bluuebunny/crossref_metadata_2025 huggingface dataset:
On the 3D Solar Corona Structure
Authors: Koutchmy S. , Molodensky M. M. , Vial J.-C.
Published: July 2016

We consider the 3D structure of the solar corona using eclipse observations. We use a pseudostereoscopic effect of the rigidly rotating corona to determine the true position of the main coronal structures: broad threads, rays and streamers. We find that observations collected by the “Multi-station International Coronal Experiment” are well suited for solving this problem. Formula and error estimation are given to demonstrate the feasibility of the method. An example of stereo-view deduced from a simple analysis of results coming from the 1991 eclipse is given. The observed apparent shifts allow for the first time to apprehend the true 3D structure of the corona. The structure of streamers was compared with the pecularities (pleats and cusps) of the solar heliosphere current sheet, deduced from the sourse surface. The positions of the two main streamers systems rays (near the N-E and S-limb) coincide with the pleats of the current heliosphere layer. We conclude that large helmet streamers are composed by the pleats of the heliosphere current sheet projected on the plane of the sky.
A Method to Obtain Stereo-Diagrams of the Solar Disc
Authors: Molodensky M. M. , Starkova L. , Koutchmy S.
Published: July 2016

In order to obtain a 3D picture of the Solar disc planoconvex spherical and elliptical lenses were made by the authors using organic glass. The comparison between the effects produced by the lenses and the results of the calculation have shown that the elliptical lenses give the best results.
Equations of State in Stellar Structure and Evolution
Authors: Van Horn H. M.
Published: July 2016

In this paper I summarize some of the recent advances in studies of dense matter. Research on phase separation in the binary ionic mixtures (BIMs) that constitute the matter in white dwarfs has been motivated by the need to obtain accurate estimates for the ages of the faintest white dwarfs and thus of the disk of our Galaxy. Substantial age increases appear possible, but it is not yet clear whether such large increases occur in real white dwarfs. A second advance is the prediction, based on state-of-the-art physical calculations, that ionization of H at low temperatures and increasing densities may occur via a first-order “plasma phase transition” (PPT). Astrophysical consequences of this result are still being explored in an effort to test this prediction. Related to these equation-of-state calculations are calculations of the enhancement of nuclear reaction rates at high densities. New thermonuclear rates have been computed for C+C reactions in BIMs, although there is currently some controversy about results at the highest densities. New pycnonuclear reaction rates have also been calculated for BIMs, and it has been suggested that He-burning at T = 0 may occur through a first-order phase transition. Finally, calculations of the equation of state of matter in strong magnetic fields and of radiative opacities at high densities have undergone very recent and substantial improvements, which are just beginning to be utilized in astrophysical calculations.
Onsager-molecule approach to screening potentials in strongly coupled plasmas
Authors: Rosenfeld Yaakov
Published: July 2016

The solution of the exact integral equation for the liquid pair-structure in the asymptotic strong coupling limit for the plasma, as mapped on the Onsager charge-smearing optimization for the energy lower bound, features “Onsager atoms” and “Onsager molecules”. The universal properties of this asymptotic limit make it a natural reference starting point for an asymptotic strong coupling expansion for the fluid structure and thermodynamics, playing the role of an “ideal liquid” state. In particular, the leading strong coupling terms for the potential energy, direct correlation functions, and screening potentials for the Coulomb and Yukawa mixtures (corresponding to classical plasmas and electron screened classical plasmas), with full thermodynamic consistency, are presented. These are in complete agreement with the Alastuey-Jancovici analysis of early simulations data by Hansen in strong coupling, and with recent highly accurate simulations data of Ogata, Iyetomi, and Ichimaru. Data analysis errors lead Ogata, Iyetomi, and Ichimaru to incorrect results for the short range screening potentials in strong coupling. Their calculations for the short range screening potentials, bridge functions, and enhancement factors for nuclear reaction rates in strongly coupled plasmas, should be revised.
High Pressure Experiments for Astrophysics
Authors: Loubeyre P.
Published: July 2016

In the past decade, measurements of the properties of H2and He systems at very high pressures have made great progress, now reaching density at the limit of the plasma phase transition of hydrogen. The potentialities and limits of static and dynamic methods will be reviewed. Then, a survey of the major experimental results is presented. It is the intention of this article to show how these measurements can bring information to model low-mass astrophysical objects. Three levels of usefulness are distinguished on selected examples: data for codes of planetary interiors, constraints for theoretical descriptions of dense matter, observations of unsuspected properties at very high density.
Giant Planet, Brown Dwarf, and Low-Mass Star Interiors
Authors: Hubbard W.B.
Published: July 2016

Astrophysical objects of low mass, ranging from giant planets to extreme dwarf main-sequence stars, have a number of physical characteristics in common due to properties of their equations of state. Their luminosities are low (much less than the solar luminosity L⊙) and their evolutionary timescales are typically measured in Gyr. So far there are few observational examples of these objects, although they are undoubtedly numerous in the galaxy. The lower mass limit is set by the object’s ability to retain hydrogen during accumulation (about the mass of Saturn), while the upper mass limit is set by the lifting of electron degeneracy by high internal temperature. Objects confined within this broad range, which extends up to about 0.1 M⊙, are governed by the thermodynamics of liquid metallic hydrogen. In this paper, we discuss the implications of this feature of their interior structure for their radii, interior temperatures, thermonuclear energy generation rates, and luminosities. We conclude with a brief assessment of the confrontation between observations and theory in galactic clusters and in the solar system.
On the Equation of State in Jovian Seismology
Authors: Provost J. , Mosser B. , Chabrier G.
Published: July 2016

