bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prospects for automated solution of the subject characterization problem in the bibliographic services
Authors: Schiminovich S. 
Published: July 2016

AbstractEvidence is presented on the feasibility of an automated generation of classification schemes and the subsequent indexing of papers with the automatically generated subject headings. The output generated for Astronomy and Astrophysics compares favorably with the schemes used by the services and is not inconsistent with recently proposed classifications. Implementation of the automatic techniques seems not only feasible but desirable. However, it would require that the services include for each paper in their database its citations to other papers.
Astronomy and Astrophysics Abstracts : a status report
Authors: Schmadel L.D. 
Published: July 2016

AbstractThe astronomical bibliography ‘Astronomy and Astrophysics Abstracts’ (AAA) is the direct successor of the well-known ‘Astronomischer Jahresbericht’ (AJB). AAA is now going into its 13th year of existence. It is the aim of this contribution to outline the present status and the future plans of the abstracting and indexing work at the Rechen-Institut.
Improved Coude Efficiency of Existing Telescopes
Authors: Grundmann W.A. , Richardson E.H. 
Published: July 2016

AbstractThe ordinary coudé train has a single, large, aluminum coated mirror at each reflection point. This introduces considerable light loss because several reflections are required, and the long light path in turbulent air blurs the stellar image by telescope “seeing” effects. The transmission can be increased and the blur decreased by a train of small mirrors with high reflectance coatings. The high reflectance coatings have the added advantages that they can reduce polarization effects and flatten response curves.
Use of Large Telescopes in Fast Focal Ratio Mode – Application to the 6m Telescope (BTA)
Authors: Courtes G. , Boulesteix J. , Sivan J.P. , Petit H. , Karachentsev I. 
Published: July 2016

AbstractLarge aperture telescopes usually have an unavoidably long focal length so that stellar image diameters are often much larger than the resolution of the detector. The detection of extended sources can take advantage of a faster focal ratio and both stellar and extended monochromatic sources can be detected with great sensitivity by using interference filters and a focal reducer, without much loss in resolution. Extragalactic results obtained with the 6 meter telescope at focal ratio f/1 are given as examples.
Information Efficiencies of Telescopes and their Instrumentation
Authors: Rylov V.S. 
Published: July 2016

AbstractA criterion based upon information content allows one to obtain objective estimates of the efficiencies of astronomical observations for the whole system of light receiving and recording equipment, including the conditions of observation. The proposed method for calculating this information efficiency relies on the analysis of the output observational material and not on the characteristics of optical and electronic components of the instrumentation. The method is quite simple to use for comparison of different astronomical observations and instrumentation (Rylov, 1977, 1979; Karapetian and Oskanian, 1978).
The 200-Channel Spectrometer of the Crimean Astrophysical Observatory
Authors: Abramenko A.N. , Alexandrin Ju.S. , Prokof'eva V.V. , Yakushin V.N. 
Published: July 2016

AbstractA simple, low cost, television spectrometer has been constructed at the Crimean Astrophysical Observatory using an I-Isocon image tube for analog-digital recording of stellar spectra. High quantum efficiency (0.04) together with good accuracy (±0.3%) and repeatability are obtained.
Speckle Interferometry with the BTA Telescope
Authors: Dudinov V.N. , Konichek V.V. , Kuz'menkov S.G. , Tsvetkova V.S. , Rylov V.S. , Gyavgyanen L.V. , Erokhin V.N. 
Published: July 2016

AbstractThe description of a speckle camera used with the BTA 6-meter telescope is given. Observational data recorded on photographic film are processed with a Fourier optical spectrum analyzer. Results of binary star measurements are presented. Analysis of short exposure images of a point source obtained with telescopes of various sizes allows the estimation of atmospheric parameters which are necessary for correct application of speckle interferometry.
Experiments in Differential Speckle Interferometry
Authors: Beckers Jacques M. , Hege E. Keith 
Published: July 2016

