bluuebunny/crossref_metadata_2025 huggingface dataset:
Survival of halophilic Archaea in Earth's cold stratosphere
Authors: DasSarma P. , Laye V.J. , Harvey J. , Reid C. , Shultz J. , Yarborough A. , Lamb A. , Koske-Phillips A. , Herbst A. , Molina F. , Grah O. , Phillips T. , DasSarma S.
Published: October 2016

Halophilic Archaea are known to tolerate multiple extreme conditions on Earth and have been proposed as models for astrobiology. In order to assess the importance of cold-adaptation of these microorganisms in surviving stratospheric conditions, we launched live, liquid cultures of two species, the mesophilic model Halobacterium sp. NRC-1 and the cold-adapted Antarctic isolate Halorubrum lacusprofundi ATCC 49239, on helium balloons. After return to Earth, the cold-adapted species showed nearly complete survival while the mesophilic species exhibited slightly reduced viability. Parallel studies found that the cold-adapted species was also better able to survive freezing and thawing in the laboratory. Genome-wide transcriptomic analysis was used to compare the two haloarchaea at optimum growth temperatures versus low temperatures supporting growth. The cold-adapted species displayed perturbation of a majority of genes upon cold temperature exposure, divided evenly between up-regulated and down-regulated genes, while the mesophile exhibited perturbation of only a fifth of its genes, with nearly two-thirds being down-regulated. These results underscore the importance of genetic responses of H. lacusprofundi to cold temperature for enhanced survival in the stratosphere.
Dangerous Liaisons. New light on the reasons for the expulsion of the violinist G.B. Viotti from Britain in 1798
Authors: Yim Denise
Published: October 2016

In March 1798 the violinist Giovanni Battista Viotti was expelled from Britain, suspected of being a Jacobin sympathizer. He was allowed to return to England in the summer of 1799 under circumstances that have remained vague to this day. In 1811 he was granted British denizenship, but only after petitioning the Crown. To understand the British Government’s determined stance against Viotti it is necessary to examine his life in Paris in the period 1789–92 – his friendship with the Jacobin journalist-diplomat Hugues Bernard Maret, his entrepreneurial activities, and his attempted takeover of the Paris Opera. These activities were remembered by two eccentric characters of the age, both spies for the British government. The first was an unscrupulous French ultraroyalist, the Comte d’Antraigues. The second was the dogmatic and at times irrational Englishman W.A. Miles, who was especially suspicious of Viotti’s pupil Pierre Rode, who made an unexpected landing in Britain in early 1798. In this article I re-examine the question of Viotti’s expulsion from Britain in light of new evidence against the violinist, some of it apparently damning, and attempt to determine once and for all whether the order was justified.
Long-term orbital stability of exosolar planetary systems with highly eccentric orbits
Authors: Antoniadou Kyriaki I. , Voyatzis George
Published: October 2016

Nowadays, many extrasolar planetary systems possessing at least one planet on a highly eccentric orbit have been discovered. In this work, we study the possible long-term stability of such systems. We consider the general three body problem as our model. Highly eccentric orbits are out of the Hill stability regions. However, mean motion resonances can provide phase protection and orbits with long-term stability exist. We construct maps of dynamical stability based on the computation of chaotic indicators and we figure out regions in phase space, where the long-term stability is guaranteed. We focus on regions where at least one planet is highly eccentric and attempt to associate them with the existence of stable periodic orbits. The values of the orbital elements, which are derived from observational data, are often given with very large deviations. Generally, phase space regions of high eccentricities are narrow and thus, our dynamical analysis may restrict considerably the valid domain of the system's location.
Tidal evolution of stars hosting massive close-in planets
Authors: Ferraz-Mello S. , Moda L. F. R. , do Nascimento J. D. , Pereira E. S.
Published: October 2016

Close-in massive planets transfer angular momentum to their host stars and influence their rotation through the torques associated with the tides raised on the star by the planet. For a star hosting a hot Jupiter, the limit of distance below which tidal torques cannot be neglected grows from a ~0.04 to a ~0.07 AU as the mass of the planet grows from 0.5 to 4MJup.
Focus Meeting 2, “Astronomical Heritage: Progressing the UNESCO–IAU Initiative” Introduction and overview
Authors: Ruggles Clive , Sidorenko Anna
Published: October 2016

Marking seven years of formal cooperation between the IAU and the UNESCO World Heritage Centre to implement UNESCO's “Astronomy and World Heritage” Thematic Initiative, this Focus Meeting reviewed achievements, challenges, and progress on particular World Heritage List nomination projects.
As international as they would let us be
Authors: Trimble Virginia
Published: October 2016

Astronomers wanting to chart the whole sky, or even part of it, 24/7, must collaborate across nations, continents, and hemispheres. The Greeks were perhaps the first to do this, though Eratosthenes' measurement of the diameter of the earth was done when Alexandria and Syene were both part of Ptolemaic Egypt. The Golden Age of Arabic/Moslem astronomy coincided with times when there were very large caliphates and similar empire-like structures. The situation was very different for European astronomy at all times, with periods of successful international collaborations alternating with periods of disaster. Von Zach's “celestial police” agreed in 1800 at Lilienfeld to divide up the sky and look for the “missing” planet between Mars and Jupiter. The observatory was ransacked and papers burned by retreating Napoleonic soldiers in 1813. Skipping ahead most of a century, the Carte du Ciel, George Ellery Hale's Solar Union, Kapteyn's selected areas, and several other cooperative projects had scarcely started when the Great War broke out, and a German eclipse expedition under Erwin Freundlich, which had gone to the Crimea to look for bending of starlight, was imprisoned. All members eventually got home, but the equipment was never recovered.

