods for connecting the proper motions to the galaxies. The one used under the direction of A. N. Deutsch at Pulkovo, and the other method at the Lick Observatory.Only the method used by the Lick Observatory allows the use of overlapping plates. It is the only one which will be dealt with in this first part.
Theoretical Computations on the Efficiency of the Overlap Method in the Lick Program
Authors: Lacroute P. , Valbousquet A. 
Published: July 2016

The theoretical computations suggested in section 5 of the preceeding paper have now been done.It is necessary to do many approximations in order that the successive values of ∑β2 give the limit. We have done as many as 8. After that the computation becomes too difficult.
Exact Statistical Mechanics of a One-Dimensional Self-Gravitating System
Authors: Rybicki George B. 
Published: July 2016

AbstractThe statistical mechanics of an isolated self-gravitating system consisting ofNuniform mass sheets is considered using both canonical and microcanonical ensembles. The one-particle distribution function is found in closed form. The limit for large numbers of sheets with fixed total mass and energy is taken and is shown to yield the isothermal solution of the Vlasov equation. The order of magnitude of the approach to Vlasov theory is found to be 0(1/N). Numerical results for spatial density and velocity distributions are given.
Evolutionary Models of Nucleosynthesis in the Galaxy
Authors: Truran J. W. , Cameron A.G.W. 
Published: July 2016

AbstractA model of the galaxy is constructed and evolved in which the integrated influence of stellar and supernova nucleosynthesis on the composition of the interstellar gas is traced numerically. Our detailed assumptions concerning the character of the matter released from evolving stars and supernovae are guided by the results of recent stellar evolutionary calculations and hydrodynamic studies of supernova events. Stars of main sequence mass in the range 4 ≤M≤ 8 M⊙are assumed to give rise to supernova events, leaving remnants we identify with neutron stars and pulsars and forming both the carbon-to-iron nuclei and the r-process heavy elements in the explosive ejection of the core material. For more massive stars, we assume the core implosion will result in the formation of a Schwarzschild singularity, that is, a black hole or ‘collapsar’. The straightforward assumptions (1) that the gas content of the galaxy decreases exponentially with time to its present level of ~ 5 % and (2) that the luminosity function characteristic of young clusters and the solar neighborhood is appropriate throughout galactic history, lead to the prediction that ≈ 20% of the unevolved stars of approximately one solar mass (M⊙) in the galaxy today should have metal compositionsZ ≲0.1 Z⊙. As Schmidt has argued from similar reasoning, this is quite inconsistent with current observations; an early generation dominated by more massive stars – which would by now have evolved – is suggested by this difficulty. Many of these massive stars, according to our assumptions, will end their lives as collapsed black hole remnants. It is difficult to visualize an epoch of massive star formation in the collapsing gas cloud which formed our galaxy which would enrich the gas rapidly enough to account for the level of heavy element abundances in halo population stars; we have therefore proposed a stage of star formation which is entirely pregalactic in character. We suggest that the Jeans’ length-sized initial condensations in the expanding universe discussed by Peebles and Dicke may provide the appropriate setting for this first generation of stars. Guided by these considerations, and by the need for a substantial quantity of ‘unseen’ mass to bind our local group of galaxies, we have constructed a model of the galaxy in which this violent early phase of massive star formation produces both (1) approximately 25 % of the level of heavy elements observed in the solar system and (2) an enormous unseen mass in the form of black holes. The implications of our model for other features of the galaxy, including supernova nucleosynthesis, the cosmic ray production of the light elements, and cosmochronology, are discussed in detail.
On Combined Operational Method for Transfer Problems in Homogeneous, Spherical Media
Authors: Kho T. H. , Sen K. K. 
Published: July 2016

AbstractIn this paper, the Combined Operational Method developed by Busbridge (1961) in connection with the radiative transfer problems in plane-parallel atmospheres has been extended to similar problems in isotropic scattering, homogeneous spherical media. The relevant auxiliary equation has been formulated, the scattering function defined and the integro-differential equation for such function deduced. For a medium having radial distribution of source in addition to the incident flux at the outer surface, the integro-differential equations for source function and emergent intensity have been established.
Doppler Motions in Active Regions and in the Surrounding Photosphere
Authors: Bumba V. , Klvaňa M. 
Published: July 2016

AbstractWe present the preliminary results of photoelectric measurements of line-of-sight motions in the quiet and active photosphere. We show the topology, amplitudes and signs of Doppler motion distribution in active regions and their surroundings. We pinpoint the different characters of both topologies.
Polarimetric Measurements of the Fine Structure of a Sunspot Penumbra
Authors: Hofmann J. , Deubner F.-L. , Fleck B. , Schmidt W. 
Published: July 2016

