bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coronal Heating: Theoretical Ideas
Authors: Hollweg Joseph V. 
Published: June 2019

After four decades of study, the mechanisms for heating the corona are not understood. However, the development of the field is vigorous. A variety of new ideas have been proposed, and these new ideas have generated lively debate. The goal of this short review is to present a broad overview of the ideas currently under consideration.It is now accepted that the solar magnetic field is the key ingredient. It is not known whether waves are important or not, but it is agreed that the magnetic (and possibly associated kinetic) energy must eventually appear in thin structures so that the (generally weak) dissipative processes can heat the plasma. This poses a problem of how the heat gets distributed throughout the corona.
The Molecular Spiral Structure in M51 Derived from CO(J=2-1) Line Observations
Authors: Guélin M. , Garcia-Burillo S. , Blundell R. , Cernicharo J. , Despois D. , Steppe H. 
Published: June 2019

AbstractWe present preliminary results of a high angular resolution-high sensitivity survey of CO(J = 2—1) line emission in M51 made with the IRAM 30 m telescope.
Co Observations of the Central Region of NGC4258
Authors: Sofue Yoshiaki 
Published: June 2019

Abstract12CO(J = 1-0) observations of the central region of NGC4258 at a resolution of 17” revealed a high-density concentration of molecular gas toward the center. The molecular clump lies on a central depression in the HI bar. No clear interaction of the molecular gas with the continuum anomalous arms has been found.
The Ratio of H2 to HI Gas in Infrared Luminous Galaxies
Authors: Mirabel I. F. , Sanders D. B. 
Published: June 2019

AbstractThe majority of infrared active galaxies (ffir/fb ≥ 2) have molecular to atomic mass fractions in the range of 0.5 to 2.0. Among the galaxies with the higher infrared excesses there are spectacular cases of HI deficient systems, where less than 15% of the total mass of interstellar gas is in atomic form. The optical morphology of luminous infrared galaxies suggest that the overall mass fractions of molecular to atomic gas, and the infrared luminosities per nucleon of interstellar gas are enhanced during galaxy-galaxy interactions.
Recent Ginga Results on Galactic X-Ray Binaries
Authors: Tanaka Y. 
Published: June 2019

AbstractBased on the recent Ginga results, following topics on X-ray binaries are briefly discussed: The cyclotron resonnance features observed from several X-ray pulsars, and related problem of the magnetic field decay. Search for millisec. pulsations from LMXRBs. Very bright transients which are suspected to be new black hole candidates, and an estimation of the number of such black hole sources in our galaxy.
Sigma Observations of the Galactic Centre
Authors: Cordier B. , Ballet J. , Goldwurm A. , Paul J. , Bouchet L. , Roques J.P. , Mandrou P. , Vedrenne G. , Sunyaev R. , Churazov E. , Gilfanov M. , Diachkov A. , Khavenson N. , Chulkov I. , Kuznetzov A. , Novikov B. 
Published: June 2019

AbstractAfter the first year of performance of SIGMA, more than 390 hours of data on the Galactic Centre region have been recorded. This survey establishes the extremely variable nature of this region. During a period of 6 months, 3 sources have dominated successively: 1E 1740.7-2942, GRS 1758-258, GX1 + 4. Concerning the two first sources, their spectral shape and their variability suggest to include them in the list of the black hole candidates.
The First EUV Survey: White Dwarfs and Cool Stars
Authors: Jordan C. , Pounds K.A. 
Published: June 2019

AbstractPreliminary results from the survey carried out with the Wide Field Camera (WFC) on ROS AT are presented. 732 sources were detected, of which 230 were observable in both the S1 and S2 filters. The distribution of sources with galactic longitude, near the galactic plane, shows the greatest number in the quadrant where H I absorption is least. The identifiable sources include a high proportion of hot white dwarfs and ‘normal’ late-type stars. The optical follow-up programme has identified over 40 new white dwarfs and over 60 late-type stars including RS CVn systems and cataclysmic variables. Emission from some A stars detected appears to come from white dwarf companions. Individual sources of particular interest are discussed. The systematic analysis of a sample of late-type stars has begun.
The Cosmic Infrared Background
Authors: Hauser M. G. 
Published: June 2019

