bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hipparcos – The Tycho Input Catalogue
Authors: Russell J.L. , Egret D. 
Published: June 2019

AbstractThe Tycho Input Catalogue will be used as a finding list to identify the stellar data within the stream of raw data received from the Hipparcos star mappers. It is based on an a priori list of stars, namely the Guide Star Catalogue being created for the Hubble Space Telescope at the Space Telescope Science Institute. The Guide Star Catalogue will contain positions and magnitudes for objects in the sky complete to at least 14 mag, and will contain about 20 million stars. The data for the sky complete to approximately 12.5 mag, extracted from the Guide Star Catalogue, along with some additional data from the SIMBAD data base of about 500 000 stars at the Strasbourg Stellar Data Centre, will form the Tycho Input Catalogue of approximately 2 million objects. As of the 1985 IAU General Assembly nearly 50 per cent of the plates for the Guide Star Catalogue had been measured, and 10 per cent of them were completely processed and catalogued.
New Radio Telescopes
Authors: Kellermann K. I. 
Published: June 2019

AbstractNearly all of the exciting discoveries in radio astronomy have come from new instruments or techniques which have provided new frequencies, high sensitivity, higher spatial or time resolution, or improved image quality. Since the last General Assembly a number of major new radio telescopes have been completed while construction of others have only just begun. At the same time telescopes of the more distant future are still in the conceptual stage. This paper summarizes a full-day meeting of Commission 40 on recently completed radio telescopes, new radio telescopes now under construction, and radio telescopes of the future.
New Developments in Documentation and Data Services for Astronomers
Authors: Wilkins G. A. 
Published: June 2019

AbstractThe meeting provided a forum in which those responsible for documentation and data services in astronomy could interact with users of these services in an endeavour to establish how new techniques for the distribution and retrieval of information may be used to best advantage by astronomers. The report contains summaries of each of the short papers that were presented during the four sessions and brief accounts of the ensuing discussions. The principal topics were: the preparation and publication of papers and reports; bibliographic data services; electronic-mail facilities; archiving of current observational data; the changing role of libraries; and the maintenance of the historical record of astronomical activities.
The J vs. M Relation for Binary Stars
Authors: Tohline J. E. 
Published: June 2019

AbstractFor a given mass M and environmental temperature T, there is a well-defined angular momentum Jmax above which physical systems cannot exist as self-gravitating entities. The quantity Jmax α M2 T−½. Observations of J and M in young binary systems should put useful constraints on the temperature of the medium from which they formed.
Iras Dust Bands and the Origin of the Zodiacal Cloud
Authors: Dermott S. F. , Nicholson P. D. 
Published: June 2019

AbstractPrevious discussions of the origin of the zodiacal cloud have attempted to distinguish between an asteroidal and a cometary source on the basis of collisional dynamics, that is, by calculating the rates of production and destruction of particles from the two possible sources. The uncertainties in these calculations are too large to permit a useful conclusion. The recognition that the solar system dust bands discovered by IRAS are probably produced by the gradual comminution of the asteroids in the major Hirayama asteroid families may allow us to estimate, with comparative confidence, the contribution to the zodiacal cloud of the asteroid belt as whole.
The Volatile Composition of Comets
Authors: Weaver H. A. 
Published: June 2019

ABSTRACTComets may be our best probes of the physical and chemical conditions in the outer regions of the solar nebula during that crucial period when the planets formed. The volatile composition of cometary nuclei, in particular, can be used to decide whether comets are the product of a condensation sequence similar to that invoked to explain the compositions of the planets and asteroids, or if comets are simply agglomerations of interstellar grains which have been insignificantly modified by the events that shaped the other bodies in the solar system. Although cometary nuclei are not generally accessible to observation, observations of cometary comae can illuminate at least some of the mysteries of the nuclei provided one has a detailed knowledge of the excitation conditions in the coma and also has access to basic atomic and molecular data on the many species present in comets. This paper examines the status of our knowledge of the volatile composition of cometary nuclei and discusses how these data are obtained.
Recent Observations of the Beams in SS 433
Authors: Vermeulen R.C. 
Published: June 2019

