ABSTRACT Many parameters constraining the spectral appearance of exoplanets are still poorly understood. We therefore study the properties of irradiated exoplanet atmospheres over a wide parameter ...range including metallicity, C/O ratio, and host spectral type. We calculate a grid of 1D radiative-convective atmospheres and emission spectra. We perform the calculations with our new Pressure-Temperature Iterator and Spectral Emission Calculator for Planetary Atmospheres (PETIT) code, assuming chemical equilibrium. The atmospheric structures and spectra are made available online. We find that atmospheres of planets with C/O ratios ∼1 and 1500 K can exhibit inversions due to heating by the alkalis because the main coolants CH4, H2O, and HCN are depleted. Therefore, temperature inversions possibly occur without the presence of additional absorbers like TiO and VO. At low temperatures we find that the pressure level of the photosphere strongly influences whether the atmospheric opacity is dominated by either water (for low C/O) or methane (for high C/O), or both (regardless of the C/O). For hot, carbon-rich objects this pressure level governs whether the atmosphere is dominated by methane or HCN. Further we find that host stars of late spectral type lead to planetary atmospheres which have shallower, more isothermal temperature profiles. In agreement with prior work we find that for planets with K the transition between water or methane dominated spectra occurs at C/O ∼ 0.7, instead of ∼1, because condensation preferentially removes oxygen.
ABSTRACT The composition of a planet's atmosphere is determined by its formation, evolution, and present-day insolation. A planet's spectrum therefore may hold clues on its origins. We present a ..."chain" of models, linking the formation of a planet to its observable present-day spectrum. The chain links include (1) the planet's formation and migration, (2) its long-term thermodynamic evolution, (3) a variety of disk chemistry models, (4) a non-gray atmospheric model, and (5) a radiometric model to obtain simulated spectroscopic observations with James Webb Space Telescope and ARIEL. In our standard chemistry model the inner disk is depleted in refractory carbon as in the Solar System and in white dwarfs polluted by extrasolar planetesimals. Our main findings are: (1) envelope enrichment by planetesimal impacts during formation dominates the final planetary atmospheric composition of hot Jupiters. We investigate two, under this finding, prototypical formation pathways: a formation inside or outside the water iceline, called "dry" and "wet" planets, respectively. (2) Both the "dry" and "wet" planets are oxygen-rich (C/O < 1) due to the oxygen-rich nature of the solid building blocks. The "dry" planet's C/O ratio is <0.2 for standard carbon depletion, while the "wet" planet has typical C/O values between 0.1 and 0.5 depending mainly on the clathrate formation efficiency. Only non-standard disk chemistries without carbon depletion lead to carbon-rich C/O ratios >1 for the "dry" planet. (3) While we consistently find C/O ratios <1, they still vary significantly. To link a formation history to a specific C/O, a better understanding of the disk chemistry is thus needed.
We present ALMA Cycle 2 observations at 0 5 resolution of TW Hya of CS emission. The radial profile of the integrated line emission displays oscillatory features outward of 1 5 ( au). A dip-like ...feature at 1 6 is coincident in location, depth, and width with features observed in dust scattered light at near-infrared wavelengths. Using a thermochemical model indicative of TW Hya, gas-grain chemical modeling, and non-LTE radiative transfer, we demonstrate that such a feature can be reproduced with a surface density depression, consistent with the modeling performed for scattered-light observations of TW Hya. We further demonstrate that a gap in the dust distribution and dust opacity only cannot reproduce the observed CS feature. The outer enhancement at 3 1 is identified as a region of intensified desorption due to enhanced penetration of the interstellar far-UV radiation at the exponential edge of the disk surface density, which intensifies the photochemical processing of gas and ices.
We present scattered light images of the TW Hya disk performed with the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument in Polarimetric Differential Imaging mode at 0.63, 0.79, 1.24, ...and 1.62 m. We also present H2/H3-band angular differential imaging (ADI) observations. Three distinct radial depressions in the polarized intensity distribution are seen, around 85, 21, and 6 au.21 The overall intensity distribution has a high degree of azimuthal symmetry; the disk is somewhat brighter than average toward the south and darker toward the north-west. The ADI observations yielded no signifiant detection of point sources in the disk. Our observations have a linear spatial resolution of 1-2 au, similar to that of recent ALMA dust continuum observations. The sub-micron-sized dust grains that dominate the light scattering in the disk surface are strongly coupled to the gas. We created a radiative transfer disk model with self-consistent temperature and vertical structure iteration and including grain size-dependent dust settling. This method may provide independent constraints on the gas distribution at higher spatial resolution than is feasible with ALMA gas line observations. We find that the gas surface density in the "gaps" is reduced by 50% to 80% relative to an unperturbed model. Should embedded planets be responsible for carving the gaps then their masses are at most a few 10 . The observed gaps are wider, with shallower flanks, than expected for planet-disk interaction with such low-mass planets. If forming planetary bodies have undergone collapse and are in the "detached phase," then they may be directly observable with future facilities such as the Mid-Infrared E-ELT Imager and Spectrograph at the E-ELT.
