bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamo Scaling Relationships
Authors: Augustson Kyle , Mathis Stéphane , Brun Sacha , Toomre Juri 
Published: July 2017

AbstractThis paper provides a brief look at dynamo scaling relationships for the degree of equipartition between magnetic and kinetic energies. Two simple models are examined, where one that assumes magnetostrophy and another that includes the effects of inertia. These models are then compared to a suite of convective dynamo simulations of the convective core of a main-sequence B-type star and applied to its later evolutionary stages.
What can magnetic early B-type stars tell us about early B-type stars in general?
Authors: Shultz Matthew , Wade Gregg , Rivinius Thomas , Neiner Coralie , Alecian Evelyne , Petit Véronique , Grunhut Jason ,   the MiMeS & BinaMIcS Collaborations
Published: July 2017

AbstractSome magnetic early B-type stars display Hα emission originating in their Centrifugal Magnetospheres (CMs). To determine the rotational and magnetic properties necessary for the onset of emission, we analyzed a large spectropolarimetric dataset for a sample of 51 B5-B0 magnetic stars. New rotational periods were found for 15 stars. We determined physical parameters, dipolar magnetic field strengths, magnetospheric parameters, and magnetic braking timescales. Hα-bright stars are more rapidly rotating, more strongly magnetized, and younger than the overall population. We use the high sensitivity of magnetic braking to the mass-loss rate to test the predictions of Vink et al. (2001) and Krtička (2014) by comparing agestto maximum spindown agestS, max. For stars withM*< 10M⊙this comparison favours the Krtička recipe. For the most massive stars, both prescriptions yieldt≪tS, max, a discrepancy which is difficult to explain via incorrect mass-loss rates alone.
First results from Project SUNBIRD: Supernovae UNmasked By Infra-Red Detection
Authors: Kool Erik C. , Ryder Stuart D. , Kankare Erkki , Mattila Seppo 
Published: July 2017

AbstractA substantial number of core-collapse supernovae (CCSNe) are expected to be hosted by starbursting luminous infrared galaxies (LIRGs). However, so far very few CCSNe have been discovered in LIRGs, most likely as a result of dust extinction and lack of contrast in their typically luminous and complex nuclear regions. We present the first results of Project SUNBIRD (Supernovae UNmasked By InfraRed Detection), where we aim to uncover dust-obscured nuclear supernovae by monitoring over 30 LIRGs, using near-infrared state-of-the-art Laser Guide Star Adaptive Optics (LGSAO) imaging on the Gemini South and Keck telescopes. Such discoveries are vital for determining the fraction of supernovae which will be missed as a result of dust obscuration by current and future optical surveys.
HDUST3 — A chemically realistic, 3-D, NLTE radiative transfer code
Authors: Carciofi Alex C. , Bjorkman Jon E. , Zsargó Janos 
Published: July 2017

AbstractHDUST is a 3D, NLTE radiative transfer code based on the Monte Carlo method. We report on recent advancements on the code, which is now capable of handling He and other elements in the NLTE regime and in 3D configurations. In this contribution we show initial comparisons with CMFGEN, made with spherical wind models composed of H + He.
A multi-wavelength view of NGC 1624-2
Authors: David-Uraz A. , Petit V. , MacInnis R. , Erba C. , Owocki S. P. , Fullerton A. W. , Walborn N. R. , Cohen D. H. 
Published: July 2017

AbstractLarge magnetometric surveys have contributed to the detection of an increasing number of magnetic massive stars, and to the recognition of a population of magnetic massive stellar objects with distinct properties. Among these, NGC 1624-2 possesses the largest magnetic field of any O-type star; such a field confines the stellar wind into a circumstellar magnetosphere, which can be probed using observations at different wavelength regimes. Recent optical and X-ray observations suggest that NGC 1624-2’s magnetosphere is much larger than that of any other magnetic O star. By modeling the variations of UV resonance lines, we can constrain its velocity structure. Furthermore, recent spectropolarimetric observations raise the possibility of a more complex field topology than previously expected. Putting all of these multi-wavelength constraints together will allow us to paint a consistent picture of NGC 1624-2 and its surprising behavior, giving us valuable insight into the very nature of massive star magnetospheres.
Emission-line Diagnostics of Nearby HII Regions Including Supernova Hosts
Authors: Xiao Lin , Eldridge J. J. , Stanway Elizabeth , Galbany L. 
Published: July 2017

