bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Analytic Model Approach to the Frequency of Exoplanets
Authors: Traub Wesley A. 
Published: October 2016

AbstractThe underlying population of exoplanets around stars in the Kepler sample can be inferred by a simulation that includes binning the Kepler planets in radius and period, invoking an empirical noise model, assuming a model exoplanet distribution function, randomly assigning planets to each of the Kepler target stars, asking whether each planet's transit signal could be detected by Kepler, binning the resulting simulated detections, comparing the simulations with the observed data sample, and iterating on the model parameters until a satisfactory fit is obtained. The process is designed to simulate the Kepler observing procedure. The key assumption is that the distribution function is the product of separable functions of period and radius. Any additional suspected biases in the sample can be handled by adjusting the noise model or selective editing of the range of input planets. An advantage of this overall procedure is that it is a forward calculation designed to simulate the observed data, subject to a presumed underlying population distribution, minimizing the effect of bin-to-bin fluctuations. Another advantage is that the resulting distribution function can be extended to values of period and radius that go beyond the sample space, including, for example, application to estimating eta-sub-Earth, and also estimating the expected science yields of future direct-imaging exoplanet missions such as WFIRST-AFTA.
Atomic Data for Stellar Nucleosynthesis
Authors: Sneden Christopher , Lawler James E. , Den Hartog Elizabeth A. , Wood Michael E. 
Published: October 2016

AbstractStellar chemical composition analyses can only yield reliable abundances if the atomic transition parameters are accurately determined. During the last couple of decades a renewed emphasis on laboratory spectroscopy has produced large sets of useful atomic transition probabilities for species of interest to stellar spectroscopists. In many cases the transition data are of such high quality that they play little part in the abundance uncertainties. We summarize the current state of atomic parameters, highlighting the areas of satisfactory progress and noting places, where further laboratory progress will be welcome.
Untangling the Formation Mechanisms of Biorelevant Molecules in the ISM with Photoionization Reflectron Time-of-Flight Mass Spectrometry
Authors: Förstel Marko , Kaiser Ralf I. 
Published: October 2016

AbstractExploiting reflectron time of flight mass spectrometry coupled with single photon ionization of the subliming molecules (PI-ReTOF-MS) during the temperature programmed desorption (TPD) and combining these data with on line and in situ infrared spectroscopy (FTIR), a versatile experimental approach has been established to elucidate the formation pathways of complex organic molecules in interstellar analog ices upon interaction with ionizing radiation at astrophysically relevant temperatures as low as 5 K.
Interstellar dust modelling: Interfacing laboratory, theoretical and observational studies (The THEMIS model)
Authors: Jones Anthony P. 
Published: October 2016

AbstractThe construction of viable and physically-realistic interstellar dust models is only possible if the constraints imposed by laboratory data on interstellar dust analogue materials are respected and used within a meaningful theoretical framework. These “physical” dust models can then be directly compared to observations without the need for any tuning to fit the observations. Such models will generally fail to achieve the excellent fits to observations that “empirical” models are able to achieve. However, the physically-realistic approach will necessarily lead to a deeper insight and a fuller understanding of the nature and evolution of interstellar dust. The THEMIS modelling approach, based on (hydrogenated) amorphous carbons and amorphous silicates with metallic Fe and/or FeS nano-inclusions appears to be a promising move in this direction.
Telescope Observations of Interstellar and Circumstellar Ices: Successes of and Need for Laboratory Simulations
Authors: Boogert A. C. A. 
Published: October 2016