We have investigated the effect on the seismological properties of the giant planet Jupiter of different descriptions of the equation of state (EOS) of the fluid hydrogen helium envelop. Recent Jovian models by Chabrier et al. 1992 use the equation of state of Saumon et al. (1992) which predicts the PPT (plasma phase transition). We show that different hypothesis at the level of the PPT induce large differences in the internal structure of the corresponding models, specially the sound speed. This gives rise to substantial differences of the oscillation frequencies up to 100 μHz, for modes of degrees l up to 20. These results show the great capability of Jovian seismology to test the physics involved in the interior of the giant planets.
Theoretical Description of the Coulomb Interaction by Padé-Jacobi Approximants
Authors: Stolzmann W. , Blöcker T.
Published: July 2016

Coulomb interactions for the Free Helmholtz energy and the pressure are studied in a partial new formulation which described more exactly the numerical evaluation of many body theories.
Low Temperature Opacities
Authors: Neuforge C.
Published: July 2016

The importance of low temperature opacities in stellar calibrations led us to compute new sets of Rosseland mean opacities for different Z-values. For the solar metallicity, these tables have been compared to those of Alexander (1975), Cox (1983), Sharp (1991) and Kurucz (1992).
A Note on Coordination of Remote Clocks
Authors: Abraham H. J. M.
Published: July 2016

Punta Indio and Mount Stromlo each determines clock corrections and each reports in terms of UTC, but if a systematic error of (say) 0. 1 ms were to occur, then an apparent east-west displacement by – about 1 ft. could seem to have taken place. It may also becomes necessary or desirable to maintain coordination to 0. 1 ms for use in other methods of studying the geographical coordinates, e. g. by the lunar corner reflector, radio tracking by artificial satellites or by radio interferometers. Consequently, the local time scale needs to be specified and its relationships – known.
A Simple Method for the Solution of the Stellar Structure Equations Including Rotation and Tidal Forces
Authors: Kippenhahn R. , Thomas H.-C.
Published: July 2016

In the following a method is presented for computing the internal structure of nonspherical stars assuming that the force per gram causing the deviation from spherical symmetry is conservative. The method has the advantage that in a normal (spherical) stellar structure code only slight changes have to be made in order to obtain nonspherical stellar models. The method can be applied as well to rotating stars as to stars distorted by tidal effects. Although it is similar to that of Faulkner et al. (1968) in the case of purely rotating stars, it is not necessary to use the division into two zones, where either slow rotation or negligible contribution to the gravitional potential is assumed.
Rotational Correlation in Binary Stars
Authors: Steinitz Raphael , Pyper Diane M.
Published: July 2016

A method for testing the possible correlation between axial rotations of pairs of stars is developed. The test is applied to a sample of visual binaries. It is concluded that some kind of coupling between the spins of components of visual binaries does in fact exist.
Double Stars with Common Proper Motion
Authors: Luyten Willem J.
Published: July 2016

The proper Motion Survey with the 48-in Schmidt telescope has now progressed far enough such that we may begin to make some meaningful statistical discussions of the results obtained. Altogether 135 regions have been blinked – one seventh of the total -and in particular all fifty plates covering the area of the North Polar Cap, north of declination +69 (1855) have been blinked and completely measured. This area covers 1360 square degrees, almost exactly one thirtieth of the entire sphere, and, since the galactic latitude of the Pole is 27°, and its distance from the ‘average’ solar apex is about 55° this region may be considered as not too unrepresentative for the whole sky.
Réflexions sur quelques méthodes de mesures d’étoiles doubles et leur emploi
Authors: Lacroute P.
Published: July 2016

J’ai été conduit à m’intéresser à la mesure des étoiles doubles au cours d’un projet de mesures spatiales de positions d’étoiles par une méthode de balayage photoélectrique. L’existence d’étoiles doubles perturbe les mesures. J’ai donc étudié les limitations imposées aux mesures de position par balayage d’images du fait de composantes d’étoiles doubles. Cette étude m’a donné l’occasion de réfléchir au problème de la mesure des étoiles doubles et voici le résultat de mes réflexions.
Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types
Authors: Galkina T. S.
Published: July 2016

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.

Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.
Errors of Observation in Double-Star Work
Authors: Heintz W. D.
Published: July 2016

Astronomical observation frequently is focused on minute quantities, and on digging information even from below the ‘noise level’. In all cases of long-term variations, such as visual binary motions, measurements over a long time interval have to be combined. All of this requires a knowledge of the observational errors in the past and present. We usually are not at liberty to discard old observations since we cannot repeat them at any later time desired. Visual observations leave no re-measurable records, so we have to take the word of the observer, and make the best of it.
Intérêt de la caméra électronique Lallemand pour la photométrie des binaires visuelles
Authors: Laques P.
Published: July 2016