ABSTRACTPreliminary results are presented of an intensive multifrequency observing campaign on SS 433 conducted in 1987. There were participants from all over the world; they brought all the observations together at the 1988 Dwingeloo workshop on SS 433. With a rapid sequence of VLBI maps, we have been able to follow the onset and evolution of a series of radio flares. We have also obtained a wealth of optical spectra allowing studies of the variability of the Doppler shifted lines on timescales of hours. There is little correlation between the activity in the radio regime, and that seen in the Doppler shifted lines.
Solar and Stellar Flares
Authors: Benz A.O. 
Published: June 2019

AbstractThis review concentrates on some selected topics concerning the release of magnetic energy and associated phenomena in flares. Emphasis is on microflares, recent studies of different phases of flares, and propagation and trapping of flare accelerated electrons. The ongoing analysis of the observations of the previous solar cycle reaches a state where quantitative models become possible. The subject of solar flares can be broken up into several, now well defined physical problems.
CCD Data Taking Modes and Flatfielding Problems
Authors: Djorgovski S. , Dickinson M. 
Published: June 2019

AbstractWe briefly review some problems in the flatfielding of CCD images, in the context of three data-taking modes: stare, short scan, and drift scan. The principal sources of flatfielding imperfections are: (1) mismatch in the spectra of the astronomical sources of interest and the flatfield illumination; (2) a variety of low-level additive errors; and (3) nonlinearities of the CCD response. Residual flatfielding errors are probably the limiting factor in high-precision astronomical photometry. Flatfielding accuracies of the order of 1 – 2% per pixel are commonly achieved; with some effort, accuracies of ~ 0.1% can be reached; higher accuracies require a substantial effort, or improvements in the quality of CCD chips. In general, scanning data taking modes outperform the “standard” stare mode.
The Extreme Ultraviolet Explorer Mission
Authors: Bowyer Stuart , Jelinsky Patrick , Christian Carol , Hawkins Isabel 
Published: June 2019

AbstractThe Extreme Ultraviolet Explorer mission is described. For the first six months, an all-sky survey will be carried out covering 90 to 750 Å, or essentially the entire extreme ultraviolet (EUV) bandpass. This EUV survey will be made in four bands, or colors: λλ 90-150 Å, 170-250 Å, 400-600 Å, and 550-750 Å. A portion of the sky which is free from the normally intense 304 Å geocoronal helium background will be surveyed at greater sensitivity; the wavelength coverage of this band is from 90 to 400 Å. Following the sky survey portion of the mission, spectroscopy of individual sources will be carried out. Three spectrometers employing novel variable line-space gratings will provide spectra with ~1 Å resolution over the band from 70 to 760 Å. This spectroscopy will be carried out by guest observers chosen by NASA in a manner roughly analogous to the International Ultraviolet Explorer (IUE) guest observer program.
The Hipparcos Astrometry Satellite – Two Years After Launch
Authors: Perryman M.A.C. 
Published: June 2019

AbstractLaunched in August 1989 into a geostationary transfer orbit, the Hipparcos astrometry satellite failed to reach its intended geostationary orbit through the failure of its apogee boost motor. Present indications are that the possible operational lifetime should nevertheless extend beyond the end of 1992, with extremely high-quality scientific data being returned for some 65 per cent of the time. For an assumed 3-year operational lifetime, the original mission goals (positions, parallaxes, and annual proper motions with an accuracy of about 2 milli-arcsec) should be achievable (the pre-launch expectations of the planned 2.5-year mission would be achievable with a 3.5-year mission in the revised orbit). This paper describes the in-orbit performance of the satellite most relevant to the scientific goals.
The Lack of Fundamental Atomic and Molecular Data: A Crisis in Space Astronomy?
Authors: Bruhweiler Frederick C. 
Published: June 2019