While British eclipse expeditions organized by Eddington saw the bending of light from Sobral and Principe in 1919, the IAU, founded in the same year, explicitly excluded Germany, Austria-Hungary, Turkey, and the other central powers (even neutrals were not admitted for several years). Indeed Germany did not adhere until 1952. IAU membership now is generally driven by financial issues, but the solution of one nation, two adhering organizations for China was a major victory for international compromise. Coming down to the present, it is interesting that Europe, the site of the outbreak of both the World Wars, has led in the establishment of the European Southern Observatory, the European Space Research Organization (now ESA), and Astronomy and Astrophysics. Even the USA is gradually learning to cooperate with other astronomical nations (though we are still not brilliantly good at it). And the current projects for very large ground-based observing facilities, with acronyms like LOFAR, SKA, GMT, EVLT, and TMT, involve most of Europe, North America, China, Japan, India, and other parts of Asia and South America. A printed version of my FM2 presentation is in press for Vol. 43 (December 2015 issue) of the Journal of American Association of Variable Star Observers (roughly half of whose membership resides outside the US).

I thank Gudrun Wolfschmidt for a list of the astronomers who made up the “celestial police”.
The Development of Mauna Kea as an Astronomical Site Panelists: John Jefferies, Ann Boesgaard, Alan Stockton, Eric Becklin, and Alan Tokunaga
Authors: Harmony Teasel Muir , DeVorkin David ,   (moderators)
Published: October 2016

On August 11 we held a panel discussion at the 2015 IAU General Assembly, within the three-day Focus Meeting FM2, “Astronomical Heritage: Progressing the UNESCO–IAU Initiative”. Our purpose was to both honor and explore the contributions of John Jefferies to the creation and development of Mauna Kea as an astronomical site.
Behind the Spam: A “Spectral Analysis” of Predatory Publishers
Authors: Beall Jeffrey
Published: October 2016

Most researchers today are bombarded with spam email solicitations from questionable scholarly publishers. These emails solicit article manuscripts, editorial board service, and even ad hoc peer reviews. These “predatory” publishers exploit the scholarly publishing process, patterning themselves after legitimate scholarly publishers yet performing little or no peer review and quickly accepting submitted manuscripts and collecting fees from submitting authors. These counterfeit publishers and journals have published much junk science? especially in the field of cosmology? threatening the integrity of the academic record. This paper examines the current state of predatory publishing and advises researchers how to navigate scholarly publishing to best avoid predatory publishers and other scholarly publishing-related perils.
Stellar rotation period inference with Gaussian processes
Authors: Angus Ruth , Aigrain Susanne , Foreman-Mackey Daniel
Published: October 2016

The light curves of spotted, rotating stars are often non-sinusoidal and Quasi-Periodic (QP) and a strictly periodic sinusoid is therefore not a representative generative model. Ideally, a physical model of the stellar surface would be conditioned on the data, however the parameters of such models can be highly degenerate.
A probabilistic and automated tool for the vetting of transit candidates
Authors: Demangeon Olivier , Bordé Pascal
Published: October 2016

We developed, based on the CoRoT experience, an automated tool called BART for Bayesian Analysis for the Ranking of Transit in order to perform a homogeneous and automated ranking of planetary candidates. We applied it to the candidates detected in the campaign 1 of K2.
Reliable inference of light curve parameters in the presence of systematics
Authors: Gibson Neale P.
Published: October 2016

Time-series photometry and spectroscopy of transiting exoplanets allow us to study their atmospheres. Unfortunately, the required precision to extract atmospheric information surpasses the design specifications of most general purpose instrumentation. This results in instrumental systematics in the light curves that are typically larger than the target precision. Systematics must therefore be modelled, leaving the inference of light-curve parameters conditioned on the subjective choice of systematics models and model-selection criteria. Here, I briefly review the use of systematics models commonly used for transmission and emission spectroscopy, including model selection, marginalisation over models, and stochastic processes. These form a hierarchy of models with increasing degree of objectivity. I argue that marginalisation over many systematics models is a minimal requirement for robust inference. Stochastic models provide even more flexibility and objectivity, and therefore produce the most reliable results. However, no systematics models are perfect, and the best strategy is to compare multiple methods and repeat observations where possible.
Active Asteroids: Main-Belt Comets and Disrupted Asteroids
Authors: Hsieh Henry H.
Published: October 2016

