bluuebunny/crossref_metadata_2025_split huggingface dataset:
Census of the Kuiper-Belt Objects - The Taiwan-America Occultation Survey (TAOS)
Authors: Chen W.P. 
Published: March 2016

AbstractMore than two hundred transneptunian Kuiper-Belt Objects (KBOs) have so far been identified. Because of their large distances from the Sun, and their intrinsically small sizes, only the largest members (diameters more than 100 km) can be observed by direct imaging with large telescopes. Even smaller KBOs, though expected to be more numerous on theoretical grounds, cannot be seen directly unless they happen to block out the light from background stars. The Taiwan-America Occultation Survey (TAOS) project is a collaboration among the Lawrence Livermore Laboratory (USA), Academia Sinica, National Central University (both of Taiwan), and other institutes, that aims to measure the frequency of such chance stellar occultations, and thereby conduct the census of the Kuiper-Belt population down to a few kilometer sizes. An array of robotic telescopes are being set up in central Taiwan to monitor the brightness variation of several thousand stars at a rate of a few Hz. Observations will be operated in a synchronized and coincidence mode, so the sequence and timing of any candidate occultation event can be recorded and distinguished against a false detection. The full survey is expected to start in the fall of 2000.
Main Sequence Evolution, Abundance Anomalies and Particle Transport
Authors: Michaud Georges , Richard Olivier , Richer Jacques 
Published: March 2016

AbstractThe availability of large atomic data bases has made it possible to calculate stellar evolution models taking into detailed account the abundance variations of all important contributors to opacity. In a first step, in addition to nuclear reactions, the atomic diffusion, radiative accelerations and opacity are continuously calculated during evolution taking the abundance changes of 28 species into account. This leads to the first self consistent main sequence stellar evolution models. In A and F stars (M ≥ 1.5Mʘ) an iron peak convection zone is shown to appear at a temperature of 200000 K. The calculated surface abundance anomalies, that follow without any arbitrary parameter, are very similar to those observed in AmFm stars in open clusters except that they are larger by a factor of about 3. The second step, is then to introduce a competing hydrodynamical process. To reduce the calculated anomalies to the observed ones, turbulence has been introduced. It is found that the mixed zone must be about 5 times deeper than the iron convection zone. Detailed comparisons to a few AmFm stars have been carried out. The determination of the abundance anomalies of a large number of atomic species (20 to 30 are probably accessible) makes it possible to constrain stellar hydrodynamics. In clusters, the original abundances and age may be known and the accurate determination of surface abundances may constrain turbulence, mass loss and differential rotation when the required atomic data bases are available and used for the modeling of particle transport in stellar evolution.
Hydrodynamical Models of Mixing beyond a Convection Zone
Authors: Freytag Bernd 
Published: March 2016

AbstractNumerical radiation hydrodynamics simulations of stellar surface convection have gained a high level of reliability and perform very well in the confrontation with observations. Similar simulations of convection zones in stellar interiors are much more difficult to set up because of the huge range of time-scales to cover. Therefore, simplified models have to be used, where the results have to be carefully extrapolated to apply them to stellar interiors. Simulations of shallow surface convection zones show that the overshooting velocity fields extend far beyond the region with significant convective energy flux.
Early Observations and Modern Ephemerides
Authors: Standish E.M. 
Published: March 2016

AbstractThere is a great variety of planetary and lunar observations recorded throughout history. Even today, some of these are useful for the improvement of ephemerides, though one must use a lot of judgment and caution - for surprising reasons. Five different sets of observations are presented, each with a story and a lesson: Galileo’s observations of Neptune, Lalande’s observations of Neptune, Williams’ measurements of the 1780 solar eclipse, Robertson’s 1811 transit timings, and solar eclipses in general.
Oxygen Abundances: New Results from [O I] Lines
Authors: Sneden Christopher , Primas Francesca 
Published: March 2016

AbstractFrom new high resolution spectra of metal-poor giants we use equivalent widths of [O I], Sc II, and Fe II lines to derive new values of [O/Sc] and [O/Fe]. These results are generally consistent with previous determinations of oxygen abundances from [O I] lines, but the star-to-star scatter is greatly reduced.
Spectroscopic Influence of Temperature Inhomogeneities
Authors: Cayrel Roger , Steffen Matthias 
Published: March 2016