AbstractWe propose to develop a technique to achieve submillisecond of arc resolution on stellar objects. It uses the fact that the spectrum of the light emitted by such an object often changes across its surface either because of Doppler shifts, Zeeman splitting, abundance anomalies or changes in the stellar atmosphere. By an appropriately designed experiment using narrow band (0.5 – 1 Å) filters, it is then possible to obtain differences between the position of speckles in the stellar image when viewed in slightly different wavelengths. It is possible to determine these differences in the position of the speckles with an accuracy much higher than the speckle size itself using techniques which are already developed for binary star-speckle research. We propose to use the technique of “Differential Speckle Interferometry” to study stellar rotation, evolution of stellar systems, spectroscopic binaries, the mass-luminosity relation, and peculiar A stars.
Measurements of Photon Statistics with Nanosecond Resolution
Authors: Dravins Dainis 
Published: July 2016

AbstractA photon-counting astronomical instrument for optical observations with nanosecond time resolution is being developed to observe the statistical distribution of photons in time. The purpose of this ‘quantum-optical spectrometer’ is to measure quantum-statistical properties of the photon gas and to study the physics of radiative deexcitation. The amount of photon bunching in time contains information on parameters such as the fraction of stimulated emission and the degree of frequency redistribution that the light has undergone.
Molecular clouds: comet factories?
Authors: Clube S.V.M. 
Published: July 2016

AbstractRecent discoveries seem to indicate a catastrophic history of terrestrial evolution, explicable in terms of Oort cloud disturbance by molecular clouds in the Galactic disc. The problem of Oort cloud replenishment thus assumes considerable significance and reasons are given for supposing comet exchange takes place during actual penetration of molecular clouds. The number density of comets in molecular clouds, thereby implied, seems to suggest primary condensations of ≤103km in a dense precursor state of spiral arms. If chemical and/or isotopic signatures of comets should indicate an extra-Solar System source, the theory of terrestrial catastrophism may place new constraints on our understanding of the origin of molecular clouds.
Empirical data from Oort’s cloud
Authors: Delsemme A.H. 
Published: July 2016

AbstractEmpirical evidence about the size and the origin of the Oort’s cloud of comets is confronted with theories about its origin. The slow diffusion of the orbits of the “new” comets into the inner solar system implies a redefinition of the concept of “new” comet. A gradual transfer of orbital angular momentum occurs from the planets to the comets as the comets grow older on shorter period orbits. The observed retrograde to prograde ratio of the new comets is difficult to explain. Either it comes from a poorly understood observational bias, or from a neglected secular action of the Galaxy, or it implies a recent asymmetrical perturbation of the Oort’s cloud (less than 10−20 million years ago). The grazing incidence of a giant molecular cloud or an exceptionally close stellar passage would introduce such an asymmetry; this would also be true for the unseen hypothetical stellar companion of the Sun recently invoked to explain the periodicity of the geological extinction of species through violent cometary showers.
Interrelations between comets and asteroids
Authors: Rickman Hans 
Published: July 2016

AbstractVarious aspects of comet/asteroid distinctions and interrelations are reviewed with emphasis on recent work and paying special attention to the following problems: characteristics of cometary activity at large heliocentric distance and uniqueness of comet P/Schwassmann-Wachmann 1 with respect to physical properties, the rôle of Trojans and other small bodies in the outer planetary system concerning comet/asteroid classification, possibilities for physical evolution of comets into asteroids, orbital and dynamical overlap of the comet and asteroid populations, and the cometary versus asteroidal origin of Earth-approaching asteroids. With regard to these latter questions it is argued that recent discoveries indicate a more substantial probability for Jupiter family comets to develop into asteroidal objects than earlier believed, and several examples of cometary association for newly discovered Apollo-Amor asteroids are also referred to. However, the fractional cometary contribution to the traditional Apollo-Amor asteroid population (aphelia far inside Jupiter’s orbit) apparently can not yet be reliably estimated.
On the rotation of cometary nuclei and small asteroids
Authors: Farinella P. , Paolicchi P. , Zappala V. 
Published: July 2016

AbstractThe spin rate distributions of comet nuclei and small asteroids are compared, and it is shown that Whipple’s (1982) finding of a faster average rotation for the asteroid sample was due to observational biases. In fact, the presently available rotational data do not exhibit any clear differentiation among comet nuclei and asteroids, except possibly for a higher abundance of short rotational periods among the Apollo-Amor objects.
Statistical and numerical studies of the orbital evolution of short-period comets
Authors: Carusi A. , Valsecchi G.B. 
Published: July 2016