AbstractIces play a key role in the formation of simple and complex molecules in dense molecular clouds and in the envelopes and protoplanetary disks surrounding young stars. Some fraction of the interstellar ices may become building blocks of comets, and thus be delivered to the early Earth. Laboratory simulations have proven to be crucial in the derivation of ice abundances, in quantifying reaction rates on cold grain surfaces, in determining the thermal and energetic processing history of the ices, and in understanding the interaction between the ices and the underlying refractory grain surfaces. In this invited topical paper I will review possible ways forward in improving our knowledge of the composition of the ices, as many signatures in the interstellar spectra are still poorly identified. I will also emphasize the observed importance of thermal processing of the ices (crystallization, segregation), which likely affects the chemistry after the initial dominance of grain surface reactions. Continued laboratory work is warranted in view of the upcoming observational data from, for example, the James Webb Space Telescope (JWST), which is ideally suited for ices studies. For an exhaustive review on this topic I refer to Boogert, Gerakines & Whittet (2015).
Recent Status of Multi-Dimensional Core-Collapse Supernova Models
Authors: Kotake Kei , Nakamura Ko , Takiwaki Tomoya 
Published: October 2016

AbstractWe report a recent status of multi-dimensional neutrino-radiation hydrodynamics simulations for clarifying the explosion mechanism of core-collapse supernovae (CCSNe). In this contribution, we present two results, one from two-dimensional (2D) simulations using multiple progenitor models and another from three-dimensional (3D) rotational core-collapse simulation using a single progenitor. From the first ever systematic 2D simulations, it is shown that the compactness parameter ξ that characterizes the structure of the progenitors is a key to diagnose the explodability of neutrino-driven explosions. In the 3D rotating model, we find a new type of rotation-assisted explosion, which makes the explosion energy bigger than that in the non-rotating model. The unique feature has not been captured in previous 2D self-consistent rotational models because the growth of non-axisymmetric instabilities is the key to foster the explosion by enhancing the energy transport from the proto-neutron star to the gain region.
East African ROAD
Authors: Tekle Kelali 
Published: October 2016

AbstractIn the developing world astronomy had been treated as the science of elites. As a result of this overwhelming perception, astronomy compared with other applied sciences has got less attention and its role in development has been insignificant. However, the IAU General Assembly decision in 2009 opened new opportunity for countries and professionals to deeply look into Astronomy and its role in development. Then, the subsequent establishment of regional offices in the developing world is helping countries to integrate astronomy with other earth and space based sciences so as to progressively promote its scientific and development importance. Gradually nations have come to know that space is the frontier of tomorrow and the urgency of preeminence on space frontier starts at primary school and ascends to tertiary education. For this to happen, member nations in east African region have placed STEM education at the center of their education system. For instance, Ethiopian has changed University enrollment strategy to be in favor of science and engineering subjects, i.e. every year seventy percent of new University entrants join science and engineering fields while thirty percent social science and humanities. Such bold actions truly promote astronomy to be conceived as gateway to science and technology. To promote the concept of astronomy for development the East African regional office has actually aligned it activities to be in line with the focus areas identified by the IAU strategy (2010 to 2020).
Portuguese Language Expertise Center for the OAD
Authors: Doran Rosa , Canas Lina , Anjos Sara , Heenatigala Thilina , Retrê João , Afonso José , Alves Ana 
Published: October 2016

AbstractSupporting the use of astronomy as a tool for development in specific regions and languages, the International Astronomical Union's (IAU) Office of Astronomy for Development (OAD) has established a Portuguese ‘Language Expertise Centre for the OAD’ (PLOAD), hosted at Núcleo Interactivo de Astronomia (NUCLIO), in collaboration with the Institute of Astrophysics and Space Sciences (IA) in Portugal. The centre is one of the new coordinating offices announced at the IAU General Assembly in Honolulu, Hawaii on 13 August 2015.
Session 21.8 – Challenges and Solutions to Light Pollution, RFI and Implementing IAU Resolution 2009 B5
Authors: Green Richard 
Published: October 2016

