bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diamagnetic Temperature Control in the Solar Wind
Authors: Steinitz R. , Sekeles B. 
Published: July 2016

AbstractWe have developed a model to account for changes in velocity distributions of protons in the solar wind. The essential operative mechanism is the diamagnetic effect on charged particles. Through numerical simulation, we explore the (distance 0.3 AU to 1 AU) evolution of thermal anisotropy. We find that as the initial ratio T+/T∥is increased, there is a larger growth in bulk speed, as is observed. Since any form of wave-particle interactions is exluded from our simulations but they fit well the observations, we conclude that the diamagnetic effect is most relevant in controlling both thermal anisotropy and bulk speed evolution.
Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: II. Viscous Effects
Authors: Erdélyi R. , Goossens M. 
Published: July 2016

AbstractResonant absorption of MHD waves in coronal loops is studied in linear, viscous MHD. Viscosity is described by Braginskii’s viscosity stress tensor. The dependence of the process of resonant absorption on the viscosity coefficients is studied. The compressive viscosity and viscosity due to the finite Larmor radius do not produce absorption. Shear viscosity produces absorption and is a viable candidate for heating coronal loops. The width of the dissipation layer is found to be proportional to, whereη1is the shear viscous coefficient of the full viscous stress tensor.
The spatial Golf project
Authors: Turck-Chieze S. ,   the GOLF scientific and technical team, Bocchia R. , Boumier P. , Cantin M. , Charra J. , Cougrand B. , Cretolle J. , Denis N. , Duc R. , Dzitko H. , Decaudin M. , Gabriel A. , Herreros J. , Grec G. , Petrou N. , Cortes T. Roca , Robillot J.M. 
Published: July 2016

AbstractThis spatial experiment is under construction and has been defined as a 2 years mission on board SOHO, a satellite dedicated to the Sun which will be launched in mid 95. The main objectives are the detection of solar low degree acoustic modes and solar gravity modes for improving our knowledge of the solar nuclear region.
Denis
Authors: Forveille T. 
Published: July 2016

AbstractThe DENIS survey will survey the southern sky in the near-IR J (1.2 micron) and K (2.2 microns) bands at 3” resolution and to limiting magnitudes in J and K of respectively 16 and 14.5 (lmJy in both cases), and at 1” resolution in the red I band (0.9 microns). Astrophysical motivation is provided by basic problems concerning structure and evolution of galaxies, of types ranging from our own to active galaxies, and concerning specific stellar populations including stars with low temperature photospheres, those still embedded in their protostellar envelopes, and those currently losing mass on the AGB.
Coronal Heating by the Resonant Absorption of Alfvén Waves
Authors: Ofman L. , Davila J. M. , Steinolfson R. S. 
Published: July 2016

AbstractNonlinear evolution and stability of the resonant absorption layer is considered by solving the time-dependent 3D, low-β, resistive MHD equations with the Lax-Wendroff explicit method. The calculations are initiated with the solutions of the linearized version of the MHD equations (Steinolfson and Davila, 1993, Ofmanet al., 1994), with inhomogeneous background density, and a constant magnetic field. The narrow resonant heating layers are deformed by the self-consistent shear flow. When the driver amplitude is small compared to the average Alfvén speed the dissipation layer appears to be stable and the driver-period-averaged ohmic heating rate saturates at a slightly higher than the linear rate. When the driver amplitude is large (Fd≈ 1) the resonant heating may become unstable.
Some Spectroscopic Observations of Visual Binaries
Authors: Scarfe C.D. 
Published: July 2016

AbstractThe use of a coudé spectrograph for securing the high-resolution spectrograms necessary to follow the slow variations of radial velocity exhibited by visual binaries is discussed. Recent observations, using the spectrograph at the coudé focus of the Dominion Astrophysical Observatory’s 48-in. reflector, are then presented for the systems ofαUMa,εHya,βLMi andγLeo.
The Yale – Columbia Southern Proper Motion Program
Authors: Wesselink A.J. 
Published: July 2016

This program is the southern counterpart of the well-known Lick proper motion program. These programs are almost identical in design and execution, their chief feature being the use of faint extragalactic nebulae and QSO’s as stationary reference objects.The Lick program has been described by S. Vasilevskis on various occasions; it serves as an example to the Yale-Columbia work.
Determinations of Precession (Invited Review Paper)
Authors: Fricke Walter 
Published: July 2016

