bluuebunny/crossref_metadata_2025_split huggingface dataset:
Young Stellar Clusters in the ULIRG IRAS 17208–0014
Authors: Reddy Naveen A. , Jogee Shardha , Scoville Nick 
Published: March 2016

AbstractHigh resolution studies reveal that luminous young stellar clusters and their associations are ubiquitous within 1 kpc of ULIRGs, and could be the precursors to globular clusters. We have undertaken a study of the ages, masses, extinction, and dust properties of the clusters found in the brightest ULIRG in the extended IRAS BGS Sample, IRAS 17208–0014, using it as a unique system in which to study the formation and evolution of clusters in gas-rich mergers. Using NICMOS JHK and WFPC2 I–band images, we have compared the near-IR colors of the clusters with those expected from a Bruzual & Chariot model. There are a few clusters whose colors can be explained by moderate values of extinction (1 – 3 mag), but others require some contribution from hot (400 – 1000 K) dust. We derive ages of a few tens of Myr and masses from 106 to 107 M⊙. These clusters may be supermassive compared to globular clusters, or could be unresolved associations of clusters.
Non-Thermal Activity and Particle Acceleration in Clusters of Galaxies
Authors: Petrosian Vahe’ 
Published: March 2016

AbstractEvidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons, and new windows (in EUV and Hard X-ray ranges) have provided more powerful tools for its investigation. The hard X-ray observations, notably from Coma, are summarized and results of a new RXTE observations of a high red-shift cluster are presented. It is shown that the most likely emission mechanism for these radiations is the inverse Compton scattering of the cosmic microwave background photons by the same electrons responsible for the radio radiation. Various scenarios for acceleration of the electrons are considered and it is shown that the most likely model is episodic acceleration by shocks or turbulence, presumably induced by merger activity, of high energy electrons injected into the inter-cluster medium by galaxies or active galactic nuclei.
MODEST: Modeling Stellar Evolution and (Hydro)dynamics
Authors: Hut Piet 
Published: March 2016

AbstractSimulations of dense stellar systems currently face two major hurdles, one astrophysical and one computational. The astrophysical problem lies in the fact that several major stages in binary evolution, such as common envelope evolution, are still poorly understood. The best we can do in these cases is to parameterize our ignorance, in a way that is reminiscent of the introduction of a mixing length to describe convection in a single star, or an alpha parameter in modeling an accretion disk. The hope is that by modeling a whole star cluster in great detail, and comparing the results to the wealth of observational data currently available, we will be able to constrain the parameters that capture the unknown physics. The computational problem is one of composition: while we have accurate computer codes for modeling stellar dynamics, stellar hydrodynamics, and stellar evolution, we currently have no good way to put all this knowledge together in a single software environment. A year ago, a loosely-knit organization was founded to address these problems, MODEST for Modeling DEnse STellar systems, with nine working groups and a series of meetings that are held every half year. This report reviews the first year of this initiative. Much more detail can be found on the MODEST web site http://www.manybody.org/modest.html.
Young Star Clusters: Progenitors of Globular Clusters!?
Authors: Anders Peter , Alvensleben Uta Fritze – v. , Grijs Richard de 
Published: March 2016

AbstractStar cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. Young clusters are observed to form in a variety of such galaxies, a substantial number resembling the progenitors of globular clusters in mass and size, but with significantly enhanced metallicity. From studies of the metal-poor and metal-rich star cluster populations of galaxies, we can therefore learn about the violent star formation history of these galaxies, and eventually about galaxy formation and evolution. We present a new set of evolutionary synthesis models of our GALEV code, with special emphasis on the gaseous emission of presently forming star clusters, and a new tool to compare extensive model grids with multi-color broad-band observations to determine individual cluster masses, metallicities, ages and extinction values independently. First results for young star clusters in the dwarf starburst galaxy NGC 1569 are presented. The mass distributions determined for the young clusters give valuable input to dynamical star cluster system evolution models, regarding survival and destruction of clusters. We plan to investigate an age sequence of galaxy mergers to see dynamical destruction effects in process.
Challenges in Stellar Models from Helioseismology to Asteroseismology
Authors: Turck-Chièze Sylvaine , Nghiem Phu Anh Phi , Piau Laurent 
Published: March 2016

