bluuebunny/crossref_metadata_2025_split huggingface dataset:
Search for cool extrasolar giant planets combining coronagraphy, spectral and angular differential imaging
Authors: Maire Anne-Lise , Boccaletti Anthony , Rameau Julien , Chauvin Gaël , Lagrange Anne-Marie , Bonnefoy Mickaël , Desidera Silvano , Sylvestre Mélody , Baudoz Pierre , Galicher Raphaël , Mouillet David 
Published: January 2014

AbstractSpectral differential imaging (SDI) is part of the observing strategy of current and on-going high-contrast imaging instruments on ground-based telescopes. Although it improves the star light rejection, SDI attenuates the signature of off-axis companions to the star, just like angular differential imaging (ADI). However, the attenuation due to SDI has the peculiarity of being dependent on the spectral properties of the companions. To date, no study has investigated these effects. Our team is addressing this problem based on data from a direct imaging survey of 16 stars combining the phase-mask coronagraph, the SDI and the ADI modes of VLT/NaCo. The objective of the survey is to search for cool (Teff<1000-1300 K) giant planets at separations of 5-10 AU orbiting young, nearby stars (<200 Myr, <25 pc). The data analysis did not yield any detections. As for the estimation of the sensivity limits of SDI-processed images, we show that it requires a different analysis than that used in ADI-based surveys. Based on a method using the flux predictions of evolutionary models and avoiding the estimation of contrast, we determine directly the mass sensivity limits of the survey for the ADI processing alone and with the combination of SDI and ADI. We show that SDI does not systematically improve the sensitivity due to the spectral properties and self-subtraction of point sources.
Successes and challenges of the APP Coronagraph
Authors: Kenworthy Matthew A. , Quanz Sascha , Otten Gilles , Meshkat Tiffany , Codona Johanan , Snik Frans , Meyer Michael E. , Kasper Markus , Girard Julien 
Published: January 2014

AbstractThe Apodizing Phase Plate (APP) coronagraph has been used to image the exoplanet β Pictoris b and the protoplanet candidate around HD 100546, and is currently in use in surveys with NaCo at the VLT. Its success is due to its tolerance to tip-tilt pointing errors in current AO systems, which degrade the performance of nearly all other coronagraphs. Currently the sensitivity of the APP is limited by non-common path errors in the science camera systems and by its chromatic behaviour. We present the achromatized Vector APP coronagraph and address how we will measure and minimise non-common path errors with Focal Plane Wavefront Sensing algorithms.
Companion search around β Pictoris with the newly commissioned L'-band vector vortex coronagraph on VLT/NACO
Authors: Mawet D. , Absil O. , Milli J. , Baudoz P. , Boccaletti A. , Chauvin G. , Delacroix C. , Girard J. H. , Lagrange A. M. , O'Neal J. , Bourget P. , Forsberg P. , Gonte F. , Habraken S. , Hanot C. , Karlsson M. , Kasper M. , Lizon J.-L. , Muzic K. , Olivier R. , Peña E. , Slusarenko N. , Tacconi-Garman L. E. , Surdej J. 
Published: January 2014

AbstractHere we present the installation and successful commissioning of an L'-band Annular Groove Phase Mask (AGPM) coronagraph on VLT/NACO. The AGPM is a vector vortex coronagraph made from diamond subwavelength gratings tuned to the L' band. The vector vortex coronagraph enables high contrast imaging at very small inner working angle (here 0″.09, the diffraction limit of the VLT at L'), potentially being the key to a new parameter space. During technical and science verification runs, we discovered a late-type companion at two beamwidths from an F0V star (Mawet et al. 2013), and imaged the inner regions of β Pictoris down to the previously unexplored projected radius of 1.75 AU. The circumstellar disk was also resolved from ≃ 1″ to 5″ (see J. Milli et al., these proceedings). These results showcase the potential of the NACO L-band AGPM over a wide range of spatial scales.
Debris Disk Science with the Palomar ExAO System: First Results
Authors: Wahl Matthew , Metchev Stanimir , Patel Rahul , Serabyn Eugene , Mawet Dimitri , Dekany Richard , Roberts Jennifer , Burruss Rick , Bouchez Antonin , Truong Tuan , Baranec Christoph , Guiwits Stephen , Hale David , Angione John , Trinh Thang , Zolkower Jeffry , Shelton J. Christopher , Palmer Dean , Henning John , Croner Ernest , Troy Mitchell , McKenna Dan , Tesch Jonathan 
Published: January 2014