AbstractCosmic infrared background radiation, expected to carry the radiative record of luminous objects since they first formed, has yet to be detected. The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) satellite is designed to search for this primeval background over the spectral range from 1 to 300 μm. Initial examination of data from this experiment show that foreground radiations from the solar system and Galaxy dominate the diffuse infrared sky brightness, with relative minima near 3.5 μm and in the submillimeter wavelength range. DIRBE measurements do not confirm some previous data from rockets and IRAS. Preliminary upper limits on the cosmic infrared background are generally above theoretical expectations for pregalactic and protogalactic sources, and substantially above estimated lower limits based upon observations of external galaxies. Careful foreground modeling is required to reduce these limits or identify an isotropic residual.
RATAN-600 and CMB Anisotropy: New RATAN-600 Limits
Authors: Parijskij Yu. N. , Erukhimov B. L. , Mingaliev M. G. , Chernenkov V. N. , Verkhodanov O. V. , Chepurnov A. V. 
Published: June 2019

AbstractWe present new limits on the small scale 3 K emission anisotropy. At scales of 1°-3.3° all seven harmonics have amplitudes below 10-5 in ΔT/T at our wavelength of 7.6 cm. At the 6.1x103 to 17.5x103 (rad-1) scale, this limit is about 2.8x10-4 (at 2.7 cm wavelength) and the observations may be fully explained by contributions from discrete sources. The low baryonic content of the Universe and present limit on the ΔT/T at the horizon scale suggest that (ΔM/M)gravitating ≪ (ΔM/M)baryonic. speculate that the 3 K anisotropy measurements prove a) the existence of the dark matter, b) the nonbaryonic nature of this dark matter and c) that the space distribution of this matter is much more homogeneous than that of the visible one.
The Hipparcos Observing Programme. Performances of the Input Catalogue
Authors: Turon C. , Arenou F. , Crifo F. , Gómez A. , Morin D. 
Published: June 2019

AbstractThe Hipparcos observing programme is composed of 118 000 selected stars, one QSO (3C273), 48 minor planets, and 2 satellites of major planets. These objects were selected on the ground of scientific proposals submitted by the world-wide astronomical community, while taking into account die specific operating mode of the satellite and using at best its observing possibilities. The content of the stellar part of this observing programme and the way in which the star selection was performed is described in details in a paper accepted for publication in Astronomy & Astrophysics.
Accuracy Uniformity of Hipparcos Parallaxes and Proper Motions: Strategy and Current Status
Authors: Crézé M. , Chareton M. 
Published: June 2019

AbstractEven before the launch difficulties, it was planned to monitor the trend of the accuracy acquisition resulting from the adopted observing process and eventually to modulate the initial values of the observing strategy parameters whenever it may help correcting distorsions in the final uniforme accuracy. Of course this monitoring of accuracy acquisition became more important when, as a result of the revised orbit, large departures from the nominal observations take place. The observing strategy and the associated modulation process behave according to expectation and may smooth out on the long range inhomogeneities. However important effects due to the complete lack of long sequences of observations in the early period in some regions will not be compensated unless the real mission extends substantially beyond the end of 92.
First Results of the Sphere Solution Based on HIPPARCOS Data
Authors: Lindegren L. , van Leeuwen F. , Petersen C. , Söderhjelm S. 
Published: June 2019

AbstractResults from a test solution of the positions and parallaxes for about 10,000 stars are presented in statistical form. The solution is based on about 1300 hours of Hipparcos observations made from November 1989 to February 1991, representing about 1/5 of the scientifically useful data collected in that period. Due to the short time span of the data no attempt was made to determine proper motions. The positions, many of which are already in the 2-5 milli-arcsec accuracy range, clearly reveal systematic errors of up to 0.2 arcsec in the ground-based positions of the Input Catalogue. Perhaps the most convincing evidence of the quality of the satellite data is provided by the distribution of trigonometric parallaxes determined in this solution. By comparison with the expected distribution of true parallaxes, based on a standard model of the Galaxy, we conclude that the external errors of the best parallaxes have a standard deviation around 5 milli-arcsec. Any global offset of the parallax zero point appears to be less than 1 milli-arcsec. The accuracy obtained is consistent with pre-launch predictions, if allowance is made for the reduced data collection efficiency due to the faulty orbit, and supports the assertion that the 2 milli-arcsec goal can still be reached in the present orbit. Details of the solution are being published in Astronomy & Astrophysics.
HIPPARCOS Main Mission Photometric Processing
Authors: Mignard F. , Froeschlé M. , Falin J.L. 
Published: June 2019