AbstractExperience in helioseismology provides guidance for modeling challenges in asteroseismology. It guides choices of targets and conditions of observation. The main objectives are the interplay between rotation and convection and the knowledge of the internal magnetic field. Progress on the structure of the outer layers is crucial to avoid mode identification problems.
Solar Meridional Flows: Recent Findings
Authors: Haber Deborah A. , Hindman Bradley W. 
Published: March 2016

AbstractWe report new measurements of the sun’s global meridional circulation within the near-surface shear layer for the years 1996 to 2003. The flows are obtained using the local helioseismic technique of ring analysis applied to MDI Dynamics Program data. The most recent estimates of the solar p-angle correction to this data have been incorporated. Previously published accounts that the solar meridional circulation possesses multiple cells within the northern hemisphere (Haber et al. 2002) are not contradicted by the new findings. We do find, however, that with the inclusion of the p-angle correction, cross-equator flows have been eliminated.
Observations and Interpretation of Subsurface Magnetic Structures
Authors: Cally P. S. , Crouch A. D. 
Published: March 2016

AbstractImmediate subsurface local solar structures – flow, magnetic, and thermal – especially those associated with active regions, are of considerable interest, and are potentially accessible using high ℓ helioseismology. In recent years, classical modal seismology has been supplemented with new approaches, such as time-distance helioseismology, Hankel analysis, and acoustic holography. Results from time-distance helioseismology on shallow subsurface wave speed are at odds with those from the other methods. A simple model is presented which yields good agreement with the observed Hankel phase shifts of p modes passing through sunspots.
Ortho-To-Para Ratio of Cometary Water and Ammonia
Authors: Kawakita Hideyo , Watanabe Jun-ichi , Furusho Reiko , Fuse Tetsuharu 
Published: March 2016

AbstractSince the time that the ortho-to-para ratio (OPR) of cometary water was first Determined from observations of Comet Halley, the real meaning of OPR has not been discussed in detail. Here we review the OPRs of water and ammonia and discuss the possibilities that the OPRs were modified in the coma or the nucleus. Our conclusion indicates that the OPRs were not altered after comet nucleus formation, i.e., the OPRs reflect the temperatures in the solar nebula or the pre-solar molecular cloud.
Light Scattering as a Clue to Cometary Dust Structure
Authors: Levasseur-Regourd A. Chantal , Hadamcik E. , Lasue J. 
Published: March 2016

AbstractThe linear polarization of comets depends upon the cometary dust physical properties, as well as upon the phase angle and the wavelength. The observed similarities and discrepancies provide drastic constraints on the physical properties of the dust. A series of measurements of light scattering properties on clouds of particles and of the aggregates they form under microgravity conditions should allow the interpretation of the observations in terms of physical properties of the dust.
A Mechanism of Crystallization of Cometary Silicates
Authors: Yamamoto Tetsuo , Chigai Takeshi 
Published: March 2016

AbstractWe propose a new mechanism of crystallization of cometary silicate. The crystallization is due to heat released by chemical reactions in the organic refractory mantle of Greenberg’s model of cometary dust induced by moderate heating by solar radiation. It is shown that the strength of the crystalline feature observed in the comets can be reproduced by the present mechanism of crystallization.
Stellar Abundances in Local Group Galaxies
Authors: Tolstoy Eline , Venn Kim 
Published: March 2016

AbstractHere we describe some of our latest results from measuring detailed abundances in Local Group dwarf galaxies with the VLT. Combining spectroscopic abundances with Color-Magnitude diagrams allows the effective measurement of detailed chemical evolution with time in these galaxies. Although there are not yet significant numbers of individual stars observed in local group dwarf galaxies, the uniformity of the abundance patterns of the majority of stars in galaxies with very different star formation histories must hint at general properties of all star formation in these small systems.
Summary of IAU Joint Discussion 16, “The International Celestial Reference System, Maintenance and Future Realizations
Authors: McCarthy Dennis D. 
Published: March 2016