AbstractThe closing session included a panel on the challenge of raising cultural awareness of the negative effects of light pollution and RFI, and a discussion about the means to implement the IAU Resolution on the Right to Starlight. The strongest arguments to the public are that light pollution wastes precious energy and adds greenhouse gases, and that artificial light at night can be damaging to human health and to the natural environment. As astronomers, our community is concerned that the world is blinding itself to the electromagnetic radiation connecting us to the Universe. An outcome of successful advocacy would be to create demand for commercial products that minimize blue light and upward radiation. Implementation of the resolution on the Right to Starlight has multiple aspects. The IAU, through its site protection commission, should provide a clear technical description of "astronomy friendly" lighting and specifications for protection of the near zones around optical observatories. In addition, the commission should provide reference materials for astronomers giving public presentations, provide a forum for those seeking stronger local or national regulation, seek IAU approval for endorsement of protected status of sites and regions, and support the process of gaining UNESCO World Heritage Status for observatories and their regions.
New Theory of Stellar Convection without the mixing-length parameter: new stellar atmosphere models
Authors: Pasetto Stefano , Chiosi Cesare , Cropper Mark 
Published: October 2016

AbstractStellar convection is customarily described by the mixing-length theory, which makes use of the mixing-length scale to express the convective flux, velocity, and temperature gradients of the convective elements and stellar medium. The mixing-length scale is taken to be proportional to the local pressure scale height, and the proportionality factor (the mixing-length parameter) must be determined by comparing the stellar models to some calibrator, usually the Sun. No strong arguments exist to suggest that the mixing-length parameter is the same in all stars and all evolutionary phases. Because of this, all stellar models in the literature are hampered by this basic uncertainty.In a recent paper (Pasettoet al.2014) we presented a new theory that does not require the mixing length parameter. Our self-consistent analytical formulation of stellar convection determines all the properties of stellar convection as a function of the physical behavior of the convective elements themselves and the surrounding medium. The new theory of stellar convection is formulated starting from a conventional solution of the Navier-Stokes/Euler equations, i.e. the Bernoulli equation for a perfect fluid, but expressed in a non-inertial reference frame co-moving with the convective elements. In our formalism, the motion of stellar convective cells inside convective-unstable layers is fully determined by a new system of equations for convection in a non-local and time-dependent formalism.We obtained an analytical, non-local, time-dependent solution for the convective energy transport that does not depend on any free parameter. The predictions of the new theory are compared with those from the standard mixing-length paradigm with positive results for atmosphere models of the Sun and all the stars in the Hertzsprung-Russell diagram.
Convective mixing in intermediate mass stars
Authors: Bressan Alessandro 
Published: October 2016

AbstractStellar evolution can nowadays be modelled with a high degree of accuracy and completeness up to the most advanced stages. However in spite of the progresses, complex physical processes exist that still suffer of large uncertainties even in the most placid evolutionary phases. The straightforward drawback is that models lose their predictive power and this is particularly critical for stellar population synthesis. Here I will focus on one of such processes, convective mixing, and briefly review potentially helpful observational tests to decipher its efficiency during the main nuclear burning phases of intermediate mass stars.
What can the Occult do for you? STarlight Attenuation & Reddening Survey of Multiple Occulting Galaxies (STARSMOG)
Authors: Holwerda B. W. , Keel W. C. 
Published: October 2016

AbstractInterstellar dust is still the dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses HST observation of occulting galaxy pairs to accurately map the distribution of dust in foreground galaxies in fine (<100 pc) detail. Furthermore, Integral Field Unit observations of such pairs will map the effective extinction curve in these occulting galaxies, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy.The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: the dust geometry, a probability function of the amount of dimming as a function of galaxy type, its dependence on wavelength, and evolution of all these properties with cosmic time using distant, high-redshift pairs.
Properties of young massive clusters obtained with different massive-star evolutionary models
Authors: Wofford Aida , Charlot Stéphane 
Published: October 2016

AbstractWe undertake a comprehensive comparative test of seven widely-used spectral synthesis models using multi-band HST photometry of a sample of eight YMCs in two galaxies. We provide a first quantitative estimate of the accuracies and uncertainties of new models, show the good progress of models in fitting high-quality observations, and highlight the need of further comprehensive comparative tests.
Stellar populations in the highest redshift galaxies
Authors: Bunker Andrew J. 
Published: October 2016

