bluuebunny/crossref_metadata_2025_split huggingface dataset:
HST Imaging of New Edge-on Circumstellar Disks in Nearby Star-forming Regions
Authors: Stapelfeldt K.R. , Duchêne G. , Perrin M. , Wolff S. , Krist J.E. , Padgett D.L. , Ménard F. , Pinte C. 
Published: January 2014

AbstractEdge-on, optically thick circumstellar disks have been previously imaged at subarcsecond resolution around about a dozen nearby young stellar objects. In these systems the central star is occulted from direct view, bright star image artifacts are absent, and the disk reflected light is clearly seen. Comparison of Hubble Space Telescope (HST) edge-on disk images with scattered light models has allowed key disk structural parameters and dust grain properties to be determined. Edge-on disks have been systematically undercounted to date: while 10% of young stars should statistically be occulted by their disk, the observed frequency is much less. Thus there is a significant potential for discovering and imaging new examples. Spitzer Space Telescope legacy science programs have provided the first good spectral energy distribution (SED) measurements for the previously known edge-on disks. These can be used as templates to identify new candidates in far-infrared survey datasets.We report on the results of our HST program to image twenty-one edge-on disk candidates mostly selected from their SEDs. Eleven are well-resolved with radii ranging from 30-400 AU, nine for the first time and six showing highly collimated jets. Outstanding individual sources include a large and symmetric new template object, a highly flattened disk not accreting onto its central star, and an asymmetric disk with a misaligned jet which likely traces tidal perturbations in a binary system. Follow-up work to obtain ancillary data and perform scattered light modeling of the most symmetric disks is now being pursued. The results of this program will guide a new round of searches for these rare but important snapshots of protoplanetary disk evolution.
Planet gaps in the dust layer of 3D proto-planetary disks: Observability with ALMA
Authors: Gonzalez J.-F. , Pinte C. , Maddison S. T. , Ménard F. 
Published: January 2014

AbstractAmong the numerous known extrasolar planets, only a handful have been imaged directly so far, at large orbital radii and in rather evolved systems. The Atacama Large Millimeter/submillimeter Array (ALMA) will have the capacity to observe these wide planetary systems at a younger age, thus bringing a better understanding of the planet formation process. Here we explore the ability of ALMA to detect the gaps carved by planets on wide orbits.
Probing protoplanetary disks with Aperture Masking
Authors: Lacour S. , Tuthill P. , Casassus S. 
Published: January 2014

AbstractThe interaction between planetary formation and protostellar disks is among the most critical remaining pieces in the puzzle of solar system assembly. Leading theoretical models are constructed around two distinct scenarios: gravitational instabilities and core accretion. The physics of each applies to quite different epochs of formation, and exhibits complex dependencies on parameters like disk density and viscosity. Untangling the effects such processes have on the final planetary statistics necessitates direct observation of exoplanets in their primordial state, prior to orbital migration. Furthermore, detailed study of the environment, such as the way the planets shape the protostellar disk by driving accretion streams across disk gaps, will also constrain formation models. Aperture masking interferometry has demonstrated a unique ability to probe the gaps within stellar disks. It has twin advantages of a higher dynamic range at the diffraction limit (λ/D) than differential imaging, while at the same time giving very extensive UV coverage compared to long baseline interferometry.
A Herschel View of Dust Evolution in Protoplanetary Disks
Authors: Espaillat Catherine 
Published: January 2014

AbstractThe details of how protoplanetary disks evolve from initially well-mixed distributions of gas and dust to systems composed mostly of rocky planets and gas giants like our own solar system is a fundamental question in astronomy. It is widely accepted that the first step in planet formation is dust grain growth and settling to the disk midplane. This dust evolution in disks can be studied in greater detail with far-infrared and submillimeter wavelength observations, which offer us unique access to the outer disk's deeper layers. Here we present Herschel far-infrared and submillimeter spectra of GM Aur taken with PACS and SPIRE. GM Aur is a transitional disk, whose inner disk hole is proposed to have been cleared by yet unseen planets. By utilizing Herschel data, we can potentially link the properties of dust evolution in the outer disk to dust clearing in the inner disk. In particular, preliminary SED modeling presented here suggests that GM Aur may have a lower gas-to-dust mass ratio than typically assumed for disks, which may be linked to disk clearing by planets. With further study, such Herschel data may provide insight for theoretical modeling of dust evolution and planet formation.
A First Look at the Disk Population in the Auriga-California Molecular Cloud
Authors: Broekhoven-Fiene Hannah , Matthews Brenda C. , Harvey Paul M. ,   members of the Spitzer Gould Belt Survey
Published: January 2014