AbstractRecent determinations of lunisolar precession and of the motion of the equinox are reviewed. Methods of determination are discussed which are based on proper motions referred to fundamental systems, on planetary motions, and on proper motions referred to galaxies. It is concluded that a new fundamental catalogue, which will replace the FK4 at some future date, should be based on revised values of precession and freed from errors in the motion of the equinox.
On Intensity, Magnetic Field, and Velocities of Small Bright Points in the Ca+ Network
Authors: Soltau Dirk 
Published: July 2016

AbstractMore than 1000 small isolated bright Ca+ structures (facular points) have been observed with the German VTT at the Observatorio del Teide, Tenerife. An analysis of Stokes V and Stokes I profiles of magnetically sensitive lines exhibit some typical properties of these features. The investigation is concentrated on those 40% of the observed structures for which the magnetic filling factor is larger than 10%
Spectral Characteristics of a Coronal Oscillation with a Period of the Order of 10 MS
Authors: Zhiguo Xia , Jingying Chen , Xiangmin Zheng , Yuan Ma 
Published: July 2016

AbstractA coronal oscillation with a changing period was observed with the acousto-optic radio spectrometer of Yunnan Observatory. The bandwidth of the oscillation was about 10 MHz. It accompanied radiation which lasted for about 500 ms. A corresponding burst was found on a radio spectrogram obtained at Weissenau, Germany. A 245 MHz burst was reported at the same time and we found a bright spot on the Hα film records of Yunnan Observatory. In this paper, we present a series of spectra of the oscillation at 10 ms intervals. In the spectra the oscillation appears in the form of a 3.5 MHz drift of radio flux with frequency.
The Spontaneous Reconnection of Force Free Magnetic Field
Authors: Xing Li , Hu Y.Q. 
Published: July 2016

AbstractTwo dimensional, three components compressible MHD equations are solved with multistep implicit scheme. The spontaneous reconnection of current sheets with force free field background is simulated. In comparison with the case where the background is potential field, a great difference is found. Our conclusion is that the force free magnetic field can accelerate reconnection. It may have important scientific significance to solar physics, for force free field is widely present in solar atmosphere.
Electric Conductivity of Lower Solar Atmosphere
Authors: Wang Jingxiu 
Published: July 2016

AbstractElectric conductivity tensor of partly-ionized plasma is deduced. Four atmospheric models are used then to estimate the conductivity in the lower atmosphere. The parallel conductivity reaches its minimum value in the temperature minimum zone, which is 1 to 2 orders smaller than the conductivity of fully-ionized plasmas of the same condition; the effective perpendicular conductivity, or Cowling conductivity, becomes 5 to 6 orders smaller than the fully-ionized value in the lower chromosphere.
Flux Emergence and the Evolution of Large-Scale Photospheric Field Patterns
Authors: Wang Y.-M. , Sheeley N. R. 
Published: July 2016

AbstractStackplot displays of the photospheric magnetic field show long-lived patterns that often rotate at rates differing from the intrinsic photospheric rate. These complex patterns are produced naturally by the flux-transport model, in which magnetic flux emerging in the form of active regions is dispersed over the solar surface by differential rotation, supergranular diffusion, and a poleward meridional flow. Numerical simulations show that long-lived patterns with slopes similar to the observed ones arise even when the longitudes of the erupting flux are randomized, suggesting that a deep-seated longitudinal organization is not required to explain the qualitative nature of the patterns. Both autocorrelation analysis and visual comparison between the slopes of the observed and simulated patterns indicate that the equatorial rotation period of the Sun is close to 26.75 days, significantly shorter than the traditional 26.9 day value of Snodgrass and Newton & Nunn but in agreement with the recent measurements of Komm, Howard, & Harvey. A complete discussion of these results may be found in Sheeley, Wang, & Nash, ApJ, 401, 378 (1992).
Oscillations of the Magnetic Network
Authors: Lites Bruce W. , Rutten Robert J. , Kalkofen Wolfgang 
Published: July 2016

AbstractWe present high-quality power spectra of oscillations in the quiet solar chromosphere measured from the Ca II H line. They show unambiguously that the network does not participate in chromospheric three-minute oscillations, but that instead it oscillates in slow wave motions which are neither present in the surrounding non-magnetic chromosphere, nor in the underlying photosphere.
Fractal MHD Waves in the Solar Atmosphere
Authors: Nocera Luigi 
Published: July 2016

