bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Models of Galactic Dynamos
Authors: Elstner Detlef
Published: March 2016

The 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.
On the Nonlinear Nature of the Turbulent α-Effect
Authors: Cattaneo Fausto , Hughes David W. , Thelen Jean-Claude
Published: March 2016

Galactic magnetic fields are, typically, modelled by mean-field dynamos involving the α-effect. Here we consider, very briefly, some of the issues involving the nonlinear dependence of α on the mean field.
Mean Field Dynamo Saturation: Toward Understanding Conflicting Results
Authors: Blackman Eric G. , Field George B.
Published: March 2016

Mean 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

A 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

Kilometer-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

Recent 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

Cosmic 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

Spectra 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

Our 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.
Origin and Bulk Chemical Composition of Mercury
Authors: Prentice Andrew J. R. , Jontof-Hutter Daniel
Published: March 2016

The origin of Mercury’s high metal content is examined within a gas ring model for the condensation of the planetary system. Mercury’s axial moment-of-inertia factor is predicted to be 0.325 ± 0.002.
The BepiColombo Lander – MSE
Authors: Thomas Nicolas , Schulz Rita , Falkner Peter
Published: March 2016

The 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.
Magnetohydrodynamic 3-D Models of the Solar Convection Zone
Authors: Brun Allan Sacha
Published: March 2016

We have conducted 3-D simulations of the complex magnetohydrodynamics of the solar convective envelope in spherical shells using our anelastic spherical harmonics (ASH) code (Brun & Toomre 2002). We here briefly discuss the properties of the kinetic and current helicities established in such systems.
Helicity and The Alpha-Effect: Dynamo Theory and Observations
Authors: Kuzanyan Kirill
Published: March 2016

Spatial 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.
Magnetic Helicity Propagation from Inside the Sun
Authors: Longcope Dana
Published: March 2016

Models of twisted flux tube evolution provide a picture of how magnetic helicity is propagated through the solar convection zone into the corona. According to the models, helicity tends toward an approximately uniform length-density along a tube, rather than concentrating at wider portions. Coronal fields lengthen rapidly during active region emergence, requiring additional helicity to propagate from the submerged flux tube. Recent observations of emerging active regions show an evolution consistent with this prediction, and no evidence of helicity concentrating in wider sections.
Generation and Annihilation of Magnetic Helicity in Active Regions
Authors: Kusano K.
Published: March 2016

Generation and annihilation processes of magnetic helicity in solar coronal active regions are investigated based on the observations and the simulations. We first examined the reliability of the numerical techniques, which enable to measure the magnetic helicity flux through the photosphere based on the magnetogram data. Secondly, in terms of the new technique, we found that magnetic helicities of the both signs are simultaneously injected into active regions. Motivated by this result, finally, we investigated the nonlinear process of the magnetic helicity annihilation, using the three-dimensional numerical simulations. The simulations clearly indicated that the helicity reversal can cause the eruption of large-scale plasmoid through the nonlinear process of the resistive instability growing on the helicity inversion layer. From these studies, we point out that the annihilation of magnetic helicity is a key process for the onset mechanism of solar flares.
Transport of Magnetic Helicity and Dynamics of Solar Active Regions
Authors: Georgoulis M. K. , LaBonte B. J. , Rust D. M.
Published: March 2016

We introduce a method to calculate the magnetic helicity density in a given active-region vector magnetogram, and a lower limit of it, based on a linear force-free (Iff) approximation. Moreover, we provide a lower limit of the total magnetic helicity in the active region (AR). A time series of magnetograms can be used to calculate the rate of helicity transport. The results can be then correlated with manifestations of the dynamical activity in ARs, such as flares and filament eruptions.
Solar and Interplanetary Magnetic Helicity Balance of Active Regions
Authors: Mandrini Cristina H. , Démoulin Pascal , van Driel-Gesztelyi Lidia , Dasso Sergio , Green Lucinda M. , Fuentes Marcelo López
Published: March 2016