The study of active asteroids has attracted a great deal of interest in recent years since the recognition of main-belt comets (which orbit in the main asteroid belt, but exhibit comet-like activity due to the sublimation of volatile ices) as a new class of comets in 2006, and the discovery of the first disrupted asteroids (which, unlike MBCs, exhibit comet-like activity due to a physical disruption such as an impact or rotational destabilization, not sublimation) in 2010. In this paper, I will briefly discuss key areas of interest in the study of active asteroids.
The asteroid-comet continuum from laboratory and space analyses of comet samples and micrometeorites
Authors: Engrand Cécile , Duprat Jean , Bardin Noémie , Dartois Emmanuel , Leroux Hugues , Quirico Eric , Benzerara Karim , Remusat Laurent , Dobrică Elena , Delauche Lucie , Bradley John , Ishii Hope , Hilchenbach Martin ,   the COSIMA team
Published: October 2016

Comets are probably the best archives of the nascent solar system, 4.5 Gyr ago, and their compositions reveal crucial clues on the structure and dynamics of the early protoplanetary disk. Anhydrous minerals (olivine and pyroxene) have been identified in cometary dust for a few decades. Surprisingly, samples from comet Wild2 returned by the Stardust mission in 2006 also contain high temperature mineral assemblages like chondrules and refractory inclusions, which are typical components of primitive meteorites (carbonaceous chondrites - CCs). A few Stardust samples have also preserved some organic matter of comet Wild 2 that share some similarities with CCs. Interplanetary dust falling on Earth originate from comets and asteroids in proportions to be further constrained. These cosmic dust particles mostly show similarities with CCs, which in turn only represent a few percent of meteorites recovered on Earth. At least two (rare) families of cosmic dust particles have shown strong evidences for a cometary origin: the chondritic porous interplanetary dust particles (CP-IDPs) collected in the terrestrial stratosphere by NASA, and the ultracarbonaceous Antarctic Micrometeorites (UCAMMs) collected from polar snow and ice by French and Japanese teams. Analyses of dust particles from the Jupiter family comet 67P/Churyumov-Gerasimenko by the dust analyzers on Rosetta orbiter (COSIMA, GIADA, MIDAS) suggest a relationship to interplanetary dust/micrometeorites. A growing number of evidences highlights the existence of a continuum between asteroids and comets, already in the early history of the solar system.
Ice-gas interactions during planet formation
Authors: Öberg Karin I.
Published: October 2016

Planets form in disks around young stars. In these disks, condensation fronts or snowlines of water, CO2, CO and other abundant molecules regulate the outcome of planet formation. Snowline locations determine how the elemental and molecular compositions of the gaseous and solid building blocks of planets evolve with distance from the central star. Snowlines may also locally increase the planet formation efficiency. Observations of snowlines have only become possible in the past couple of years. This proceeding reviews these observations as well as the theory on the physical and chemical processes in disks that affect snowline locations.
Global Coordination: What are the Next Steps?
Authors: Spergel David , Williams Robert
Published: October 2016

From the transit expeditions of 1761 to JWST, ALMA, and the SKA, international projects have played an important role in driving astronomy and heliophysics. Over the past two decades, the increasing complexity and cost of new facilities, the constrained amount of funding available from individual sources, and the rapidly increasing volume of data produced by newer facilities have made international collaboration on large ground- and space-based facilities essential to moving the fields forward. As international cooperation becomes commonplace, data-sharing policies have become ever more important. All IAU members have a stake in the policy decisions made by nations and various scientific consortiums concerning data access and international collaborations. This focus meeting provided a forum to discuss how to improve coordination of global strategic planning in astronomy, astrophysics, and heliophysics in order to maximize the scientific return from research facilities.
Comet composition and Lab
Authors: Bockelée-Morvan Dominique , Biver Nicolas
Published: October 2016

Comet composition and properties provide information on chemical and physical processes that occurred in the early Solar system, 4.6 Gyr ago. The study of comets and of star-forming regions both help for a better understanding of the formation of planetary systems. A review of our present knowledge of cometary composition is presented. We also discuss laboratory studies that would be helpful for data analysis.
Magnetic field generation, Weibel-mediated collisionless shocks, and magnetic reconnection in colliding laser-produced plasmas
Authors: Fox W. , Bhattacharjee A. , Fiksel G.
Published: October 2016

Colliding plasmas are ubiquitous in astrophysical environments and allow conversion of kinetic energy into heat and, most importantly, the acceleration of particles to extremely high energies to form the cosmic ray spectrum. In collisionless astrophysical plasmas, kinetic plasma processes govern the interaction and particle acceleration processes, including shock formation, self-generation of magnetic fields by kinetic plasma instabilities, and magnetic field compression and reconnection. How each of these contribute to the observed spectra of cosmic rays is not fully understood, in particular both shock acceleration processes and magnetic reconnection have been proposed. We will review recent results of laboratory astrophysics experiments conducted at high-power, inertial-fusion-class laser facilities, which have uncovered significant results relevant to these processes. Recent experiments have now observed the long-sought Weibel instability between two interpenetrating high temperature plasma plumes, which has been proposed to generate the magnetic field necessary for shock formation in unmagnetized regimes. Secondly, magnetic reconnection has been studied in systems of colliding plasmas using either self-generated magnetic fields or externally applied magnetic fields, and show extremely fast reconnection rates, indicating fast destruction of magnetic energy and further possibilities to accelerate particles. Finally, we highlight kinetic plasma simulations, which have proven to be essential tools in the design and interpretation of these experiments.
On formation and activity of IASS
Authors: Hojaev A. S.
Published: October 2016

