bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light from Shattered Worlds: Debris from Giant Impacts
Authors: Jackson Alan P. , Wyatt Mark C. , Dent William R. F. , Roberge Aki 
Published: January 2014

AbstractLarge impacts in the outer parts of a planetary system will produce debris discs that display a strong, distinctive, asymmetry, which will last for 105 year timescales. Debris resulting from a large impact may be able to explain the asymmetries in some known debris discs that have hitherto been difficult to understand.
First High-Angular Resolution L′ Images of the β Pictoris Debris Disc with the VLT / NaCo
Authors: Milli Julien , Mawet Dimitri , Absil Olivier , Lagrange Anne-Marie , Mouillet David , Girard Julien H. , Augereau Jean-Charles 
Published: January 2014

AbstractImaging debris discs in the L′-band (3.8 μm) is a difficult task. Quasi-static speckles from imperfect optics prevail below 1″ whereas background emission is the dominant noise source beyond that separation and is much larger than at shorter wavelengths. We demonstrate here the potential of the newly commissioned AGPM coronograph on VLT/NaCo combined with advanced star and sky subtraction technique based on Principal Component Analysis, and we analyze the morphology of the β Pictoris disc.
Newly Seen Debris Disks from the HST NICMOS Archive
Authors: Perrin Marshall D. , Choquet Elodie , Chen Christine , Debes John , Golimowski David , Hagan J. Brendan , Hines Dean C. , Mittal Tushar , Moerchen Margaret , N'Diaye Mamadou , Pueyo Laurent , Reid I. Neill , Schneider Glenn , Wolff Schuyler , Soummer Remi 
Published: January 2014

AbstractBy reprocessing the NICMOS coronagraphic archive using improved PSF subtraction methods, we have obtained new images of 5 debris disks, all previously unseen using classical PSF subtractions. Three of the disks are edge on and two appear to be ring like, one of which is extremely asymmetric.Their stellar hosts are nearby, young F and G type stars (40-90 pc, 12–30 Myr), including one that is a close analog to the young sun at roughly the age at which terrestrial planets were assembling. This is a 25% increase in the sample of debris disks seen in scattered light. Analysis and modeling of the disk geometries is in process. Given these systems' youth, proximity, and brightness (V = 7.2 to 8.5), these will be superb targets for investigating planet formation, and are perfect targets for studies with GPI, SPHERE and JWST.
Collision parameters governing water delivery and water loss in early planetary systems
Authors: Maindl Thomas I. , Dvorak Rudolf 
Published: January 2014

AbstractWe investigate the distribution of encounter velocities and impact angles describing collisions in the habitable zone of the early planetary system. Here we present a catalogue of collision characteristics for a particular mass ratio of the colliding bodies and seven different planetesimal masses ranging from a tenth of Ceres' mass to 10 times the mass of the Moon. We show that there are virtually no collisions with impact speeds lower than the surface escape velocity and a similar velocity-impact angle distribution for different planetesimal masses if velocities are normalized using the escape velocity. An additional perturbing Jupiter-like object distorts the collision velocity and impact picture in the sense that grazing impacts at higher velocities are promoted if the perturber's orbit is close to the habitable zone whereas a more distant perturber has more the effect of a mere widening of the velocity dispersion.
Protoplanetary Disk Evolution and Influence of the Host Star
Authors: Baillié Kévin , Charnoz Sébastien 
Published: January 2014

AbstractBased on a self-consistent coupling between protoplanetary disk thermodynamics, photosphere geometry and dynamics we designed a 1D-hydrodynamical numerical model for the spreading of the disks as a function of the star characteristics. We found that the evolution timescale increases for more massive or for a steeper surface density disk, and decreases for bigger stars or less turbulent disks. We found a strong dependency of the mass accretion rate versus the disk mass and a weaker dependency versus the star mass. Coupled with observed similar conclusions, we derived that the disk mass is scaling as M*1.6.
Uneven Cooling: The influence of atmospheric dynamics on the thermal evolution of gas giants
Authors: Rauscher Emily , Showman Adam P. 
Published: January 2014