We analyzed the long-term evolution of two active regions (ARs), NOAA 7978 and 8100, from their emergence through their decay using observations from several instruments on board SoHO (MDI, EIT and LASCO) and Yohkoh/SXT. We computed the evolution of the relative coronal magnetic helicity from one central meridian passage to the next, combining data from MDI and SXT with linear force-free models of the coronal magnetic field. Next, we calculated the injection of helicity by photospheric differential rotation using MDI magnetic maps and a mean differential rotation profile. To estimate the depletion of magnetic helicity we counted all the CMEs of which these ARs were the source, and we evaluated their helicity assuming a one to one correspondence with magnetic clouds (MCs) with an average helicity content; this value was computed for a sample of 18 clouds using a cylindrical linear force-free model. Out of our three helicity estimates (variation of coronal magnetic helicity, injection by differential rotation and ejection via CMEs) the one with the largest uncertainty is the amount of helicity ejected via CMEs. However, we determined, by modeling a particular MC using three different approaches in cylindrical geometry (two force-free models and a non force-free model with constant current), that its magnetic helicity content was nearly independent of the model used to fit in situ field observations (Dasso et al. 2003, in preparation). This result justifies our use of the average magnetic helicity value considering only a single MC model. Comparing the three components in the helicity balance (see Table 1), we find that photospheric differential rotation is a minor contributor to the AR magnetic helicity budget. CMEs carry away at least 10 times more helicity than the one differential rotation can provide. Therefore, the magnetic helicity flux needed in the global balance should come from localized photospheric motions that, at least partially, reflect the emergence of twisted flux tubes. Taking into account the magnetic flux in the ARs and the number of turns that a uniformly twisted flux tube should have to survive its rise through the convection zone, we have found that the total helicity carried away in CMEs is approximately equal to the end-to-end helicity of the flux tubes that formed these two ARs. Therefore, we conclude that most of the helicity ejected in CMEs is generated below the photosphere and emerges with the magnetic flux. Extended versions of this work were published in Demoulin et al. (2002, Astronomy & Astrophys. 382, 650) and in Green et al. (2002, Solar Phys. 208, 43), while in Mandrini et al. (2003, Astrophys. & Space Sci., 290, 319) and van Driel-Gesztelyi et al. (2003, Adv. Space Res., 32, 1855) the helicity computations were revised to include the underestimation of magnetic flux density found in MDI data. After this revision, we confirmed our former results.
A Non-Helical Dynamo — MHD Simulations of Dynamo Action by a Non-Helical Flow
Authors: Archontis V. , Dorch S.B.F.
Published: March 2016

We illustrate that helicity is not a necessary ingredient for fast dynamo action; we use the stagger-grid method of Galsgaard, Nordlund and others (e.g. Galsgaard & Nordlund 1997, and applied to dynamos by e.g. Dorch 2000): we solve the full MHD equations including a forcing term that keeps the kinetic energy at an approximately constant level. A 3-d flow with no mean helicity (an ABC-like flow without cosines, cf. Galloway & Proctor 1992) is implemented and it turns out that apart from the high growth rate in the linear regime (compared to kinematic dynamo action, cf. Archontis & Dorch 2003a), the dynamo saturates at a level significantly higher that the intermittent turbulent dynamos (cf. Archontis & Dorch 2003b); namely at exact energy equipartition. During the linear regime, several kinematic modes are present, e.g. a sheet/vortex-mode and a mode that resembles the ABC ”double cigar” mode (e.g. Dorch 2000). In the non-linear regime, the magnetic topology is not symmetric, but the initial structure of the velocity field is retained. The presence of helicity is not a requirement for dynamo action but it is rather the stretching ability of the flow that amplifies the magnetic energy in an exponential manner (Archontis & Dorch, in preparation).
Magnetic Neutral Line Rotations in Flare-Productive Regions
Authors: Ishii Takako T. , Asai Ayumi , Kurokawa Hiroki , Takeuchi Tsutomu T.
Published: March 2016

We examined the evolution of active regions and found that rotational motions of the neutral line in the δ-type magnetic configuration are common in the flare-productive active regions.
On a Cyclic Variation of the Hemispheric Helicity Rule
Authors: Pevtsov A. A. , Hagyard M. J. , Blehm Z. , Smith J. E. , Canfield R. C. , Sakurai T. , Hagino M.
Published: March 2016

We report the result of a study of magnetic helicity in solar active regions during 1980-2000. Using the vector magnetograms from four instruments (Haleakala Stokes Polarimeter, Marshall Space Flight Center, Mitaka Solar Flare Telescope and Okayama Observatory Solar Telescope) we calculated the force-free parameter α and computed a slope dα/dφ as the linear fit of α vs. latitude φ, using annual subsets of data. The hemispheric helicity rule can be expressed in terms of this slope as dα/dφ < 0. We find that each instrument exhibits change in sign of dα/dφ for some years. However, we do not see consistency between different instruments in regards to years disobeying the rule. We show that this inconsistency can be attributed to insufficient numbers of active regions in annual subsets of data. We conclude that the present data sets do not allow to make statistically significant inference about possible cyclic variation of the hemispheric helicity rule.