AbstractWe present first imaging results from the PALM-3000 adaptive optics system and PHARO camera on the Hale 5 m telescope. Observations using a vector vortex coronagraph have given us direct detections of the two-ring dusty debris system around the star HD 141569. Our observations reveal the inner clearing in the disk to unprecedentedly small angular separations, and are the most sensitive yet at the H and K bands. We are for the first time able to measure and compare the colors of the scattered light in the inner and outer dust rings, and find that the outer ring is significantly bluer than the inner ring.
Radio Interferometry Observations of the Hallmarks of Planet Formation
Authors: Andrews Sean M. 
Published: January 2014

AbstractSome of the fundamental processes involved in the evolution of circumstellar disks and the assembly of planetary systems are just now becoming accessible to astronomical observations. The new promise of observational work in the field of planet formation makes for a very dynamic research scenario, which is certain to be amplified in the coming years as the revolutionary Atacama Large Millimeter/submillimeter Array (ALMA) facility ramps up to full operations. To highlight the new directions being explored in these fields, this brief review will describe how high angular resolution measurements at millimeter/radio wavelengths are being used to study several crucial aspects of the formation and early evolution of planetary systems, including: the gas and dust structures of protoplanetary disks, the growth and migration of disk solids, and the interactions between a young planetary system and its natal, gas-rich disk.
Panchromatic imaging and modeling of SSTtau J042021+281349: A new prototypical edge-on protoplanetary disk
Authors: Duchêne G. , Stapelfeldt K. , Isella A. , Perrin M. , Ménard F. , Padgett D. , Pinte C. , Wolff S. , Krist J. , Ghez A. , Konopacky Q. 
Published: January 2014

AbstractWe present new high-resolution observations and modeling of SSTtau J042021+ 281349, a 400 AU-radius edge-on protoplanetary disk. We have gathered visible and near-infrared scattered light images of the system with the Hubble Space Telescope and Keck adaptive optics system, as well as a 1.3 mm continuum map with CARMA. Compared to the well-known HH 30 disk, this new system is remarkable because of its spectacular bipolar jet and the high degree of lateral symmetry of the disk. Indeed, we argue that this system is a “cleaner” prototype for edge-on disks. In addition, the apparent achromaticity of dust properties (most notably the almost grey opacity law) from the visible to the near-infrared in this disk suggests that it is in an advanced stage of dust evolution.
Circumstellar Disks in Very Young Embedded Clusters
Authors: Mariñas Naibí , Lada Elizabeth A. , Teixeira Paula S. , Lada Charles J. 
Published: January 2014

AbstractWe used FLAMINGOS near-IR photometry and spectroscopy and Spitzer mid-IR photometry to study disk fractions in the 1 to 2 Myr old NGC2264 clusters. We find that stars with masses < 0.3 solar masses have lower disk fractions than stars of solar mass or higher at these early ages. We also find that most disks disappear within the first 4 Myr, which is consistent with previous studies of disk lifetimes. Our study suggests that either some very low mass stars form without disks or that their disks are less massive and/or colder than predicted from models and not detected with Spitzer/Flamingos sensitivities.
Large grains can grow in circumstellar discs
Authors: Meru Farzana , Galvagni Marina , Olczak Christoph , Garaud Pascale 
Published: January 2014

AbstractWe perform coagulation & fragmentation simulations to understand grain growth in T Tauri & brown dwarf discs. We present a physically-motivated approach using a probability distribution function for the collision velocities and separating the deterministic & stochastic velocities. We find growth to larger sizes compared to other models. Furthermore, if brown dwarf discs are scaled-down versions of T Tauri discs (in terms of stellar & disc mass, and disc radius), growth at the same location with respect to the outer edge occurs to similar sizes in both discs.
The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectability
Authors: Kennedy G. M. , Wyatt M. C. 
Published: January 2014