AbstractWe present a new model of the optical nebular emission from HII regions by combining the results of the Binary Population and Spectral Synthesis (bpass) code with the photoionization code cloudy (Ferland et al. 1998). We explore a variety of emission-line diagnostics of these star-forming HII regions and examine the effects of metallicity and interacting binary evolution on the nebula emission-line production. We compare the line emission properties of HII regions with model stellar populations, and provide new constraints on their stellar populations and supernova progenitors. We find that models including massive binary stars can successfully match all the observational constraints and provide reasonable age and mass estimation of the HII regions and supernova progenitors.
Resolving the mass loss from red supergiants by high angular resolution
Authors: Ohnaka Keiichi 
Published: July 2017

AbstractDespite its importance on late stages of the evolution of massive stars, the mass loss from red supergiants (RSGs) is a long-standing problem. To tackle this problem, it is essential to observe the wind acceleration region close to the star with high spatial resolution. While the mass loss from RSGs is often assumed to be spherically symmetric with a monotonically accelerating wind, there is mounting observational evidence that the reality is much more complex. I review the recent progress in high spatial resolution observations of RSGs, encompassing from the circumstellar envelope on rather large spatial scales (~100 stellar radii) to milliarcsecond-resolution aperture-synthesis imaging of the surface and the atmosphere of RSGs with optical and infrared long-baseline interferometers.
Massive infrared clusters in the Milky Way
Authors: Chené André-Nicolas , Ramírez Alegría Sebastian , Borissova Jordanka , Hervé Anthony , Martins Fabrice , Kuhn Michael , Minniti Dante ,   the VVV Science Team
Published: July 2017

AbstractOur position in the Milky Way (MW) is both a blessing and a curse. We are nearby to many star clusters, but the dust that is a product of their very existence obscures them. Also, many massive young clusters are expected to be located near, or across the Galactic Center, where the dust extinction is extreme (AV > 15 mag) and can be better penetrated by infrared photons. This paper reviews the discoveries and the study of new MW massive stars and massive clusters made possible by near infrared observations that are part of the VISTA Variables in the Vía Láctea (VVV) survey. It discusses what the studies of their fundamental parameters have taught us.
Properties of the O-type giants and supergiants in 30 Doradus
Authors: Ramírez-Agudelo O. H. ,   VFTS consortium
Published: July 2017

AbstractWe discuss the stellar and wind properties of 72 presumably single O-type giants, bright giants, and supergiants in the 30 Doradus region. This sample constitutes the largest and most homogeneous sample of such stars ever analyzed and offers the opportunity to test models describing their main-sequence evolution.
The evolution of magnetic fields in hot stars
Authors: Oksala Mary E. , Neiner Coralie , Georgy Cyril , Przybilla Norbert , Keszthelyi Zsolt , Wade Gregg , Mathis Stéphane , Blazère Aurore , Buysschaert Bram 
Published: July 2017

AbstractOver the last decade, tremendous strides have been achieved in our understanding of magnetism in main sequence hot stars. In particular, the statistical occurrence of their surface magnetism has been established (~10%) and the field origin is now understood to be fossil. However, fundamental questions remain: how do these fossil fields evolve during the post-main sequence phases, and how do they influence the evolution of hot stars from the main sequence to their ultimate demise? Filling the void of known magnetic evolved hot (OBA) stars, studying the evolution of their fossil magnetic fields along stellar evolution, and understanding the impact of these fields on the angular momentum, rotation, mass loss, and evolution of the star itself, is crucial to answering these questions, with far reaching consequences, in particular for the properties of the precursors of supernovae explosions and stellar remnants. In the framework of the BRITE spectropolarimetric survey and LIFE project, we have discovered the first few magnetic hot supergiants. Their longitudinal surface magnetic field is very weak but their configuration resembles those of main sequence hot stars. We present these first observational results and propose to interpret them at first order in the context of magnetic flux conservation as the radius of the star expands with evolution. We then also consider the possible impact of stellar structure changes along evolution.
The outer disk of the classical Be star ψ Per
Authors: Klement Robert , Carciofi Alex C. , Rivinius Thomas , Matthews Lynn D. , Ignace Richard , Bjorkman Jon E. , Vieira Rodrigo G. , Mota Bruno C. , Faes Daniel M. , Štefl Stanislav 
Published: July 2017