For further discussion see Hagyard et al., 2003, ApJ, submitted.
The Search for Correlation between BiSON SMMF Data and CME Events
Authors: Chaplin William J. , Dumbill Andrew M. , Elsworth Yvonne P. , Isaak George R. , McLeod Clive P. , Miller Brek A. , New Roger , Pintér Balázs
Published: March 2016

We present first attempts to compare the Birmingham Solar-Oscillations Network (BiSON) high precision solar mean magnetic field (SMMF) data of four years with the occurrence of CMEs (coronal mass ejections) as recorded by LASCO on board SOHO. The BiSON magnetic measurement technique is given in Chaplin et al. (2003). Particularly interesting results of recent SMMF high-cadence observations have come from studies of correlation between the SMMF determined by MDI and the occurrence of CMEs (Boberg and Lundstedt 2000 and Boberg et al 2002). Two frequency ranges, centered on 13 and 90 minutes, have been identified as possibly correlating with CME occurrence.

We have used BiSON SMMF data from two sites to investigate CME related SMMF signals to try to confirm the MDI results. To search methodically through our data set we have developed two correlation techniques suited to short (up to 32 minutes) and long (up to 3 hours) period wavelets, respectively. For short periods we analyzed SMMF data in the vicinity of CMEs, and for long periods we compared SMMF results for days with and without recorded CMEs. In neither period range have we yet clearly identified correlations between SMMF power excesses and CME onsets. For the details of the techniques and the results see Chaplin et al. (2004).
Eruption of a Quiescent Filament on Feb. 18, 2003
Authors: Bao Xingming , Zhang Hongqi
Published: March 2016

An eruptive process of a quiescent filament on Feb. 18, 2003 that initiated a CME was recorded by the full disk Hα telescope in HSOS (Huairou Solar Observing Station) and by the Solar and Heliospheric Observatory (SOHO). The eruption revealed a typical process of energy release and dense plasma ejection caused by magnetic instability. Filament eruptions, flares and CMEs are believed to be the same magnetic eruption and reconnection event in three different stages. This feature was shown more clearly during eruption of the quiescent filament because of the simple and regular magnetic line-of-sight field in photosphere compared to active regions with complex magnetic configurations. The filament was located near the solar northwest limb (N 30-40, W 40-80) on Feb. 18, 2003 with height about 11000 km. It began to erupt at 02:00 UT. Bright ribbons appeared at the magnetic feet of the filament in EIT/195 at 02:30 UT. The post-eruption loops formed at 04:00 UT and lasted about 6 hours. The CME appeared on EIT/C2 images at 02:30UT with an Ω shape, just the same as the filament erupted. The speed of mass ejected of the filament was about 250km/s. We also notice that the height of the filament increased and the magnetic fields with opposite polarity moved towards each other before the filament erupted. The filament eruption reveals that the filament may be held in the corona by the twisted magnetic fields which also keep the cool plasma from escaping the solar surface. If the twisted field was broken by some magnetic instabilities, the filament would erupt. The presence of post-eruption loops implies a transition process from non-potential (twisted) to potential field magnetic configuration in the filament.
M31’s Disk System of Globular Clusters
Authors: Morrison Heather , Harding Paul , Hurley-Keller Denise , Perrett Kathy
Published: March 2016

Globular cluster systems are often thought to be associated with violent formation events such as galaxy mergers or the formation of large bulges. However, formation in relatively ordered regions such as thin disks may also be an important process which has been overlooked.

Recent high-quality spectroscopic studies of the M31 globulars show that a significant number of the clusters projected on its disk belong to a rapidly rotating thin disk. This contrasts strongly with the Milky Way system, which is composed of a halo and thick disk system and has no known thin disk globulars. It is also likely that M31 has experienced no minor mergers since the globular cluster formation epoch, as such a merger would have heated the globulars into a thick disk system. The metallicity distributions of the disk and non-disk clusters are quite similar.
Extreme Globular Cluster Systems
Authors: Blakeslee John P.
Published: March 2016

The superior resolution and large format of the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) make it a powerful new tool in the study of extra-galactic globular cluster (GC) systems. We summarize some early results on GC populations from the ACS GTO program, concentrating on the extreme cases of the isolated dwarf NGC 2915 and the core of the massive lensing cluster Abell 1689.
A Tale of Giants Stealing from Dwarfs
Authors: Forbes Duncan A.
Published: March 2016

Cold Dark Matter simulations predict 10-100 x more dwarf satellite galaxies than are observed. Some of these ‘missing satellites’ may have been accreted, along with their globular clusters (GCs), by giant galaxies (Cote et al. 1998). But examples of dwarfs in the early stages of disruption have remained elusive.
The ACS Virgo Cluster Survey
Authors: Côté Patrick , West Michael J.
Published: March 2016

