bluuebunny/crossref_metadata_2025_split huggingface dataset:
Note on the Determination of the Neaely Diurnal Free Nutation (Core Nutation) and the Principal Term of Nutation Based on the Astrometric Data
Authors: Yatskiv Ya.S. , Kovbasyuk L.D. 
Published: July 2016

Due to the highly accurate determination of the corrections to the nutation terms (the IAU-1980 nutation theory) by VLBI observations, the proposal for adoption of the new nutation theory or standard model of nutation is being discussed. At this point there are two unsolved problems:(a)VLBI observations can’t provide reliable estimates of the principal nutation term. The reason is that the correlation between this term and the precession constant is high due to the insufficient time span of these observations (about 10 years).(b)period of free core nutation (FCN) which depends on the ellipticity of the mantle-core boundary has not been, so far, reliably determined from direct observations.In the present paper, we would like to draw attention to the results of the analysis of astrometric latitude and time observations which could be useful for resolving these problems.
New Initiatives for Synoptic Observations
Authors: Keller C. U. 
Published: July 2016

AbstractSeveral new synoptic facilities for long-term studies of the Sun will become operational within the next few years. This paper summarizes information on some of these projects, in particular GONG+, ISOON, GOES/SXI, and SOUS. SOUS, the Synoptic Optical Long-Term Investigations of the Sun, is currently being built by the National Solar Observatory and will become operational in 2001. It consists of a 50-cm vector spectromagnetograph, a 14-cm full-disk patrol, and an 8-mm sun-as-a-star spectrometer.
The Large-Scale Magnetic Field and Sunspot Cycles
Authors: Makarov V. I. , Tlatov A. G. 
Published: July 2016

Extended abstractWe report on the correlation between the large scale magnetic field and sunspot cycles during the last 80 years that was found by Makarovet al. (1999) and Makarov &amp; Tlatov (2000) in H-αspherical harmonics of the large scale magnetic field for 1915–1999. The sum of intensities of the low modes 1 = 1 and 3, A(t), was used for comparison with the Wolf number, W(t). It was shown that the large scale magnetic field cycles, A(t), precede the sunspot cycles, W(t), by 5.5 years.Let us consider the behaviour in time of the harmonics with low numbers 1 = 1 and 1 = 3. The radial component B(r) of the magnetic field may be expanded in terms of the spherical harmonicswhereθandϕare the latitude and longitude,are Legendre polynomials andandare coefficients of expansion on the spherical functions.The magnetic moments of a dipole (1 = 1) and an octopole (1 = 3) are determined by the following equations:Let us enter the parameter describing their intensity,
Cyclic Evolution of Sunspots: Gleaning New Results from Old Data
Authors: Solanki S. K. , Fligge M. , Pulkkinen P. , Hoyng P. 
Published: July 2016

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.
Vector Magnetic Fields, Sub-surface Stresses and Evolution of Magnetic Helicity
Authors: Canfield Richard , Pevtsov Alexei 
Published: July 2016

AbstractObservations of the strength and spatial distribution of vector magnetic fields in active regions have revealed several fundamental properties of the twist of their magnetic fields. First, the handedness of this twist obeys a hemispheric rule: left-handed in the northern hemisphere, right-handed in the southern. Second, the rule is weak; active regions often disobey it. It is statistically valid only in a large ensemble. Third, the rule itself, and the amplitude of the scatter about the rule, are quantitatively consistent with twisting of fields by turbulence as flux tubes buoy up through the convection zone. Fourth, there is considerable spatial variation of twist within active regions. However, relaxation to a linear force-free state, which has been documented amply in laboratory plasmas, is not observed.
Stokes Polarimetry at the Kodaikanal Tower Tunnel Telescope
Authors: Sankarasubramanian K. , Srinivasulu G. , Ananth A. V. , Venkatakrishnan P. 
Published: July 2016

AbstractA Stokes polarimeter has been developed using a masked CCD arrangement for the measurement of the vector magnetic field of sunspots. Charge shifting within the CCD is used to record near simultaneous orthogonal polarisation. The testing of the Stokes polarimeter and the behavior of the integrated system combined with the Kodaikanal tower tunnel telescope will be discussed.
An Operator Perturbation Method of Polarized Line Transfer V. Diagnosis of Solar Weak Magnetic Fields
Authors: Nagendra K. N. , Frisch H. , Faurobert-Scholl M. , Paletou F. 
Published: July 2016