AbstractThe Auriga-California Molecular Cloud (AMC) is one of two nearby (within 500 pc) giant molecular clouds, the other being the Orion A Molecular Cloud (OMC). We aim to study the properties of circumstellar disks in the AMC to compare the planet formation potential and processes within the AMC to those for other clouds. A first look with measurements from Spitzer observations suggests that AMC disk properties, such as the distribution of disk luminosities and the evolution of the mid-IR excesses, are not vastly different from those in other regions. Follow-up observations in the submm, mm and cm can be used to measure disk masses and the degree of grain growth from spectral slopes to more completely characterize the disk population.
Ice Lines in Circumbinary Protoplanetary Disks
Authors: Clanton Christian D. 
Published: January 2014

AbstractI find the location of the ice line in circumbinary disks heated by steady mass accretion and stellar irradiation, comparing the position with the minimum stable semimajor axis, interior to which planetary orbits are unstable. I show that there is a critical binary separation for which binaries with separations larger than this critical value have ice lines that lie interior to the boundary of stability. The critical separation for an equal-mass binary of 1 M⊙ stars is ≈ 1.04 AU, scaling weakly with mass accretion rate and Rosseland mean opacity of the disk. For a steady mass accretion rate of Ṁ ~ 10−8 M⊙ yr−1 and a Rosseland mean opacity of κR ~ 1 cm2 g−1, I show that ≳ 80% of all binary systems with component masses M☆ ≲ 2.0 M⊙ have ice lines interior to the boundary of stability. This suggests that rocky planets should not be common in these systems. Searching for planets around binaries with separations larger than the critical separation with Kepler or microlensing will provide a test of this prediction.
Dynamics of the inner edge of the dead zone in protoplanetary disks
Authors: Faure Julien , Fromang Sebastien , Latter Henrik 
Published: January 2014

AbstractIn protoplanetary disks, the inner boundary between an MRI active and inactive region has recently been suggested to be a promising site for planet formation. A set of numerical simulations has indeed shown that vortex formation mediated by the Rossby wave instability is a natural consequence of the disk dynamics at that location. However, such models have so far considered only the case of an isothermal equation of state, while the complex thermodynamics is at the heart of how this region works. Using the Godunov code Ramses, we have performed 3D global numerical simulations of protoplanetary disks that relax the isothermal hypothesis. We find that, at the interface, the disk thermodynamics and the turbulent dynamics are intimately entwined, because of the importance of turbulent dissipation and thermal ionisation.
The Early Era: How do protostellar discs form?
Authors: Joos Marc , Hennebelle Patrick , Ciardi Andrea , Fromang Sébastien 
Published: January 2014

AbstractDiscs are a key element in star and planet formation; however, magnetic fields can efficiently transport angular momentum away from the central region of the collapsing core during the dense core collapse, preventing disc formation. We perform numerical simulations of magnetically supercritical collapsing cores with a misalignment between the rotation axis and the magnetic field (Joos et al. 2012) and in a turbulent environment (Joos et al. 2013). The early formation of massive discs can take place at moderate magnetic intensities if the rotation axis is tilted or in a turbulent environment, because of misalignment and turbulent diffusion.
Gas signatures of Herbig Ae/Be disks probed with Herschel SPIRE spectroscopy
Authors: van der Wiel Matthijs H. D. , Naylor David A. , Aresu Giambattista , Olofsson Göran 
Published: January 2014

AbstractHerbig Ae/Be objects, like their lower mass counterparts T Tauri stars, are seen to form a stable circumstellar disk which is initially gas-rich and could ultimately form a planetary system. We present Herschel SPIRE 460–1540 GHz spectra of five targets out of a sample of 13 young disk sources, showing line detections mainly due to warm CO gas.
Orbital Motion and Multi-Wavelength Monitoring of LkCa15 b
Authors: Ireland Michael J. , Kraus Adam L. 
Published: January 2014