J’ai montré ultérieurement les résultats des mesures astrométriques d’étoiles doubles, obtenus au moyen de la caméra électronique. Mais il est certain que l’on doit utiliser, en même temps, les propriétés intrinsèques de ce récepteur pour les mesures photométriques des binaires, complément nécessaire des mesures astrométriques.
Observational “Facts” of Binary Mass Loss
Authors: Koch Robert H.
Published: July 2016

My present understanding of this problem is formulated in a differential fashion: what is the rate of loss of mass from at least one close binary component over and above what it would have to lose were it a single star? This question implies another: is the mass loss that is expected to occur at certain stages of single star evolution inhibited in any way by membership in a binary system? I do not believe we are yet at the stage of being able to answer these questions, and I would like to use this opportunity to scrutinize as critically as possible the observational data and our interpretation of the results that are in hand. A summary of mass loss trends in single stars may be found in the paper by Deutsch (1969) at the 1968 Trieste Conference or alternately in the review paper by Weymann (1963).
Kinematics of Faint Stars, and the Reduction from Relative to Absolute Proper Motion
Authors: Murray C. A. , Clube S. V. M.
Published: July 2016

With the imminent completion of AGK3 in the northern hemisphere, and the prospect of results from the SRS programme in the southern hemisphere becoming available within the next few years, we may regard the problem of the establishment of a fundamental reference frame for proper motions down to about mpg = 11 as, in principle, solved. This reference frame, through the large number of stars involved, will be readily accessible to photographic observers, with carte-du-ciel type, and even longer focus telescopes, for the reduction of relative proper motions to an absolute system.
Proceedings of IAU Colloquium No. 9, The IAU System of Astronomical Constants, Heidelberg, 12-14 August 1970
Authors: Emerson B. , Wilkins G. A.
Published: July 2016

The principal purpose of IAU Colloquium No. 9 on the IAU System of Astronomical Constants was to discuss whether further action should be taken to revise those fundamental constants (namely the constants of precession and nutation and the system of planetary masses) that were left unchanged when new values of the other constants were adopted at Hamburg in 1964. The opportunity to discuss other relevant matters was also taken.
A Determination of the Masses of the Five Outer Planets
Authors: Duncombe R. L. , Klepczynski W. J. , Seidelmann P. K.
Published: July 2016

Planetary masses are determined from an extensive analysis of observations of the five outer planets and of seven selected minor planets.
The Hose-Pipe Instability in Stellar Systems
Authors: Kulsrud R. M. , Mark James W. K. , Caruso A.
Published: July 2016

Indications are that instabilities play an important role in many of the phenomena of stellar dynamics. Examples of such phenomena are: the formation of spiral arms, and the evolution of stellar clusters at a rate faster than one would expect from normal two-body collisions. The analogy with the situation in plasma physics, where similar phenomena are known to be dominated by instabilities, is very suggestive that one might seek for instabilities in stellar dynamics that correspond to similar ones in plasma physics.
On the Number of Isolating Integrals in Systems with Three Degrees of Freedom
Authors: Froeschle Claude
Published: July 2016

Dynamical systems with three degrees of freedom can be reduced to the study of a four-dimensional mapping. We consider here, as a model problem, the mapping given by the following equations:

We have found that as soon as b ≠ 0, i.e. even for a very weak coupling, a dynamical system with three degrees of freedom has in general either two or zero isolating integrals (besides the usual energy integral).
Small-Scale Structures in Active Regions
Authors: Keller Christoph U.
Published: July 2016

Within the last few years significant progress has been made in our understanding of the small-scale structures in active regions. Here I present some of the newest findings obtained by using speckle interferometric techniques. There exist continuum bright points with a contrast of about 30% that are cospatial with strong magnetic fields. The observations are consistent with the assumption that some facular and network bright points are the white-light signature of magnetic fluxtubes with a diameter of about 200 km. Magnetic elements larger than about 300 km are mainly darker than the average quiet sun. Their properties are similar to what has been called magnetic knots or invisible sunspots. In highly magnetic areas there is no clear relationship between continuum intensity and magnetogram signal at the smallest spatial scales. The magnetic field of pores extends beyond the dark umbra. There radially elongated structures may appear that are similar to penumbral filaments in sunspots.
Flares and Velocity Fields in AR 5528, AR 5629 and AR 6891
Authors: Chen Jimin , Huang Yinliang , Liu Zhenxing
Published: July 2016

In regards to the spatial associations of flares to velocity fields, Martres and Soru-Escaut (1977) found that flares occurred in the vicinity of the site where the magnetic neutral linesB∥=0 and the velocity neutral linesV∥=0 lines were crossing in the photosphere; Harvey and Harvey (1976) revealed that flares were related to velocity patterns different from Evershed flows. Recently Ai et al. (1991) discovered that flares occurred on the red-shift side of the velocity inversion lines (V∥=0) of theHβDopplergrams observed half to two hours before flares. In this paper we further examined the associations with high resolution data obtained by Solar Magnetic Field Telescope at Huairou. A reconnection model applied to the magnetosphere is adopted here to tentatively interpret some of the observational results.
The Sizes of Active Regions and Convective Triggering of the Buoyant Loop Instability
Authors: Petrovay K. , Szakály G.
Published: July 2016