AbstractWe present an application of the PALI (Polarized Approximate Lambda Iteration) method to the resonance scattering in spectral lines formed in the presence of weak magnetic fields. The method is based on an operator perturbation approach, and can efficiently give solutions for oriented vector magnetic fields in the solar atmosphere.
Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening
Authors: Raman K. Sundara , Ramesh K. B. , Selvendran R. , Aleem P. S. M. , Hiremath K. M. 
Published: July 2016

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust &amp; Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust &amp; Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.
Parametric Study of Molecular Line Polarization in the Solar Atmosphere
Authors: Rangarajan K. E. , Rao D. Mohan 
Published: July 2016

Extended AbstractThe polarimetric observations of the quiet sun show linear polarization in molecular lines of C2, MgH, etc. The molecular lines are very faint in the intensity spectrum. Q branch transitions of MgH are considered in this study. Using radiative transfer calculations, we find that the intensity and polarization profiles of MgH lines can be matched for a range of inelastic collisional rates (ΓI) and depolarizing elastic collision rates (D(2)) of the transitions in solar atmosphere. It is shown that the physical constraints imposed on these parameters can be used to estimate them. This procedure also allows us to get the oscillator strength (f). It is found for the strong line 5156.652 Å,f= 0.12, ΓI, = 5.59 × l07sec−1andD(2)= 1.29 × 108sec−1. Most of the other lines observed are weak by a factor of 3 in intensity compared to the 5156.652 Å line but show a polarization value of the order of 0.08%. One such typical line is 5156.997 Å. This line can be fitted for the parametersf= 0.04, ΓI, = 1.22 × 107sec−1andD(2)= 2.95 × 107sec−1.
Dynamical Processes in Flux Tribes and their Role in Chromospheric Heating
Authors: Hasan S. S. 
Published: July 2016

AbstractWe model the dynamical interaction between magnetic flux tubes and granules in the solar photosphere which leads to the excitation of transverse (kink) and longitudinal (sausage) tube waves. The investigation is motivated by the interpretation of network oscillations in terms of flux tube waves. The calculations show that for magnetic field strengths typical of the network, the energy flux in transverse waves is higher than in longitudinal waves by an order of magnitude. But for weaker fields, such as those that might be found in internetwork regions, the energy fluxes in the two modes are comparable. Using observations of footpoint motions, the energy flux in transverse waves is calculated and the implications for chromospheric heating are pointed out.
Perspectives on the Interior of the Sun
Authors: Chitre S. M. 
Published: July 2016

AbstractThe interior of the Sun is not directly accessible to observations. Nonetheless, it is possible to infer the physical conditions inside the Sun with the help of structure equations governing its equilibrium and with the powerful observational tools provided by the neutrino fluxes and oscillation frequencies. The helioseismic data show that the internal constitution of the Sun can be adequately represented by a standard solar model. It turns out that a cooler solar core is not a viable solution for the measured deficit of neutrino fluxes, and the resolution of the solar neutrino puzzle should be sought in the realm of particle physics.
Helioseismic Search for Magnetic Field in the Solar Interior
Authors: Antia H. M. , Chitre S. M. , Thompson M. J. 
Published: July 2016

AbstractThe observed splittings of solar oscillation frequencies can be utilized to study possible large-scale magnetic fields present in the solar interior. Using the GONG data on frequency splittings an attempt is made to infer the strength of magnetic fields inside the Sun.
Solar Internal Rotation and Dynamo Waves: A Two-Dimensional Asymptotic Solution in the Convection Zone
Authors: Belvedere Gaetano , Kuzanyan Kirill , Sokoloff Dmitry 
Published: July 2016

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan &amp; Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.
The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO
Authors: Curdt W. , Dwivedi B. N. , Feldman U. 
Published: July 2016

AbstractWe present results from sunspot observations obtained by SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of systematic downflow. We also discuss the properties of sunspot oscillations.
Multibaseline Observations of the Occultation of Crab Nebula by the Solar Corona at Decameter Wavelengths
Authors: Subramanian K. R. 
Published: July 2016

Extended abstractInformation about the outer solar corona can be obtained by observing the occultation of radio sources by the solar corona. As the radio waves pass through the corona they get scattered due to the fact that the electron density and consequently the refractive index varies from point to point. The effect of scattering is manifested by an apparent increase in the angular size of the radio source which can be measured by suitable interferometers. We present here multibaseline observations on the occultation of Crab Nebula at 34.5 MHz with baselines extending upto 4.9 km during June 1986 and 1987.
Heliospheric Magnetic Fields, Energetic Particles, and the Solar Cycle
Authors: Király Péter 
Published: July 2016