AbstractNonlinear MHD waves forced into a bounded cavity exhibit structural instability of their equilibria and periodic orbits as the forcing varies. For some values of the forcing the computed Poincaré maps, Lyapunov exponents and phase-space correlation reveal that the waves become chaotic; the Haussdorff dimension of the waves’ attracting set lies between its correlation dimension (≈ 2.2) and its information dimension (≈ 2.25).
MHD Simulations of Solar and Interplanetary Phenomena
Authors: Dryer M. 
Published: July 2016

AbstractWorkers in the field of magnetohydrodynamics (MHD) have been interested in the hypothesis that observed solar activities can be utilized in a deterministic way to predict the bulk flow consequences of these activities in the three-dimensional heliosphere. Exploration of this hypothesis, using the conventional/classic initial boundary value approach, will be reviewed against the background of basic, ideal (except for shocks) one-fluid approximations. This work has been divided into two parts: near-Sun simulations in two dimensions of coronal mass ejections (CMEs) as well as interplanetary simulations in 2D and 3D of propagating shocks. In the latter case, the flows behind the shocks should be thought of as interplanetary “ICMEs”, i.e., the interplanetary, evolutionary consequences of the near-Sun simulations.Initialization of these simulations has been based on observations (optical, soft X-ray, radio) from both ground- and space-based instruments. Simulation outputs have been compared within situplasma and field observations and interplanetary scintillations (IPS). Improvements in the initialization procedures - spatial/temporal variations of solar plasma and field parameters at the coronal base - are expected from YOHKOH, SOHO, CORONAS-I, and TRACE experiments. “Ground truth” observations from WIND, SOHO, ACE, and INTERBALL experiments should then be compared with three-dimensional MHD outputs in tests of the fluid hypothesis noted above.
MHD Compressive Turbulence in the Solar Wind and the Nearly Incompressible Approach
Authors: Bavassano B. , Bruno R. , Rosenbauer H. 
Published: July 2016

AbstractAt MHD scales density fluctuations in the solar wind generally have a relative amplitude less than 0.1. The nearly incompressible MHD theory would seem then appropriate to describe a major part of the compressive turbulence at these scales. As a test of the theory, we focus on the scaling properties of density fluctuations with turbulent Mach numbers and on the level of correlation between density and temperature fluctuations. Our findings do not appear in favour of an extended applicability of the nearly incompressible theory to MHD compressive turbulence in the solar wind.
Interplanetary Consequences of Transient Coronal Events Observed with YOHKOH SXT: A Case Study of Polar Coronal Transient on 15 May 1992
Authors: Watanabe T. , Nakagawa Y. , Kojima M. 
Published: July 2016

AbstractA large area (5 × 1010km2) of a coronal hole disappeared in concert with a transient brightening of a nearby high-latitude coronal arcade in the northern hemisphere on 15 May 1992. This coronal-hole disappearance took place in a time scale of half a day. It is suggested that the large-scale and quick change in coronal-hole geometry induced the eruption of originally closed coronal magnetic structure of the high-latitude arcade. An associated solar wind disturbance with the plasma speed of > 700 km/sec was observed by IPS, and geomagnetic sudden commencement was reported on 18 May 1992.
Luminosity Function and Evolution of Optically Selected QSOs
Authors: Wisotzki Lutz 
Published: July 2016

AbstractI summarise a few recent results on the evolution of optically selected QSOs, with special emphasis on the notoriously difficult but physically important extremes at low and high luminosities and redshifts. It seems that quasar evolution is a more complex phenomenon than has often been assumed, and the new generation of surveys is just about to make this visible.
The Byurakan-IRAS Galaxy (BIG) Sample: The Redshift Survey
Authors: Mickaelian A.M. , Balayan S.K. , Hakopian S.A. 
Published: July 2016

AbstractThe Byurakan-IRAS Galaxy (BIG) sample (1967 galaxies) is based on optical identifications of IRAS PSC sources at δ>+61° and |b| >15° (FBS area). A redshift survey for brighter objects (B<18m) is being carried out with the Byurakan Observatory 2.6m, Special Observatory 6m, and Observatoire de Haute-Provence 1.93m telescopes. 213 objects have been observed, and redshifts in the range 0.008-0.173 have been measured. For this subsample, 15% of the objects are AGNs, and 15% are LIGs and ULIGs.
AGN Populations from Optical Identification of ASCA Surveys
Authors: Akiyama Masayuki , Ueda Yoshihiro , Ohta Kouji 
Published: July 2016