AbstractThis contribution summarises the first characterisation of the 12 μm warm dust (“exo-Zodi”) luminosity function around Sun-like stars, focussing on the dustiest systems that can be identified by the WISE mission (Kennedy & Wyatt 2013). We use the sample of main-sequence stars observed by Hipparcos within 150pc as an unbiased sample, and report the detection of six new warm dust candidates. The ages of five of these new sources are unknown, meaning that they may be sites of terrestrial planet formation or rare analogues of other old warm dust systems. We show that the dustiest old (> Gyr) systems such as BD+20 307 are 1 in 10,000 occurrences. Bright warm dust is much more common around young (<120 Myr) systems, with a ~1% occurrence rate. We show that a two component in situ model where all stars have initially massive warm disks and in which warm debris is also generated at some random time along the stars' main-sequence lifetime, perhaps due to a collision, can explain the observations. However, if all stars only have initially massive warm disks these would not be visible at Gyr ages, and random collisions on the main-sequence are too infrequent to explain the high disk occurrence rate for young stars. That is, neither component can explain the observations on their own. Despite these conclusions, we cannot rule out an alternative dynamical model in which comets are scattered in from outer regions because the distribution of systems with the appropriate dynamics is unknown. Our in situ model predicts that the fraction of stars with exo-Zodi bright enough to cause problems for future exo-Earth imaging attempts is at least roughly 10%, and is higher for populations of stars younger than a few Gyr. This prediction of roughly 10% also applies to old stars because bright systems like BD+20 307 imply a population of fainter systems that were once bright, but are now decaying through fainter levels. Our prediction should be strongly tested by the Large Binocular Telescope Interferometer, which will provide valuable constraints and input for more detailed evolution models. A detection fraction lower than our prediction could indicate that the hot dust in systems like BD+20 307 has a cometary origin due to the quirks of the planetary dynamics. Population models of comet delivery need to be developed to help distinguish between different possible origins of warm dust.
A companion star in the SED modeling of the HD 142527 stellar system
Authors: Nagel Erick 
Published: January 2014

AbstractThe discovery of a likely companion of the Herbig Ae/Be star HD 142527 motivates the study of the effect that it produces on the SED. The main change on the system configuration is the formation of a gap in the disk in which the companion is embedded, following the orbit of the secondary star. This results in the formation of a wall (at the outer gap edge), which is illuminated by stellar radiation. We present a model for the SED, taking into account all the components of the system: the two stars, the disk with two gaps (one produced by the stellar companion and the other by potential planets), three walls (two associated with the gaps and the other with dust sublimation), optically thin material in the gaps and in a halo. The size of the modeled spherical halo is smaller than found in a previous study.
Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
Authors: Haywood R. D. , Cameron A. C. , Queloz D. , Barros S. C. C. , Deleuil M. , Fares R. , Gillon M. , Hatzes A. , Lanza A. F. , Lovis C. , Moutou C. , Pepe F. , Pollacco D. , Santerne A. , Ségransan D. , Unruh Y. 
Published: January 2014

AbstractSince the discovery of the transiting Super-Earth CoRoT-7b, several investigations have been made of the number and precise masses of planets present in the system, but they all yield different results, owing to the star's high level of activity. Radial velocity (RV) variations induced by stellar activity therefore need to be modelled and removed to allow a reliable detection of all planets in the system. We re-observed CoRoT-7 in January 2012 with both HARPS and the CoRoT satellite, so that we now have the benefit of simultaneous RV and photometric data. We fitted the off-transit variations in the CoRoT lightcurve using a harmonic decomposition similar to that implemented in Queloz et al. (2009). This fit was then used to model the stellar RV contribution, according to the methods described by Aigrain et al. (2011). This model was incorporated into a Monte Carlo Markov Chain in order to make a precise determination of the orbits of CoRoT-7b and CoRoT-7c. We also assess the evidence for the presence of one or two additional planetary companions.
Exoplanet Transit Spectroscopy of Hot Jupiters Using HST/WFC3
Authors: Haynes Korey , Mandell Avi M. , Sinukoff Evan , Madhusudhan Nikku , Burrows Adam , Deming Drake 
Published: January 2014