We describe the ACS Virgo Cluster Survey, an HST imaging survey of early-type galaxies in the Virgo Cluster. Multi-color ACS images for one hundred member galaxies, spanning a range of 450 in luminosity, are being used to study the central regions of these galaxies, their globular cluster systems, and the three-dimensional structure of Virgo itself. In terms of depth, spatial resolution, sample size and homogeneity, this represents the most comprehensive imaging survey to date of early-type galaxies in dense environments.
Stellar Population Models with Variable Element Abundance Ratios
Authors: Thomas Daniel , Maraston Claudia , Bender Ralf
Published: March 2016

We present a comprehensive set of new generation stellar population models of Lick absorption line indices, which for the first time include element abundance ratios different from solar. We computed the 21 Lick indices CN1, CN2, Ca4227, G4300, Fe4383, Ca4455, Fe4531, C24668, Hβ, Fe5015, Mg1, Mg2, Mgb, Fe5270, Fe5335, Fe5406, Fe5709, Fe5782, Na D, TiO1, and TiO2, in the wavelength range 4000 ≲ λ ≲ 6500 Å. Models are provided with: [α/Fe] = 0.0, 0.3, 0.5, [α/Ca] = -0.1, 0.0, 0.2, 0.5, and [α/N] = −0.5, 0.0; ages from 1 to 15 Gyr; total metallicities from 1/200 to 3.5 solar (-2.25 ≤ [Z/H] ≤ 0.67).
Self-Induced Formation of Metal-Rich Globulars in Bulges?
Authors: Kravtsov Valery V.
Published: March 2016

Taken together, the latest key observations assume that (i) old metal-rich globular cluster populations (MRGCPs) in bulges were able to form due to an increased self-induced star formation rate (SFR) in their host galaxies, while galaxy merging played an additional role; (ii) massive star cluster populations (MSCPs) in irregulars may be young, less prominent counterparts of the old MRGCPs in spheroids.
Evolution of Globular Cluster Populations in Compact Galaxy Groups
Authors: Leon S. , Perea J. , Del Olmo A. , Athanassoula E. , Bergond G. , Meylan G. , Gomez C. Garcia
Published: March 2016

The redistribution of globular clusters within compact groups of galaxies is followed through N-body simulations. Particular emphasis is given to the globular clusters released in the Intra-Group Medium (IGM) and to the final configuration of the evolution.
Chemical Abundances in the Sagittarius Galaxy: Terzan 7
Authors: Tautvaišienė Gražina , Wallerstein George , Geisler Doug , Gonzalez Guillermo , Charbonnel Corinne
Published: March 2016

Abundances of 21 chemical elements have been determined in three red giants in Terzan 7 using high-resolution spectra obtained with the UVES spectrograph on the ESO 8.2 m Kueyen telescope. The mean [Fe/H]= –0.61 ±0.07. The relative elemental abundance ratios indicate a close similarity of Terzan 7 to its host galaxy.
Mergers and Non-Thermal Processes in Clusters
Authors: Sarazin Craig L.
Published: March 2016

Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Mergers drive shocks in the intra-cluster gas which heat the intra-cluster gas. Mergers disrupt cluster cooling cores. Mergers produce large, temporary increases in the X-ray luminosities and temperatures of cluster; such merger boost may bias estimates of cosmological parameters from clusters. Chandra observations of the X-ray signatures of mergers, particularly “cold fronts,” will be discussed. X-ray observations of shocks can be used to determine the kinematics of the merger. As a result of particle acceleration in shocks and turbulent acceleration following mergers, clusters of galaxies should contain very large populations of relativistic electrons and ions. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from non-thermal particles accelerated in these shocks are described.
A Physicist’s View of Stellar Dynamics: Dynamical Instability of Stellar Systems
Authors: Gurzadyan V.G.
Published: March 2016

I argue that the widely adopted framework of stellar dynamics survived since 1940s, is not fitting the current knowledge on non-linear systems. Borrowed from plasma physics when several fundamental features of perturbed non-linear systems were unknown, that framework ignores the difference in the role of perturbations in two different classes of systems, in plasma with Debye screening and gravitating systems with no screening. Now, when the revolutionary role of chaotic effects is revealed even in planetary dynamics i.e. for nearly integrable systems, one would expect that for stellar systems, i.e. non-integrable systems, their role have to be far more crucial. Indeed, ergodic theory tools already enabled to prove that spherical stellar systems are exponentially instable due to N-body interactions, while the two-body encounters, contrary to existing belief, are not the dominating mechanism of their relaxation. Chaotic effects distinguish morphological and other properties of galaxies. Using the Ricci curvature criterion, one can also show that a central massive object (nucleus) makes the N-body gravitating system more instable (chaotic), while systems with double nuclei are even more instable than those with a single one.
Formation of Young Star Clusters
Authors: Elmegreen Bruce
Published: March 2016