AbstractTo understand luminous AGNs in the z < 1 universe, the ASCA AGN samples are the best at present. Combining the identified sample of AGNs from the ASCA Large Sky Survey and Medium Sensitivity Survey, the sample of hard X-ray selected AGNs has been expanded up to 108 AGNs above a flux limit of 10-13 erg s-1 cm-2 in the 2-10 keV hard X-ray band. We discuss the fraction of absorbed AGNs in the hard X-ray selected AGN sample, and the nature of absorbed luminous AGNs.
AGN and the Demographics of Supermassive Black Holes
Authors: Green Richard F. 
Published: July 2016

AbstractHigh angular resolution observations from WFPC and STIS now allow well-constrained dynamical measurement of the masses of supermassive black holes (SMBH) in nearby galaxies. An initial statistical analysis by Magorrian et al. showed that 97% of bulges host SMBH. Black hole mass is correlated moderately with bulge luminosity and strongly with the velocity dispersion of the whole bulge, suggesting that black hole formation may be an intrinsic aspect of bulge formation. Black hole masses for AGN determined from reverberation mapping fall on the same relationship with bulge velocity dispersion as those determined from stellar dynamical measurements. The prospect is therefore that the large-scale distribution of black hole masses in distant quasars may be determined through relatively straightforward measurement. Integral constraints show consistency between the total AGN luminosity density and the total volume density in SMBH contained in galaxy bulges. The strong peak of the high-luminosity quasar luminosity function at early cosmic time is consistent with the association of the build-up of SMBH through accretion and bulge formation. Alternate scenarios requiring substantial build-up of the most massive black holes at later cosmic times are more difficult to reconcile with the evolution of the LF.
The orbital evolution of some near-Earth asteroids
Authors: Timoshkova E.I. 
Published: July 2016

AbstractThe orbital evolution of the selected Near-Earth asteroids is studied by the numerical integration of the differential equations taking into account the perturbations due to all major planets for a time interval representing approximately 2000 revolutions of Jupiter. The new accurate DINCH integration procedure was used. Together with the orbital elements the Tisserand invariant is selected as a parameter to be investigated.
Spectral observations of comets with simple instruments
Authors: Avila G. , Guirao C. , Rodríguez J. , Alcalá J.M. , Pittichová J. 
Published: July 2016

AbstractLow resolution optical spectra of comet Hale-Bopp 1995 O1 taken with a simple equipment are presented. A small fiber feed spectrograph was used linked first to a telescope of 0.1 m aperture and then to another one of 0.25 m aperture. The qualitative survey of the evolution of the Na (λ5893) doublet in comet Hale-Bopp is reported.
Cometary dust trails and ejection velocities
Authors: Gajdošík M. , Klačka J. 
Published: July 2016

AbstractSome physical quantities are recalculated on the basis of the data for cometary dust trails presented in Sykes and Walker (1992). The final results for ejection velocities of meteoroids ejected from comets, trail ages and cometary mass loss rates are different from those presented in Sykes and Walker (1992). As a consequence, cometary mass loss rates may be higher than generally considered.
From the Solar system comet cloud to near-Earth space
Authors: Emel'yanenko V.V. 
Published: July 2016

AbstractThe dynamical evolution of objects from different zones of the solar system comet cloud to near-Earth space has been investigated. The steady-state number of objects with perihelion distancesq&lt; 1.5 AU and periodsP &lt;20 yr, arising from the near-parabolic flux of comets with absolute magnitudes brighter thanH10= 7 is ∼ 200 − 1000. The corresponding number for Halley-type comets is hundreds of times larger than the number of known Halley-type comets. The flux of objects in the Centaurs zone, captured from the near-parabolic flux is 300 times as large as the flux of new comets. The total number of cometary objects with semi-major axesain the range 50 &lt;a&lt; 500 AU andq∼ 1 AU is ∼ 10 times as large as the number of active comets. The probability of the transfer of objects from the trans-Neptunian orbits with 35 &lt;q&lt; 50 AU anda∼ 600 AU into the Jupiter family is ∼ 0.0001. The calculations show that trans-Neptunian objects on high-eccentricity orbits can be a significant continuous source for both the replenishment of the Oort cloud and the capture to short-period orbits.
Particle Acceleration in Solar Flares
Authors: Vlahos Loukas 
Published: July 2016