AbstractPlanets cool and contract as they age, with a cooling rate that depends on the efficiency with which they can transport heat out to space, first through the convective interior and then radiatively out through the atmosphere. The bottleneck for this cooling is the radiative-convective boundary (RCB), where the heat transport is the least efficient. Due to differential heating and atmospheric dynamics, the depth of the RCB can vary with latitude and longitude, meaning that the actual global cooling rate may differ from what would be calculated assuming a spherically symmetric RCB, as in 1D evolutionary models. Here we present models of the deep atmosphere of a generic hot Jupiter, calculate inhomogeneity in the RCB, and determine the resulting effect on the global thermal evolution. Although this issue can apply to any differentially heated gas giant, we focus on the hot Jupiter class of planet because: 1) the thick radiative zones above their deep RCBs can have a stronger influence on deforming the surface of the RCB than would generally be the case for a less-irradiated planet, and 2) an uneven RCB should increase the cooling rate, potentially exacerbating the mismatch between the large radii measured for some hot Jupiters and the smaller radii expected from evolutionary models.
Tidal Dissipation and Eccentricity Pumping: Implications for the Depth of the Secondary Eclipse of 55 Cnc e
Authors: Bolmont E. , Selsis F. , Raymond S. N. , Leconte J. , Hersant F. , Maurin A.-S. , Pericaud J. 
Published: January 2014

AbstractWe use the super-Earth 55 Cnc e (Fischer et al. 2008) as a case-study to address an observable effect of tidal heating. This transiting short-period planet belongs to a compact multiple system with massive planets. We investigate whether planet-planet interactions can force the eccentricity of this planet to a level that would affect the eclipse depth observed with Spitzer.
CARMENES: Blue Planets Orbiting Red Dwarfs
Authors: Quirrenbach A. , Amado P. J. , Caballero J. A. , Mandel H. , Mundt R. , Reiners A. , Ribas I. , Carrasco M. A. Sánchez , Seifert W. , Azzaro M. , Galadí D. ,   the CARMENES Consortium
Published: January 2014

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) will conduct a radial-velocity survey of ~ 300 M dwarfs with the 3.5m telescope at the Calar Alto Observatory. The CARMENES instrument is currently under construction; it consists of two independent échelle spectrographs, which together cover the wavelength range 0.55 – 1.7μm at a spectral resolution of R = 82,000. The spectrographs and the fiber input are designed with a goal of 1m/s radial velocity precision using simultaneous calibration with emission-line lamps.
Solar Prominence Fine Structure and Dynamics
Authors: Berger Thomas 
Published: January 2014

AbstractWe review recent observational and theoretical results on the fine structure and dynamics of solar prominences, beginning with an overview of prominence classifications, the proposal of possible new “funnel prominence” classification, and a discussion of the recent “solar tornado” findings. We then focus on quiescent prominences to review formation, down-flow dynamics, and the “prominence bubble” phenomena. We show new observations of the prominence bubble Rayleigh-Taylor instability triggered by a Kelvin-Helmholtz shear flow instability occurring along the bubble boundary. Finally we review recent studies on plasma composition of bubbles, emphasizing that differential emission measure (DEM) analysis offers a more quantitative analysis than photometric comparisons. In conclusion, we discuss the relation of prominences to coronal magnetic flux ropes, proposing that prominences can be understood as partially ionized condensations of plasma forming the return flow of a general magneto-thermal convection in the corona.
Prominence Seismology
Authors: Ballester J. L. 
Published: January 2014

AbstractQuiescent solar prominences are cool and dense plasma clouds located inside the hot and less dense solar corona. They are highly dynamic structures displaying flows, instabilities, oscillatory motions, etc. The oscillations have been mostly interpreted in terms of magnetohydrodynamic (MHD) waves, which has allowed to perform prominence seismology as a tool to determine prominence physical parameters difficult to measure. Here, several prominence seismology applications to large and small amplitude oscillations are reviewed.
The formation and disappearance of filament barbs observed by SDO
Authors: Li Leping , Zhang Jun 
Published: January 2014