Turbulence, self-gravity, and cooling convert most of the interstellar medium into cloudy structures that form stars. Turbulence compresses the gas into clouds directly and it moves pre-existing clouds around passively when there are multiple phases of temperature. Self-gravity also partitions the gas into clouds, forming giant regular complexes in spiral arms and in resonance rings and contributing to the scale-free motions generated by turbulence. Dense clusters form in the most strongly self-gravitating cores of these clouds, often triggered by compression from local stars. Pre-star formation processes inside clusters are not well observed, but the high formation rates and high densities of pre-stellar objects, and their power law mass functions suggest that turbulence, self-gravity, and energy dissipation are involved there too.
Eclipsing Binaries in the Magellanic Clouds
Authors: Udalski Andrzej
Published: March 2016

We present results of a search for eclipsing binaries in the Magellanic Cloud fields covering central parts of these galaxies. The data were collected during the second phase of the Optical Gravitational Lensing Experiment survey (OGLE-II) in 1997-2000. In total, about 1500 and 3000 eclipsing stars were found in the Small and Large Magellanic Cloud, respectively (Udalski et al. 1998, Wyrzykowski et al. 2003). The photometric data of all objects are available to the astronomical community from the OGLE Internet archive (http://sirius.astrouw.edu.pl/~ogle/). OGLE-II data contain a full variety of classical eclipsing objects of all types: Algol EA-type, β-Lyr EB-type and W UMA EW-type stars. Large samples of stars allow to study in detail statistical properties of eclipsing objects. OGLE data also contain many very unusual eclipsing stars. Examples include eclipsing variable B-type stars (Mennickent et al. 2003), many spotted stars or eclipsing stars with a Cepheid as a component (Udalski et al. 1999). Recently three objects from the LMC revealing simultaneously RR Lyr and eclipsing binary type variability were discovered (Soszyński et al 2003). If the follow-up observations confirm that both components are physically bound and not optical blends these stars will provide a unique opportunity of direct determination of physical parameters of RR Lyr pulsating stars.
Orbital Elements of MACHO Project Eclipsing Binary Stars
Authors: Alcock Charles
Published: March 2016

Large scale photometric surveys can deliver very large numbers of eclipsing binary stars. It is not presently possible to obtain radial velocity information for more than a small fraction of these. We have made some progress in the estimation of the statistical distributions of orbital elements (including semi-major axis and eccentricity) in the MACHO Project catalog of eclipsing binary stars. We see the well-known tendency to circularization in short period orbits and also detect late tidal circularization during the giant phase. The extension of these techniques to newer surveys will also be discussed.
Extragalactic Binaries as Core-Collapse Supernova Progenitors
Authors: Dyk Schuyler D. Van
Published: March 2016

Core-collapse supernovae (SNe) come in a variety of subtypes. The SNe II-plateau (II-P) show a long plateau in their light curves, as well as classical P Cygni Balmer line profiles in their spectra. The SNe Il-linear (II-L) show a linear decline in their light curves after maximum, and the blue absorption trough in the Balmer lines is missing, leaving only broad emission profiles. The SNe II-narrow (IIn) show a narrow profile atop a broad base to the Balmer emission. The SNe lb exhibit no hydrogen lines, but prominent He lines instead. The SNe Ic also show no H, but also weak or no He, with their spectra dominated by intermediate-mass elements. The SNe lib start out appearing as SNe II(P), but in time evolve spectrally to resemble SNe lb, with a later resumption of broad Balmer profiles, as in the case of SN 1993J (see Filippenko 1997 for a review of SN types). The progression from SNe II-P, II-L, Iln, lib, lb, through Ic may be due to the degree of stripping of the H-rich stellar envelope. Binary star systems are likely the progenitors of many core-collapse SNe. In fact, we might expect ≳40-50% of all such SNe to arise from binaries (e.g., De Donder & Vanbeveren 1998).
Apparent Inconsistencies in the Formation of Cometary Matter
Authors: Huebner W. F. , Keller H. U.
Published: March 2016

The Joint Discussion (JD14) is intended to focus attention on several apparent inconsistencies found in comet observations when compared with observations of collapsing interstellar clouds, star-forming regions, and models of the solar nebula. The JD is not intended to resolve these problems, for that a one-day discussion is too short. It rather is intended to draw attention to the inconsistencies to be discussed and resolved in future workshops.
Cometary Silicates: Interstellar and Nebular Materials
Authors: Wooden Diane H.
Published: March 2016

Evidence for interstellar material in comets is deduced from IR spectra, in situ measurements of Comet Halley, and chondritic porous interplanetary dust particles (CP IDPs). IR spectra of comets reveal the spectrally active minerals: amorphous carbon, amorphous silicates, and (in some comets) crystalline silicates. Evidence suggests amorphous silicates are of interstellar origin while crystalline silicates are of nebular origin.