AbstractIn addition to its astrometric capabilitie the Hipparcos main detector proves to be a good phototometer. The main features of the reduction are outlined altogether with a presentation of some conspicuous results which already provide good clues as to the quality of the final results when more than three years of data are analysed.
Long Period Variable Stars in the Hipparcos Observing Program
Authors: Barthes D. , Boughaleb H. , Figueras F. , Foster E. G. , Mattei J. A. , Mennessier M. O. , Waagen E. O. 
Published: June 2019

AbstractAmong the long period variable stars included in the Hipparcos observing program, 245 large-amplitude ones require brightness predictions during the mission in order to allocate the necessary observing time. We present the computation of the light ephemerides with numeric and symbolic methods using AAVSO’s 75-year data on maxima and minima dates and magnitudes and 20 years of individuai observations; the evaluation and revision of the ephemerides using ground-based observations compiled monthly by the AAVSO from observers world-wide and real-time monitoring of ephemerides stars from satellite observations performed at ESOC; the statistical results derived from one-and-a-half years of simultaneous ground-based and Hipparcos observations. We show the usefulness of all this work in understanding the physics of these pulsating variable stars.
A Progress Report on optical and Radio Astrometry of Hipparcos Inertial Link Objects
Authors: Vegt C. De , Zacharias N. , Hughes J.A. , Hindsley R. , Johnston K.J. 
Published: June 2019

AbstractThe status of our longterm joint optical- and radio observing program for the establishment of a new inertial optical- and radio reference frame is described. A special attempt is made to provide a suitable number of extragalactic sources and radiostars for an inertial HIPPARCOS reference link.
Accuracy Predictions and Final Prospects for the HIPPARCOS Mission
Authors: Lindegren L. , Kovalevsky J. 
Published: June 2019

AbstractThe pre-launch accuracy prediction for the Hipparcos mission is reviewed with regard to the observed performance and expected lifetime of the satellite in its present orbit. Given the excellent quality of the data it is likely that the target accuracy of 2 milli-arcsec for typical programme stars can be achieved if operations continue at least until the end of 1993. We emphasize that any extension of the operational lifetime beyond that point strongly enhances the scientific value of the results.
Comparison of preliminary StarMapper positions with Carlsberg meridian circle observations
Authors: Morrison L.V. , van Leeuwen F. , Evans D.W. 
Published: June 2019

AbstractThe process of satellite attitude reconstruction carried out at RGO enables the assumed positions of the stars taken from INCA to be improved. The attitude reconstruction is determined from polynomial fits to the residuals between the observed StarMapper positions and those taken from INCA. The degree of the polynomial is such that smoothing occurs over a typical arc length of about 10°. The positions from different passes are combined, giving a typical internal accuracy for a star of 0"·02 in RA and Dec. The observations discussed here were accumulated from provisional magnetic tapes received from Darmstadt before the end of 1990.
HST Imaging of PSR1913+16
Authors: Crane Philippe 
Published: June 2019

AbstractAn image of the region of the binary pulsar PSR1913+16 has been obtained with the Planetary Camera on board the Hubble Space Telescope. This image confirms previous observations of a source coincident with the radio position of the pulsar to within 0,15 arcsec. The image shows a marginal extension not seen in other so urce of similar brightness in the field.
FOC Observations of SN 1987A
Authors: Panagia N. 
Published: June 2019

AbstractWe present and discuss the first images of SN 1987A obtained on day 1278 with the FOC on board the Hubble Space Telescope. The supernova is well detected and resolved spatially in the four observed bands. The UV luminosity of SN 1987A is found to be comparable to that emitted in the visible and infrared spectrum. Narrow-band [OUI] imaging reveals that the circumstellar nebula surrounding SN 1987A has the shape of a perfectly elliptical ring, implying an inclination of 43° ±3°. A comparison of the ring angular size with its absolute size derived from an analysis of the light curves of narrow UV lines measured with IUE, gives an accurate determination of the distance to SN 1987A, i.e. d(1987A) = 51.2±3.1 kpc. Allowing for the relative position of SN 1987A within the LMC, the distance to the center of the LMC turns out to be 50.1 ± 3.1 kpc. This value agrees very well with the determinations obtained from light curve analyses of variable stars.
White Dwarf Stars: Evolution of the Envelope Composition
Authors: Liebert James 
Published: June 2019