AbstractEmploying six-day (August 16-21, 2010) SDO/AIA observations, we systematically investigate the formation and disappearance of 58 barbs of a northern (~N60) polar crown filament. Three different ways of barb formation are discovered, including (1) the convergence of surrounding moving materials (55.2%), (2) the flows of materials from the filament (37.9%), and (3) the material injections from neighboring brightening regions (6.9%). We also find three different types of barb disappearance, involving: (i) the bi-lateral movements (44.8%), and (ii) the outflowing (27.6%) of barb material resulting in the barb disappearance, as well as (iii) the barb disappearance associated with neighboring brightenings (27.6%). We propose that barbs exchange materials with the filament, surrounding atmosphere, and nearby brightening regions, causing the barb formation and disappearance.
The damping of transverse oscillations of prominence threads: a comparative study
Authors: Soler Roberto , Oliver Ramon , Ballester Jose Luis 
Published: January 2014

AbstractTransverse oscillations of thin threads in solar prominences are frequently reported in high-resolution observations. The typical periods of the oscillations are in the range of 3 to 20 min. A peculiar feature of the oscillations is that they are damped in time, with short damping times corresponding to few periods. Theoretically, the oscillations are interpreted as kink magnetohydrodynamic waves. However, the mechanism responsible for the damping is not well known. Here we perform a comparative study between different physical mechanisms that may damp kink waves in prominence threads. The considered processes are thermal conduction, cooling by radiation, resonant absorption, and ion-neutral collisions. We find that thermal conduction and radiative cooling are very inefficient for the damping of kink waves. The effect of ion-neutral collisions is minor for waves with periods usually observed. Resonant absorption is the only process that produces an efficient damping. The damping times theoretically predicted by resonant absorption are compatible with those reported in the observations.
Modelling of quiescent prominence fine structures
Authors: Gunár S. 
Published: January 2014

AbstractWe review here the current status and the latest results of the modelling of quiescent prominence fine structures. We begin with the simulations of the prominence magnetic field configurations, through an overview of the modelling of the fine structure formation and dynamics, and with the emphasis on the radiative transfer modelling of the realistic prominence fine structures. We also illuminate the future directions of the field that lie in the combining of the existing approaches into more complex multi-disciplinary models.
On the nature of the prominence - corona transition region
Authors: Parenti Susanna , Vial Jean-Claude 
Published: January 2014

AbstractDue to the complexity of their environment, prominences properties are still a matter of controversy. Prominences cool and dense plasma is suspended in the hot corona by a magnetic structure poorly known. Their thermal insulation from the corona results in a thin geometrical interface called prominence-corona-transition-region (PCTR). Here we will review the main properties of such a region as derived primarily from observations. We will introduce the thermal structure properties, describe the fine structure together with the Doppler-shift and width properties of lines of the emitting plasma. We will introduce the proposed interpretations of such observations and the limits of our knowledge imposed by the present instrumentation. We will conclude with a perspective for the future observations of the PCTR.
Rayleigh–Taylor instability in partially ionized prominence plasma
Authors: Khomenko E. , Díaz A. , de Vicente A. , Collados M. , Luna M. 
Published: January 2014

AbstractWe study Rayleigh–Taylor instability (RTI) at the coronal–prominence boundary by means of 2.5D numerical simulations in a single-fluid MHD approach including a generalized Ohm's law. The initial configuration includes a homogeneous magnetic field forming an angle with the direction in which the plasma is perturbed. For each field inclination we compare two simulations, one for the pure MHD case, and one including the ambipolar diffusion in the Ohm's law, otherwise identical. We find that the configuration containing neutral atoms is always unstable. The growth rate of the small-scale modes in the non-linear regime is larger than in the purely MHD case.
Determination of Prominence Plasma β from the Dynamics of Rising Plumes
Authors: Hillier Andrew , Hillier Richard , Tripathi Durgesh 
Published: January 2014