The sizes of solar active regions were quantitatively studied using Debrecen Heliographic Results 1977 data. The size-total area dependence was also examined. The size of a region was defined as the distance between the area-weighted mean positions of p- and f-polarity subgroups at the time when the total (umbral + penumbral) area of the spot group is at its maximum. Excluding the groups for which this occurred on the invisible hemisphere and other dubious cases, 68 active regions were left in the present one-year sample. Despite the smallness of this sample, the average size of the regions was found to be 58 400 km with a relatively low error of 3000km (though the individual regions show a considerable scatter in size). It is proposed that the toroidal magnetic flux tubes lie in a sufficiently subadiabatic layer to be linearly stable and they are only destabilized by finite-amplitude convective disturbances that lift parts of them into the unstable layers. In such circumstances the typical size will be determined by the horizontal correlation length of the finite disturbances, thereby explaining the observed size.
Monochromatic Images of Sunspots in Linearly Polarized Radiation and Structure of their Magnetic Fields
Authors: Shi-Hui Ye , Jie-Hai Jin
Published: July 2016

The monochromatic images of unipolar sunspots in the Stokes parameters Q and U of magneto-sensitive lines display a complicated structure. This is caused by the magneto-optical effect and also connected with the 3-D structure of spot magnetic fields. In the process of numerical simulation it is possible to check the regularities of the change of the angle of inclination of magnetic lines of force with distance from spot center.
Ten Years of the Okayama Vector Magnetograph
Authors: Makita Mitsugu , Sakurai Takashi , Shibasaki Kiyoto , Koyano Hisashi
Published: July 2016

The vector magnetograph of the Okayama Astrophysical Observatory (Makita et al. 1985a,c) is equipped on the 65cm solar coude telescope with the 10m Littrow spectrograph. Results of observations are vector magnetograms, velocitygrams, maps of the broadband polarizations, maps of the magnetic lines of force, and maps of the electric currents. Their examples are given in figure 1. The data books, which give the vector magnetograms, have been published every year since 1983.

Calibrations of the polarization degree and the overall accuracy were discussed (Makita et al. 1982, 1987; Makita and Li 1992). The accuracy of the polarization measurement is 10−3for the line observation and 10−4 for the continuum observation. Conversion of the polarization degrees to the magnetic field vector has been tried by Sakurai (1987) with the use of the weak field theory and the observed magnetic field strength of sunspots. A simultaneous observation of the same active region was once made with the Sayan Observatory (Makita et al. 1985b). Distributions of the magnetic polarity were quite similar and azimuths of the magnetic field agreed very well.
Filter Magnetograph Measurements at Meudon Observatory
Authors: Dollfus Audouin , Moity Jacques
Published: July 2016

We report observational studies of solar active regions n°6150 and n°6850 during cycle 22. Observations were carried out with a tunable monochromatic birefringent filter coupled with a line-shifter and a Stokesmeter as well as with a spectro-magnetograph, both at Meudon Observatory. AR n°6150 is typical of emerging flux regions, while AR n° 6850, with a complex preceding δ-spot, exhibits characteristic configurations of the transverse magnetic field for flaring activity: shear along the neutral line, and curvature coupled with anomalous Evershed mass motions.
The Interaction of Weak and Strong Fields on the Sun
Authors: Zirin Harold
Published: July 2016

The problems associated with unresolved flux elements are discussed. It is pointed out that the hypothesis that these fields are strong does explain various problems of solar magnetic fields, but, as all invisible phenomena, is difficult to test. It is pointed out that Zeeman splitting measurements, which give the true field, have revealed field strengths down to the lower limit of conventional spectroscopy (about 400 gauss) for years. Not one spectrogram showing larger splitting in plages or network has been produced. The power-law distribution of weak-field strengths suggests a hierarchy of field strengths, and the simple arithmetic of weak-field elements and tiny pores is on the edge of ruling out strong fields, and further improvement in resolution should do so.

Observations in the 12μ lines have shown plage fields of a few hundred gauss and broadening of the σ components due to field variation within the field of view. These data have been explained away on the basis of height variation in the field, but the requisite transverse field strength or center-limb behavior are not observed.
Structures of Chromospheric Magnetic Fields in Active Regions
Authors: Zhang Hongqi , Ai Guoxiang , Li Wei , Chen Jimin
Published: July 2016

In this paper, we study the distribution of chromospheric magnetic fields and analyze reversed polarity structures on chromospheric magnetograms in active regions.
Analysis of EUV, Microwave, and Magnetic Field Observations of Solar Plage
Authors: Brosius J W , Davila J M , Jones H P , Thompson W T , Thomas R J , Holman G D , White S M , Gopalswamy N , Kundu M R
Published: July 2016

We obtained simultaneous images of solar plage on 7 May 1991 with Goddard Space Flight Center’s Solar EUV Rocket Telescope and Spectrograph (SERTS), the Very Large Array (VLA), and the NASA/NSO spectromagnetograph at Kitt Peak. Using intensity ratios of Fe XVI to Fe XV emission lines, we find that the coronal plasma temperature is 2.5 ± 0.3 ×lO6 K throughout the region. The column emission measure ranges from 2.6 × 1027 to 1.3 × 1028 cm−5. The calculated structure and intensity of the 20 cm wavelength thermal bremsstrahlung emission from the hot plasma observed by SERTS is quite similar to the observed structure and intensity of the 20 cm microwave emission observed by the VLA. Using the revised coronal iron abundance of Meyer (1991, 1992), we find no evidence for either cool absorbing plasma or for contributions from thermal gyroemission. Combining the observed microwave polarization and the SERTS plasma parameters, we calculate a map of the coronal longitudinal magnetic field. The resulting values, ~ 30 – 60 Gauss, are comparable to extrapolated values of the potential field at heights of 5,000 and 10,000 km.
On the Formulae for Calculating the Magnetic Field in the Source of Solar Microwave Bursts
Authors: Zhao Ren-Yang
Published: July 2016