AbstractThe evolutionary paths connecting cometary reservoirs in the outer solar system and the population of periodic comets involve stellar and planetary perturbations. Close planetary encounters play a special role, making the dynamical evolution slow or fast depending on the orbital elements of the comet at various stages of the process. In this paper numerical work done in the last decades on this subject, using both real and fictitious objects, is reviewed.
The aging and lifetimes of comets
Authors: Kresák Lubor 
Published: July 2016

AbstractThe aging of comets is evidenced by a number of observable phenomena: production of gas, dust and meteor particles, splitting of cometary nuclei, nongravitational effects in the comet’s motion, sudden and progressive absolute brightness variations, and ultimate disappearance. Statistical data on comet losses, absolute magnitudes and orbits also bear signatures of their aging. The knowledge of potential active lifetimes of individual objects is a prerequisite of any realistic model of the long-term evolution of the whole comet complex. This paper reviews different sources of information on the aging process and summarizes implications for the mean lifetimes of comets, their dispersion and dependence on the orbital parameters. Two alternative end fates of comets - their total disintegration or change into an inactive asteroid-like object - are also discussed.
The International Cometary Explorer (ICE) Mission to comet Giacobini-Zinner (G/Z)
Authors: Brandt J.C. , Farquhar R.W. , Maran S.P. , Niedner M.B. , von Rosenvinge T. 
Published: July 2016

AbstractThe ICE spacecraft will pass through the tail of P/Giacobini-Zinner on September 11, 1985, to make in situ measurements of particles, fields, and waves that will contribute significantly to the knowledge of plasma tails and other aspects of the cometary/solar wind interaction. By obtaining data on the downstream side of G/Z, the ICE will complement the later upstream measurements obtained by the Comet Halley probes.
Recent Rocket Observations of the Ultraviolet Spectrum of the Zodiacal Light
Authors: Feldman P.D. , Cebula R.P. , Tennyson P.D. , Henry R.C. 
Published: July 2016

AbstractObservations of the spectrum of the zodiacal light in the wavelength range 1800-3000 Å have been obtained in two recent sounding rocket experiments. The September 1979 observation was made close to the ecliptic plane at elongation angles of 20° and 28° and with a spectral resolution of 25 Å, while in April 1981 the elongation was 125° (inclination 60°), and the spectral resolution 50 Å. Both observations confirm the slight reddening in the ultraviolet reported previously and show the same dependence on elongation as in the visible. There appears to be some structure in the ultraviolet albedo of the dust grains near 2800 Å but the exact nature of this structure cannot be determined at the low spectral resolution of the present observations. Detailed descriptions of the two observations has been given by Cebula and Feldman (1982) and Tennyson (1983), respectively.
A Search for Small Scale Structures in the Zodiacal Light
Authors: Hong S.S. , Misconi N.Y. , van Dijk M.H.H. , Weinberg J.L. , Toller G.N. 
Published: July 2016

AbstractGegenschein observations from Pioneer 10 were found to have brightness structures with an amplitude of about 10% and a period of several to ten degrees in elongation. A search is made for such structures in high angular resolution ground-based observations from Mt. Haleakala, Hawaii. A new empirical method is used to correct for atmosphere-originated radiation. Background starlight is subtracted using Pioneer 10 observations from beyond the asteroid belt. Preliminary analysis of the ground data also indicates the presence of small amplitude structures in the brightness distribution.
IRAS Observations of the Interplanetary Dust Emission
Authors: Hauser M.G. , Gautier T.N. , Good J. , Low F.J. 
Published: July 2016

AbstractThe Infrared Astronomical Satellite (IRAS) has completed a sensitive, highly redundant survey of the full sky in four broad photometric bands at 12, 25, 60, and 100 micrometers wavelength. The survey measured interplanetary dust emission over elongation angles ranging from 60 to 120 degrees. Bright emission from the main cloud is consistent with optically thin blackbody emission. The grains are evidently quite black, with an “apparent albedo” of about 0.07. The data show clear evidence for deviation of the dust symmetry surface from the ecliptic plane. Surprising bands of emission were discovered near the ecliptic plane and about ten degrees on either side of it. The heliocentric distance of this material, suggested to be asteroidal in origin, is inferred to be about 2.5 AU from both color temperature and parallax measurements.
A Balloon Observation of the Thermal Radiation from the Circumsolar Dust Cloud in the 1983 Total Eclipse
Authors: Maihara T. , Mizutani K. , Hiromoto N. , Takami H. , Hasegawa H. 
Published: July 2016