AbstractTo this date ψ Per is the only classical Be star that was angularly resolved in radio (by the VLA at λ = 2 cm). Gaussian fit to the azimuthally averaged visibility data indicates a disk size (FWHM) of ~500 stellar radii (Dougherty & Taylor 1992). Recently, we obtained new multi-band cm flux density measurements of ψ Per from the enhanced VLA. We modeled the observed spectral energy distribution (SED) covering the interval from ultraviolet to radio using the Monte Carlo radiative transfer code HDUST (Carciofi & Bjorkman 2006). An SED turndown, that occurs between far-IR and radio wavelengths, is explained by a truncated viscous decretion disk (VDD), although the shallow slope of the radio SED suggests that the disk is not simply cut off, as is assumed in our model. The best-fit size of a truncated disk derived from the modeling of the radio SED is 100+5−15 stellar radii, which is in striking contrast with the result of Dougherty & Taylor (1992). The reasons for this discrepancy are under investigation.
The Massive stellar Population at the Galactic Center
Authors: Najarro Francisco , de la Fuente Diego , Geballe Tom R. , Figer Don F. , Hillier D. John 
Published: July 2017

AbstractWe present results from our ongoing infrared spectroscopic studies of the massive stellar content at the Center of the Milky Way. This region hosts a large number of apparently isolated massive stars as well as three of the most massive resolved young clusters in the Local Group. Our survey seeks to infer the presence of a possible top-heavy recent star formation history and to test massive star formation channels: clusters vs isolation.
Modelling the thermal X-ray emission around the Galactic centre from colliding Wolf-Rayet winds
Authors: Russell Christopher M. P. , Wang Q. Daniel , Cuadra Jorge 
Published: July 2017

AbstractWe compute the thermal X-ray emission from hydrodynamic simulations of the 30 Wolf-Rayet (WR) stars orbiting within a parsec of Sgr A*, with the aim of interpreting the Chandra X-ray observations of this region. The model well reproduces the spectral shape of the observations, indicating that the shocked WR winds are the dominant source of this thermal emission. The model X-ray flux is tied to the strength of the Sgr A* outflow, which clears out hot gas from the vicinity of Sgr A*. A moderate outflow best fits the present-day observations, even though this supermassive black hole (SMBH) outflow ended ~100 yr ago.
The Most Massive Heartbeat: Finding the Pulse of ι Orionis
Authors: Pablo Herbert , Richardson Noel , Fuller Jim , Moffat Anthony F. J. ,   BEST and Ritter Observing team
Published: July 2017

Abstractι Orionis is a massive binary system consisting of O9III + B1 III/IV stars. Though the system has been well studied, much about its fundamental properties have been difficult to determine. In this paper we report on the discovery of the heartbeat phenomenon in ι Orionis making it the most massive heartbeat system currently known. Using this phenomenon we have found empirical values for the masses and radii of both components. Moreover, we report the detection of tidally induced oscillations in an O-type star for the first time. These discoveries open a new avenue for exploring asteroseismology in massive stars.
OWN Survey: a spectroscopic monitoring of Southern Galactic O and WN-type stars
Authors: Barbá Rodolfo H. , Gamen Roberto , Arias Julia I. , Morrell Nidia I. 
Published: July 2017

AbstractWe summarize the status and results of the OWN Survey, a high-resolution monitoring program of Southern Galactic O- and WN-type stars, after twelve years of observing campaign.
The Young and the Massive: Stars at the upper end of the Initial Mass Function
Authors: Caballero-Nieves Saida M. , Crowther P. A. 
Published: July 2017