A crisis is now confronting space astronomy. Many current and future investigations at UV and Extreme-UV wavelengths with space observatories such as the International Ultraviolet Explorer (IUE), Hubble Space Telescope (HST), Extreme UV Explorer, and Lyman are limited by the current availability of good fundamental atomic data such as accurate energy levels, wavelengths, and oscillator strengths.Until very recently, spectroscopic studies using the IUE of hot O-subdwarfs have revealed the vast majority of the photospheric features could not be identified. Our recent detection of species such as Fe V, VI, and VII in very hot white dwarfs was unexpected and has definite implications for observations to be obtained by the EUVE and Lyman. Coadded spectra of these degenerate objects show many other unidentified features. Accurate atomic data for these highly ionized species will be a prerequisite to doing any quantitative analysis of these species and understanding the flux distributions in the EUV, where the strongest lines of these highly-ionized species are located.
Gender, Nation, and Situated Intersectionality: The Case of Catalan Pro-independence Feminism
Authors: Rodó-Zárate Maria 
Published: June 2019

AbstractDebates on nation, self-determination, and nationalism tend to ignore the gender dimension, women's experiences, and feminist proposals on such issues. In turn, feminist discussions on the intersection of oppressions generally avoid the national identity of stateless nations as a source of oppression. In this article, I relate feminism and nationalism through an intersectional framework in the context of the Catalan pro-independence movement. Since the 1970s, Catalan feminists have been developing theories and practices that relate gender and nationality from an intersectional perspective, which may challenge hegemonic genealogies of intersectionality and general assumptions about the relation between nationalism and gender. Focusing on developments made by feminist activists from past and present times, I argue that women are key agents in national construction and that situated intersectional frameworks may provide new insights into relations among axes of inequalities beyond the Anglocentric perspective.
Shortening Accommodated by Thrust and Strike‐Slip Faults in the Ili Basin, Northern Tien Shan
Authors: Grützner C. , Campbell G. , Walker R.T. , Jackson J. , Mackenzie D. , Abdrakhmatov K. , Mukambayev A. 
Published: June 2019

AbstractThe Tien Shan accommodates a significant portion of the India‐Eurasia N‐S convergence. In its northern part a zigzag pattern of mountain ranges bounds the western Ili Basin. The role of this basin in the overall shortening and the regional kinematics is not well understood. Geodetic data and instrumental seismicity are not sufficient to infer the role of individual faults and fault systems. We analyze GPS data and earthquake slip vectors and present the results of fault mapping based on remote sensing and field campaigns in the western Ili Basin. These observations indicate that E‐W thrust faults are active at the basin margins, and oblique and strike‐slip faults, both in the basin and in the Paleozoic rocks within the mountain ranges, have been active in the Late Quaternary. We propose a regional tectonic model in which the left‐lateral strike‐slip faults at the NW margin of the basin accommodate ~3‐mm/year NE‐SW shear. Smaller right‐lateral oblique faults transfer the motion in between the left‐lateral faults, and also take up shortening by rotations about vertical axes. We see the onset of internal deformation within the Ili Basin, although it has a strong basement. Our kinematic model is consistent with geodetic data, earthquake seismology, historical, and prehistorical surface faulting, and describes the first‐order features of active deformation that can be observed in the northern Tien Shan. Our study illustrates the importance of combining these different data sets to understand the regional tectonics.
Empirical Stream Thermal Sensitivities May Underestimate Stream Temperature Response to Climate Warming
Authors: Leach Jason A. , Moore R. Dan 
Published: June 2019