AbstractOver the last several years, evidence has been unfolding that the surface abundances of white dwarfs may evolve as the stars cool. It is possible that some post-AGB stars enter the white dwarf sequence with far less hydrogen and helium than predicted by standard theory of the quenching of shell sources, and with atmospheres dominated by C and O. The interplay of diffusion and episodes of convective mixing may lead first to He-rich atmospheres, then H-rich, and finally He-rich again.
Coronal Holes and the Solar Wind
Authors: Leer Egil 
Published: June 2019

Around the turn of the century Professor Kristian Birkeland at the University of Kristiania (Oslo) carried out laboratory studies of the emission of charged particles from the Sun and their interaction with comets and magnetized planets. He found that cathode rays emitted by a magnetized sphere are bent toward the equator along trajectories similar to the structures observed in the solar corona during the 1901 eclipse. He also concluded that comet tails are formed by charged particles from the Sun interacting with dust and gas around the comet.Birkeland carried out extensive observing programs of the aurora, geomagnetic storms, and the zodiacal light. During a 9 months campaign from mid 1902 he observed recurrent geomagnetic storms from stations in Northern Norway, at Novaja Semlja, Iceland, and Spitsbergen, and correlated the occurence and periodicity of magnetic storms with solar activity. He found that the period of recurrent geomagnetic storms was generally larger than the period of “near equator” solar phenomena. He also found that “Very often large maxima of storminess are not accompanied by any sun-spots at all”. (Birkeland 1913, p. 524).
No Backside Infall into the Great Attractor
Authors: Mathewson D.S. , Ford V.L. , Buchhorn M. 
Published: June 2019

AbstractWe have recently completed a survey of the peculiar velocities of 1355 southern spiral galaxies. The Tully – Fisher relation was used to estimate the distances to the spirals. The photometry was done in the I-band using CCDs on the lm telescope and the Anglo-Australian Telescope at Siding Spring Observatory. The rotational velocities were measured from 1042 H-alpha rotation curves obtained with the 2.3m telescope at SSO and 609 H 1 profiles obtained with the Parkes radio telescope.
Textures and Galaxy Formation
Authors: Spergel David N. 
Published: June 2019

AbstractTextures will produce positively skewed non-Gaussian primordial fluctuations. This implies that galaxies and quasars formed earlier in this model than in a Gaussian model with the same power spectrum. The model also predicts the existence of more high velocity dispersion clusters and richer superclusters. We describe the texture model and our numerical simulations of the origin of structure in the model.
A New Text from Asia Minor
Authors: Reynolds Joyce 
Published: June 2019

By courtesy of the owner, I publish a standard weight found in Asia Minor and now in the Collection Breusch. It is a hexagonal plaque of lead, pierced at one angle for suspension by a cord, of maximum width 0·16 m. and weight 2·6 kg. Both faces are inscribed with letters in relief, within a raised border. On face (a) the letters are above and on either side of a relief showing the bust of a curly-headed man facing right and carrying a caduceus over his left shoulder—certainly Hermes Agoraios, patron of the market-place. The inscription on face (b) is upside down to that on face (a).Face (a). Letters, c. 0·012; (See Plate I.)The final is badly formed and looks more like
Early Hellenistic Elegy: P. Sorbonn. 2254
Authors: Page Dennys 
Published: June 2019

Apart from Callimachus, I know no new piece of Hellenistic elegy more interesting than P. Sorbonn. inv. 2254, first published by M. Papathomopoulos in Recherches de Papyrologie II and most admirably edited by Professor Barns and Professor Lloyd-Jones in SIFC xxxv, 205 ff.Lloyd-Jones proves, I believe beyond question, two points:(a) That this elegy belongs to the world as it was before Callimachus; it is only our fourth large specimen of the literary elegy from the early part of the third century, the others being the long extracts from Hermesianax, Phanocles and Alexander Aetolus most conveniently read in Powell's Collectanea Alexandrina.(b) That the subject-matter is of a very unusual nature; the lines are ‘spoken by an unknown person threatening an enemy with a punishment quite out of the ordinary’ – viz. with tattooing on his skin the images of punishments suffered by notorious legendary sinners. The poet's enemy is to be tattooed with a picture of the stone of Tantalus, with another of the Calydonian boar sent to punish Oeneus, and with at least one other (there is a fragmentary second column, one line beginning στίξ[ω).
Horatian Notes II: Despised Readings in the Manuscripts of the Odes, Book II
Authors: Brink C. O. 
Published: June 2019