Based on the theory of gyro-synchrotron radiation from both thermal and nonthermal electrons, and adopting the relation between the peak frequency and the corresponding rise time of microwave bursts, we have derived several analytical formulae for calculating the magnetic field in the source regions of solar microwave bursts.
Panoramic Analyzer of Radio Spectra — Instrument for Measurements of Coronal Magnetic Fields on the Sun
Authors: Bogod V. M. , Vatrushin S. M. , Abramov-Maximov V. E. , Tsvetkov S. V. , Dikij V. N.
Published: July 2016

The study of solar radio emission in a wide (covering many octaves) wavelength range is of great importance for plasma diagnostics of all types of solar activity. Here we describe a new spectroanalyzer covering a wide range in frequency from 1 to 18 GHz, which is used at the RATAN-600 radio telescope beginning 1991 December 20. Coronal magnetic fields have been measured with the various radio astronomical methods presented in these proceedings by Gelfreikh et al. and Bogod et al.

Of special value are collaborative spectral-polarization observations using the RATAN-600 and high-spatial resolution observations with the VLA and WSRT (Akhmedov et al. 1986; Bogod et al. 1992; Alissandrakis et al. 1992).
Diagnostics of the Velocity Field in the Lower Atmosphere of Solar Flares
Authors: Cheng Fang , Su-Ying Yin , Ming-De Ding , Hiei Eijiro
Published: July 2016

Based on the analyses of Call K line profiles of 12 solar flares, the characteristics of the red asymmetry of Call K line are summarized. Non-LTE calculations indicated that a downward motion of plasma above the temperature minimum region (TMR) as well as a contracting motion of plasma toward TMR can well explain the red asymmetry observed at the Ki positions. The typical velocity is 10-30 km s−1. This result is consistent with the observations of metallic lines of solar flares.
Line-of-Sight and Proper Motions in the Flaring June 1991 ( NOAA 6659 ) Active Region
Authors: Bumba Václav , Klvaňa Miroslav , Kalman Bela , Györi Lajos
Published: July 2016

We present the results of comparison of photoelectrically and photographically made measurements of Doppler and proper motions with the distribution of the longitudinal magnetic field and spot topology in this large complex region.
A Sufficient Condition for Krall’s Criterion and its Modifications
Authors: Linxiang Wu
Published: July 2016

In order to determine the sense of the photospheric transverse magnetic field measured with a magnetograph, it is shown that: (1) If the magnetic lines of force through the photospheric plane are both divergent and convex upward, Krall’s criterion

is true for the transverse field B⊥ much more strongly than for the longitudinal field Bz and the inequality in general becomes

(2) If the magnetic lines of force are only divergent upward, we have instead the inequality

for a force-free field.
Properties of Emerging Bipolar Active Regions
Authors: Harvey Karen L.
Published: July 2016

Characteristics and the emergence pattern of bipolar active regions are investigated using NSO/KP full disk magnetograms. Discussed in this paper are two samples of newly emerged bipolar regions: 9492 ephemeral regions and 978 active regions. Their distributions in size, latitude, and orientation are compared. It is concluded that ephemeral regions are the small scale end of a wide spectrum of active regions.
Observations of Waves and Oscillations in the Solar Magnetic Fine Structure
Authors: Fleck B. , Deubner F.-L. , Schmidt W.
Published: July 2016

We study the oscillatory behaviour of small-scale magnetic flux-tube concentrations and their immediate surroundings by analysing high spatial resolution time series of spectra of four Zeeman sensitive lines (Fe I 5247.1, Cr I 5247.6, Fe I 5250.2, Fe I 5250.7) taken simultaneously in left-hand and right-hand circularly polarized light with the Echelle spectrograph at the Vacuum Tower Telescope in Izaña, Tenerife. The velocity field inside the magnetic elements is dominated by the 5-min oscillations which also show up as periodic variations in the relative amplitude asymmetry of the Stokes V profiles. In other parameters as for instance the Stokes V peak separation we cannot detect an oscillatory component. Neither the magnetic line ratio nor the thermal line ratio is affected by the 5-min oscillations, although the latter reveals remarkable spatiotemporal variations.
Siphon Flow Across the Magnetic Neutral-Line of an Active Region
Authors: Solanki S.K. , Rüedi I. , Rabin D.
Published: July 2016

We present accurate measurements, based on the g = 3 line at 1.5648/µm, of the field strength and longitudinal velocity in the vicinity of the magnetic neutral-line of a solar active region. We find that very close to the neutral line the field strength and the flow velocity are correlated in the sense that the magnetic polarity with the larger field strength is associated with a downflow, while the polarity with the weaker field shows an upflow. This is exactly the signal predicted by theoretical models of siphon flows, and constitutes the first reliable detection of a siphon flow on the sun.
Low Density Drivers of Strong Interplanetary Shocks
Authors: Hewish A.
Published: July 2016