A brief description of International Aerospace School (IASS) is given.
The Role of Astronomy in Development: The Case of Uganda
Authors: Jurua Edward
Published: October 2016

Science and technology play a key role in economic development; and Universities have a direct stake in this process. A knowledge-based economy requires scientific and technological expertise that is strongly influenced by the strength of training in science and technology. However, in Uganda not many students opt for science subject at higher levels, and subsequently in the University. Therefore, there is need to encourage and motivate students to study science subjects in order for this to be successful. This can be achieved through introduction of stimulating subjects such as astronomy in the university curriculum. Astronomy is considered as the most appealing subject and an excellent tool for conveying scientific knowledge to young students. In this paper, the role that astronomy has played to motivate and interest students to study physics in Mbarara University of Science and Technology, in Uganda, is discussed.
Space Awareness: Inspiring A New Generation of Space Explorers
Authors: Russo Pedro
Published: October 2016

Space Awareness (EUSPACE-AWE) will use the excitement of space to attract young people into science and technology and stimulate European and global citizenship. Our main goal is to increase the number of young people that choose space-related careers.
Unconference session at the IAU General Assembly 2015
Authors: Nava Tibisay Sankatsing , Venugopal Ramasamy , Verdolini Silvia
Published: October 2016

The Astronomy For Development Focus Meeting 20 at the IAU General Assembly encompassed an ‘Unconference’ session as part of the proceedings. Unstructured conferences, with their potential to unleash innovative ideas, are gaining traction in various conferences and symposia. Astronomy For Development is a field that is applicable to the entire Astronomy community (and even beyond) and hence an unconference inviting ideas and fostering frank dialogue is very pertinent.

Officially one of the final sessions of the the 2015 General Assembly, the unconference session was intended to provide a balanced platform for a diverse set of participants and act as an informal setting to promote open discussion on topics of relevance to Astronomy for Development.
Session 21.6: Preserving Dark Skies and Protecting Against Light Pollution in a World Heritage Framework
Authors: Smith Malcolm G.
Published: October 2016

This session opened with a crucial explanation by Michel Cotte of how astronomers first need to understand how to apply UNESCO World Heritage Criteria if they want to motivate their government(s) to make the case to UNESCO for World Heritage recognition. UNESCO World Heritage cannot be obtained just to protect dark skies.

Much more detail of this and the other presentations in this session, along with many images, can be found at the session website: http://www.noao.edu/education/IAUGA2015FM21.

The next speaker, John Hearnshaw, described the Aoraki Mackenzie International Dark Sky Reserve and the work it carries out . This was followed by a wide-ranging summary (by Dan Duriscoe and Nate Ament) of the U.S. National Park Service (NPS) Night Skies Program. The abstract of Cipriano's Marin's paper, “Developing Starlight connections with UNESCO sites through the Biosphere Smart" was shown in his absence. The final presentation (by Arkadiusz Berlicki, S. Kolomanksi and T. Mrozek) discussed the bi-national Izera Dark Sky Park.
Powering and Shaping Planetary Nebulae: The Physics of Common Envelopes
Authors: Nordhaus Jason , Spiegel David S.
Published: October 2016

The diversity of collimated outflows in post-asymptotic-giant-branch stars and their planetary nebula progeny are often explained by a combination of close binary interactions and accretion. The viability of such scenarios can be tested by comparing kinematic outflow data to determine minimum accretion rates necessary to power observed outflows. While many binary channels have been ruled out with this technique, common envelope interactions can accommodate the current observational constraints, are potentially common, lead to a diverse array of planetary-nebula shapes, and naturally produce period gaps for companions to white dwarfs.
Planck on Extragalactic Radio Sources: Data and Findings
Authors: Partridge Bruce ,   on behalf of the Planck Collaboration
Published: October 2016

Planck scanned the entire sky every six months at nine frequencies bands from 28 to 857 GHz with enough sensitivity to detect over a thousand radio sources. It thus provided measurements of the mm and sub-mm spectra of these sources in a regular cadence, even at wavelengths hard to observe from the ground. Polarization measurements (or upper limits) are provided for brighter sources at 28-353 GHz. Finally, Planck is calibrated to <1% accuracy in most of its frequency bands. I briefly introduce the valuable data set Planck provides on extragalactic sources, then describe some of the scientific conclusions drawn from the Planck measurements.
Two-dimensional models of early-type fast rotating stars: the ESTER project
Authors: Rieutord Michel
Published: October 2016

In this talk I present the latest results of the ESTER project that has taken up the challenge of building two dimensional (axisymmetric) models of stars rotating at any rotation rate. In particular, I focus on main sequence massive and intermediate mass stars. I show what should be expected in such stars as far as the differential rotation and the associated meridional circulation are concerned, notably the emergence of a Stewartson layer along the tangent cylinder of the core. I also indicate what may be inferred about the evolution of an intermediate-mass star at constant angular momentum and how Be stars may form. I finally give some comparisons between models and observations of the gravity darkening on some nearby fast rotators as it has been derived from interferometric observations. In passing, I also discuss how 2D models can help to recover the fundamental parameters of a star.
Characterizing Blue Straggler Star Populations in Globular Clusters using HST Photometric Survey Data
Authors: Simunovic Mirko , Puzia Thomas H.
Published: October 2016