Prescription opioid use has increased steadily in many Western countries over the past two decades, most notably in the US, Canada, and most European countries, including the Netherlands. Especially ...the increasing use of prescription opioids for chronic non-cancer pain has raised concerns. Most opioids in the Netherlands are prescribed in general practices. However, little is known about variation in opioid prescribing between general practices. To better understand this, we investigated practice variation in opioid prescribing for non-cancer pain between Dutch general practices.
Data from 2017-2019 of approximately 10% of all Dutch general practices was used. Each year included approximately 1000000 patients distributed over approximately 380 practices. The primary outcome was the proportion of patients with chronic (>90 days) high-dose (≥90 oral morphine equivalents) opioid prescriptions. The secondary outcome was the proportion of patients with chronic (<90 oral morphine equivalents) opioid prescriptions. Practice variation was expressed as the ratio of the 95th/5th percentiles and the ratio of mean top 10/bottom 10. Funnel plots were used to identify outliers. Potential factors associated with unwarranted variation were investigated by comparing outliers on practice size, patient neighbourhood socioeconomic status, and urbanicity.
Results were similar across all years. The magnitude of variation for chronic high-dose opioid prescriptions in 2019 was 7.51-fold (95%/5% ratio), and 15.1-fold (top 10/bottom 10 ratio). The percentage of outliers in the funnel plots varied between 13.8% and 21.7%. Practices with high chronic high-dose opioid prescription proportions were larger, and had more patients from lower income and densely populated areas.
There might be unwarranted practice variation in chronic high-dose opioid prescriptions in primary care, pointing at possible inappropriate use of opioids. This appears to be related to socioeconomic status, urbanicity, and practice size. Further investigation of the factors driving practice variation can provide target points for quality improvement and reduce inappropriate care and unwarranted variation.
Observing transiting planets with JWST Molliere, P; van Boekel, R; Bouwman, J ...
Astronomy and astrophysics (Berlin),
4/2017, Letnik:
600
Journal Article
Recenzirano
Context. The James Webb Space Telescope will enable astronomers to obtain exoplanet spectra of unprecedented precision. The MIRI instrument especially may shed light on the nature of the cloud ...particles obscuring planetary transmission spectra in the optical and near-infrared. Aims. We provide self-consistent atmospheric models and synthetic JWST observations for prime exoplanet targets in order to identify spectral regions of interest and estimate the number of transits needed to distinguish between model setups. Methods. We select targets that span a wide range of planetary temperatures and surface gravities, ranging from super-Earths to giant planets, that have a high expected signal-to-noise ratio. For all targets, we vary the enrichment, C/O ratio, presence of optical absorbers (TiO/VO), and cloud treatment. We calculate atmospheric structures, emission, and transmission spectra for all targets and use a radiometric model to obtain simulated observations. Further, we analyze JWST's ability to distinguish between various scenarios. Results. We find that in very cloudy planets, such as GJ 1214b, less than ten transits with NIRSpec may be enough to reveal molecular features. Furthermore, the presence of small silicate grains in atmospheres of hot Jupiters may be detectable with a single JWST MIRI transit. For a more detailed characterization of such particles less than ten transits are necessary. Finally, we find that some of the hottest hot Jupiters are well fitted by models which neglect the redistribution of the insolation and harbor inversions, and that 1-4 eclipse measurements with NIRSpec are needed to distinguish between the inversion models. Conclusions. Wet thus demonstrate the capabilities of JWST for solving some of the most intriguing puzzles in current exoplanet atmospheric research. Further, by publishing all models calculated for this study we enable the community to carry out similar studies, as well as retrieval analyses for all planets included in our target list.
Abstract
HD 169142 is an excellent target for investigating signs of planet–disk interaction due to previous evidence of gap structures. We perform
J
-band (∼1.2
μ
m) polarized intensity imaging of ...HD 169142 with VLT/SPHERE. We observe polarized scattered light down to 0.″16 (∼19 au) and find an inner gap with a significantly reduced scattered-light flux. We confirm the previously detected double-ring structure peaking at 0.″18 (∼21 au) and 0.″56 (∼66 au) and marginally detect a faint third gap at 0.″70–0.″73 (∼82–85 au). We explore dust evolution models in a disk perturbed by two giant planets, as well as models with a parameterized dust size distribution. The dust evolution model is able to reproduce the ring locations and gap widths in polarized intensity but fails to reproduce their depths. However, it gives a good match with the ALMA dust continuum image at 1.3 mm. Models with a parameterized dust size distribution better reproduce the gap depth in scattered light, suggesting that dust filtration at the outer edges of the gaps is less effective. The pileup of millimeter grains in a dust trap and the continuous distribution of small grains throughout the gap likely require more efficient dust fragmentation and dust diffusion in the dust trap. Alternatively, turbulence or charging effects might lead to a reservoir of small grains at the surface layer that is not affected by the dust growth and fragmentation cycle dominating the dense disk midplane. The exploration of models shows that extracting planet properties such as mass from observed gap profiles is highly degenerate.