10 μm spectra of comets and sub-micron amorphous silicate spherules in CP IDPs have shapes similar to absorption spectra through lines-of-sight in the ISM. Thermal emission models of cometary IR spectra require Fe-bearing amorphous silicates. Fe-bearing amorphous silicates may be Fe-bearing crystalline silicates formed in AGB outflows that are amorphized through He+ ion bombardment in supernova shocks in the ISM.

Crystalline silicates in comets, as revealed by IR spectra, and their apparent absence in the ISM, argues for their nebular origin. The high temperatures (>1000 K) at which crystals form or are annealed occur in the inner nebula or in nebular shocks in the 5 – 10 AU region. Oxygen isotope studies of CP IDPs show only 1% by mass of the silicate crystals are of AGB origin. Together this suggests crystalline silicates in comets are probably primitive grains from the early solar nebula.
Collisional Simulations of Cometary Nuclei
Authors: Sirono Sin-iti
Published: March 2016

Collisional simulations of cometary nuclei (icy dust aggregates) are conducted. Conditions for sticking are determined as a function of the impact velocity and mechanical properties of nuclei. Possible collisional outcomes in three evolutionary stages of icy-dust aggregates are discussed.
Uncertainties in Stellar Abundance Analyses
Authors: Asplund Martin
Published: March 2016

Over the last half-century quantitative stellar spectroscopy has made great progress. However, most stellar abundance analyses today still employ rather simplified models, which can introduce severe systematic errors swamping the observational errors. Some of these uncertainties for late-type stars are briefly reviewed here: atomic and molecular data, stellar parameters, model atmospheres and spectral line formation.
Evolution of Metals and Stars in Damped Lyman-Alpha Galaxies
Authors: Kulkarni Varsha P.
Published: March 2016

Damped Lyman-alpha absorbers in quasar spectra provide a unique tool to directly measure the abundances of elements in galaxies at red-shifts 0 < z < 5, and hence probe the chemical evolution of galaxies over > 90% of the age of the Universe. Since cosmic chemical evolution models predict the global metallicity of galaxies to increase with time, it is of great interest to determine whether DLAs actually show such a trend. We discuss statistical analysis of existing DLA Zn data to examine the metallicity-redshift relation, and a comparison of the observed data with models of cosmic chemical evolution. We also describe efforts to expand the DLA abundance sample at z < 1.5, where the current data are particularly sparse. Finally, we discuss emission-line imaging studies of the absorber galaxies and compare constraints on their star formation rates with models based on the global star formation history.
Iron Kα Spectra from an Atomic Modeling Perspective
Authors: Liedahl Duane A.
Published: March 2016

In order to upgrade the diagnostic capability associated with Fe Kα spectra, we have calculated detailed atomic models that include the effects of inner-shell photoionization, autoionization, collisional excitation at relatively high particle number densities, and photoexcitation in plasmas with high X-ray and/or UV energy densities. I discuss some of the potential uses of these models in the context of compact X-ray sources.
Photorecombination and Photoionization Experiments at Heavy-Ion Storage-Rings and Synchrotron-Light Sources
Authors: Schippers Stefan
Published: March 2016

Recent experimental work on the photorecombination and the photoionization of astrophysically relevant atomic ions employing the merged-beams technique at heavy-ion storage-rings and synchrotron-light sources, respectively, is summarized. The resulting absolute photoionization cross sections and recombination rate coefficients benchmark corresponding theoretical calculations and are needed for the accurate determination of ionization equilibria in astrophysical plasmas.
The Ionized Gas and Nuclear Environment in NGC 3783
Authors: Netzer Hagai
Published: March 2016

The 900 ks Chandra spectrum of NGC 3783 was analyzed in various ways to study the properties of the absorbing gas. The main findings are: 1) On a time scale of 20-120 days, the source exhibits two very different spectral shapes with different softness ratios. The absorbing gas is not responding to these continuum variations. 2) Detailed photoionization modeling based on 10 silicon and sulphur lines near 5-7Å produces a satisfactory fit of the entire 3-25 A spectrum of the source. The only discrepancy is in the central wavelength of the iron UTA feature. 3) A combination of three ionized absorbers, each split into two kinematic components, can explain the strengths of almost all the absorption lines and bound-free edges. The three components span a large range of ionization and have a total column of about 4×1022 cm-2. Moreover, all three components are thermally stable and seem to have the same gas pressure.
Muses-C as a Benchmark Mission for the S-Type Asteroid Group
Authors: Fujiwara Akira , Abe Masanao , Yano Hajime
Published: March 2016