AbstractStream temperature has been increasing in tandem with air temperature, with potentially negative impacts on cold‐water fish such as salmon. Assessing future stream temperature change is critical for developing effective management responses. Empirical models of stream thermal sensitivity generally predict less future warming compared to physically based models. Here we reconcile these discrepancies by using a process‐based hydrology and temperature model to simulate daily flow and water temperature for forested headwater catchments in a maritime region under both historic and projected future climatic conditions. The primary reason that the empirical approach underestimates thermal response to climate change is that it does not account for thermal memory in the catchment, especially related to the effect of snow cover. Empirical thermal sensitivities thus may underestimate stream temperature response to future climate warming. In addition, groundwater‐fed streams may only resist warming in the short‐medium term, due to lagged response of groundwater temperature. More process‐based understanding and modeling of stream thermal regimes is needed to effectively manage aquatic ecosystems.
Possible Increases in Flood Frequency Due to the Loss of Eastern Hemlock in the Northeastern United States: Observational Insights and Predicted Impacts
Authors: Knighton James , Conneely Justin , Walter M. Todd 
Published: June 2019

AbstractTrees exert a fundamental control on the hydrologic cycle, yet previous research is unclear about the nuanced relationship between forest cover and riverine flood frequency. In the Northeastern United States, warming air temperatures have resulted in a decline of Eastern Hemlock (EH), and subsequent increases in observed catchment water yield. We evaluated the possibility of EH loss leading to a changed flooding regime. We first investigated plant hydraulic regulation by root water uptake in EH and American Beech (AB; a candidate successional species) through stable isotope analysis of stream, soil water, and plant xylem water. EH xylem water showed evidence of deeper soil water uptake than AB during both wet and dry seasons, suggesting species succession may be an important mechanism for altering catchment “plant accessible water.” Next, we estimated catchment flood frequency with mechanistic hydrologic simulations for present conditions, and two hypothetical cases where all EH is succeeded by AB. The largest change to catchment extreme discharge after AB succession coincided with fall season tropical moisture export‐derived precipitation. We observed reduced sensitivity under future climatic forcing with an ensemble simulation of five localized constructed analogs downscaled general circulation models. Thus, the influence of forest composition on the flood regime may be most related to the temporal alignment of the synoptic‐scale processes that generate Atlantic Basin tropical cyclones and regional plant phenology of the Northeast United States. Our results provide a justification for using physically based hydrologic models incorporating plant hydraulic regulation when evaluating future flooding frequency.
Suspended Sediment Mineralogy and the Nature of Suspended Sediment Particles in Stormflow of the Southern Piedmont of the USA
Authors: River Mark , Richardson Curtis J. 
Published: June 2019

AbstractThe majority of annual sediment flux is transported during storm events in many watersheds across the world. Using X‐ray diffraction, we analyzed the mineralogy of grab samples of suspended sediment during different stages of storm hydrographs in the Southern Piedmont. Mineralogy of suspended sediment changes drastically from quartz‐dominated during the rising limb to clay dominated during the late falling limb/baseflow. Changes in mineralogy can shed insight into turbidity relationships, suspended sediment sources, energy versus supply‐limited sediment transport, and other suspended sediment parameters such as anion exchange capacity and trace element chemistry. An unexpected key finding, confirmed by X‐ray diffraction and electron microscopy, is that both kaolinite and quartz are primarily transported as discrete crystalline minerals of different size classes in our watersheds; this contrasts with existing scientific literature stating that in most fluvial systems suspended sediment is transported primarily as composite particles composed of a heterogeneous mix of all particle sizes. Our findings also support existing literature that turbidity can be a good proxy for elements such as P, which are preferentially adsorbed onto iron oxide coatings thus in situ turbidity probes have great potential to provide relatively inexpensive estimates of P flux when calibrated for specific watersheds.
Changing Climate Over Chad: Is the Rainfall Over the Major Cities Recovering?
Authors: Pattnayak Kanhu Charan , Abdel‐Lathif Ahmat Younous , Rathakrishnan K. V. , Singh Muskan , Dash Renuka , Maharana Pyarimohan 
Published: June 2019