Abstract
EX Lup is the prototype of a class of pre-main-sequence eruptive stars defined by their repetitive outbursts lasting several months. In 2008 January–September EX Lup underwent its ...historically largest outburst, brightening by about 4 mag in visual light. In previous studies we discovered ongoing silicate crystal formation in the inner disk during the outburst, but also noticed that the measured crystallinity fraction started decreasing after the source returned to the quiescent phase. Here we present new observations of the 10
μ
m silicate feature, obtained with the MIDI and VISIR instruments at Paranal Observatory. The observations demonstrate that within five years practically all crystalline forsterite disappeared from the surface of the inner disk. We reconstruct this process by presenting a series of parametric axisymmetric radiative transfer models of an expanding dust cloud that transports the crystals from the terrestrial zone to outer disk regions where comets are supposed to form. It is possible the early Sun also experienced similar flare-ups, and the forming planetesimals might have incorporated crystalline silicate material produced by such outbursts. Finally, we discuss how far the location of the dust cloud could be constrained by future
James Webb Space Telescope
observations.
Context. Protoplanetary disks show large diversity regarding their morphology and dust composition. With mid-infrared interferometry the thermal emission of disks can be spatially resolved, and the ...distribution and properties of the dust within can be studied. Aims. Our aim is to perform a statistical analysis on a large sample of 82 disks around low- and intermediate-mass young stars, based on mid-infrared interferometric observations. We intend to study the distribution of disk sizes, variability, and the silicate dust mineralogy. Methods. Archival mid-infrared interferometric data from the MIDI instrument on the Very Large Telescope Interferometer are homogeneously reduced and calibrated. Geometric disk models are used to fit the observations to get spatial information about the disks. An automatic spectral decomposition pipeline is applied to analyze the shape of the silicate feature. Results. We present the resulting data products in the form of an atlas, containing N band correlated and total spectra, visibilities, and differential phases. The majority of our data can be well fitted with a continuous disk model, except for a few objects, where a gapped model gives a better match. From the mid-infrared size–luminosity relation we find that disks around T Tauri stars are generally colder and more extended with respect to the stellar luminosity than disks around Herbig Ae stars. We find that in the innermost part of the disks (r ≲ 1 au) the silicate feature is generally weaker than in the outer parts, suggesting that in the inner parts the dust is substantially more processed. We analyze stellar multiplicity and find that in two systems (AB Aur and HD 72106) data suggest a new companion or asymmetric inner disk structure. We make predictions for the observability of our objects with the upcoming Multi-AperTure mid-Infrared SpectroScopic Experiment (MATISSE) instrument, supporting the practical preparations of future MATISSE observations of T Tauri stars.
Aims. WASP-43b is the closest-orbiting hot Jupiter, and it has high bulk density. It causes deep eclipse depths in the system’s light curve in both transit and occultation that is attributed to the ...cool temperature and small radius of its host star. We aim to secure a broad-band transmission spectrum and to detect its near-infrared thermal emission in order to characterize its atmosphere. Methods. We observed one transit and one occultation event simultaneously in the g′, r′, i′, z′, J, H, K bands using the GROND instrument on the MPG/ESO 2.2-m telescope, where the telescope was heavily defocused in staring mode. After modeling the light curves, we derived wavelength-dependent transit depths and flux ratios and compared them to atmospheric models. Results. From the transit event, we have independently derived WASP-43’s system parameters with high precision and improved the period to be 0.81347437(13) days based on all the available timings. No significant variation in transit depths is detected, with the largest deviations coming from the i′-, H-, and K-bands. Given the observational uncertainties, the broad-band transmission spectrum can be explained by either (i) a flat featureless straight line that indicates thick clouds; (ii) synthetic spectra with absorption signatures of atomic Na/K, or molecular TiO/VO that in turn indicate cloud-free atmosphere; or (iii) a Rayleigh scattering profile that indicates high-altitude hazes. From the occultation event, we detected planetary dayside thermal emission in the K-band with a flux ratio of 0.197 ± 0.042%, which confirms previous detections obtained in the 2.09 μm narrow band and KS-band. The K-band brightness temperature 1878+108-116 K favors an atmosphere with poor day- to nightside heat redistribution. We also have a marginal detection in the i′-band (0.037+0.023-0.021%), corresponding to TB = 2225+139-225 K, which is either a false positive, a signature of non-blackbody radiation at this wavelength, or an indication of reflective hazes at high altitude.
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