AbstractThe heliosphere is the region filled with magnetized plasma of mainly solar origin. It extends from the solar corona to well beyond the planets, and is separated from the interstellar medium by the heliopause. The latter is embedded in a complex and still unexplored boundary region. The characteristics of heliospheric plasma, fields, and energetic particles depend on highly variable internal boundary conditions, and also on quasi-stationary external ones. Both galactic cosmic rays and energetic particles of solar and heliospheric origin are subject to intensity variations over individual solar cycles and also from cycle to cycle. Particle propagation is controlled by spatially and temporally varying interplanetary magnetic fields, frozen into the solar wind. An overview is presented of the main heliospheric components and processes, and also of the relevant missions and data sets. Particular attention is given to flux variations over the last few solar cycles, and to extrapolated effects on the terrestrial environment.
Stochasticity of the Orbit of the Asteroid 1989 AC
Authors: Benest D. , Froeschlé C. , Gonczi R. 
Published: July 2016

AbstractUsing mainly Lyapunov Characteristic Indicators, the stochasticity of the orbit of the asteroid 1989 AC has been investigated in the framework of three-body, five-body and seven-body restricted models. From our first results, the orbit of 1989 AC has been found fairly chaotic, through an interplay of the 3/1 resonance with Jupiter and close approaches with the inner planets.
Linear Polarization in Close Binaries
Authors: Parman S.K. , Peraiah A. 
Published: July 2016

AbstractTheoretical models have been computed for estimating linear polarization from the extended dusty outer layers of the components of close binary stars whose surfaces are distorted by rotation and tidal effects due to the presence of secondary. We have assumed plane-parallel layers of the dusty atmospheres of the components. We have employed a wavelength dependent scattering coefficient, and Rayleigh phase function is used in solving the equation of radiative transfer . It is noticed that polarization increases with decreasing the wavelength and increasing the particle size. Polarization for uniform rotation is larger than that for non-uniform rotation. Polarization for the single stars is always less than that for a binary component.Subject headings: polarization - radiative transfer - stars: binaries - stars: late-type
Encounter in the Keplerian Field: Analytical Treatment
Authors: Brumberg V.A. , Ivanova T.V. 
Published: July 2016

AbstractIn extending the results of Henon and Petit (Celes.Mech., 38,67, 1986) an algorithm is suggested to construct the series representing the general encounter-type solution of the spatial eccentric Hill’s problem. The series are arranged in powers of the eccentricity E of Hill’s problem and two integration constants e and k characterizing eccentricity and inclination of the relative motion. A particular non-periodic solution of Henon and Petit corresponding to E = e = k = 0 is taken as an intermediary. The perturbations to this solution are constructed similar to the Lunar theory of Hill and Brown with; the Universal Poissonian Processor. From theoretical point of view Hill’s problem for the encounter case is of particular interest. In distinction from the Lunar problem we do not have here angular arguments with different frequencies. Moreover, the perturbations related with the external eccentricity E (analogous to the perturbations in the motion of the motion of the Moon caused by the eccentricity of the orbit of the Sun) are of resonance character.
Hierarchy of Periodic Solutions for Hamiltonian Systems and their Applications to Celestial Mechanics
Authors: Barkin Yu.V. 
Published: July 2016

AbstractA systematic investigation has been carried out for periodic solutions for standard-form Hamiltonian systems containing a small parameter/the principal problem of dynamics/. An efficient method of investigation of conditions for periodicity of solutions has been developed. Besides fitting the initial conditions of the action-angle variables, the idea of fitting the values of the parameters of the problem is used. Constructive conditions are obtained for the existence of periodic solutions in both principal and degenerate cases, as well as necessary conditions for their stability; algorithms have been developed for constructing these solutions as series in integer powers of the small parameter. To study particular periodic solutions /by high order resonances/, canonical transformations of the initial equations to a special form are used.
In-Situ Exploration of Dust in the Solar System and Initial Results from the Galileo Dust Detector
Authors: Grün E. , Fechtig H. , Hanner M. S. , Kissel J. , Lindblad B.-A. , Linkert D. , Morfill G. , Zook H. A. 
Published: July 2016

AbstractIn-situ measurements of interplanetary dust have been performed in the heliocentric distance range from 0.3 AU out to 18 AU. Due to their small sensitive areas (typically 0.01 m2for the highly sensitive impact ionization sensors) or low mass sensitivities (≥10−9g of the large area penetration detectors) previous instruments recorded only a few 100 impacts during their lifetimes. Nevertheless, important information on the distribution of dust in interplanetary space has been obtained between 0.3 and 18 AU distance from the Sun. The Galileo dust detector combines the high mass sensitivity of impact ionization detectors (10−15g) together with a large sensitive area (0.1 m2). The Galileo spacecraft was launched on October 18, 1989 and is on its solar system cruise towards Jupiter. Initial measurements of the dust flux from 0.7 to 1.2 AU are presented.
Aqueous Alteration in Hydrated Interplanetary Dust Particles
Authors: Tomeoka Kazushige 
Published: July 2016