AbstractThe effect of temperature inhomogeneities on the formation of two oxygen lines and one Fe II line has been investigated based on 2-D radiation hydrodynamics simulations of convection in the atmospheres of metal-poor stars. It was expected that the IR O I triplet lines would be enhanced by the temperature inhomogeneities, more than the forbidden [O I] line or Fe II lines. The actual computations done on two snapshots under the assumption of LTE have not confirmed this expectation, instead suggesting that the main difference between ‘classical’ and ‘dynamical’ atmospheres of metal-poor dwarfs is the significantly cooler mean temperature of the dynamical upper photosphere (τRoss ≾ 0.01).
An Independent View?
Authors: Lambert David L. 
Published: March 2016

AbstractThe current dispute over the oxygen abundance in metal-poor stars has been viewed from a distance by this observer who would claim a measure of independence despite an intermittent interest in ox-gen abundance determinations over 3 decades. This summary attempts to persuade all participants whether they advocate a ‘high’ or ‘low’ oxygen abundance or are simply bemused by the dispute that in resolving the present disagreements we shall learn not only about the oxygen abundance of these oldest Galactic stars but shall achieve a deeper understanding of the atmospheres of the stars.
Atomic Hydrogen at High Redshift
Authors: Briggs F.H. 
Published: March 2016

AbstractAfter the production of the ionizing background by the first generation of
stars, neutral gas must be confined to sufficiently high density to be self-shielding and remain neutral. Neutral gas is an identifier of the presence of confining gravitational potentials and a tracer of the kinematics of the potential. Kinematical studies are being extended to neutral atomic gas at high redshift.
Hidden Star Formation: The Ultraviolet Perspective
Authors: Meurer G.R. , Heckman T.M. , Seibert M. , Goldader J. , Calzetti D. , Sanders D. , Steidel C.C. 
Published: March 2016

AbstractMany recent estimates of the star formation rate density at high redshift rely on rest-frame ultraviolet (UV) data. These are highly sensitive to dust absorption. Applying a correlation between the far-infrared (FIR) to UV flux ratio and UV color found in local starbursts to galaxy samples out to z ∼ 3, one can account for most of the FIR background. However, the correlation is based on a sample that does not include the most extreme starbursts, Ultra Luminous Infrared Galaxies (ULIGs). Our new UV images of ULIGs show that their FIR fluxes are underpredicted by this correlation by factors ranging from 7 to 70. We discuss how ULIGs compare to the various types of high-z galaxies: sub-mm sources, Lyman Break Galaxies, and Extremely Red Objects.
Prospects for Future Far-Infrared/Submillimeter Studies of the High-Redshift Universe
Authors: Blain Andrew W. 
Published: March 2016

AbstractObservations made using COBE, SCUBA, ISO and MAMBO have provided a reasonable working knowledge of both the intensity of the submm and far-infrared background radiation and the source counts of luminous high-redshift dusty galaxies. However, because there are uncertainties in the background intensity determinations, the samples of detected galaxies are small, and most importantly, their redshift distributions are very incomplete, details of the evolution of dusty galaxies remain unresolved. The next steps forward in the field will be the launches of SIRTF and ASTRO-F, the commissioning of SOFIA and new, more capable ground-based mm/submm-wave cameras - BOLOCAM, SHARC-II and SCUBA-II - the use of ultra-long duration balloon experiments, such as BLAST, the construction of ALMA and the arrival of FIRST, and ultimately the advent of space-borne far-infrared interferometers, such as SPECS. There are also exciting prospects for direct mm/submm-wave CO-line redshift surveys using wide-band spectrographs. Using these new facilities, the number of high-redshift dusty galaxies known will be increased dramatically. Spectroscopy using SIRTF, SOFIA and FIRST will probe the astrophysical processes within these sources in detail, hopefully addressing the open question of the fraction of the counts and background radiation that is generated by the formation of high-mass stars and by active galactic nuclei (AGNs). The spatial and spectral structure of distant dusty galaxies will finally be resolved in detail using ALMA and SPECS.
Optical Analysis of Cluster Mergers
Authors: Girardi Marisa 
Published: March 2016