AbstractI discuss stellar populations in galaxies at high redshift (z > 6), in particular the blue rest-frame UV colours which have been detected in recent years through near-IR imaging with HST. These spectral slopes of β < −2 are much more blue than star-forming galaxies at lower redshift, and may suggest less dust obscuration, lower metallicity or perhaps a different initial mass function. I describe current work on the luminosity function of high redshift star- forming galaxies, the evolution of the fraction of strong Lyman-α emitters in this population, and the contribution of the ionizing photon budget from such galaxies towards the reionization of the Universe. I also describe constraints placed by Spitzer/IRAC on stellar populations in galaxies within the first billion years, and look towards future developments in spectroscopy with Extremely Large Telescopes and the James Webb Space Telescope, including the JWST/NIRSpec GTO programme on galaxy evolution at high redshift.
Observational constraints on the progenitor of core-collapse supernovae
Authors: Elias-Rosa Nancy 
Published: October 2016

AbstractIt is well-known that some massive stars evolve to an end state which results in the collapse of the stellar core, as the hydrostatic pressure can no longer support gravity, leading to powerful explosions called supernovae (SNe). Even with over 6000 known SNe, we have only direct information about the progenitor star for a handful of explosions. Here, I summarise the observational constraints of the massive progenitor stars of several core-collapse supernovae.
Red supergiants as supernova progenitors
Authors: Negueruela Ignacio , Dorda Ricardo , González-Fernández Carlos , Marco Amparo 
Published: October 2016

AbstractRecent searches for supernova II-P progenitors in external galaxies have led to the identification of red objects with magnitudes and colours indicative of red supergiants, in most cases implying quite low luminosities, and hence masses. Current results would suggest that all explosions come from objects less massive than ~ 18 M⊙ and that some explosions come from stars with masses well below 10 M⊙. Stellar models, on the other hand, can only produce explosions from objects more massive than > 9 M⊙. What does our knowledge of local red supergiants tell us about the expected properties of such objects? We present the results of complementary large spectroscopic surveys and detailed studies of open clusters that point to substantially different observational characteristics depending on metallicity.
Studying stellar explosions with Athena
Authors: O'Brien P. , Jonker P. 
Published: October 2016

AbstractAthena is the second large mission selected in the ESA Cosmic Vision plan. With its large collecting area, high spectral-energy resolution (X-IFU instrument) and impressive grasp (WFI instrument), Athena will truly revolutionise X-ray astronomy. The most prodigious sources of high-energy photons are often transitory in nature. Athena will provide the sensitivity and spectral resolution coupled with rapid response to enable the study of the dynamic sky. Potential sources include: distant Gamma-Ray Bursts to probe the reionisation epoch and find missing baryons in the cosmic web; tidal disruption events to reveal dormant supermassive and intermediate-mass black holes; and supernova explosions to understand progenitors and their environments. We illustrate Athenas capabilities and show how it will be able to constrain the nature of explosive transients including gas metallicity and dynamics.
Galactic chemical evolution and GRB host identification
Authors: Matteucci Francesca , Grieco Valentina 
Published: October 2016

AbstractWe describe a method to identify GRB host galaxies by means of their chemical abundances. We apply this method to three GRB hosts by comparing detailed chemical evolution models, including dust, of galaxies of different morphological type to observed abundance ratios. We conclude that none of them is likely to be a dwarf irregular galaxy, as it is believed for the majority of GRB hosts, but rather two of them (GRB081008 and GRB120327A) are likely to be spirals and the third is likely to be an elliptical (GRB120815). In addition, we have derived their chemical ages: in particular, the elliptical host is only 15 Myr old, while the other two hosts are 50 Myr (GRB120327A) and 320 Myr (GRB130815).
Evolution of supermassive black hole binaries in gaseous environments
Authors: Lodato Giuseppe 
Published: October 2016