AbstractObservations of a fairly regular sunspot penumbra near disk center have been carried out using a Stokes V polarimeter at the German Vacuum-Tower-Telescope in Izaña, Tenerife. We obtained two-dimensional spectral data by scanning the limb oriented sector of the penumbra in steps of 1” with the slit parallel to the solar limb. From Stokes V and Stokes I spectra of four magnetic sensitive lines (Fe I 5247.1, Cr I 5247.6, Fe I 5250.2, and Fe I 5250.7) obtained with 1024 × 1024 pixel CCDs we have determined Doppler shifts and several magnetic parameters. The results of a correlation analysis point out a clear relation between continuum brightness and magnetic field inclination in the sense of steeper field lines in the bright penumbral filaments. There is also a doubtless connection between intensity and Doppler shift. We did find indications for a correlation between field strength and brightness which is not uniform across the penumbra, though.
Field Strength Vs. Temperature Relation and the Structure of Sunspots
Authors: Solanki S.K. , Walther U. , Livingston W. 
Published: July 2016

AbstractThe relationship between the magnetic vector and the temperature of a large symmetric sunspot is studied on the basis of 1.56 µm spectra. From this relation we estimate the shape of the τ = 1 surface. i.e. the Wilson depression, as a function of radial distance in the sunspot. We find that the Wilson depression is relatively small throughout the penumbra and changes by 200–500 km at the umbral boundary. We also estimate the magnitude of magnetic gradients and curvature forces.
Evershed Effect in Sunspots and their Canopies
Authors: Solanki S.K. , Montavon C. , Livingston W. 
Published: July 2016

AbstractAn analysis of Stokes I and V profiles of 1.56 µm lines of sunspots near the solar limb shows that the magnetic field continues outside the visible contours of sunspots in the form of a low-lying superpenumbral canopy. We also find that the V profiles formed in the canopy exhibit the Evershed effect (with line shifts of 1–2 km s−1), while the matter below it shows no sign of a flow. Therefore, the Evershed effect definitely is present beyond the visible sunspot boundary. However, if we interpret the line shifts in terms of stationary flows, then only a small fraction of the matter seen to be flowing outwards in the penumbra can be accounted for by the outward flow in the superpenumbral canopy. Therefore, although the Evershed “flow” does not stop at the boundary of the spot, most of the flowing matter stops or disappears there.
The Distribution of Sunspot Decay Rates
Authors: Pillet V. Martínez , Moreno-Insertis F. , Vázquez M. 
Published: July 2016

AbstractThe distribution of sunspot decay rates is studied using the Greenwich Photoheliographic Results (GPR). The decay rates are seen to be lognormally distributed. An analysis of the lognormal distributions associated to each sunspot group type and for isolated spots is presented. As a remarkable property of the decay process, we show that it happens at a constant total to umbral area ratio.
Delta-Sunspots and X Class Flares in Solar Cycle 22
Authors: Shi Zhongxian , Wang Jingxiu 
Published: July 2016

AbstractA sample of 221 active regions with δ magnetic configurations from 1986 to 1991 in Solar Cycle 22 is used to investigate the characteristics of δ-sunspots and the relationship between the δ-sunspots and X class X-ray flares.
Computational Modeling of Solar Magnetic Fields
Authors: Sakurai Takashi 
Published: July 2016

AbstractModeling techniques for solar magnetic fields are discussed. As an extension of the source surface model for large scale solar magnetic fields, a method based on the Green’s function approach to the Laplace equation is proposed. In the force-free field modeling, a proper definition of the boundary condition is an important but still unresolved problem. A condition based on the continuity of the Maxwell stress is newly proposed.
Thermal and Hall-Current Instabilities in a Current Sheet and the Triggering of two Ribbon Flares
Authors: Jae Li Sang 
Published: July 2016

AbstractThermal stability of a current sheet is investigated when the magnetic field is not perfectly anti-parallel at the sheet. If the effect of Hall electric current is taken into account, a new instability (the Hall instability) appears. The result is applied to the activation of dark filaments often seen prior to solar flares. The growth time of the instability is evaluated and found to be consistent with the observed time scale of the filament activation.
On the Inference of Magnetic Field Vectors from Stokes Profiles: A Generalization of the Weak-Field Approximation
Authors: Qu Zhong-Quan , Ding You-Ji , Xuan Jia-Yu , Ye Shi-Hui 
Published: July 2016