We present early results from a detailed analysis of the BSS population in Galactic GCs based on HST data. Using proper motion cleaning of the color-magnitude diagrams we construct a large catalog of BSSs and study some population properties. Stellar evolutionary models are used to find stellar mass and age estimates for the BSS populations in order to establish constraints related to the dynamical interactions in which they may have formed.
Dust formation in evolved stars and supernovae: new advances and unsolved problems
Authors: Cherchneff Isabelle
Published: October 2016

This paper briefly reviews some advances and unsolved problems related to the formation of cosmic dust in the evolved environments of AGB stars and supernovae.
Panchromatic star formation rate indicators and their uncertainties
Authors: da Cunha Elisabete
Published: October 2016

The star formation rate (SFR) is a fundamental property of galaxies and it is crucial to understand the build-up of their stellar content, their chemical evolution, and energetic feedback. The SFR of galaxies is typically obtained by observing the emission by young stellar populations directly in the ultraviolet, the optical nebular line emission from gas ionized by newly-formed massive stars, the reprocessed emission by dust in the infrared range, or by combining observations at different wavelengths and fitting the full spectral energy distributions of galaxies. In this brief review we describe the assumptions, advantages and limitations of different SFR indicators, and we discuss the most promising SFR indicators for high-redshift studies.
Element abundance ratios in stellar population modelling
Authors: Thomas Daniel
Published: October 2016

I review the implementation of the effects from varying chemical element abundance ratios in stellar population modelling. Recent highlights include the adoption of new flux calibrated libraries, the inclusion of a wide range of chemical elements, the calculation of error estimates on the model, and the consideration of element variation effects on full spectra. Some key results on the element ratios measured in early-type galaxies are discussed.
Using the X-ray Lightcurves of Young Supernovae to Probe the Stellar Environment and Supernova Progenitors
Authors: Dwarkadas Vikram V.
Published: October 2016

We have aggregated together data available in the literature, or analysed by us, to compute the lightcurves of most young supernovae (SNe) that have been detected in X-rays. Currently the database contains about 60 SNe spanning all the various types, but it is expanding rapidly. We use this library of lightcurves and spectra to explore the diversity of SNe, the characteristics of the environment into which they are expanding, and the implications for their progenitors. X-ray spectra can provide insight into the density structure, composition and metallicity of the surrounding medium, and the ionization level, through the spectra themselves as well as the X-ray absorption. Since core-collapse SNe expand mainly in environments created by the progenitor star mass-loss, this can provide crucial information about the nature of the progenitor star, and its mass-loss parameters in the decades or centuries before its death. In a few cases, via detailed modelling, we can distinguish the composition of the SN ejecta from that of the environment. X-ray observations therefore provide an invaluable probe into the stellar environments of core-collapse SNe, complementing data available at other wavelengths. We provide an overview of the X-ray lightcurves of various SN types, the implications for their environment, and clues to their progenitor stars.
Evolution and Feedback Effects of High-z Star-Forming Galaxies
Authors: Ouchi Masami
Published: October 2016

I review the recent observational progresses of star-forming galaxies at a redshift up to z~10. Inconjunction with gravitational lensing magnifications, deep HST observations obtain first density estimates of UV continuum radiation given by young massive stars, and reveal that the star-formation rate density (SFRD)continuously decreases from z~2-3 to z~10. This SFRD decrease towards high-z should be explained by thecombination of the cosmic structure formation and radiative cooling+feedback effects in a halo. To decouple thecontribution of the cosmic structure formation from the SFRD decrease, the stellar-to-halo mass ratios (SHMR) ofhigh-z galaxies are derived by intensive clustering analyses with HST and Subaru survey data. The SHMR-halo massrelation shows a clear evolution from z~0 to 6, suggesting that the cooling and feedback effects are different betweenthe present and early epochs of the cosmic history. By deep imaging and spectroscopic observations, feedbacksignatures are found in 10-100 kpc-scale outflow of ionized oxgen gas identified around star-forming galaxies with andwithout an AGN heating. There are similarly-large hydrogen Lyα halos and blobs associated with high-z star-forminggalaxies, but the physical origin of these Lyα halos and blobs is an open question. At z≳6, UV radiation of ionizingphotons produced by star-forming galaxies contribute to the cosmic reionization, while it is thought that the UVradiation prevent formation of next generation stars in dwarf galaxies at the early cosmic epoch, which works as acosmological feedback effect. I discuss this reionizations cosmological feedback effect with the up-to-date resultsfrom the HST and Planck data.
Formation of cold clumps and filaments around superbubbles
Authors: Ntormousi E. , Hennebelle P. , Dawson J. , Del Sordo F.
Published: October 2016

The majority of young massive stars are found in close binary systems. Recently, dedicated observing campaigns have provided strong constraints on the binary fraction as well as the distribution of the parameters that characterize the binary systems: the masses of both components, the orbital period and eccentricities. Most strikingly these findings imply that the majority of massive stars experience strong interaction (roche lobe overflow, a common envelope phase and or a merger) with a binary companion before their final explosion. I will discuss recent results from detailed binary star models and population synthesis models.
ALMA molecular observations of supernova 1987A
Authors: Matsuura Mikako , Indebetouw R. , Kamenetzky J. , McCray R.
Published: October 2016

Twenty-six years after the explosion, we conducted a molecular line survey for supernova 1987A, using the ALMA observatory. The detection of molecules in the ejecta can uncover evidence of mixing and dynamics in the early days after the supernova explosion, as well as of molecular chemistry that took place in the last 25 years.

