The ARCiS framework for exoplanet atmospheres

view Abstract Citations (44) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Warm Neutral Halos around Molecular Clouds. VI. Physical and Chemical Modeling Andersson, B. -G. ; Wannier, P. G. Abstract A combined physical and chemical modeling of the halos around molecular clouds is presented, with special emphasis on the H-to-H2 transition. On the basis of H I 21 cm observations, it is shown that the halos are extended. A physical model is employed in conjunction with a chemistry code to provide a self-consistent description of the gas. The radiative transfer code provides a check with H I, CO, and OH observations. It is concluded that the warm neutral halos are not gravitationally bound to the underlying molecular clouds and are isobaric. It is inferred from the observed extent of the H I envelopes and the large observed abundance of OH in them that the generally accepted rate for H2 information on grains is too large by a factor of two to three. Publication: The Astrophysical Journal Pub Date: January 1993 DOI: 10.1086/172161 Bibcode: 1993ApJ...402..585A Keywords: Astronomical Models; Astrophysics; Galactic Halos; Interstellar Chemistry; Molecular Clouds; Computational Astrophysics; Hydrogen; Interstellar Gas; Polytropic Processes; Radiative Transfer; Astrophysics; ISM: CLOUDS; ISM: MOLECULES full text sources ADS | data products SIMBAD (11) Related Materials (5) Part 1: 1983ApJ...268..727W Part 2: 1991ApJS...75..987W Part 3: 1991ApJ...366..464A Part 4: 1992A&A...260..355A Part 5: 1993ApJ...407..163W

Integration of an improved transformer with physical models for the spatiotemporal simulation of urban flooding depths

This paper describes the use of a swept-charge device (SCD) silicon X-ray detector in a laboratory based X-ray fluorescence (XRF) facility for calculating elemental abundance ratios from planetary analogue powder samples. The facility was developed to support the Chandrayaan-1 X-ray Spectrometer (C1XS) detector development and calibration activities prior to the flight of the instrument onboard the Indian Space Research Organisation (ISRO) Chandrayaan-1 mission to the Moon in 2008. The test facility has subsequently been used to carry out XRF analysis of homogenous samples made from mixtures of MgO, Al₂O₃ and SiO₂ powders, all of grain size <44 μm, across a range of mixture ratios and at a high level of X-ray flux data in order to develop an algorithm which will allow the calculation of elemental abundance ratios. This paper also presents an analysis of XRF data collected from lunar regolith simulant JSC-1A and an Etna Basalt powder sample to enable calibration of various model parameters. The operation of the SCD, the XRF test facility, the sample preparation methodology and the process of obtaining elemental abundance ratios from planetary analogue samples using the test facility are discussed in this paper.

Optical transmission and emission spectra in the region of the plasma frequencyωp were measured on thin potassium films evaporated on sapphire substrates of various temperatures. For the foils condensed at a temperatures of the substrateTa −165 °C transmission spectra were observed which transmission minima are displaced to frequencies less thanωp. Plasma resonance emission was observed from these foils. Comparison with calculated emission spectra gives an approximate agreement.

The United Nations <i>Intergovernmental Panel on Climate Change</i> (IPCC) agrees human CO<SUB>2</SUB> is only 5 percent and natural CO<SUB>2</SUB> is 95 percent of the CO<SUB>2</SUB> inflow into the atmosphere. The ratio of human to natural CO<SUB>2</SUB> in the atmosphere must equal the ratio of the inflows. Yet IPCC claims human CO<SUB>2</SUB> has caused all the rise in atmospheric CO<SUB>2</SUB> above 280 ppm, which is now 130 ppm or 32 percent of today's atmospheric CO<SUB>2</SUB>. To cause the human 5 percent to become 32 percent in the atmosphere, the IPCC model treats human and natural CO<SUB>2</SUB> differently, which is impossible because the molecules are identical. IPCC's Bern model artificially traps human CO<SUB>2</SUB> in the atmosphere while it lets natural CO<SUB>2</SUB> flow freely out of the atmosphere. By contrast, a simple Physics Model treats all CO<SUB>2</SUB> molecules the same, as it should, and shows how CO<SUB>2</SUB> flows through the atmosphere and produces a balance level where outflow equals inflow. Thereafter, if inflow is constant, level remains constant. The Physics Model has only one hypothesis, that outflow is proportional to level. The Physics Model exactly replicates the 14C data from 1970 to 2014 with only two physical parameters: balance level and e-time. The 14C data trace how CO<SUB>2</SUB> flows out of the atmosphere. The Physics Model shows the 14 CO<SUB>2</SUB> e-time is a constant 16.5 years. Other data show e-time for 12CO<SUB>2</SUB> is about 4 to 5 years. IPCC claims human CO<SUB>2</SUB> reduces ocean buffer capacity. But that would increase e-time. The constant e-time proves IPCC's claim is false. IPCC argues that the human-caused reduction of 14C and 13C in the atmosphere prove human CO<SUB>2</SUB> causes all the increase in atmospheric CO<SUB>2</SUB>. However, numbers show these isotope data support the Physics Model and reject the IPCC model. The Physics Model shows how inflows of human and natural CO<SUB>2</SUB> into the atmosphere set balance levels proportional to their inflows. Each balance level remains constant if its inflow remains constant. Continued constant CO<SUB>2</SUB> emissions do not add more CO<SUB>2</SUB> to the atmosphere. No CO<SUB>2</SUB> accumulates in the atmosphere. Present human CO<SUB>2</SUB> inflow produces a balance level of about 18 ppm. Present natural CO<SUB>2</SUB> inflow produces a balance level of about 392 ppm. Human CO<SUB>2</SUB> is insignificant to the increase of CO<SUB>2</SUB> in the atmosphere. Increased natural CO<SUB>2</SUB> inflow has increased the level of CO<SUB>2</SUB> in the atmosphere.