The theory that most, if not all, interplanetary shocks are caused by coronal mass ejections (CMEs) faces serious problems in accounting for the strongest shocks. The difficulties include (i) a remarkable absence of very strong shocks during solar maximum 1980 when CMEs were prolific, (ii) unrealistic initial speeds near the Sun for impulsive models, (iii) the absence of rarefaction zones behind the shocks and (iv) sustained high speed flows following shocks which are not easily explained as consequences of CME eruptions. Observations of the proton temperature near 1 AU indicate that strong shock drivers have properties similar to high speed streams emitted by coronal holes. Eruptions of fast solar wind from coronal holes influenced by solar activity can explain the occurrence of the strongest interplanetary shocks.
Shock Waves Propagation in the Turbulent Interplanetary Plasma
Authors: Chashei I.V. , Shishov V.I.
Published: July 2016

Effect of turbulence on interplanetary shock waves propagation is considered. It is shown that background turbulence results in the additional shock wave deceleration which may be comparable with the deceleration due to plasma sweeping. The turbulent deceleration is connected with the energy losses due to the strong turbulence amplification behind the moving shock front.
Inferences of Plasma Parameters from Coronal Hole Observations
Authors: Habbal Shadia Rifai
Published: July 2016

The temperature in the acceleration region of the solar wind remains one of the most elusive parameters to measure. Knowledge of the temperature as well as its gradient in the inner corona is fundamental for placing constraints on physical mechanisms thought to be responsible for the coronal heating process, as well as for understanding the flow properties of the solar wind. Estimates of the helium abundance is essential for understanding the puzzling behavior of heavier ions in the solar wind. As an illustration of the difficulties and uncertainties involved in the inferences of plasma parameters in the solar wind acceleration region, the inference of electron temperature and helium abundance will be described. Prospects for future observations will be briefly discussed.
Anisotropic Angular Broadening in the Solar Wind
Authors: Anantharamaiah K.R. , Gothoskar Pradeep , Cornwell T.J.
Published: July 2016

We present Very Large Array observations at wavelengths of 2, 3.5, 6, and 20 cm, of angular broadening of radio sources due to the solar wind in the region 2-16 solar radii. Angular broadening is anisotropic with axial ratios in the range 2-16. Larger axial ratios are observed preferentially at smaller solar distances. Assuming that anisotropy is due to scattering blobs elongated along magnetic field lines, the distribution of position angles of the elliptically broadened images indicates that the field lines are non-radial even at the largest heliocentric distances observed here. At 5R⊙, the major axis scattering angle is ~ 0.7" at λ = 6 cm and it varies with heliocentric distance as R−1.6. The level of turbulence, characterized by the wave structure function at a scale of 10 km along the major axis, normalized to λ = 20 cm, has a value 20±7 at 5R⊙ and varies with heliocentric distance as R−3. Comprison with earlier results suggest that the level of turbulence is higher during solar maximum. Assuming a power-law spectrum of electron density fluctuations, the fitted spectral exponents have values in the range 2.8–3.4 for scales sizes between 2–35 km. The data suggests temporal fluctuations (of up to 10%) in the spectral exponent on a time scale of a few tens of minutes. The observed structure functions at different solar distances do not show any evidence for an inner scale; the upper limits are 1 km at 2R⊙ and 4 km at 13R⊙. These upper limits are in conflict with earlier determinations and may suggest a reduced inner scale during solar maximum.
Numerical Modelling of Shock Waves in the Solar Wind
Authors: Hu Y. Q.
Published: July 2016

This review briefly surveys some recent progress in the numerical simulation study of magnetohydrodynamic (MHD) shock waves in the solar wind.
North-South Asymmetry of the Polar Solar Wind and Some Characteristics of Solar Magnetic Field
Authors: Girish T.E. , Gopkumar G.
Published: July 2016

We have found correlated variations of the yearly averaged north-south asymmetry in the polar solar wind speed (Δsol) and the ratio of the zonal quadrupolar to the zonal dipolar contribution in the inferred coronal magnetic field during the declining phase of sunspot cycle 21. A physically meaningful association between Δsol and some polar solar magnetic field proxies is also observed during the low sunspot activity periods of the above cycle.
Solar Activity Dependence of Interplanetary Disturbances
Authors: Manoharan P.K.
Published: July 2016

Interplanetary scintillation measurements obtained inside 200 R⊙ using the Ooty Radio Telescope during August 1986 - April 1991 have been analysed to study the interplanetary disturbances (or events) and their occurrence rates at various phases of the solar cycle. The disturbances are identified by the increase in the level of scintillation compared with the expected value. In total, 735 events have been identified. The results show a rate of 0.49 events per day near solar maximum and a low rate of 0.16 events per day during minimum of activity. The results are compared with coronal mass ejection (CME) rates and transients rates obtained from the Doppler scintillation measurements.
IPS Observations of Short-Time Scale Interplanetary Activity
Authors: Gothoskar Pradeep , Rao A. Pramesh
Published: July 2016

We have carried out a program of continuous Interplanetary Scintillation (IPS) monitoring of the interplanetary activity using Ooty Radio Telescope (ORT). From May 1990 to March 1991, during the 22nd solar maximum, a few radio sources were monitored to provide long stretches of IPS data with a high-time resolution of few minutes. These observations covered 0.3 to 0.8 AU region (12° to 70° elongations) around the sun at several heliographic latitudes. During the observation, we detected 33 short-time scale IPS events which had significant variation in the scintillation index and solar wind velocity. These were considered to be due to travelling interplanetary disturbances.