AbstractWe present analysis of transit spectroscopy of three extrasolar planets, WASP-12 b, WASP-17 b, and WASP-19 b, using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). Measurement of molecular absorption in the atmospheres of these planets offers the chance to explore several outstanding questions regarding the atmospheric structure and composition of these highly irradiated, Jupiter-mass objects. We analyze the data for a single transit for each planet, using a strategy similar in certain aspects to the techniques used by Berta (2012), and achieve almost photon-limited results for individual spectral bins. Our final transit spectra are consistent with the presence of a broad absorption feature at 1.4 μm most likely due to water, but the amplitude of the absorption is less than expected based on previous observations with Spitzer, possibly due to hazes absorbing in the NIR. However, the degeneracy of models with different compositions and temperature structures combined with the low amplitude of any features in the data preclude our ability to place unambiguous constraints on the atmospheric composition without a comprehensive multi-wavelength analysis.
From spectra to atmospheres: solving the underconstrained retrieval problem for exoplanets
Authors: Barstow Joanna K. , Aigrain Suzanne , Irwin Patrick G. J. , Bowles Neil , Fletcher Leigh N. , Lee Jae-Min 
Published: January 2014

AbstractSpectroscopic observations of transiting exoplanets have provided the first indications of their atmospheric structure and composition. Optimal estimation retrievals have been successfully applied to solar system planets to determine the temperature, composition and aerosol properties of their atmospheres, and have recently been applied to exoplanets. We show the effectiveness of the technique when combined with simulated observations from the proposed space telescope EChO, and also discuss the difficulty of constraining a complex system with sparse data and large uncertainties, using the super-Earth GJ 1214b as an example.
Hα Absorption in Transiting Exoplanet Atmospheres
Authors: Christie Duncan , Arras Phil , Li Zhi-Yun 
Published: January 2014

AbstractRecent observations by Jensen et al. of Hα absorption by the upper atmosphere of HD189733b have motivated the need for a theoretical understanding of the distribution of n=2 hydrogen within hot Jupiter atmospheres. With this in mind, we model the n=2 state of atomic hydrogen in a hydrostatic atmosphere in thermal and photoionization equilibrium. Both collisional and radiative transitions are included in the calculation of the n = 2 state level population. In our model, the Hα absorption is dominated by a τ ~ 1 shell composed of metastable 2s hydrogen located within the neutral atomic layer, with the contribution coming roughly uniformly throughout the layer instead of from a specific impact parameter. An ionization rate an order of magnitude over the expected value can reproduce the observed transit depth.
The Role of Oxygen Abundances in Exoplanet Host Star C/O Ratios: A Case Study of 55 Cnc
Authors: Teske Johanna K. , Cunha Katia , Smith Verne V. , Schuler Simon C. , Griffith Caitlin A. 
Published: January 2014

AbstractWe derive the C/O ratio for the exoplanet host star 55 Cnc based on archive Keck/HIRES spectra. The C/O ratio varies widely depending on which oxygen abundance indicator – the 6300.3 Å [O I] line, the 6363.8 Å [O I] line, or the 7774 Å O I triplet – is used, and we find there is still a large uncertainty even based on individual abundance indicators. This case study demonstrates that caution and care are necessary when determining exoplanet host star C/O ratios, and when considering host star C/O ratios in inferring exoplanet compositions.
A Resolved Millimeter Emission Belt in the AU Mic Debris Disk
Authors: MacGregor Meredith 
Published: January 2014

AbstractImaging debris disks at millimeter wavelengths is important, because emission at these long wavelengths is dominated by large grains with dynamics similar to the population of dust-producing planetesimals. We have used the SMA and ALMA to make 1.3 millimeter observations of the debris disk surrounding the nearby (9.9 pc), ~10 Myr-old, M-type flare star AU Microscopii. We characterize the disk by implementing Markov Chain Monte Carlo methods to fit parametric models to the visibilities. The millimeter observations reveal a belt of dust emission that peaks at a radius of 40 AU. This outer size scale agrees with predictions for a reservoir of planetesimals (a “birth ring”) based on the shape of the midplane scattered light profile. We do not find any significant asymmetries in the structure or the centroid position of the emission belt. The ALMA observations with a resolution of 0.6 arcsec (6 AU) also reveal a previously unknown central emission peak, ~6 times brighter than the stellar photosphere at these wavelengths. This central component remains unresolved and could be explained by stellar activity or an inner planetesimal belt located ≲3 AU from the star and containing roughly 1% the mass of the outer belt. Future observations with higher angular resolution will be able to distinguish between these possibilities.
LIDT-DD: A New Self-Consistent Debris Disc Model Including Radiation Pressure and Coupling Dynamical and Collisional Evolution
Authors: Kral Q. , Thebault P. , Charnoz S. 
Published: January 2014