AbstractAn increasing amount of data has revealed that many clusters are very complex systems. Optical analyses show that several clusters contain subsystems of galaxies suggesting that they are still in the phase of relaxation, possibly after a phase of cluster merging. I briefly review the main results about substructure, and the connection between cluster dynamical status and galaxy properties. Useful comparisons with the results derived from X-ray data are also discussed.
First Results from the FUSE Mission
Authors: Sonneborn George , Moos H. Warren 
Published: March 2016

AbstractThe Far Ultraviolet Spectroscopic Explorer (FUSE) provides high-resolution spectroscopy at far ultraviolet (FUV) wavelengths (905–1187Å) of many astronomical objects in order to address fundamental questions related to the origin of the universe. FUSE, a cooperative project of the United States, Canada, and France, was launched in June 1999 for a three-year primary mission. The instrument sensitivity permits studies of many extragalactic sources at high spectral resolution. The key science drivers for the mission design are absorption-line spectroscopy of the ISM and IGM to investigate D/H, O VI, and molecular hydrogen abundances and distribution in the Galaxy and beyond to z ~ 0.3. Most of the observing time is available to Guest Investigators. This Joint Discussion summarizes some of the scientific results determined primarily from the first several months of FUSE observations.
Composition and Cloud Structure of Jupiter’s Deep Atmosphere
Authors: Atreya Sushil K. , Mahaffy Paul R. , Niemann Hasso B. , Owen Tobias C. 
Published: March 2016

AbstractAbundances of ammonia, hydrogen sulfide, water, methane and other hydrocarbons, noble gases and their isotopes, etc. were measured for the first time to the 22 bar level. The ratios of the heavy elements to hydrogen were found to be enriched by a factor of 2-3 relative to solar, implying a large influx of cold planetesimals into Jupiter.
Spectroscopy of Planetary Atmospheres and Surfaces with ISO
Authors: Bézard Bruno 
Published: March 2016

AbstractSpectroscopic observations of Solar-System objects with ISO provided a wealth of new and exciting results. Major findings relevant to planetary atmospheres and surfaces are presented here. Rotational lines of HD were observed for the first time in the four giant planets, yielding reliable determinations of the D/H ratio. The 14N/15N ratio could also be measured in the upper troposphere of Jupiter. Many new hydrocarbons were detected in the giant planets, improving our understanding of the methane photochemistry. In addition, oxygen compounds (H2O and CO2) were detected in their upper atmospheres and in Titan, pointing to exogenic sources of oxygen. Many bands of SO2 ice were observed on Io, providing information on the physical state of this volcanic compound on the surface. Finally, spectra of Mars revealed the presence of a few so-far undetected mineralogical features, tentatively attributed to carbonates.
The Surface of Titan from Adaptive Optics Observations
Authors: Gibbard Seran G. , Macintosh Bruce A. , Max Claire E. , Roe Henry , de Pater Imke , Young E.F. , McKay Christopher P. 
Published: March 2016

AbstractSaturn’s largest moon Titan is the only satellite in the Solar System with a substantial atmosphere. Photolysis of methane creates a hydrocarbon haze in Titan’s atmosphere that is opaque to visible light. The new adaptive optics system on the 10–meter W. M. Keck Telescope enables us to observe Titan with a resolution of 0.04 arcseconds, or 20 resolution elements across the disk. By observing at near-infrared wavelengths that are methane band windows we can see through Titan’s hydrocarbon haze to the surface beneath. Recent adaptive optics images of Titan both in broadband (J, H, and K) filters and in narrowband filters that selectively probe Titan’s surface and atmosphere allow us to determine surface albedo and properties of the hydrocarbon haze layer. Future observations will include high-resolution spectroscopy coupled with adaptive optics to obtain spectra of individual surface features.
Advances in Understanding of the Martian Climate
Authors: Richardson Mark I. 
Published: March 2016