AbstractChad is the largest country of the Sahel region with different climatic zones, varying from arid in the north to tropical in the south. These climatic zones respond differently to climate change signals. Therefore, their detection over major cities, which are scattered within different climatic zones, is of utmost importance. The changes in hydroclimatic fields such as rainfall and temperature were examined over the major cities in various regions for the period 1950 to 2014. Rainfall shows a significant decreasing trend especially over cities close to Lake Chad (Lere, Mondou, Mongo, and Sarh), whereas no significant trend is observed for cities farther from the Lake. However, a consistently increasing trend in temperature is found across all cities. The cities in the north (Faya, Abeche, and Ati) receive far less rainfall than those located in southern Chad. All cities (except Faya and Lere) received higher rainfall during 1950–1965 (wet period), entering a dry regime between 1966 and 1990 (dry period) and subsequently recovering rainfall totals, toward previous levels, between 1991 and 2014 (recovery phase). A substantial rise in air temperature is observed after 1980–1985, reflecting the gradual rise of temperature in recent times. In summary, rainfall is recovering from a dry regime and temperature is rising over all the major cities of Chad. More researches in this region is needed to develop local scale mitigation strategies and adaptation technology.
EMIC Waves in the Outer Magnetosphere: Observations of an Off‐Equator Source Region
Authors: Vines S. K. , Allen R. C. , Anderson B. J. , Engebretson M. J. , Fuselier S. A. , Russell C. T. , Strangeway R. J. , Ergun R. E. , Lindqvist P. A. , Torbert R. B. , Burch J. L. 
Published: June 2019

AbstractElectromagnetic ion cyclotron (EMIC) waves at large L shells were observed away from the magnetic equator by the Magnetospheric MultiScale (MMS) mission nearly continuously for over four hours on 28 October 2015. During this event, the wave Poynting vector direction systematically changed from parallel to the magnetic field (toward the equator), to bidirectional, to antiparallel (away from the equator). These changes coincide with the shift in the location of the minimum in the magnetic field in the southern hemisphere from poleward to equatorward of MMS. The local plasma conditions measured with the EMIC waves also suggest that the outer magnetospheric region sampled during this event was generally unstable to EMIC wave growth. Together, these observations indicate that the bidirectionally propagating wave packets were not a result of reflection at high latitudes but that MMS passed through an off‐equator EMIC wave source region associated with the local minimum in the magnetic field.
Dust Radiative Effects on Climate by Glaciating Mixed‐Phase Clouds
Authors: Shi Yang , Liu Xiaohong 
Published: June 2019

AbstractMineral dust plays an important role in the primary formation of ice crystals in mixed‐phase clouds by acting as ice nucleating particles (INPs). It can influence the cloud phase transition and radiative forcing of mixed‐phase clouds, both of which are crucial to global energy budget and climate. In this study, we investigate the dust indirect effects on mixed‐phase clouds through heterogeneous ice nucleation with the U.S. Department of Energy (DOE) Energy Exascale Earth System Model (E3SM). Dust and INP concentrations simulated from two versions of E3SM with three ice nucleation parameterizations were evaluated against observations in the Northern Hemisphere. Constrained by these observations, E3SM shows that dust INPs induce a global mean net cloud radiative effect of 0.05 to 0.26 W/m2 with the predominant warming appearing in the Northern Hemisphere midlatitudes. However, a cooling effect is found in the Arctic due to reduced longwave cloud forcing.
Deep Learning for Picking Seismic Arrival Times
Authors: Wang Jian , Xiao Zhuowei , Liu Chang , Zhao Dapeng , Yao Zhenxing 
Published: June 2019

AbstractArrival times of seismic phases contribute substantially to the study of the inner working of the Earth. Despite great advances in seismic data collection, the usage of seismic arrival times is still insufficient because of the overload manual picking tasks for human experts. In this work we employ a deep‐learning method (PickNet) to automatically pick much more P and S wave arrival times of local earthquakes with a picking accuracy close to that by human experts, which can be used directly to determine seismic tomography. A large number of high‐quality seismic arrival times obtained with the deep‐learning model may contribute greatly to improve our understanding of the Earth's interior structure.