AbstractThe IAU Joint Discussion 16 (JD16) was held in conjunction with the XXVth General Assembly in July, 2003. Papers related to the maintenance of the International Celestial Reference System were presented in the one-day session, and these were followed by discussion that pointed out the need for standard nomenclature. This issue was addressed by the formation of a Division 1 Working Group on the subject. JD16 also pointed out the requirement for a dynamical expression for precession which was addressed by the creation of a Division 1 Working Group on Precession and the Ecliptic. It also showed that although plans are being implemented to provide reference frames for the future, there is a need for improved coordination of astrometric observations. Finally it should be noted that the discussion pointed out the concern for the future organization of IAU Division 1.
Atomic Physics Calculations for Iron L-line Spectra
Authors: Dubau Jacques , Porquet Delphine , Zabaydullin Oleg 
Published: March 2016

AbstractAbsorption L-lines of iron ions are observed, in spectra of Seyfert 1 galaxies by the new generation of X-ray satellites: Chandra and XMM-Newton. Lines associated to Fe 23+ to Fe16+ have been already observed in emission, in the solar corona and in laboratory. Whereas, those corresponding to Fe 15+ to Fe6+ have not been observed as emission lines, the upper level of the transition decaying preferentially by autoionization. Many atomic data are available for the first ion set. For the second set, some data have been recently published for n=2 to n’=3 transitions. We have recalculated them using another theoretical approach and have extended them to n’=4.
The CHIANTI Database
Authors: Landi E. , Dere K.P. , Young P.R. , Landini M. , Mason H.E. , Zanna G. Del 
Published: March 2016

AbstractThe CHIANTI database contains assessed atomic energy levels, wavelengths, radiative transition probabilities and excitation rates necessary to calculate line emissivities and synthetic spectra of a large number of ions of astrophysical interest. CHIANTI also includes a suite of programs to carry out plasma diagnostics. In the present paper we describe the contents of the CHIANTI database, its main applications and its future developments.
TIPTOPbase
Authors: Palmeri P. , Mendoza C. 
Published: March 2016

AbstractAn overview of the online atomic database referred to as TIPTOPbase is given, in particular its opacity server (OPserver) and current developments regarding online atomic structure calculations. Efforts to include atomic data for X-ray line modeling and to integrate TIPTOPbase within the International Virtual Observatory Alliance (IVOA) are also mentioned.
Distinguishing Models for ACIS Data of Diffuse Emission
Authors: Leahy D.A. 
Published: March 2016

AbstractDiscussed here is the issue of discriminating different spectral models for diffuse emission observations with the Chandra ACIS. First background models are considered. Then standard source models such as non-ionization equilibrium and ionization equilibrium models and models with different metal abundances are considered. The datasets used are from Chandra ACIS observations of diffuse emission, in particular of the Cygnus Loop supernova remnant.
Dawn Discovery Mission: Symbiosis with 1 AU Observations
Authors: Russell C. T. 
Published: March 2016

AbstractThe Dawn mission, the ninth in the series of NASA Discovery missions, is scheduled for launch in late May 2006 on a voyage to both Vesta and Ceres. The mission carries a framing camera, visible and infrared mapping spectrometer, gamma ray and neutron spectrometer, laser altimeter and magnetometer to understand and contrast these two very different bodies. Vesta apparently accreted dry, differentiated, and formed an iron core. Ceres apparently contains much water and ice and has remained relatively cool over its lifetime. The community of 1AU observers can help optimize the Dawn mission by improving the knowledge of Vesta and Ceres rotation axes, thus improving our knowledge of when regions and features will be best illuminated. The detection of any satellites would not just identify a potential hazard, and a secondary target of interest, but would also determine the mass of the primaries, enabling better mission planning. Characterization of the surface in any way, including identifying potential targets for detailed study, is also most welcome.
ISO: Asteroid Results and Thermophysical Modeling
Authors: Müller Thomas G. 
Published: March 2016