AbstractA generalization of Jefferies et al’s weak-field approximation for the inference of the strength and polar angle of magnetic field vectors from Stokes profiles is obtained while the inference of azimuthal angle follows a relationship derived by Landi Degl’Innocenti’s perturbative solutions to the transfer equations in which the magneto-optical effect is taken account. It is found that the weak-field condition (ΔλH / ΔλD ≤1) is not necessary for the new method when the fitting is done in the line wings.
Numerical Simulation of the Explosive Events in the Solar Atmosphere
Authors: Jiu Shu-Ping 
Published: July 2016

AbstractExplosive events are the earliest indicators of flare activity and potentially predict the imminent occurrence of a flare at a specific location. They are highly energetic small-scale phenomena which are frequently detected throughout the quiet and active sun. The observations show that explosive events are related to emerging magnetic flux and tend to occur on the edges of high photospheric magnentic field regions. The cancellation of photospheric magnetic flux are the manifestation of explosive events, so that they are identified as the magnetic reconnection of flux elements. We assume that emerging flux are convected to the network boundaries with the typical velocity of intranetwork elements. Two-dimension (2D) compressible MHD simulations are performed to explore the reconnection process between emerging intranework flux and network field. The numerical results clearly show the cancellation of magnetic flux and the acceleration of the plasma flow.
Progress in the Measurement of Solar Magnetic Fields
Authors: Ai Guoxiang 
Published: July 2016

AbstractThe historical development of optical instruments for solar physics is outlined, from white light to unpolarized and polarized monochromatic light, to Stokes profiles and simultaneous fields of view, from points to lines, plane to cube. An evolutionary series and classificaton of instruments for the solar magnetic field is described. As a next step the 2-D real time polarizing spectrograph has been proposed. The planned instruments in China for measurements of solar magnetic and velocity fields are briefly introduced.
SIMURIS: High-Resolution Solar Physics
Authors: Rutten Robert J. , Damé Luc 
Published: July 2016

AbstractThe magnetic fields of the Sun provide the major incentive to do solar physics. The small spatial extent of the magnetically constrained structures and processes in the solar atmosphere provide the major incentive for high resolution solar telescopes. The visibility of the outer solar atmosphere in the ultraviolet and X-ray domains provide the major incentive for solar space telescopes. Cost provides the major incentive to use interferometric techniques. SIMURIS employs short-wave interferometry from space to measure solar structures and processes with high resolution.
Solar Radio S-Component Variation with the Magnetic Field of Active Regions
Authors: Zhao Ren-Yang 
Published: July 2016

AbstractAccording to an active region model proposed in the present paper, i.e. three-dimensional and continuous distributions of the three plasma parameters (electron temperature, electron density, and magnetic field) from the active region to the quiet region, and using the combined mechanisms of gyroresonance radiation and bremsstrahlung, we have researched the solar radio S-component (i.e. the slowly varying component or SVC) variation with the magnetic field of active regions.
Solar Activity Observed with the New Nobeyama Radioheliograph
Authors: Enome Shinzo , Nakajima Hiroshi , Shibasaki Kiyoto , Nishio Masanori , Takano Toshiaki , Hanaoka Yoichiro , Torii Chikayoshi , Sekiguchi Hideaki , Kawashima Susumu , Bushimata Takeshi , Shinohara Noriyuki , Irimajiri Yoshihisa , Koshiishi Hideki , Kosugi Takeo , Shiomi Yasuhiko , Sawa Masaki , Kai Keizo 
Published: July 2016

AbstractThe new Nobeyama Radioheliograph was completed in March 1992 after two years of construction. It is a T-shaped array operating as a multiple spacing grating-type radio interferometer at 17 GHz and is dedicated to full disk solar observations. Routine observations began in late June, 1992, after three months of system integration, fine tuning, and test observations. During the course of test observations it was shown that major items of the system performance exceeded the designed values, and that the image quality or the dynamic range of the images is better than the designed value. In the three months of routine observations two X-class flares, several M-class flares and a number of small flares were observed. In this report we present a summary of initial observational results and preliminary comparisons with YOHKOH HXT and SXT observations.
Flows, Evolution of Magnetic Fields, and Flares
Authors: Wang Haimin 
Published: July 2016

AbstractThis paper reviews observations on the evolution of magnetic fields and flows in active regions which produce major flares. It includes the following topics: (1) Relationship between magnetic shear and flares; (2) Relationship between electric currents and flares; (3) Flows in active regions, particularly the emergence of new flux inside sheared penumbrae, and the mixed magnetic polarity nature of this kind of flux emergence; and (4) Changes of magnetic structure immediately before and after major solar flares; in particular, I will describe some recent findings that shear may increase after major flares.