AbstractIn this contribution, I discuss some aspects of the dynamical evolution of supermassive black hole binaries and their accretion discs. Firstly, I discuss the issue of alignment of the spins of the two binary component, which has important implications for the shape of the gravitational wave emitted at merger and for the possibility of a strong recoil of the remnant black hole. Even under the favourable assumption that mass flow through the gap is not inhibited by tidal torque, we demonstrate that differential accretion onto the two components of the systems results in a very different spin evolution of the two black holes. Secondly, I revisit the issue of how much mass can flow within the cavity carved in the disc by an equal mass binary. Recent simulations have shown that the tidal torque of the binary is generally not sufficient to prevent accretion onto the binary component. Here, I demonstrate that such results are heavily dependent on the disc thickness. While for H/R ~ 0.1 (the value adopted in most simulations to date), we reproduce the previous results, we show that as H/R is decreased to ~ 0.01, mass flow through the gap is essentially shut off almost completely. Thirdly, I show numerical simulations of the process of gas squeezing during the merger proper, demonstrating that most of the disc mass is accreted producing a super-Eddington flare.
A Periodically Varying Luminous Quasar at z = 2 from the Pan-STARRS1 Medium Deep Survey: A Candidate Supermassive Black Hole Binary in the Gravitational Wave-Driven Regime
Authors: Liu Tingting , Gezari Suvi 
Published: October 2016

AbstractSupermassive black hole binaries (SMBHBs) should be an inevitable consequence of the hierarchical growth of massive galaxies through mergers and the strongest sirens of gravitational waves (GWs) in the cosmos. Yet, their direct detection has remained elusive due to the compact (sub-parsec) orbital separations of gravitationally bound SMBHBs. Here we exploit a theoretically predicted signature of SMBHBs in the time domain. We have begun a systematic search for SMBHB candidates in the Pan-STARRS1 Medium Deep Survey (MDS) and reported our first significant detection of such a candidate from our pilot study of MD09 in Liu et al. (2015). Our candidate PSO J334.2028+01.4075 has a detected period of 542 days, varying persistently over the available baseline. From its archival spectrum, we estimated the black hole mass of the z = 2.06 quasar to be ∼1010 M⊙. The inferred ∼7 Rs binary separation therefore puts this candidate in the regime of GW-dominated orbital decay, opening up the exciting possibility of finding GW sources detectable by pulsar timing arrays (PTAs) in a wide-field optical synoptic survey.
Search for water and life's building blocks in the Universe: An Introduction
Authors: Kwok Sun 
Published: October 2016

AbstractWater and organics are commonly believed to be the essential ingredients for life on Earth. The development of infrared and submillimeter observational techniques has resulted in the detection of water in circumstellar envelopes, interstellar clouds, comets, asteroids, planetary satellites and the Sun. Complex organics have also been found in stellar ejecta, diffuse and molecular clouds, meteorites, interplanetary dust particles, comets and planetary satellites. In this Focus Meeting, we will discuss the origin, distribution, and detection of water and other life's building blocks both inside and outside of the Solar System. The possibility of extraterrestrial organics and water on the origin of life on Earth will also be discussed.
Water in the interstellar media of galaxies
Authors: van der Tak Floris F. S. 
Published: October 2016

AbstractThis paper reviews recent observations of water in Galactic interstellar clouds and nearby galactic nuclei. Two results are highlighted: (1) Multi-line H2O mapping of the Orion Bar shows that the water chemistry in PDRs is driven by photodissociation and -desorption, unlike in star-forming regions. (2) High-resolution spectra of H2O and its ions toward 5 starburst / AGN systems reveal low ionization rates, unlike as found from higher-excitation lines. We conclude that the chemistry of water strongly depends on radiation environment, and that the ionization rates of interstellar clouds decrease by at least 10 between galactic nuclei and disks.