It is still not well understood to what extent the macroscopic mixing occurred after the supernova explosion. Molecules can provide a new tool to probe and test the extent of mixing: macroscopic mixings stir the elements from different layers of nuclear-reaction zones in the stellar core, opening the possibilities to form molecules that were composed of elements from different nuclear-burning zones, which the ALMA can detect. Additionally, the ALMA measured the line profiles of molecules, which unveiled the dynamics of ejecta. The high sensitivity observations of molecules can open a new window to determine SN explosion mechanisms and allow us to probe macroscopic mixing after the explosion.
LGRB hosts in emission and in absorption
Authors: Vreeswijk Paul M.
Published: October 2016

Long-duration gamma-ray bursts (LGRBs) provide a unique way of selecting a sample of actively star-forming galaxies independent of their brightness and at practically any redshift. I will review what we know about the hosts and more immediate environments of LGRBs from two different perspectives: ultraviolet absorption-line spectroscopy of the bright early afterglow, and observations of their hosts in emission once the afterglow has faded away.
The Swift GRB Host Galaxy Legacy Survey
Authors: Perley Daniel A.
Published: October 2016

I will describe the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelengthprogram to characterize the demographics of the GRB host population and its redshift evolution from z=0 to z=7.Using unbiased selection criteria we have designated a subset of 119 Swift gamma-ray bursts which are now beingtargeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained andanalyzed, with major programs ongoing at Keck, GTC, Gemini, VLT, and Magellan to obtain complementaryoptical/NIR photometry and spectroscopy to enable full SED modeling and derivation of fundamental physicalparameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiasedmeasurement of the GRB host-galaxy luminosity and mass distributions and their evolution with redshift, compareGRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor andthe ability of GRBs to serve as tools for measuring and studying cosmic star-formation in the distant universe.
Absorption features in the X-shooter GRB afterglow sample
Authors: de Ugarte Postigo Antonio ,   for the X-shooter GRB collaboration
Published: October 2016

Since 2009 X-shooter has collected spectroscopy of over 80 gamma-ray burst afterglows with redshifts ranging from 0.05 to 6.3. Thanks to its efficiency, broad wavelength coverage (3,000 to 24,800 Å), and intermediate spectral resolution (R~8,000) it has become the most efficient tool for gamma-ray burst afterglow spectroscopy. In this Focus Meeting we presented the sample and some preliminary results of the analysis of absorption systems.
Progress Toward a Space-Based Gravitational Wave Observatory
Authors: Livas Jeffrey C. , Stebbins Robin T.
Published: October 2016

The discovery of binary pulsar PSR 1913+16 by Hulse & Taylor in 1974 established the existence of gravitational waves, for which the 1983 Nobel Prize was awarded. However, the measurement of astrophysical parameters from gravitational waves will open an entirely new spectrum for discovery and understanding of the Universe, not simply a new window in the electromagnetic spectrum like gamma ray telescopes in the 1970s. Two types of ground-based detectors, Advanced LIGO/Virgo and Pulsar Timing Arrays, are expected to directly detect gravitational waves in their respective frequency bands before the end of the decade. However, many of the most exciting sources are in the band from 0.1–100 mHz, accessible only from space due to seismic and gravity gradient noise on Earth. The European Space Agency (ESA) has chosen the 'Gravitational Universe' as the science theme for its L3 Cosmic Visions opportunity, planned for launch in 2034. NASA is planning to participate as a junior partner. Here we summarize progress toward realizing a gravitational wave observatory in space.
Hiding in plain sight - red supergiant imposters? Super-AGB stars
Authors: Doherty Carolyn , Gil-Pons Pilar , Lattanzio John , Siess Lionel
Published: October 2016

Super Asymptotic Giant Branch (Super-AGB) stars reside in the mass range ≈ 6.5-10 M⊙ and bridge the divide between low/intermediate-mass and massive stars. They are characterised by off-centre carbon ignition prior to a thermally pulsing phase which can consist of many tens to even thousands of thermal pulses. With their high luminosities and very large, cool, red stellar envelopes, these stars appear seemingly identical to their slightly more massive red supergiant counterparts. Due to their similarities, super-AGB stars may therefore act as stellar imposters and contaminate red supergiant surveys. The final fate of super-AGB stars is also quite uncertain and depends primarily on the competition between the core growth and mass-loss rates. If the stellar envelope is removed prior to the core reaching ≈ 1.375 M⊙, an O-Ne white dwarf will remain, otherwise the star will undergo an electron-capture supernova (EC-SN) leaving behind a neutron star. We determine the relative fraction of super-AGB stars that end life as either an O-Ne white dwarf or as a neutron star, and provide a mass limit for the lowest mass supernova over a broad range of metallicities from the Z=0.02 to 0.0001.
Red Supergiant Stars as Supernova Progenitors – the X-ray Perspective
Authors: Dwarkadas Vikram V.
Published: October 2016