AbstractThrough a recently developed thermophysical model, observations from the Infrared Space Observatory (ISO) were combined with visual photometry, lightcurves, close-up observations and direct measurement. In this way, many applications were possible, ranging from simple diameter and albedo determination of serendipitously seen asteroids to sophisticated studies of mineralogic aspects and regolith properties, like emissivity, roughness or thermal inertia for well-known asteroids. The possibility to combine all sources of information in one single model lead also to a better understanding of thermophysical effects, like beaming or the before/after opposition effect. Thus, the mineralogic signatures can be recognized easier and asteroid data from infrared surveys and individual IR photometry can be interpreted more accurately, even in cases where shape or rotational behaviour are not known. Some well-studied asteroids are now even considered as excellent far-infrared calibrators.
High Spatial/Spectral Resolution Studies of Eta Carinae
Authors: Gull Theodore R. ,   Eta Carinae HST Treasury Team
Published: March 2016

AbstractWe have used the high spatial and high spectral resolution of the Space Telescope Imaging Spectrograph (STIS) to study Eta Carinae and the Homunculus. Since the last minimum in 1998.0, CCD spectral modes have followed changes in the Eta Carinae, and large-scale changes in the Homunculus. Since 2001.7, MAMA echelle-mode observations have followed changes in the Eta Carinae and the very nearby ejecta through the 2003.5 minimum. Very significant changes in the star and nebular occur as the X-Ray drop occurs in the minimum.
Molecular Hydrogen in the High Redshift Damped Ly-α Systems:
Authors: Srianand R. , Petitjean P. , Ledoux C. , Ferland G. 
Published: March 2016

AbstractThis review talk summarizes the main results obtained from the just completed survey of molecular hydrogen in damped Lyman-a systems (DLAs). Preliminary results based on modeling ionization conditions and chemical network is also presented. The presence of H2 and fine-structure lines of C 1 in 13-20% of DLAs allow one to investigate the physical conditions using the techniques that are commonly used in the studies of the Galactic ISM. It is shown that the DLAs with H2 trace regions with higher density, lower temperature, moderate to high dust depletion, and local star-formation. Absence of H2 in DLAs with moderate dust depletion could just be a simple consequence of lower densities in the systems.
Molecular Absorption Lines in Galaxies
Authors: Wiklind Tommy 
Published: March 2016

AbstractMolecular absorption lines have become an important tool in studying the astrochemistry of the dense and cold interstellar medium in both our own Galaxy and high redshift systems. The sensitivity is to first order only dependent on the observed continuum flux. Apart from a few nearby galaxies, molecular absorption lines have been used to study the molecular ISM in 4 galaxies at redshifts 0.25-0.89. A large number of molecular species and transitions have been observed, allowing a detailed comparison with molecular gas in our own Galaxy. Planned instruments, such as ALMA, will allow studies of a larger number of molecular absorption line systems.
Magellanic Diffuse Interstellar Bands and Carbon Chemistry
Authors: Ehrenfreund P. , Cox N. , Cami J. , Foing B.H. , Kaper L. , d’Hendecourt L. , Maier J.P. , Salama F. , Sarre P. , Snow T. , Sonnentrucker P. 
Published: March 2016

AbstractWith the Ultraviolet Visual Echelle Spectrograph mounted at the Very Large Telescope, we have observed at unprecedented spectral resolution the absorption spectrum toward reddened stars in the Magellanic Clouds over the wavelength range of 3500-10500 Å. This range covers the strong transitions associated with neutral and charged large carbon molecules of varying sizes and structures. We report the first detection of diffuse interstellar bands (DIBs) at 5780 and 5797 Å in the Small Magellanic Cloud and the variation of those DIBs toward several targets in the Large Magellanic Cloud. The variation of DIBs in the Magellanic Clouds compared with Galactic targets may be governed by a combination of the different chemical processes prevailing in low-metallicity regions and the local environmental conditions. The analysis of high-resolution absorption spectra allows us to reveal the global effects in the chemistry and recycling of cosmic dust in the Magellanic Clouds which are relevant for the chemical pathways forming large organic molecules in external galaxies.
Site Testing at Dome C—Cloud Statistics from the ICECAM Experiment
Authors: Ashley Michael C. B. , Burton Michael G. , Calisse Paolo G. , Phillips Andre , Storey John W. V. 
Published: March 2016