AbstractDuring the totality on June 11, 1983 in East Java, Indonesia, a near infrared photometric observation of the solar corona was made using a stratospheric balloon, which was successfully launched by a joint team of ISAS, Japan and LAPAN, Indonesia. The surface brightness distributions in four near infrared bands: at 1.25, 1.65, 2.25 and 2.8 μm, have been obtained in the outer coronal region. Noticeable excess emissions superposed on the strong coronal background emission have been recorded in the scan profiles at 1.25 and 1.65 μm, and less conspicuously at 2.25 μm as well, at about 4 R⊙ from the sun. From the observed spectral and spatial characteristics, the excess emission component appears to originate in the thermal radiation from the circumsolar dust ring made of relatively large particles of about 100 μm in radius and with the olivine-like optical properties.
On the Earth’s Dust Envelope
Authors: Barsukov V.L. , Nazarova T.N. 
Published: July 2016

AbstractThe data of studying meteoric particles on Elektron-1 and Elektron-3 space vechicles were processed in a new way which made it possible to get the first idea of the Earth’s dust envelope structure. Meteoric matter is distributed in it not unformly, but as aggregations of particles moving around the Earth in more or less stable orbits at certain distances from the Earth’s surface.
Measurements of the Elemental and Isotopic Composition of Interplanetary Dust Collected on LDEF
Authors: Fechtig H. , Hörz F. , Igenbergs E. , Jessberger E. , Kuczera H. , Lange G. , Pailer N. , Sutton S. , Swan P. , Walker R. , Zinner E. 
Published: July 2016

AbstractA passive interplanetary dust collection experiment, currently in orbit aboard LDEF (Long Duration Exposure Facility), is described. The collectors, germanium target plates covered by metallized Mylar foils, are designed for secondary ion mass spectrometry (SIMS) measurements of the elemental and isotopic compositions of residues resulting from micrometeoroid (> 10−10 grams) impacts. Impact simulation experiments have demonstrated the validity of the collection concept. Quantitative elemental analyses are complicated by the non-uniform distribution of projectile-derived elements.
A Discover of Iron Spherules with Golden Ni-Fe Core and Silicate Spherules With Golden Ni-Fe Inclusion in Deep-Sea Sediments
Authors: Hanchang Peng , Shijie Zhuang , Zhenkun Liu , Zhong Yu 
Published: July 2016

AbstractRecently, we found iron spherules with golden Ni-Fe core and silicate spherules with golden Ni-Fe inclusion in deep-sea sediments. This finding is of significance for further understanding of the origin of the deep-sea spherules.
26A1/10Be in Deep Sea Spherules as Evidence of Cometary Origin
Authors: Raisbeck G.M. , Yiou F. , Klein J. , Middleton R. , Brownlee D. 
Published: July 2016

AbstractUsing accelerator mass spectrometry the cosmogenic isotopes 26A1 (half-life 716,000 years) and 10Be (1.5 × 106 years) have been measured in deep sea magnetic spherules. Because 26A1 can be abundantly produced by relatively low energy solar flare particles, while 10Be is mainly produced by higher energy galactic cosmic rays, the ratio 26Al/10Be of a body irradiated in space increases as the size of the body decreases. Our measured ratios of 26Al/10Be in the spherules are much larger than found in meteorites, and indicate irradiation in interplanetary space of a parent body of ≲ 1 cm diameter. Since most bodies of this size entering the atmosphere are associated with cometary orbits, our results strongly suggest that these spherules represent cometary debris. Our results also suggest an irradiation time in space of the order of 106 years for the parent bodies.
Chemical and Isotopic Compositions of Refractory Elements in Deep Sea Spherules
Authors: Yamakoshi Kazuo , Honma Koichi 
Published: July 2016