AbstractThe upper mass limit of stars remains an open question in astrophysics. Here we discuss observations of the most massive stars (greater than 100 solar masses) in the local universe and how the observations fit in with theoretical predictions. In particular, the Large Magellanic Cloud plays host to numerous very massive stars, making it an ideal template to study the roles that environment, metallicity, and multiplicity play in the formation and evolution of the most massive stars. We will discuss the work that is instrumental in laying the groundwork for interpreting future observations by James Webb of starburst regions in the high redshift universe.
Massive stars, successes and challenges
Authors: Meynet Georges , Maeder André , Georgy Cyril , Ekström Sylvia , Eggenberger Patrick , Barblan Fabio , Song Han Feng 
Published: July 2017

AbstractWe give a brief overview of where we stand with respect to some old and new questions bearing on how massive stars evolve and end their lifetime. We focus on the following key points that are further discussed by other contributions during this conference: convection, mass losses, rotation, magnetic field and multiplicity. For purpose of clarity, each of these processes are discussed on its own but we have to keep in mind that they are all interacting between them offering a large variety of outputs, some of them still to be discovered.
The mass-loss before the end: two luminous blue variables with a collimated stellar wind
Authors: Agliozzo C. , Trigilio C. , Buemi C. , Leto P. , Umana G. , Pignata G. , Phillips N. M. , Nikutta R. , Prieto J. L. 
Published: July 2017

AbstractWe gathered a multiwavelength dataset of two well-known LBVs. We found a complex mass-loss, with evidence of variability, such as has been seen previously. In addition, our data reveal signatures of collimated stellar winds. We propose a new scenario for these two stars where the nebula shaping is influenced by the presence of a companion star and/or fast rotation.
Common envelope: progress and transients
Authors: Ivanova Natalia 
Published: July 2017

AbstractWe review the fundamentals and the recent developments in understanding of common envelope physics. We report specifically on the progress that was made by the consideration of the recombination energy. This energy is found to be responsible for the complete envelope ejection in the case of a prompt binary formation, for the delayed dynamical ejections in the case of a self-regulated spiral-in, and for the steady recombination outflows during the transition between the plunge-in and the self-regulated spiral-in. Due to different ways how the recombination affects the common envelope during fast and slow spiral-ins, the apparent efficiency of the orbital energy use can be different between the two types of spiral-ins by a factor of ten. We also discuss the observational signatures of the common envelope events, their link a new class of astronomical transients, Luminous Red Novae, and to a plausible class of very luminous irregular variables.
HD151018: strong magnetic field in a giant O-type star?
Authors: Rubinho M. S. , Damineli A. , Carciofi A. , Moser D. 
Published: July 2017

AbstractHD151018 is a normal O-type giant with periodic variability of the wind seen in both spectroscopy and linear polarimetry. The characteristics of the wind emission strongly indicate a magnetically confined wind. This work presents the observational results and an initial modelling of the polarimetric modulation of this star.
Implicit Theories of Ability and Self-Efficacy
Authors: Chen Jason A. , Shane Tutwiler M. 
Published: July 2017

Abstract. Our overall goal was to empirically test what we called the “growth mindset as inoculation” hypothesis using a series of latent profile analytical approaches. This inoculation hypothesis, which is consistent with the way in which Dweck and Leggett (1988) described their social cognitive approach, states that believing in the malleability of intelligence serves a protective role against negative motivational and achievement outcomes. Participants were Grade 6 students (n = 504) from a middle school and Grade 10 students (n = 354) from two high schools in the Southeastern part of the United States. Two distinct patterns emerged, which corresponded to a growth mindset profile, and an all moderate profile. Our findings did not completely confirm or disconfirm the inoculation hypothesis – rather, a more nuanced conclusion should be drawn. Although there was evidence that the growth mindset profile evinced more adaptive outcomes compared to the all moderate alternative, which reinforced Dweck and Leggett’s claims, there was no evidence of any profiles with a distinct fixed theory of ability. This was true even when we forced our data to conform to such a model. Results refine Dweck and Leggett’s social cognitive approach to motivation.
Digital spiral object identification using random light
Authors: Yang Zhe , Magaña-Loaiza Omar S , Mirhosseini Mohammad , Zhou Yiyu , Gao Boshen , Gao Lu , Rafsanjani Seyed Mohammad Hashemi , Long Gui-Lu , Boyd Robert W 
Published: July 2017