AbstractParticle acceleration during solar flares is a complex process where the main ‘actors’ (Direct (D.C.) or turbulent electric fields) are hidden from us. It is easy to construct a successful particle accelertion model if we are allowed to impose on the flaring region arbitrary conditions (e.g., strength and scale length of the D.C. or turbulent electric fields), but then we have not solved the acceleration problem; we have simply re-defined it. We outline in this review three recent observations which indicate that the following physical processes may happen during solar flares : (1) Release of energy in a large number of microflares ; (2) short time-scales; (3) small length scales; and (4) coherent radiation and acceleration sources. We propose that these new findings force us to reformulate the acceleration process inside a flaring active region assuming that a large number of reconnection sites will burst almost simultaneously. All the well-known acceleration mechanisms (electric fields, turbulent fields, shock waves, etc.) reviewed briefly here, can be used in a statistical model where each particle is gaining energy through its interaction with many small reconnection sites.
On-line Computing Facilities at Jodrell Bank
Authors: Davies J. G. 
Published: July 2016

An on-line computer has been in use at Jodrell Bank since 1964, both controlling the Mk II radio telescope and performing data processing functions in connection with it. However this system is now being superseded, and the following describes the present state of development, including some facilities that are only now being constructed.An Argus 400 computer is associated with each of the two main telescopes. Each has 12 000 words of core store, the word length being 24-bits, and the time for obeying most functions is 12 μs. The 24-bit word length is well suited to the application since more than 16-bit accuracy is required in the coordinate transformation. This fact, and the very versatile organization of the Argus computer, makes the effective speed relatively higher when compared with faster machines of smaller word size. In addition a drum store of about 50,000 words capacity will be fitted to each machine, and CRT and graphical output devices are available. Each machine operates a permanent program, which performs a number of functions, including in the case of the Mk II telescope the control of the instrument itself. In addition, up to three “user” programs may be operated simultaneously; these may be on-line data collection, with links to the telescope control sections, or completely off-line background jobs. A wide selection of library routine, available to all programs, is permanently in the core store, and this makes the writing of programs a relatively simple matter.
V1016 Cygni, Spectral Observations 1968—1971
Authors: Fitzgerald M. Pim 
Published: July 2016

AbstractIdentification of approximately 230 emission lines between 3120 Å and 5045 Å have been made on twelve plates taken between 1968 and 1971. The line intensities and ratios fail to give a consistent detailed picture of the nebula, but indicate that on average the electron pressure and density have changed little. The Balmer decrement has become less steep since 1968, indicating higher optical depth. However, the permitted iron lines have completely gone, indicating lower density. Excitation is increasing in some parts of the nebula, as indicated by the increased strength of the [Fe V] lines, and the recent appearance of strong lines of [Ne Y]. The continuum remains weak, though it is easily seen on plates taken on April 8, 1969, and on those taken in June 1971. The radial velocity of the object fluctuates between —50 and — 70 km/sec, and the line widths remain about 120 km/sec. The wing to the violet of the emission lines is still present. The continued brightness of this object, and the relative lack of change in the spectrum over several years, indicate even more strongly that V 1016 Cygni is likely to be a planetary nebula in the stages of formation.
OAO-2 Observations of Beta Lyrae and a Provisional Interpretation
Authors: Kondo Yoji , McCluskey George E. , Houck Ted E. 
Published: July 2016

AbstractSix-color ultraviolet photoelectric observations of Beta Lyrae obtained with OAO-2 are presented. These observations, made at 1380 Ǡ, 1500 Ǡ, 1920 Ǡ, 2460 Ǡ, 2980 Ǡ, and 3330 Ǡ, represent the first truly continual coverage of the light changes of Beta Lyrae during one orbital revolution and were obtained in November 1970. The photometric data are supplemented by spectral scans in the wavelength intervals 3800 Ǡ to 1800 Ǡ and 2000 Ǡ to 1050 Ǡ; the latter interval was scanned at 10 Ǡ resolution once during every OAO-2 orbit, i. e., about 100 minutes. Anomalous features, such as asymmetries and short and long term variations, are present in the light curves. A tentative discussion of solutions of the light curves is given. The problems of combining the photometric and spectroscopic information to arrive at a model of the system are also discussed.