AbstractData collected by the Viking mission to Mars resulted in a picture of the Martian climate which stood largely unmodified for over a decade. When a challenge did come in the mid-1990’s it resulted from ground-based and HST observations which suggested lower global-average temperatures and dust opacities, and more atmospheric water ice than inferred from Viking. These observations prompted suggestions of climate change orders of magnitude larger and faster than anything contemplated for the Earth. A combination of new data from the Mars Global Surveyor Thermal Emission Spectrometer (TES) and reanalysis of Viking-era data have resulted in a new picture of the Martian climate. It is now clear that no significant climate change has occurred and that the “cooler and cloudier” conditions observed in the 1990’s for northern summer applied equally well to the Viking era. TES observations have provided detailed information on the cycle of air temperature and water ice clouds which support and extend the ground-based and HST observations. The disagreement with Viking observations has been found to result from faults in the Viking Orbiter Infrared Thermal Mapper (IRTM) 15 µm channel, the lack of analysis of IRTM data applicable to water ice, and the misinterpretation of Viking Lander opacity measurements. The TES observations provide a rich data base which is now allowing a new picture of the Martian climate to be constructed in which water vapour and water ice clouds may play a significant role in modulating the annual cycles of dust and air temperature.
Statistical Effects from Hipparcos Astrometry
Authors: Arenou Frédéric , Luri Xavier 
Published: March 2016

AbstractThe Hipparcos astrometry is used mainly for the derivation of stellar physical quantities such as luminosity, masses and velocity. However, sample selections on data with observational errors or an intrinsic dispersion may lead to biased estimates, especially when the error distributions are non-Gaussian. We review the classical biases and the ways to avoid them through the use of statistical methods.
Magnetic Fields in Irregular Galaxies
Authors: Chyży Krzysztof T. 
Published: March 2016

AbstractRadio data of large irregular galaxies reveal some extended synchrotron emission with a substantial degree of polarization. In the case of NGC 4449 strong galaxy-scale regular magnetic fields were found, in spite of the lack of ordered rotation required for the conventional dynamo action. The rigidly rotating large irregular NGC 55 shows vertical polarized spurs connected with a network of ionized gas filaments. Small dwarf irregulars show only isolated polarized spots.
Numerical Models of Galactic Dynamos
Authors: Elstner Detlef 
Published: March 2016

AbstractThe state of the art for dynamo models in spiral galaxies is reviewed. The comparison of numerical models with special properties of observed magnetic fields yields constraints for the turbulent diffusivity and the α-effect. The derivation of the turbulence parameters from the vertical structure of the interstellar medium gives quite reasonable values for modelling the regular magnetic fields in galaxies with an α2Ω-dynamo. Considering the differences of the turbulence between spiral arms and interarm regions, the observed interarm magnetic fields are recovered in the numerical models due to the special properties of the α2Ω-dynamo.
Mean Field Dynamo Saturation: Toward Understanding Conflicting Results
Authors: Blackman Eric G. , Field George B. 
Published: March 2016

AbstractMean field dynamos may explain the origin of large scale magnetic fields of galaxies, but controversy arises over the extent of dynamo quenching by the growing field. Here we explain how apparently conflicting results may be mutually consistent, by showing the role of magnetic helicity conservation and boundary terms usually neglected. We estimate the associated magnetic energy flowing out of the Galaxy but emphasize that the mechanism of field escape needs to be addressed.
Special Session: Astronomy for Developing Countries
Authors: Batten A.H. 
Published: March 2016

AbstractA Special Session was held during the XXIV General Assembly on the topic “Astronomy for Developing Countries”. During two-and-a-half days, thirty-eight oral papers were presented and a similar number of poster papers were displayed. Edited summaries of the oral papers are presented here. Full texts of those papers and abstracts of the posters appear in a separate volume published in 2001 by the ASP.
High-energy Neutrino Astronomy: From AMANDA to IceCube
Authors: Halzen Francis 
Published: March 2016

AbstractKilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature accelerates protons and photons to energies in excess of 1020 and 1013 eV, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the reach of its extension, IceCube.
Neutrinos from Pulsar Environments
Authors: Melatos A. 
Published: March 2016