AbstractIn order to study the inhomogeneity of the solar materials at the initial state, the enrichment factors and isotopic anomalies of refractory elements in deep sea spherules relative to the average solar abundance were examined using instrumental neutron activation analysis. Fairly high enrichment factors and isotopic anomalies of refractory elements were observed in several spherules, however, after the ablation process of the spherules during the atmospheric heatings they were not inconsistent with those of normal values in the solar system.
Remote Sensing of the Zodiacal Cloud along Secants to Earth’s Orbit
Authors: Dumont René , Levasseur-Regourd Anny-Chantal 
Published: July 2016

AbstractPartial but significant localization along the line of sight (l.o.s.) of the contributions to the integrated zodiacal brightness can be achieved, without recourse to rash physical assumptions, if we focus on the two intersections between the l.o.s. and the terrestrial orbit. Then, there exists on the l.o.s. two other points or “nodes”, the contributions of which can be retrieved with outstandingly low uncertainty. The photometric results at these nodes (heliocentric change of scattering efficiency, backscattering phase function etc.) are highly reminiscent of previously ascertained features, and they encourage extensions to the polarimetric, the spectrometric and the radiometric cases. The salient results are, respectively: a positive radial gradient of local polarization degree; orbital velocities in excess over the keplerian ones, at least outside the earth’s orbit; the derivation of local temperatures from IRAS data.
Experimental Results on Scattering by Irregular and Meteoritic Dust Particles Related to Photopolarimetry of Zodiacal Light and Comets
Authors: Weiss-Wrana K. , Giese R.H. , Zerull R.H. 
Published: July 2016

AbstractThe investigations of light scattering by larger meteoritic and terrestrial single grains (size range 20 μm to 120 μm ) demonstrate that the scattering properties of irregularly shaped dark opaque particles with very rough surfaces resemble the characteristic features of the empirical scattering function as derived from measurements of the zodiacal light. Purely transparent or translucent irregularly shaped particles show a quite different scattering behaviour. Furthermore irregular and multicomponent fluffy particles in the size range of a few microns were modelled by microwave analog measurements in order to explain positive and negative polarization of the light scattered by cometary dust grains.
On the Bimodal Nature of the Particle-Size-Distribution Function of Cometary Dust
Authors: Liu C.P. , Kimura H. 
Published: July 2016

AbstractThe bimodal nature of distribution function f(γ) is confirmed by analysing the optical isophotal maps of comets Kohoutek 1973 XII and Bennett 1970 II. Extending the dynamic analysis to the infra-red data of two comets, Kohoutek 1973 XII and IRAS-Araki-Alcock 1983 d, we demonstrate that the secondary component f2(γ), which dominates in the range of large particles, plays a much more important role in emitting the thermal radiation (IR) than in the case of light scattering (optical). The relative weight of two components, measured by their height ratio, g2/g1, should be increased by a factor of about 20, in order to obtain a good fitting to the infra-red data.
On the Electrical Effects of the Presence of Fluff on the Surface of Cosmic Dust Grains
Authors: Lafon J.P. , Millet J.M. 
Published: July 2016

AbstractWe give a n analytical model describing the effects of “fluff” on the potential and the electric field on and close to a charged spherical body embedded in an astrophysical plasma. The consequences are investigated for dust grains biased at positive or negative potentials but large enough for electron or ion field emission to be active.
Dynamics of Dust Particles in the Solar System
Authors: Burkhardt G. 
Published: July 2016

This short communication is part of a thesis at the University of Heidelberg, FRG.It deals with some dynamical aspects of small interplanetary particles, which are affected by non-gravitational forces like the Poynting - Robertson Effect.The equations of motion of test particles are numerically integrated. The forces acting on these particles include the gravitational attraction of the Sun and the Planets as well as forces due to incident solar radiation.The ephemerides of the Planets in the heliocentric rectangular 3-dimensional coordinate system used here are taken from the Development Ephemeris DE-102 (Newhall et al. 1983) . This restricts the time span of the integration to about 4412 years.
Broad-Band Spectroscopy of Late-Type Stars with Exosat
Authors: Landini M. , Monsignori-Fossi B.C. , Pallavicini R. 
Published: July 2016

AbstractWe analyze 6–300Å observations of late-type stars obtained with EXOSAT. We discuss the problem of deriving source temperature and other physical parameters from broad-band EXOSAT observations.