AbstractAs part of a deep multi-year non-redundant aperture mask infrared imaging campaign observing transition disks, we present multi-epoch monitoring of the resolved emission seen within the disk gap of LkCa 15. Orbital motion of both the central source and extended lobes as presented in Kraus and Ireland (2012) is clearly detected at the level of ~4 degrees/year (deprojected), in both K and L'-bands. Based on these data as well as single-epoch H and M bands epochs, we present two models for the central source - thermal emission as a planetary accretion signature and scattering. The thermal emission model is preferred.
A VLT/X-Shooter study of accretion and photoevaporation in Transitional Disks
Authors: Manara C. F. , Testi L. , Natta A. , Ricci L. , Benisty M. , Rosotti G. , Ercolano B. 
Published: January 2014

AbstractWe present preliminary results of a detailed study of the accretion, stellar, and wind properties of transitional disks (TDs) carried out with the X-Shooter spectrograph. Combining new and archival spectra, we collected a sample of more than 20 TDs from different nearby star-forming regions. Our sample includes objects with both small (<5-15 AU) and large (>20–30 AU) known inner hole size from the literature (either from mm-observations or IR SED fitting). We check their stellar parameters (Teff, L*, AV, M*) and derive their accretion properties (Lacc, Ṁacc) in a self-consistent way, which makes use of the wide wavelength coverage of X-Shooter, and study their wind properties by mean of different forbidden emission lines analysis.
Magnetocentrifugal jets and chondrule formation in protostellar disks
Authors: Salmeron Raquel , Ireland Trevor 
Published: January 2014

AbstractChondrite meteorites are the building blocks of the solar nebula, out of which our Solar System formed. They are a mixture of silicate and oxide objects (chondrules and refractory inclusions) that experienced very high temperatures, set in a matrix that remained cold. Their prevalence suggests that they formed through a very general process, closely related to stellar and planet formation. However the nature and properties of the responsible mechanism have remained unclear. The evidence for a hot solar nebula provided by this material seems at odds with astrophysical observations of forming stars. These indicate that the typical temperatures of protostellar disks are too low to melt and vapourise silicate minerals at the radial distances sampled by chondrule-bearing meteorites. Here, we show that processing of precursors in a protostellar outflow at radial distances of about 1 – 3 AU can heat them to their melting points and explain their basic properties, while retaining association with the colder matrix.
Properties of the young gas giant planet β Pictoris b
Authors: Bonnefoy Mickaël , Boccaletti Anthony , Lagrange Anne-Marie , Allard France , Mordasini Christoph , Beust Hervé , Chauvin Gaël , Girard Julien H. V. , Homeier Derek , Apai Daniel , Lacour Sylvestre , Rouan Daniel , Rameau Julien , Klahr Hubert 
Published: January 2014

AbstractThe young (12+8−4 Myr) and nearby (19.44±0.05 pc) star β Pictoris is considered one of the best laboratories for the study of early phases of planetary systems formation since the identification of an extended debris disk surrounding the star in 1984. In 2009, we imaged at 3.8 μm with NaCo at VLT a gas giant planet around β Pictoris, roughly along the disk mid-plane, with a semi-major axis between 8 and 14 AU. We present here the first images of the planet in the J (1.265 μm), H (1.66 μm), and M' (4.78 μm) bands obtained between 2011 and 2012. We used these data to build the 1-5 μm spectral energy distribution (SED) of the companion, and to consolidate previous semi-major axis (8-10 AU) estimates. We compared the SED to seven atmospheric models to derive Teff = 1700 ± 100 K. We used the temperature and the luminosity of β Pictoris b to estimate new masses for the companion. We compared these masses to independent constraints set by the orbital parameters and the radial velocities and use them to discuss the formation history of the object.
Direct imaging of Beta Pictoris b with first-light Magellan Adaptive Optics
Authors: Morzinski Katie M. , Close Laird M. , Males Jared R. , Hinz Phil M. , Puglisi Alfio , Esposito Simone , Riccardi Armando , Pinna Enrico , Xompero Marco , Briguglio Runa , Follette Kate , Kopon Derek , Gasho Victor , Uomoto Alan , Hare Tyson , Skemer Andy , Arcidiacono Carmelo , Quiros-Pacheco Fernando , Argomedo Javier , Busoni Lorenzo , Rodigas T. J. , Wu Ya-Lin 
Published: January 2014