Red Supergiants (RSGs) have for decades been assumed to be the progenitors of Type IIP supernovae (SNe). They are expected to have dense winds with mass-loss rates up to 10−4 M⊙ yr−1. We have created a database of available X-ray lightcurves of SNe. Type IIP SNe are found to have the lowest X-ray luminosities among all classes, which is surprising given the high mass-loss rate winds expected from their red supergiant progenitors, and therefore the high density medium into which Type IIP SNe are expected to expand into. We show that the low X-ray luminosity sets a limit on the mass-loss rate of the progenitor star which can collapse to become a RSG, which is about 10−5 M⊙ yr−1. This in turn can be used to set a limit on the initial mass of a RSG star which can become a Type IIP progenitor, which is about 19 M⊙. This is consistent with the limit obtained via direct optical progenitor identification. Optically identified progenitors of Type IIP SNe are found to be RSGs with masses less than about 17 M⊙ (Smartt (2009)). We discuss the implications of this result for stellar evolution, theorize on the fate of RSG stars with initial mass > 19 M⊙, and discuss what type of SNe they will produce at the end of their lifetime.
A spectro-interferometric view of ℓ Carinae's modulated pulsations
Authors: Anderson Richard I. , Mérand Antoine , Kervella Pierre , Breitfelder Joanne , Eyer Laurent , Gallenne Alexandre
Published: October 2016

Classical Cepheids are radially pulsating stars that enable important tests of stellar evolution and play a crucial role in the calibration of the local Hubble constant. ℓ Carinae is a particularly well-known distance calibrator, being the closest long-period (P ~ 35.5 d) Cepheid and subtending the largest angular diameter. We have carried out an unprecedented observing program to investigate whether recently discovered cycle-to-cycle changes (modulations) of ℓ Carinae's radial velocity (RV) variability are mirrored by its variability in angular size. To this end, we have secured a fully contemporaneous dataset of high-precision RVs and high-precision angular diameters. Here we provide a concise summary of our project and report preliminary results. We confirm the modulated nature of the RV variability and find tentative evidence of cycle-to-cycle differences in ℓ Car's maximal angular diameter. Our analysis is exploring the limits of state-of-the-art instrumentation and reveals additional complexity in the pulsations of Cepheids. If confirmed, our result suggests a previously unknown pulsation cycle dependence of projection factors required for determining Cepheid distances via the Baade-Wesselink technique.
Spectroscopic mode identification of γ Doradus stars: frequencies, modes, rotation and wave leakage
Authors: Pollard Karen R. , Brunsden E. , Davie M. , Greenwood A. , Cottrell P. L.
Published: October 2016

The gravity modes present in γ Doradus stars probe the deep stellar interiors and are thus of particular interest in asteroseismology. The MUSICIAN programme at the University of Canterbury has been successfully identifying frequencies and pulsation modes in many γ Doradus stars using hundreds of precise, high resolution spectroscopic observations obtained with the 1.0 m telescope and HERCULES spectrograph at the Mt John Observatory in New Zealand. In this paper we present a summary of our spectroscopic frequency and mode identifications. Of particular interest from our spectroscopic analyses are: the prevalence of (ℓ, m) = 1, 1 modes in many γ Dor stars; the importance of stellar rotation in the interpretation of the frequency and mode identification; and finally, possible evidence of wave leakage in one of these stars.
2-D and 3-D models of convective turbulence and oscillations in intermediate-mass main-sequence stars
Authors: Guzik Joyce A. , Morgan T. H. , Nelson N. J. , Lovekin C. , Kosak K. , Kitiashvili I. N. , Mansour N. N. , Kosovichev A.
Published: October 2016

We present multidimensional modeling of convection and oscillations in main-sequence stars somewhat more massive than the Sun, using three separate approaches: 1) Using the 3-D planar StellarBox radiation hydrodynamics code to model the envelope convection zone and part of the radiative zone. Our goals are to examine the interaction of stellar pulsations with turbulent convection in the envelope, excitation of acoustic modes, and the role of convective overshooting; 2) Applying the spherical 3-D MHD ASH (Anelastic Spherical Harmonics) code to simulate the core convection and radiative zone. Our goal is to determine whether core convection can excite low-frequency gravity modes, and thereby explain the presence of low frequencies for some hybrid γ Dor/δ Sct variables for which the envelope convection zone is too shallow for the convective blocking mechanism to drive gravity modes; 3) Applying the ROTORC 2-D stellar evolution and dynamics code to calculate evolution with a variety of initial rotation rates and extents of core convective overshooting. The nonradial adiabatic pulsation frequencies of these nonspherical models are calculated using the 2-D pulsation code NRO. We present new insights into pulsations of 1-2 M⊙ stars gained by multidimensional modeling.
Determining the evolutionary stage of HD163899 on the basis of its oscillation spectrum
Authors: Ostrowski Jakub , Daszyńska-Daszkiewicz Jadwiga , Cugier Henryk
Published: October 2016