AbstractRecent calculations of the neutrino fluxes and spectra from pulsar magnetospheres and wind nebulae are reviewed. The neutrinos, produced in pp and pγ collisions via pion decays, are a signature of TeV ions accelerated electrostatically in the magnetosphere, in the wind termination shock (Fermi), or in the wind neutral sheet (wave surfing and/or reconnection). The fluxes and spectra are related to the energy and density of the accelerated ion beam and the densities of the target species, thereby constraining ion-loaded pulsar wind models originally developed to explain the variable wisps in pulsar-driven supernova remnants. The neutrino signal may be detectable by km2 telescopes (e.g. IceCube) and is correlated with TeV γ-ray emission. Related sources are also reviewed, such as early-phase post-supernova pulsar winds, pulsar-driven γ-ray-burst afterglows, and accreting neutron stars. The possibility of long baseline oscillation experiments, to search for fine splitting of neutrino mass eigenstates and non-radiative neutrino decays, is noted.
A Window on the Ultra-High Energy Universe
Authors: Blasi Pasquale 
Published: March 2016

AbstractCosmic rays with energy around and in excess of 1020 eV have been detected. Despite the uncertainties associated with the difficult measurements of extremely low fluxes (about a particle per square kilometer per century) the same existence of such high energy cosmic rays raises important questions that deserve an appropriate answer. I briefly summarize here what are these questions and how to look for the answers.
SpeX Spectroscopy of Mercury: 0.8 – 5.2 µm
Authors: Sprague Ann L. , Warell Johan , Emery Joshua , Long Angela , Rayner John , Cushing Mike 
Published: March 2016

AbstractSpectra of Mercury were obtained at the Infrared Telescope Facility on Mauna Kea, HI using SpeX. There is no indication of any absorption feature associated with FeO in Mercury’s regolith. There is a 5μ m excess in thermal flux similar to that observed from the Kuiper Airborne Observatory (KAO) using HIFOGS. Spectra from varying locations do exhibit different slopes and flux indicating different surface temperatures at different locations.
An Accurate Model of Mercury’s Spin-Orbit Motion
Authors: Rambaux Nicolas , Bois Eric 
Published: March 2016

AbstractOur work deals with the physical and dynamical causes that induce librations of Mercury around an equilibrium state defined by the 3:2 spin-orbit resonance. In order to integrate the spin-orbit motion of Mercury, we have used our gravitational model of the solar system including the Moon’s spin-orbit motion. This model, called SONYR (acronym of Spin-Orbit N-bodY Relativistic model), was previously built by Bois, Journet and Vokrouhlicky in accordance with the requirements of the Lunar Laser Ranging observational accuracy.Using the model, we have identified the main perturbations acting on the spin-orbit motion of Mercury such as the planetary interactions or the dynamical figure of the planet. Moreover, the complete rotation of Mercury exhibits two proper frequencies, namely 15.847 and 1066 years, and in addition one spin-orbit secular resonance (298 898 years). A new determination of the mean obliquity of Mercury has been proposed. Besides, we have identified in the Hermean librations the impact of the uncertainty of the greatest principal moment of inertia (C/MR2) on the obliquity as well as on the libration in longitude (2.3 mas and 0.45 as respectively for an increase of 1% on the C/MR2 value). These accurate relations have to be taken into account in the context of the two upcoming missions BepiColombo and MESSENGER.
The BepiColombo Lander – MSE
Authors: Thomas Nicolas , Schulz Rita , Falkner Peter 
Published: March 2016

AbstractThe European Space Agency’s BepiColombo mission to the planet, Mercury, is planned for launch in 2012. A lander called the MSE (Mercury Surface Element) has been proposed for the mission. To be compatible with all the constraints for a soft-landing on Mercury, the payload must be highly miniaturized. Although the requirements are challenging, significant study, design, and bread-board work has been performed which suggests that excellent science can be accomplished within a total payload mass of around 7 kg. The MSE would provide a substantial increase in our knowledge of the Hermean surface after that which can be obtained from orbital remote sensing.
Helicity and The Alpha-Effect: Dynamo Theory and Observations
Authors: Kuzanyan Kirill 
Published: March 2016

AbstractSpatial and temporal distributions of tracers of the alpha-effect in the solar convection zone, such as current helicity and twist factor averaged over solar active regions are available by vector magnetographic observations. We discuss the data obtained at Huairou Solar Observing Station of Chinese Academy of Sciences and confront them with predictions of dynamo theory. At the present time, though the observations are rough, we still have a statistically representative sampling to conclude that the observations do not contradict the theory.