A multi-component model of plasma density enhancement was developed to estimate the geometry and physical properties of these IPS events. Detailed analysis of 20 of these events suggests, 1. fast IPS events were interplanetary signatures of Coronal Mass Ejections (CMEs), 2. the average mass and energy of these events was ~ 1016 gm and 1033 erg respectively, 3. 80% of IPS events were associated with X-ray flares on the sun and 50% were associated with geomagnetic activity at earth. Detailed study of the multi-component model suggests IPS observations at smaller elongations (hence at higher radio frequencies) are more suited to detect fast-moving interplanetary disturbances such as produced by CMEs.
IPS Observations at STELAB for the Fruitful Coming Decade
Authors: Asai K. , Ishida Y. , Kojima M. , Maruyama K. , Misawa H. , Yoshimi N.
Published: July 2016

We have been carrying out solar wind measurements using the interplanetary scintillation (IPS) method. Our IPS observation system is operated at a frequency of 327MHz and consists of four stations located at Toyokawa, Fuji, Sugadaira and Kiso. The present system, however, has insufficient sensitivity to measure enough IPS sources for observing the solar wind with adequate spatial and temporal resolution. Therefore we have been excuting the upgrade project since 1994 in order to observe a larger number of compact radio sources. The Fuji system has been improved successfully and has achieved sensitivity by a factor over five compared with the previous system. The upgrade project is now in progress for the Toyokawa and Sugadaira station.
First Results from the Gauribidanur Radio Heliograph
Authors: Subramanian K.R. , Ramesh R. , Sundara Rajan M.S. , Sastry Ch.V.
Published: July 2016

Observations of the Sun at two frequencies (51 and 77 MHz) using the East-West arm of the Gauribidanur Radio heliograph are presented.
The Population of AGNs in Nearby Galaxies
Authors: C. Ho Luis
Published: July 2016

This contribution reviews the properties of nuclear activity in nearby galaxies, with emphasis on results obtained from current optical surveys and multiwavelength follow-up observations thereof.
Objective-Prism Emission-Line Searches for Active Galactic Nuclei
Authors: Gronwall Caryl , Sarajedini Vicki L. , Salzer John J.
Published: July 2016

Objective-prism surveys for UV-excess and emission-line objects, especially the First and Second Byurakan Surveys, have been central to the study of active galactic nuclei (AGNs). We review previous line-selected surveys for AGNs and discuss their contribution to our understanding of the AGN phenomena. In addition, we present results from the KPNO International Spectroscopic Survey, a modern digital objective-prism survey for emission line objects. This survey is discovering substantial numbers of new AGNs, in particular low-luminosity AGNs and LINERs.
Comparison of ELG and UV Galaxies from the SBS Survey
Authors: Gyulzadian M. V.
Published: July 2016

In this paper we compare the results of spectrophotometric observations for more then 40 emission line galaxies (ELG) without UV-excess and 70 galaxies with UV-excess (UV-galaxies) from the Second Byurakan Survey (SBS) carried out with the scanner on the 6-m telescope of the Special Astrophysical Observatory. The comparison was aimed to answer the questions: are there any essential differences between these two types of galaxies? And what is the fraction of AGN among ELG and UV-galaxies? To answer this question we have investigated some physical parameters. Great care was taken in classifying the spectra of these galaxies as “HII region-like or “AGN-like” using a new diagnostic method for emission-line galaxies (Rola et al.). We find that 14% of emission line galaxies (ELG) have Sy2 and LINER-like spectra. The transition or ambiguous objects among them comprise 20%. The fraction of LINER-like and Sy2 objects among UV-galaxies is 21% while that of the transition or ambiguous objects in UV-galaxies is 28%. From SBS galaxies, 18% are Sy2s and LINER-like galaxies.
Properties of the Low-z NELGs from the VPM Survey
Authors: Meusinger Helmut , Brunzendorf Jens
Published: July 2016

We discuss the properties of the low-redshift narrow-emission line galaxies detected in the framework of a variability-and-proper motion (VPM) search for AGNs. The VPM-NELG sample is obviously not a random selection of normal field galaxies.
Spectroscopic Diagnostics for AGNs
Authors: Veilleux Sylvain
Published: July 2016

A review of the spectroscopic tools needed to characterize AGNs is presented. This review focusses on ultraviolet, optical and infrared emission-line diagnostics specifically designed to help differentiate AGNs from starburst-dominated galaxies. The strengths and weaknesses of these methods are discussed in the context of on-going and future AGN surveys.
Unveiling the Evolution of Type I AGNs in the IR (15μm) — As Seen by ISO in the ELAIS-S1 Region
Authors: Matute Israel , Franca Fabio La , Gruppioni Carlotta , Pozzi Francesca , Lari Carlo
Published: July 2016