AbstractMagAO is the newly-commissioned adaptive optics (AO) instrument on the Magellan Clay telescope at Las Companas Observatory, Chile. MagAO has two co-mounted science cameras: VisAO for visible-light direct and spectral-differential imaging; and Clio for near to thermal IR direct imaging, non-redundant-mask interference, and prism spectroscopy. We demonstrate MagAO's simultaneous visible and infrared AO performance via direct images of exoplanet Beta Pictoris b. The planet was detected in 5 passbands from 0.9–5μm. Here we show the infrared images; the visible observations are presented in Males et al. 2013. MagAO is the first AO system to offer good performance with extensive coverage across the O/IR spectrum and thus offers an unprecedented opportunity to study the spectral energy distributions of directly-imaged extrasolar planetary atmospheres.
The BT-Settl Model Atmospheres for Stars, Brown Dwarfs and Planets
Authors: Allard F. 
Published: January 2014

AbstractWe present a grid of stellar and substellar atmosphere models covering the range from solar-mass stars to the latest-type T and Y dwarfs with a single setup. For the first time our synthetic spectra and photometry reproduce the formation of clouds and in particular their clearing at the L/T transition. The BT-Settl models also naturally explain the dustier infrared properties of planets as an effect of low surface gravity.
Detecting Circumbinary Exoplanets: Understanding Transit Timing
Authors: Armstrong David , Martin David V. , Pollacco Don 
Published: January 2014

AbstractWe have derived and tested a simple analytical model for placing limits on the transit timing variations of circumbinary exoplanets. These are generally of days in magnitude, dwarfing those found in multi-planet systems. The derived method is fast, efficient and is accurate to approximately 1% in predicting limits on the possible times of transits over a 3-year campaign.
VSTAR models of the hot Jupiter HD 189733b
Authors: Bott Kimberly , Kedziora-Chudczer Lucyna , Bailey Jeremy 
Published: January 2014

AbstractPast analysis of HD 189733b's atmosphere has been a cause for some debate, with conflicting findings regarding water and sodium abundances and the presence of a high altitude haze. We present our models of HD 189733b's atmospheric composition using VSTAR (Versatile Software for Transfer of Atmospheric Radiation). Since the effective temperature of the planet is expected to be approximately 5000K, newly available high-temperature spectral line lists were used.
Characterization of exoplanet atmospheres using future space-based infrared telescopes: challenges in detecting biomarkers
Authors: Enya Keigo 
Published: January 2014

AbstractCharacterization of exoplanet atmospheres with space-based infrared telescopes is important to detect biomarkers. A promising method is temporary differential observation. For this method, designs of a wideband infrared spectral disperser are presented. A design using a CdTe prism simultaneously covers λ=1–30 μm. Designing binary pupil masks for segmented pupils to be used in spatially resolved observations are also shown for another observational method.
The HoSTS Project: A Homogeneous Study of Transiting Systems
Authors: Chew Yilen Gómez Maqueo , Faedi Francesca , Hebb Leslie , Pollacco Don , Stassun Keivan , Cargile Phillip , Smalley Barry , Doyle Amanda , Ghezzi Luan , Barros Susana C. C. , Cameron Andrew Collier 
Published: January 2014

AbstractThe Homogeneous Study of Transiting Systems (HoSTS) will derive a consistent and homogeneous set of both the stellar and planetary physical properties for a large sample of bright transiting planetary systems with confirmed planetary masses and measured radii. Our resulting catalogs of the fundamental properties of these bright planets and their host stars will enable us to explore empirical correlations that will lead to a better understanding of planetary formation and evolution. We present our pilot study of the planet-hosting star WASP-13, and the framework of our project which will allow for the identification of true relationships among the physical properties of the systems from any systematics.
Using exoplanet systems with highly elliptical orbits to search for star-planet interactions
Authors: Hodgson John R. , Christian Damian J. , Bodewits Dennis , Hawley Suzanne 
Published: January 2014

AbstractWe are investigating if the orbital geometry of exoplanets affects the activity of their host star by studying a sample of planetary systems known to contain massive planets on short period, highly elliptical orbits. While recent studies in the optical, UV, and X-Ray have shown enhanced chromospheric activity for stars hosting exoplanets with orbital semi-major axes less than 0.1 AU (Krejcova 2012, Shkolnik 2013, Kashyap 2008, Poppenhaeger 2010), it is not yet clear whether this activity is driven by magnetic or tidal interactions. We are probing the dependence of star-planet interactions (SPI) on the orbital geometry of the planetary systems by analyzing chromospheric lines (such as Ca II H & K) for variability phased with the exoplanet's orbit. We have obtained high resolution spectra of several systems with the McDonald 2.1-m Sandiford echelle spectrograph, ARCES on the APO 3.5-m, and for HIRES on Keck I from the Keck Observatory Archive. We describe our methodology and review how our results will use orbital geometry to deduce how planets may affect the activity of their host stars.
Dynamical Constraints on Exoplanets
Authors: Horner Jonti , Wittenmyer Robert A. , Tinney Chris , Hinse Tobias C. , Marshall Jonathan P. 
Published: January 2014