AbstractPhotons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing, object identification and imaging. It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light. Here we demonstrate that the spatial signatures and phase information of an object with rotational symmetries can be identified using classical orbital angular momentum correlations in random light. The Fourier components imprinted in the digital spiral spectrum of the object, as measured through intensity correlations, unveil its spatial and phase information. Sharing similarities with conventional compressive sensing protocols that exploit sparsity to reduce the number of measurements required to reconstruct a signal, our technique allows sensing of an object with fewer measurements than other schemes that use pixel-by-pixel imaging. One remarkable advantage of our technique is that it does not require the preparation of fragile quantum states of light and operates at both low- and high-light levels. In addition, our technique is robust against environmental noise, a fundamental feature of any realistic scheme for remote sensing.
Mechanistic and structural basis for activation of cardiac myosin force production by omecamtiv mecarbil
Authors: Planelles-Herrero Vicente J. , Hartman James J. , Robert-Paganin Julien , Malik Fady I. , Houdusse Anne 
Published: July 2017

AbstractOmecamtiv mecarbil is a selective, small-molecule activator of cardiac myosin that is being developed as a potential treatment for heart failure with reduced ejection fraction. Here we determine the crystal structure of cardiac myosin in the pre-powerstroke state, the most relevant state suggested by kinetic studies, both with (2.45 Å) and without (3.10 Å) omecamtiv mecarbil bound. Omecamtiv mecarbil does not change the motor mechanism nor does it influence myosin structure. Instead, omecamtiv mecarbil binds to an allosteric site that stabilizes the lever arm in a primed position resulting in accumulation of cardiac myosin in the primed state prior to onset of cardiac contraction, thus increasing the number of heads that can bind to the actin filament and undergo a powerstroke once the cardiac cycle starts. The mechanism of action of omecamtiv mecarbil also provides insights into uncovering how force is generated by molecular motors.
CLICs-dependent chloride efflux is an essential and proximal upstream event for NLRP3 inflammasome activation
Authors: Tang Tiantian , Lang Xueting , Xu Congfei , Wang Xiaqiong , Gong Tao , Yang Yanqing , Cui Jun , Bai Li , Wang Jun , Jiang Wei , Zhou Rongbin 
Published: July 2017

AbstractThe NLRP3 inflammasome can sense different pathogens or danger signals, and has been reported to be involved in the development of many human diseases. Potassium efflux and mitochondrial damage are both reported to mediate NLRP3 inflammasome activation, but the underlying, orchestrating signaling events are still unclear. Here we show that chloride intracellular channels (CLIC) act downstream of the potassium efflux-mitochondrial reactive oxygen species (ROS) axis to promote NLRP3 inflammasome activation. NLRP3 agonists induce potassium efflux, which causes mitochondrial damage and ROS production. Mitochondrial ROS then induces the translocation of CLICs to the plasma membrane for the induction of chloride efflux to promote NEK7–NLRP3 interaction, inflammasome assembly, caspase-1 activation, and IL-1β secretion. Thus, our results identify CLICs-dependent chloride efflux as an essential and proximal upstream event for NLRP3 activation.
Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites
Authors: Draguta Sergiu , Sharia Onise , Yoon Seog Joon , Brennan Michael C. , Morozov Yurii V. , Manser Joseph S. , Kamat Prashant V. , Schneider William F. , Kuno Masaru 
Published: July 2017

AbstractMixed halide hybrid perovskites, CH3NH3Pb(I1−x
Br
x
)3, represent good candidates for low-cost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material’s optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodide-rich phases. It additionally explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.