We present the first estimate of the evolution of type 1 AGNs in the IR (15 μm) obtained from the ELAIS survey in the S1 region. We find that the luminosity function (LF) of Type 1 AGNs at 15μm is fairly well represented by a double power-law function with a bright slope of 2.9 and a faint slope of 1.1. There is evidence for significant cosmological evolution according to a pure luminosity evolution model L15(z)α(l+z)k, with in a (Ωm,ΩΛ)=(1.0,0.0) cosmology. This evolution is similar to what is observed at other wavebands. From the luminosity function and its evolution, we estimate a contribution of ~ 2% from Type 1 AGN to the total Cosmic Infrared Background (CIRB) at 15 μm.
The FIRST-APM QSO Survey (FAQS) in the SBS Region. Current Status
Authors: Chavushyan V. , Mújica R. , Valdés J.R. , Carrasco L. , Stepanian J. , Verkhodanov O.
Published: July 2016

As the first step of the Multiwavelength AGN Survey (MWAS), we have started the FIRST-APM QSO Survey (FAQS). The main goal of FAQS is to compile the most complete sample of bright QSOs, located in the area of the sky covered by the Second Byurakan Survey (SBS). Here we report the current status of an ongoing study based on the cross-identification of the FIRST radio catalog and the APM optical catalog. The overlapping sky area between FIRST and SBS is about 700 deg2. The compiled list of sources for this overlapping region contains ~ 400 quasar candidates brighter than . About 90 objects were already spectroscopically classified. During 1999-2000, we observed spectroscopically more than 150 FAQS objects with the 2.1m telescope of the Guillermo Haro Astropysical Observatory (GHAO). We have found 51 new QSOs (4 BAL QSOs), 13 Seyfert Galaxies (5 NLSyl’s), 23 emission line galaxies, 3 BL Lac objects and 57 stars.
Different Types of Radio Sources and Possible Evolution of Radio Galaxies
Authors: Ohanian Gabriel A.
Published: July 2016

Extragalactic radio sources have been studied for many years, but it is still unclear how they are formed and evolve. The sizes of the most powerful radio emitters in the Universe vary from less than one parsec to more than 1 Mpc. This large range of sizes has been interpreted as evidence for the evolution of the linear sizes of radio structure (e.g., O’Dea and Baum, 1997). A crucial element in the study of their evolution is the identification of the young compact counterparts of “old” FRI/FRII extended objects. Good candidates for young radio sources are those with peaked spectra (Gigahertz Peaked Spectrum - GPS and Compact Steep Spectrum - CSS, e.g., O’Dea 1998). Radio sources are presumably born in the very compact GPS phase, then they expand beyond 1 kpc into the CSS regime and finally, they reach a size of 20 kpc, and afterwards evolve into large-scale radio sources (young scenario, e.g., O’Dea 1998). Alternatively, GPS sources may be compact because a particularly dense environment prevents them from growing larger (old scenario, e.g., O’Dea 1998). In either scenario, the radio source host galaxy determines the time evolution of the radio structure. By studying the optical environments and host galaxies we hope to obtain clues to the evolution of the radio sources. Similarities or differences in host galaxy properties over a range of radio source types and sizes enable us to investigate possible differences or similarities of the radio size class as a whole.
Are There AGNs in the Nearby Dwarf Galaxies?
Authors: Karachentsev I. D. , V. E. Karachentseva
Published: July 2016

The presence or absence of a nucleus is considered for a sample of galaxies limited by distance, not by flux. For the 365 nearest galaxies situated within a distance of ~7 Mpc, classification of their central regions is based on large-scale images obtained with the Hubble Space Telescope as well as with the 6-m and other large ground-based telescopes. Occurrence of nucleated galaxies is considered as a function of their luminosity, morphological type and other global properties.
Spectral Variability of Some Seyfert Galaxies
Authors: Denissyuk E.K. , Gaisina V.N. , Valiullin R.R.
Published: July 2016

The very first spectrograms of 40 Seyfert galaxies are discussed. All these objects were taken from Markarian’s lists of galaxies. They were first investigated and classified at Fesenkov Astrophysical Institute during 1973-1988. Spectral study was carried out with a slit spectrograph, attached to the 70-cm telescope and equipped with a three cascades image-tube. Repeated observations of 22 galaxies were obtained in 1985-2000. An analysis of possible spectral variability of the studied galaxies over 10-26 years was made. A list of objects which are the most interesting for further observations is presented.
Analysis of Color Variability of BL Lac during the 1997 and 1999 Outbursts
Authors: Hagen-Thorn V.A. , Larionov V.M. , Hagen-Thorn A.V. , Jorstad S.G. , Temnov G.O.
Published: July 2016

The analysis of multicolor observations of BL Lac obtained in the 1997 and 1999 outbursts shows that in both cases the spectral energy distribution of the variable source was unchanged in the course of outburst. The sources have power-law spectra with slightly different spectral indices (the spectrum was flatter in the more powerful outburst of 1997). The variable source is most probably of synchrotron nature.
Energy Releases from Accreting Superdense Compact Objects in AGNs
Authors: Sadoyan Avetis Abel
Published: July 2016

We consider an accreting central symmetric object that is near to the Eddington limit, i.e., the luminosity pressure is balancing the gravity. In special cases, a layer of accreting matter will be formed near the surface of a centrally symmetric object. We discuss the conditions of formation of the layer, its inner structure and stability. If the luminosity pressure will be reduced for some reason, then the layer will collapse immediately, releasing an enormous quantity (up to 1042 erg/sec) of energy. We discuss some possible scenarios for energy releases.