I continue on die lines set out in the last volume but one of these Proceedings. 1. C. II. 2. 19–20 numero beatorum / eximit Virtus (Prahaten). The noun beatus is well established in classical verse as well as prose, although naturally it never reached the substantival status of bonus or honestus. D. R. Shackleton Bailey's repointing of 1. 37. 9–10 contaminato cum grege turpium, / morbo uirorum, etc.,2 assumes a noun tur pis; thus Hor. S. 1. 6. 63–4 qui turpi secernis hones turn / non patre praeclaro, sed uita et pectore puro, A.P. 213 rusticus urbano confusus, tur pis honesto. These two passages suggest that it was the likeness of such terms as bonus or honestus that facilitated this usage. A search in the materials of the Latin Thesaurus (for which I am much obliged to Dr W. Ehlers) shows that this development is, as one might expect, much older than Horace. I am not thinking of Pl. Poen. 338 (where the notion is ‘plain, ugly’, promoted by the contrast with pulchra), but Cic. Att. x. 8. 2 turpissimorum honores, cf. Sen. Dial. VII. 8. ι nec minus turpes dedecus suum quam honestos egregia delectant, 24. 3 in turpes indignos que, Quint. I.O. III. 38 honestis contrasted with apud turpes.Shackleton Bailey pays tribute to Bendey's taste when he said ‘in illa locutione, uirorum turpium morbo, non agnosco elegantiam Flacci’, while (rightly) refusing the same critic's conjecture opprobriorum for morbo uirorum. At first I found it hard to believe that turpium could be divorced from morbo uirorum, the words immediately following. But now I think that the pun morbo uirorum, ‘men only in vice’, is highly persuasive, and likely, even in a text without punctuation, to be effective in dissociating uirorum from turpium.
Analysis of PrP genotype in relation to performance traits in Suffolk sheep
Authors: Roden J. A. , Haresign W. , Anderson J. M. L. 
Published: June 2019

At a time of high public awareness of food safety issues, particularly with respect to transmissable encephalopathies, and a government policy to eradicate scrapie, there is increasing pressure for breeders to select for scrapie resistance in sheep. Genetic variation has been identified at the PrP locus that confers differing degrees of susceptibility to scrapie. In the Suffolk breed this variation is confined to amino acid variations at codon 171, resulting in two alleles R and Q. Animals with the genotype RR and RQ show a greater degree of resistance to scrapie than animals with genotype QQ (Hunter, Moore, Hosie, Dingwall and Greig, 1997).Genotyping of pedigree animals has now become routine for many breeders and RR animals are favoured. It is, however, unknown whether there is a relationship between PrP genotype and performance traits. The objective of this study was to analyse the relationship between PrP genotype at codon 171 and the performance traits included in the Lean Index (Simm and Dingwall, 1989), which is used for selection in the Suffolk breed.
Contrasting ENSO Types With Satellite‐Derived Ocean Phytoplankton Biomass in the Tropical Pacific
Authors: Sharma Priya , Singh A. , Marinov I. , Kostadinov T. 
Published: June 2019

AbstractObserved variations in the tropical phytoplankton community structure and biogeochemical processes have been linked to the El Niño Southern Oscillation, a driver of large‐scale natural climate variability on interannual timescales. Satellite bio‐optical algorithms have allowed us to derive complex biological parameters from the surface ocean via remote sensing, providing a scientific platform to investigate biological relationships with climate indices. Studies have focused in‐depth on contrasting types of the ENSO types with various physical parameters with only a few recent studies focusing on satellite‐observed chlorophyll‐a, with however none focusing on phytoplankton biomass itself. Here we review the types of ENSO and its effect on backscattering‐based biomass using different statistical techniques, over the 1997‐2007 period. We also contrast the responses of phytoplankton biomass with those of chlorophyll‐a and their physical drivers in various types of ENSO. Signatures of various ENSO types are observed in the physical and biological fields.