bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractActive 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

AbstractThe 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

AbstractAdopting 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

AbstractUsing 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

AbstractThe 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

AbstractWe 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.
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

AbstractObservations 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

AbstractWe 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

AbstractAn 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

AbstractObservations 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractIn 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

AbstractWe 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 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

AbstractWe 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

AbstractWe 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.
IRAS 03158+4227 - a ULIRG in a Widely Separated Pair of Galaxies
Authors: Meusinger Helmut , Stecklum Bringfried , Brunzendorf Jens 
Published: July 2016

AbstractWe present new deep optical images, optical spectroscopy, and high-resolution NIR images of IRAS 03158+4227, one of the most luminous ULIRGs from the IRAS 2 Jy sample. The data are best explained either by a multiple merger or by the assumption of a ULIRG triggered in an early phase of galaxy interaction.
The Obscured AGN Population Probed by X-ray Observations
Authors: Iwasawa K. 
Published: July 2016

AbstractX-ray properties of obscured AGN are reviewd and recent results obtained from ASCA, BeppoSAX, and Chandra are presented. There is a population of AGN that can only be revealed by hard X-ray observations. Studies of the X-ray background suggest that obscured AGN should significantly outnumber their unobscured counterparts.
Optical Identification of X-ray Sources in a High X-ray Flux Sensitivity Area from the RASS
Authors: Mújica Raúl , Zickgraf Franz-Josef , Chavushyan V. , Juárez Y. , Serrano A. , Appenzeller I. , Krautter J. 
Published: July 2016

AbstractWe have optically identified a complete sub-sample of ROSAT All-Sky Survey (RASS) X-ray sources contained in 6 study areas. Of the original 12° × 12° area near the NEP, only one-quarter was observed until now in order to keep the number of sources to a manageable size. This area is of particular interest because the RASS integration time is about a factor of ten longer than in the other areas and therefore a factor of 3-4 deeper in flux. We have started to observe the RASS sources in the remaining 3/4 of this area. First results are presented.
AGN Search from Multicolor Photometric Observations of Faint ROSAT X-ray Sources in a One Square Degree Field
Authors: Xue Suijian , Zhou Xu , Zhang Haotong 
Published: July 2016

AbstractWe report that a volume-limited, X-ray selected AGN sample, including 49 QSO like and starburst galaxies (SBs) at the 0.1-2.4 keV flux level of ≳ 5.3 × 10−14 ergs cm−2 s−1 was formed with photometric redshifts.
Decametric AGNs: FIRST and NVSS Maps and Radio Spectra
Authors: Verkhodanov O.V. , Verkhodanova N.V. , Andernach H. 
Published: July 2016

AbstractRadio sources from the decametric UTR-2 catalog were cross-identified with other radiocatalogs at higher frequencies. We used the CATS database to extract all sources within the UTR beam size (~40’) to find candidate radio identifications. Using the least squares method, we fitted the spectrum of each source with one of a set of curves. We extracted NVSS and FIRST radio images for the radio-identified sources, and looked for a possible relation between size and spectral index.
Using the NASA/IPAC Extragalactic Database (NED) and Federated Virtual Observatory Archives for Multiwavelength Studies of AGNs
Authors: Mazzarella Joseph M. ,   the NED Team_a1
Published: July 2016

AbstractWe live in an exciting era that offers increasing opportunities for people all over the world to make discoveries about the Universe using interconnected archives on the Internet as a primary research tool. We review how NED (http://ned.ipac.caltech.edu) can be used in concert with globally distributed online archives to perform multi-wavelength, crosscorrelated studies of AGNs and other galaxy types. The present status and planned evolution of NED capabilities are discussed.
Conference Summary
Authors: Sanders D. B. 
Published: July 2016

AbstractThis conference on AGN Surveys has proved to be a significant milestone in our understanding of the redshift distribution of optically selected QSOs, and in our initial understanding of the cosmic distribution of AGN from the first far-infrared and X-ray deep fields. It has also set the stage for continuing debates concerning the multiwave-length properties of AGN, the cosmological distribution of “obscured” AGN, and the “orientation versus evolution” debate on the nature of the sources discovered at different wavelengths. Much of this debate could have been anticipated from previous studies of the complete samples of optically-selected AGN provided to us by the pioneering work carried out by the staff of the Byurakan Astronomical Observatory over the past 40 years.