MUSES-C is launched in May 2003, and arrives in the vicinity of a near-Earth asteroid (25143)1998 SF36 in June 2005. The spectral type is S and its diameter is 300-600 m. During four months stay multi-band imaging, near-infrared spectra, and X-ray spectra will be taken at the nominal altitude of about 6km above the asteroid surface.. Sampling of the surface material will be made at two different locations. The total mass collected will be about 1 g. A miniature hopping lander on which imaging cameras are boarded will be dropped onto the surface. The sample will be returned to the earth in June 2007. These methods, the close-up global observation from the spacecraft, in situ observation from the lander, and detailed analysis of the returned sample, can, as well as ground-based observation of the targeted asteroid, provide information of surface material distribution in various scales, and also provide powerful benchmarks to interpretation of spectroscopic data obtained through ground-based observation of S-type asteroids.
Observations of Small Solar System Bodies with GAIA
Authors: Mignard Francois
Published: March 2016

The ESA space astrometry mission has a great potential of observation and discovery on the solar system objects. GAIA is due for launch in 2010 and the survey mission will last five years. In addition to accurate astrometry of about 1 billion stars, the mission will survey all solar system objects brighter than 20th magnitude, in astrometry and with multicolor photometry. Each object will be observed about a hundred times during the five year mission. It is expected that more than 500 000 asteroids will be repeatedly measured by the mission.
Minor Planet Binaries
Authors: Margot Jean-Luc
Published: March 2016

The first detailed characterization of a near-Earth binary (2000 DP107) provided significant insights into the formation mechanism, orbital evolution, and physical properties of the system. Near-Earth Asteroid (NEA) binaries are tidally evolved with synchronously rotating secondaries, providing constraints on asteroid mechanical properties (tidal Q and rigidity). It is expected that radar observations will permit measurements of orbital precession, with corresponding implications for the distribution of mass within asteroids.
FUSE and the Quest for High-Resolution Spectroscopy in the Far Ultraviolet
Authors: Moos H. Warren
Published: March 2016

The Far Ultraviolet Spectroscopic Explorer (FUSE) instrument covers the spectral range 912-1187 Å with a resolving power of 15,000 to 20,000. This spectral region provides unique access for the study of many atomic and ionic species found in the interstellar medium, intergalactic medium, stars, and extragalactic objects. This paper summarizes the status of the mission and then discusses the need for higher resolution spectroscopy. Although the FUSE instrumental resolution is sufficient to separate most species, it usually it is not adequate for analyzing the gas velocity structure in detail. Implications for future missions are discussed.
APEX, the Astrophysical Plasmadynamic EXplorer: An EUV High Resolution Spectroscopic Observatory
Authors: Kowalski M
Published: March 2016

APEX is a proposed Small Explorer satellite that will obtain high-resolution EUV spectra of white dwarfs, CVs, stellar coronae, and the local ISM. The APEX effective area (30-50 cm2) and resolution (~10,000) are an order of magnitude improvement over Chandra.
Mapping of Stellar Surfaces with Doppler and Zeeman Doppler Imaging
Authors: Cameron Andrew Collier
Published: March 2016

Doppler imaging has been used to image dark spots on the surfaces of rapidly rotating, magnetically active stars for the last 20 years. More recently, methods have been developed for combining line-profile information from large numbers of spectral lines simultaneously. This has allowed starspot distributions to be mapped in sufficient detail to allow tracking of individual spots over several stellar rotations, delineating surface differential rotation patterns for a number of stars. Zeeman-Doppler imaging allows the creation of stellar magnetograms, which are providing the first insights into the 3D topology of stellar coronal magnetic fields. The advent of cryogenic infrared echelle spectrographs opens up exciting new possibilities for Doppler imaging in molecular lines of species such as TiO, OH, and FeH.
Future Groundbased High-Resolution IR Spectrometers
Authors: Moorwood Alan
Published: March 2016

Plans for future high-resolution infrared spectrometers on large groundbased telescopes, their capabilities and science goals are briefly reviewed.
High Resolution Spectroscopy at Low Radio Frequencies
Authors: Chengalur Jayaram N.
Published: March 2016

In this paper I discuss two examples of the science that can be done with high-resolution spectroscopy at low radio frequencies.
Systematically Peculiar Molecular Composition in M 82: Regarding the Formation Mechanisms
Authors: Takano S. , Nakai N. , Kawaguchi K. , Takano T , Schilke P. , Winnewisser G.
Published: March 2016