AbstractInterplanetary dust particles (IDPs) characterized by chondritic composition can be divided into two principal groups, anhydrous and hydrated. This paper summarizes recent results of mineralogical and petrological studies dealing with the IDPs of hydrated type. Studies on mineralogical characteristics, infrared absorption spectra, and isotopic properties of the hydrated particles have suggested that they are primitive and may contain surviving interstellar material. The hydrated IDPs consist in major part of layer silicates and resemble CI and CM carbonaceous chondrites. Mineralogical and chemical data of both IDPs and carbonaceous chondrites have accumulated, and it is now possible to compare the mineralogies of the IDPs and the meteorites in considerable detail. Evidence was found that a significant proportion of the hydrated IDPs have been processed by aqueous alteration, and the nature of the alteration resembles that of similarly affected meteorites. The mineralogical and chemical data provide important clues to the possible origins of IDPs.
The Effect of Total Pressure on Vaporization of Alkalis from Partially Molten Chondritic Material
Authors: Shimaoka Taro , Nakamura Noboru 
Published: July 2016

AbstractIn order to examine the effect of total pressure on vaporization of alkalis (Na, K, Rb) from a partially molten chondritic material, heating experiments were carried out under various He gas pressures (~10−5-~10−1torr) at 1300°C. The rate of vaporization decreased in the order of Na &gt; K &gt; Rb with the increasing of the pressure, and reached a minimum at ~10−1torr.
Optical Constants Of Kerogen From 0.15 To 40 μm: Comparison with Meteoritic Organics
Authors: Khare B.N. , Thompson W.R. , Sagan C. , Arakawa E.T. , Meisse C. , Gilmour I. 
Published: July 2016

AbstractA vacuum evaporation technique has been used to produce thin, optical quality films of samples of Type II kerogen and of insoluble organic residue from the Murchison meteorite. Using these films, optical constants have been measured from 0.15 to 40 μm for kerogen, and from 2.5 to 40 μm for the Murchison residue. The infrared absorption properties of these materials show many similarities, although Murchison residue is more opaque throughout the infrared than is kerogen, and shows no distinct aliphatic absorptions.
Optical Constants of Basaltic Glass from 0.0173 To 50 μm
Authors: Arakawa E. T. , Young D. W. , Zhang J. M. , Eklund P. C. , Khare B. N. , Thomson W. R. , Sagan C. 
Published: July 2016

AbstractPollacket al. [Icarus19, 372 (1973)] have reported the optical constants for obsidian, basalt, andesite and basaltic glass over the wavelength range 0.2 to 50 μm, and Lamy [Icarus34, 68 (1978)] reported the optical constants from 0.10 to 0.44 μ for obsidian, basalt, and basaltic glass. We have revised the former measurements for basaltic glass and extended them into the extreme UV to 0.0173 μ.
Studies on Isotopic Ratios of Osmium and Iridium in Cosmic Spherules Using Instrumental Neutron Activation Analysis
Authors: Yamakoshi Kazuo , Nogami Ken’ichi 
Published: July 2016

AbstractStudies on isotopic anomalies in cosmic meteoroids are expected to reveal the features of nuclear synthesis in various phases of star-evolution. The respective isotopes of noble metals had been produced through various reaction processes as well as in various regions of star-eruptions. However, isotopic anomalies of 0s in extremely refractory inclusions of primordial carbonaceous chondrites have not been found up to now. In this work, isotopic ratios of the elements having high condensation temperatures, such as 0s and Ir, in the cosmic spherules are examined using instrumental neutron activation analysis(INAA).
Ultraviolet Observations of the Zodiacal Light and the Origin of Interplanetary Dust Grains
Authors: Lillie C. F. 
Published: July 2016

AbstractSurface brightness photometry of the night sky from rocket and satellite experiments shows an increase in the scattering efficiency of interplanetary dust grains in the 1500 to 3000 \ region of the spectrum. This increase is best explained by the presence of small dielectric particles with a mean radius of 0.04 microns. The most likely source of these grains is the dissolution of agglomerates of these particles which are released by comets during their perihelion passage. Many of these agglomerates have been collected in the Earth’s atmosphere by high flying aircraft. Submicron particles swept up from interplanetary space may be responsible for the high altitude haze observed in planetary atmospheres.