AbstractObservations of quiescent prominences show rising plumes, dark in chromospheric lines, that propagate from large bubbles. In this paper we present a method that may be used to determine the plasma β (ratio of gas pressure to magnetic pressure) from the rising plumes. Using the classic fluid dynamic solution for flow around a circular cylinder, the compression of the prominence material can be estimated. Application to a prominence gave an estimate of the plasma β as β=0.47−1.13 for a ratio of specific heats of γ=1.4−1.7.
Modeling Magnetic Flux Ropes
Authors: Xia Chun , Keppens Rony 
Published: January 2014

AbstractThe magnetic configuration hosting prominences can be a large-scale helical magnetic flux rope. As a necessary step towards future prominence formation studies, we report on a stepwise approach to study flux rope formation. We start with summarizing our recent three-dimensional (3D) isothermal magnetohydrodynamic (MHD) simulation where a flux rope is formed, including gas pressure and gravity. This starts from a static corona with a linear force-free bipolar magnetic field, altered by lower boundary vortex flows around the main polarities and converging flows towards the polarity inversion. The latter flows induce magnetic reconnection and this forms successive new helical loops so that a complete flux rope grows and ascends. After stopping the driving flows, the system relaxes to a stable helical magnetic flux rope configuration embedded in an overlying arcade. Starting from this relaxed isothermal endstate, we next perform a thermodynamic MHD simulation with a chromospheric layer inserted at the bottom. As a result of a properly parametrized coronal heating, and due to radiative cooling and anisotropic thermal conduction, the system further relaxes to an equilibrium where the flux rope and the arcade develop a fully realistic thermal structure. This paves the way to future simulations for 3D prominence formation.
Structure and Topology of Magnetic Fields in Solar Prominences
Authors: van Ballegooijen Adriaan A. , Su Yingna 
Published: January 2014

AbstractRecent observations and models of solar prominences are reviewed. The observations suggest that prominences are located in or below magnetic flux ropes that lie horizontally above the PIL. However, the details of the magnetic structure are not yet fully understood. Gravity likely plays an important role in shaping the vertical structures observed in quiescent prominences. Preliminary results from a time-dependent model describing the interaction of a magnetic flux rope with photospheric magnetic elements are presented.
Hemispheric Patterns in Filament Chirality and Sigmoid Shape over the Solar Cycle
Authors: Martens Petrus C. , Yeates Anthony R. , Pillai Karthik G. 
Published: January 2014

AbstractThe motivation for our research was to study the correlation between the chirality of filaments and the handedness (S- or Z-shape) of sigmoids. It was assumed that sigmoids would mostly coincide with filaments and that the S-shaped sigmoids would correlate well with filaments of sinistral chirality, which we found that to be at best a very weak relation. Since we had a full solar cycle of filament metadata at hand it was easy to verify the supposedly known hemispheric preference of filament chirality. We discovered that the hemispheric chirality rule was confirmed for the epoch where a thorough manual study had been performed, but that at other phases of the solar cycle the rule seems to disappear and sometimes even reverse.
The Formation of a Cavity in a 3D Flux Rope
Authors: Schmit Donald , Gibson Sarah 
Published: January 2014

AbstractThere are currently no three dimensional numerical models which describe the magnetic and energetic formation of prominences self-consistently. Consequently, there has not been significant progress made in understanding the connection between the dense prominence plasma and the coronal cavity. We have taken an ad-hoc approach to understanding the energetic implications of the magnetic models of prominence structure. We extract one dimensional magnetic field lines from a 3D MHD model of a flux rope and solve for hydrostatic balance along these field lines incorporating field-aligned thermal conduction, uniform heating, and radiative losses. The 1D hydrostatic solutions for density and temperature are then mapped back into three dimensional space, which allows us to consider the projection of multiple structures. We find that the 3D flux rope is composed of several distinct field line types. A majority of the flux rope interior field lines are twisted but not dipped. These field lines are density-reduced relative to unsheared arcade field lines. We suggest the cavity may form along these short interior field lines which are surrounded by a sheath of dipped field lines. This geometric arrangement would create a cavity on top of a prominence, but the two structures would not share field lines or plasma.
Global magnetic field cycle evolution and prominence eruptions
Authors: Bilenko Irina A. 
Published: January 2014