AbstractDynamical studies of new exoplanet systems are a critical component of the discovery and characterisation process. Such studies can provide firmer constraints on the parameters of the newly discovered planets, and may even reveal that the proposed planets do not stand up to dynamical scrutiny. Here, we demonstrate how dynamical studies can assist the characterisation of such systems through two examples: QS Virginis and HD 73526.
Searching for Photometric Variability across the L, T & Y Dwarf Sequence
Authors: Rajan A. , Wilson P. A. , Patience J. , Pont F. , De Rosa R. J. 
Published: January 2014

AbstractTo investigate the atmospheres of ultracool brown dwarfs with temperatures covering the range of transiting and directly imaged planets, we have monitored a sample of 76 L, T and Y brown dwarfs for infrared photometric variability. This survey was conducted in the J-band using both the SOFI camera on the 3.5-m NTT and the SWIRC camera on the 6.5-m MMT. Each target was observed for a period ranging from 2.0 hours to 6.0 hours, covering a significant fraction of the expected rotation period. Breakup of the iron and silicate clouds into a patchy cloud layer has been suggested as an explanation for the variability of several objects identified at the L/T transition, and a similar process with sulfide clouds may be manifest in T/Y transition objects; our data provides the first test of these patchy cloud scenarios across the entire brown dwarf spectral range.
A Trend Between Cold Debris Disk Temperature and Stellar Type: Implications for the Formation and Evolution of Wide-Orbit Planets
Authors: Ballering Nicholas P. , Rieke George H. , Su Kate Y. L. , Montiel Edward 
Published: January 2014

AbstractCold debris disks have the potential to answer many outstanding questions in wide-orbit planet formation and evolution. We characterized the infrared excess SEDs of 174 cold debris disks with Spitzer IRS and MIPS. We found a trend between the temperature of the disks and the stellar type of the stars they orbit. This argues against the importance of strictly temperature-dependent processes (e.g. ice lines) in setting the dimensions of cold debris disks. We also found no evidence that delayed stirring causes the trend. The trend may result from outward planet migration that traces the extent of the primordial protoplanetary disk, or from planet formation that halts at an orbital radius limited by the efficiency of core accretion. For the full details of this work, see Ballering et al. (2013).
The Population of Debris Discs Orbiting Subgiants
Authors: Bonsor Amy , Kennedy Grant M. , Crepp Justin R. , Johnson John A. , Wyatt Mark C. , Sibthorpe Bruce , Su Kate Y. L. 
Published: January 2014

AbstractWhilst debris discs orbiting main-sequence stars are well studied, very little is known regarding their fate when the star evolves onto the giant branch. For intermediate mass (A-type) stars, giants provide a unique opportunity to detect planets using the radial velocity technique, otherwise prohibited by high jitter levels and rotationally broadened lines in main-sequence intermediate mass (A-type) stars. Such stars can provide key insights into the structure of planetary systems around intermediate mass stars. In our Herschel OT1 program (PI Bonsor) we searched for the presence of debris discs orbiting a sample of 36 subgiants, half of which have RV detected companions. Our best detection is the resolved debris disc orbiting κ CrB.
Non-LTE Model Spectra for Gaseous Planetary Debris Disks around WDs
Authors: Hartmann Stephan , Nagel Thorsten , Rauch Thomas , Werner Klaus 
Published: January 2014

AbstractMetal-rich dust disks around white dwarfs are thought to be the debris of tidally disrupted rocky bodies. While normally the number of features to study the planetary material directly is very limited, ancillary gas disks around some of these white dwarfs provide the opportunity to do so. We used our Tübingen Accretion Disk code AcDc, assuming non-LTE conditions, to model the gaseous spectrum component. We investigated the chemical mixture as well as the surface density and effective temperature, and utilized the Ca ii infrared triplet to determine the geometry of the disk.