A systematically peculiar molecular composition has been found in a nearby starburst galaxy M 82. Molecules related to grain surface formation and to production reactions favorable at high-temperature are deficient in M 82 among nearby galaxies with rich gas. These molecules are SO, SiO, NH3, HNCO, CH3OH, and CH3CN. Possible reasons for this peculiarity are discussed.
New Results on the Composition of the Outer Planets and Titan
Authors: Fouchet Thierry
Published: March 2016

In this brief summary, I present recent progress on our knowledge of the Giant Planets and Titan atmospheric composition, as well as the impact of this progress on our understanding of Solar System formation, and atmospheric chemistry.
Complex Organic Solid Matter in the Outer Solar System
Authors: Cruikshank D. P.
Published: March 2016

Complex organic molecular material of non-biological origin is found in abundance in the interstellar dust in our Galaxy, and is also detected in other galaxies. Some of this material was incorporated into the solar nebula and is now found in some Solar System bodies. While some pre-solar organic material has been preserved, synthesis of complex organics in planetary atmospheres and on icy surfaces has been in progress for the entire age of the Solar System. Refractory organic solids have proven difficult to detect by traditional spectroscopic techniques, and their presence is usually inferred from the low albedo and (often) red color of the surfaces of small bodies in the outer Solar System (OSS). Color in complex organic molecules, such as polymers and polycyclic aromatic hydrocarbons, is caused by absorption in the UV and visible spectral regions arising from electronic transitions connected primarily with C-C and C-0 bonding. In particular, large hydrocarbon molecules with conjugated (alternating pairs of double and single) C-C bonds have color because the electronic transitions of the de-localized pi electrons extend into the visible spectral region; the longer the conjugated chain, the further is the extension to longer wavelength, with the result that especially large molecular material appears black.
Changes in Pluto’s Atmosphere
Authors: Elliot J. L.
Published: March 2016

Pluto’s tenuous atmosphere was probed in 1988 with a stellar occultation observed from the Kuiper Airborne Observatory (KAO, Elliot et al. 1989) and a variety of ground-based sites (Millis et al. 1993). These data, subsequent theoretical modeling (e.g. Strobel et al. 1996), and spectroscopic observations (Owen et al. 1993; Young et al. 1997), gave us the following post-occultation picture of Pluto’s atmosphere (Yelle & Elliot 1997; Elliot, Person, & Qu 2003b): N2 is the dominant constituent of the atmosphere, which also contains small amounts of CH4 and CO. These molecules are in vapor-pressure equilibrium with their surface ices, and this process acts as a thermostat to keep the N2 ice at ~38 K around the body. The temperature of the 1-3 μbar pressure region probed by the occultation was ~100 K. The KAO light curve dropped abruptly, however, just below half-light. This abrupt drop could be due to one of two potential properties of Pluto’s atmosphere: extinction, or a steep thermal gradient. Each of these explanations has strengths and weaknesses (Yelle & Elliot 1997; Elliot, et al. 2003b).
Numerical Simulation of the Jovian Wind Band as a Convective Phenomenon
Authors: Chan Kwing L. , Mayr Hans G.
Published: March 2016

Using a three-dimensional numerical spectral model, we simulate the outermost layer of Jupiter’s convective envelope (two depth cases: 1-23 bars, 1-115 bars). The physical parameters (e.g. internal energy flux, rotation rate) are chosen to be close to those expected, but solar heating as well as dynamical influences from deeper layers are ignored. The model generates a wind field pattern remarkably similar to that observed. There is a narrow, super-rotating jet at the equator, and two prominent humps in temperature also develop in the subtropics. The strength of the jet streams does not change much over depth. The maximum wind speed occasionally reach 100 m/s, but the mean amplitude of the equatorial jet is about a factor of 2-3 lower than the nominal value. The latitudes of the secondary pro-grade jets are higher than those observed, but they are dependent on the depth of the model. Though the quantitative agreement is not quite satisfactory (as might have been caused by neglected physical effects like solar radiation), this model demonstrates, in principle, the feasibility of generating a Jovian type wind pattern through the interaction of fast rotation and convection in a thin shell.
Particle Astronomy from Antarctica
Authors: Hulth Per Olof
Published: March 2016

A brief review of astroparticle activities in Antarctica is presented including balloon cosmic rays detectors and use of the clear ice sheet for large neutrino telescopes.
Millimetric Site Testing at Dome C: Results and Plans
Authors: Valenziano Luca , Dall’Oglio Giorgio , Graziani Andrea , Martinis Lorenzo , Pizzo Gabriella , Sabbatini Lucia
Published: March 2016

Results relative to three campaigns at Dome Concordia, aimed to measure the millimetric sky noise, are presented. The atmospheric noise during summer seems to be definitely lower with respect to that measured with the same instrumentation in other geographical locations. We illustrate the scientific results obtained.