AbstractAnalysis of sky images obtained from an automated experiment at Dome C, Antarctica, at 2-hourly intervals from February to November 2001 show cloud-free conditions 74% of the time. This augurs well for the prospects of future astronomical observatories at this site.
IceCube: A Kilometer-Scale Neutrino Observatory at the South Pole
Authors: Halzen Francis 
Published: March 2016

AbstractSolving the century-old puzzle of how and where cosmic rays are accelerated mostly drives the design of high-energy neutrino telescopes. It calls, along with a diversity of science goals reaching particle physics, astrophysics and cosmology, for the construction of a kilometer-scale neutrino detector. This led to the IceCube concept to transform a kilometer cube of transparent Antarctic Ice, one mile below the South Pole, into a neutrino telescope.
Extremely Large Telescopes on the Antarctic plateau
Authors: Lawrence J.S. 
Published: March 2016

AbstractThe primary limitation to the performance of any large ground-based telescope is the atmospheric properties of its site, particularly the sky emission and the turbulence structure. There are several sites on the Antarctic plateau (South Pole, Dome C and Dome A) for which the increase in infrared sensitivity relative to a mid-latitude site should be as much as two orders of magnitude. The unique turbulent structure above Dome C indicates that an extremely large telescope equipped with only a natural guide star adaptive optics system should achieve equivalent resolution to a mid-latitude extremely large telescope with a multi-conjugate multi-laser guide star system.
Adaptive Optics and Interferometry on the Antarctic Plateau
Authors: Lloyd James P. 
Published: March 2016

AbstractThe unique properties of atmospheric turbulence in atmosphere above the Antarctic plateau offer some compelling advantages for astronomical adaptive optics and interferometry. The shallow nature of the turbulent layer at the South Pole results in low scintillation and large angular coherence (Marks et al. 1996, 1999; Lloyd, Oppenheimer, & Graham 2002; Lloyd et al. 2003). Recent wintertime SODAR measurements at Dome C indicate that similar conditions exist at Dome C, but that the turbulent layer is likely both weaker and shallower. This paper discusses the outcomes of such conditions on the atmospheric properties for astronomy. Particularly due to the low wind speed at Dome C, the atmospheric properties are highly favorable for adaptive optics and interferometry. The resulting long coherence time enables adaptive optics at visible wavelengths, and the large angular coherence results in a useful field of view as a result.
Why Astronomy is Useful and Should be Included in the School Curriculum
Authors: Percy John R. 
Published: March 2016

Even in my astronomically-developed province of Ontario, Canada, with an excellent public education system, astronomy was not a compulsory topic in the school curriculum until quite recently. So I began collecting a list of reasons why it should be, in the hope of persuading those who set the curriculum.It would be instructive, however, to start by asking: “Why is astronomy not included in the curriculum?” Here are some possible reasons: (i) Astronomy is perceived to be irrelevant to practical concerns such as health, nutrition, agriculture, environment, engineering, and the economy in general; this is particularly true in developing countries, (ii) Most school teachers have little or no knowledge of astronomy, or astronomy teaching; in fact, they may have the same deeply-rooted misconceptions as their students, (iii) Astronomy is perceived as requiring night-time activities (“the stars come out at night, the students don’t”), and expensive and complex equipment such as telescopes, (iv) Astronomy is perceived as being solely “Western” by some non-Western cultures. (v) There may be conflict – real or perceived – between astronomy and personal beliefs such as religion, culture, and pseudo-science; in fact, astronomy is sometimes viewed as being as speculative as pseudo-science, (vi) Many of the available resources are designed for affluent schools in affluent countries, or for different latitudes, longitudes, and languages, (vii) Astronomy may be seen as allied with high technology, with all its real and perceived dangers.