AbstractA comparison of changes in the structure of the global solar magnetic field and that in the prominence parameters, in solar cycles 21–23, are presented. It is proposed that the observed global magnetic field structure changes and periodicities in the mean solar magnetic field are the result of the excitation of large-scale Rossby waves. The changes in the prominence parameters are assumed to be the result of the global magnetic field structure changes, which may be triggered or modulated quasi-periodically by large-scale Rossby waves.
Magnetohydrodynamic study on the effect of the gravity stratification on flux rope ejections
Authors: Pagano Paolo , Mackay Duncan H. , Poedts Stefaan 
Published: January 2014

AbstractCoronal Mass Ejections (CMEs) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the flux rope ejection model where these magnetic structures firt form in the solar corona then are ejected to produce a CME. We run simulations coupling two models. The Global Non-Linear Force-Free Field (GNLFFF) evolution model to follow the quasi-static formation of a flux rope and MHD simulations for the production of a CME through the loss of equilibrium and ejection of this flux rope in presence of solar gravity and density stratification. Our realistic multi-beta simulations describe the CME following the flux rope ejection and highlight the decisive role played by the gravity stratification on the CME propagation speed.
A confined flare above filaments
Authors: Dalmasse K. , Chandra R. , Schmieder B. , Aulanier G. 
Published: January 2014

AbstractWe present the dynamics of two filaments and a C-class flare observed in NOAA 11589 on 2012 October 16. We used the multi-wavelength high-resolution data from SDO, as well as THEMIS and ARIES ground-based observations. The observations show that the filaments are progressively converging towards each other without merging. We find that the filaments have opposite chirality which may have prevented them from merging. On October 16, a C3.3 class flare occurred without the eruption of the filaments. According to the standard solar flare model, after the reconnection, post-flare loops form below the erupting filaments whether the eruption fails or not. However, the observations show the formation of post-flare loops above the filaments, which is not consistent with the standard flare model. We analyze the topology of the active region's magnetic field by computing the quasi-separatrix layers (QSLs) using a linear force-free field extrapolation. We find a good agreement between the photospheric footprints of the QSLs and the flare ribbons. We discuss how slipping or slip-running reconnection at the QSLs may explain the observed dynamics.
The in-situ manifestation of solar prominence material
Authors: Lepri Susan T. , Zurbuchen Thomas H. , Gruesbeck Jacob R. , Gilbert Jason A. 
Published: January 2014

AbstractCoronal mass ejections observed in the corona exhibit a three-part structure, with a leading bright front indicating dense plasma, a low density cavity thought to be a signature of the embedded magnetic flux rope, and the high density core likely containing cold, prominence material. When observed in-situ, as Interplanetary CMEs (or ICMEs), the presence of all three of these signatures remains elusive, with the prominence material rarely observed. We report on a comprehensive and long-term search for prominence material inside ICMEs as observed by the Solar Wind Ion Composition Spectrometer on the Advanced Composition Explorer. Using a novel data analysis process, we are able to identify traces of low charge state plasma created during prominence eruptions associated with ICMEs. We find that the likelihood of occurrence of cold material in the heliosphere is vastly lower than that observed in the corona but that conditions during the eruption do allow low charge ions to make it into the solar wind, preserving their expansion history. We discuss the implications of these findings.
Interplanetary Disturbances Affecting Space Weather
Authors: Wimmer-Schweingruber Robert F. 
Published: January 2014

AbstractThe Sun somehow accelerates the solar wind, an incessant stream of plasma originating in coronal holes and some, as yet unidentified, regions. Occasionally, coronal, and possibly sub-photospheric structures, conspire to energize a spectacular eruption from the Sun which we call a coronal mass ejection (CME). These can leave the Sun at very high speeds and travel through the interplanetary medium, resulting in a large-scale disturbance of the ambient background plasma. These interplanetary CMEs (ICMEs) can drive shocks which in turn accelerate particles, but also have a distinct intrinsic magnetic structure which is capable of disturbing the Earth's magnetic field and causing significant geomagnetic effects. They also affect other planets, so they can and do contribute to space weather throughout the heliosphere. This paper presents a historical review of early space weather studies, a modern-day example, and discusses space weather throughout the heliosphere.