AbstractThe first attempt at developing a fully self-consistent code coupling dynamics and collisions to study debris discs (Kral et al. 2013) is presented. So far, these two crucial mechanisms were studied separately, with N-body and statistical collisional codes respectively, because of stringent computational constraints.We present a new model named LIDT-DD which is able to follow over long timescales the coupled evolution of dynamics (including radiation forces) and collisions in a self-consistent way.
Finding Asteroid belt Analogues with WISE
Authors: Patel Rahul I. , Metchev Stanimir 
Published: January 2014

AbstractWe present the detection of stars with infrared (IR) excesses attributed to circumstellar debris disks from the WISE All-Sky Survey at the WISE 12 and 22 μm bandpasses (W3 and W4, respectively). Excess flux at these wavelengths is significant because it traces material in the regions of terrestrial planet formation. We searched for debris disks by cross-matching Hipparcos main sequence stars with the All-Sky Data Release from WISE and seeking excess flux at W3 and W4. Our sample is confined to a volume of 75 pc around the sun, and outside the galactic plane (|b|>5°). Debris disk-bearing stars were identified as 95%-confidence outliers in 2MASS/WISE color distributions, after checking for erroneous photometry and contamination from unrelated nearby objects.
Making systems of Super Earths by inward migration of planetary embryos
Authors: Cossou Christophe , Raymond Sean N. , Pierens Arnaud 
Published: January 2014

AbstractUsing N-body simulations with planet-disk interactions, we present a mechanism capable of forming compact systems of hot super Earths such as Kepler 11. Recent studies show that outward migration is common in the inner parts of radiative disks. However we show that two processes naturally tip the balance in favor of inward migration. First the corotation torque is too weak to generate outward migration for planetary embryos less massive than 4M⊕. Second, system of multiple embryos generate sustained non-zero eccentricities that damp the corotation torque and again favor inward migration. Migration and accretion of planetary embryos in realistic disks naturally produce super Earths in resonant chains near the disk inner edge. Their compact configuration is similar to the observed systems.
Protostellar Disks, Planet Traps, and the Origins of Exoplanetary Systems
Authors: Pudritz Ralph E. , Hasegawa Yasuhiro 
Published: January 2014

AbstractThe mass-semimajor axis diagram for exoplanets is populated by at least three distinct planetary populations: hot Jupiters at small orbital radii, more massive Jovian planets gathered at about 1 AU, and a rapidly growing population of SuperEarths at short periods. Our work shows that low mass and rapidly migrating planetary cores get trapped at disk inhomogeneities, where strong density or thermal gradients exist (namely dead zone boundaries, ice lines, and disk heating transition regions). Planet growth and movement occur at rates dictated by planetary accretion, and the slow radial inward motion of the traps due to falling disk accretion rates during disk evolution. By combining the theory of traps in evolving disks with standard ideas about how protoplanets accrete, we develop evolutionary tracks of how planets evolve in the mass- semimajor axis diagram. Our models account for the planetary “pile-up” at 1AU, the origin of SuperEarths and hot Jupiters, and the relative scarcity of Jovian planets at large distances.
Atmospheric dynamics on tidally locked Earth-like planets in the habitable zone of an M dwarf star
Authors: Carone Ludmila , Keppens Rony , Decin Leen 
Published: January 2014

AbstractWe investigated the large scale atmospheric circulation of Gl581g, a potentially habitable planet around an M dwarf star, using an idealized dry global circulation model (GCM) with simplified thermal forcing as a first step towards a systematic extended parameter study. The results are compared with the work of Joshi et al. (1997) who investigated a tidally-locked habitable Earth analogue with less than half the rotation period of Gl581g. The extent, form and strength of the atmospheric circulation in each model generally agree with each other, even though the models differ in key parameters such as planetary radius, surface gravity, forcing scheme and rotation period. The substellar point is associated with an uprising direct circulation-branch of a Hadley-like cell with return flow over the poles. It is compelling to assume that the substellar point of a tidally locked terrestrial exoplanet behaves dynamically like the Earth's tropic associated with clouds and precipitation, making it an ideal target for habitability.