We present the new interpretation of the oscillation spectrum of HD 163899 based on the new determinations of the effective temperature, mass-luminosity ratio and rotational velocity. These new parameters strongly prefer the more massive models than previously considered. Now it is also possible that the star could be in the main sequence stage. Using the oscillation spectrum as a gauge, we intend to establish which stage of evolution corresponds better to HD 163899.
Double riches: asteroseismology in eclipsing binaries
Authors: Southworth John
Published: October 2016

The study of eclipsing binaries is our primary source of measured properties of normal stars, achieved through analysis of light and radial velocity curves of eclipsing systems. The study of oscillations and pulsations is increasingly vital for determining the properties of single stars, and investigating the physical phenomena active in their interiors. Combining the two methods holds the promise of establishing stringent tests of stellar evolutionary theory, and of calibrating model-dependent asteroseismology with empirically measured stellar properties. I review recent advances and outline future work.
Self-similar hierarchical energetics in the ICM of massive galaxy clusters
Authors: Miniati Francesco , Beresnyak Andrey
Published: October 2016

Massive galaxy clusters (GC) are filled with a hot, turbulent and magnetised intra-cluster medium (ICM). They are still forming under the action of gravitational instability, which drives supersonic mass accretion flows. These partially dissipate into heat through a complex network of large scale shocks, and partly excite giant turbulent eddies and cascade. Turbulence dissipation not only contributes to heating of the ICM but also amplifies magnetic energy by way of dynamo action. The pattern of gravitational energy turning into kinetic, thermal, turbulent and magnetic is a fundamental feature of GC hydrodynamics but quantitative modelling has remained a challenge. In this contribution we present results from a recent high resolution, fully cosmological numerical simulation of a massive Coma-like galaxy cluster in which the time dependent turbulent motions of the ICM are resolved (Miniati 2014) and their statistical properties are quantified for the first time (Miniati 2015, Beresnyak & Miniati 2015). We combine these results with independent state-of-the art numerical simulations of MHD turbulence (Beresnyak 2012), which shows that in the nonlinear regime of turbulent dynamo (for magnetic Prandtl numbers≳ 1) the growth rate of the magnetic energy corresponds to a fraction CE ≃ 4 − 5 × 10−2 of the turbulent dissipation rate. We thus determine without adjustable parameters the thermal, turbulent and magnetic history of giant GC (Miniati & Beresnyak 2015). We find that the energy components of the ICM are ordered according to a permanent hierarchy, in which the sonic Mach number at the turbulent injection scale is of order unity, the beta of the plasma of order forty and the ratio of turbulent injection scale to Alfvén scale is of order one hundred. These dimensionless numbers remain virtually unaltered throughout the cluster's history, despite evolution of each individual component and the drive towards equipartition of the turbulent dynamo, thus revealing a new type of self-similarity in cosmology. Their specific values, while consistent with current data, indicate that thermal energy dominates the ICM energetics and the turbulent dynamo is always far from saturation, unlike the condition in other familiar astrophysical fluids (stars, interstellar medium of galaxies, compact objects, etc.). In addition, they have important physical meaning as their specific values encodes information about the efficiency of turbulent heating (the fraction of ICM thermal energy produced by turbulent dissipation) and the efficiency of dynamo action in the ICM (CE).
Molecular clouds have power-law PDFs (not log-normal)
Authors: Alves João , Lombardi Marco , Lada Charles
Published: October 2016

Contrary to common belief, the column density PDFs of molecular clouds are not described well by log-normal functions, but are instead power-laws with exponents close to two. We argue that the intrinsic functional form of the PDF cannot be securely determined below AK ~ 0.1-0.2 mag, limiting our ability to investigate more complex models for the shape of the cloud PDF.
Radial Infall onto a Massive Molecular Filament
Authors: Battersby Cara , Myers Philip C. , Shirley Yancy L. , Keto Eric , Kirk Helen
Published: October 2016

The newly discovered Massive Molecular Filament (MMF) G32.02+0.05 (~ 70 pc long, 105 M⊙) has been shaped and compressed by older generations of massive stars. The similarity of this filament in physical structure (density profile, temperature) to much smaller star-forming filaments, suggests that the mechanism to form such filaments may be a universal process. The densest portion of the filament, apparent as an Infrared Dark Cloud (IRDC) shows a range of massive star formation signatures throughout. We investigate the kinematics in this filament and find widespread inverse P cygni asymmetric line profiles. These line asymmetries are interpreted as a signature of large-scale radial collapse. Using line asymmetries observed with optically thick HCO+ (1-0) and optically thin H13CO+ (1-0) across a range of massive star forming regions in the filament, we estimate the global radial infall rate of the filament to range from a few 100 to a few 1000 M⊙ Myr−1 pc−1. At its current infall rate the densest portions of the cloud will more than double their current mass within a Myr.