We present the open-source python Radiative-transfer in a Bayesian framework (pyrat bay) framework for exoplanet atmospheric modelling, spectral synthesis, and Bayesian retrieval. The modular design of the code allows the users to generate atmospheric 1D parametric models of the temperature, abundances (in thermochemical equilibrium or constant-with-altitude), and altitude profiles (in hydrostatic equilibrium); sample ExoMol and HITRAN line-by-line cross-sections with custom resolving power and line-wing cutoff values; compute emission or transmission spectra considering cross-sections from molecular line transitions, collision-induced absorption, Rayleigh scattering, grey clouds, and alkali resonance lines; and perform Markov chain Monte Carlo atmospheric retrievals for a given transit or eclipse data set. We benchmarked the pyrat bay framework by reproducing line-by-line sampling of ExoMol cross-sections, producing transmission and emission spectra consistent with petitradtrans models, accurately retrieving the atmospheric properties of simulated transmission and emission observations generated with taurex models, and closely reproducing aura retrieval analyses of the space-based transmission spectrum of HD 209458 b. Finally, we present a retrieval analysis of a population of transiting exoplanets, focusing on those observed in transmission with the HST WFC3/G141 grism. We found that this instrument alone can confidently identify when a data set shows H2O-absorption features; however, it cannot distinguish whether a muted H2O feature is caused by clouds, high atmospheric metallicity, or low H2O abundance. Our results are consistent with previous retrieval analyses. The pyrat bay code is available at PyPI (pip install pyratbay) and conda. The code is heavily documented (https://pyratbay.readthedocs.io) and tested to provide maximum accessibility to the community and long-term development stability.

The Petroleum Recovery Institute has operated a scaled steamflood physical model since 1975. The objective of this work was to define and to evaluate the capabilities and limitations of Intercomp Ltd. "s numerical steamflood simulator and the Petroleum Recovery Institute"s physical model. Three different types of laboratory experiments were selected for numerical history matching-waterflood, hot-waterflood and steamflood. The objective was to match oil, water and steam production as well as the energy balance and temperature profiles, using a single set of physical and petrophysical parameters. In addition, sensitivity studies were computed for three different grid systems, specifically a coarse cross-sectional grid (8xlx4), a fine cross-sectional grid (l6x1x8) and a three-dimensional grid (9x5x4). Excellent matching was obtained for the fluids production and for the energy balances. However, some, difficulties were encountered during attempts to match some of the temperature profiles, especially those associated with the flow of hot water along the bottom of the reservoir. As a result of the simulations, new measurements of thermal conductivity between the model and the underlying concrete bed were performed. A more complete interpretation of the physical model was obtained. The results indicate that physical model experiments offer useful data which can enable testing and calibration of numerical models, while the latter can help in obtaining a more precise description of the former. Therefore, the physical and numerical models should be used in a mutually complementary manner. INTRODUCTION Numerical simulators for steam injection oil recovery processes are being used frequently by reservoir engineers especially in the three areas of history matching(1–6), sensitivity studies(6–7) and field design and prediction(8–10). However, numerical simulators are complicated reservoir engineering tools and one has to realize their capabilities and limitations in order to use them properly. The successful design of any enhanced oil recovery process requires that one be equipped with a reliable set of reservoir data which includes geological, physical and petrophysical properties. History matching with a numerical simulator is often used to verify the parameters that have been obtained from laboratory measurements, well logs or by correlation. Typically, it is difficult to obtain a unique result from history-matching studies of field-derived performance data because a large number of parameters, involved in the calculations, must be either estimated or determined indirectly. History matching of laboratory steam flood experiments provides a better insight into the numerical simulator"s capabilities, because one has better control over most of the parameters defining the system. An additional advantage of history matching laboratory data is that more experimental data, usually of higher quality, are available to enable comparison with numerical results. The PRI Research Division has been studying steamflood oil recovery processes using a one-twelfth of an inverted seven spot, partially scaled physical model(ll.12.l3) since 1975. Some sixty experimental runs have been made to date for various steam injection rates, steam qualities, initial water saturations and oil characteristics. Three of these runs were chosen for this study – a cold-waterflood, a hot-waterf1ood and a steamflood. (Figure in full paper) Physical Model Apparatus The experimental apparatus is shown schematically in Figure 1.

We present a publicly available library of model atmospheres with radiative-convective equilibrium pressure–temperature (P-T) profiles fully consistent with equilibrium chemical abundances, and the corresponding emission and transmission spectrum with R ∼ 5000 at 0.2 µm decreasing to R ∼ 35 at 30 µm, for 89 hot Jupiter exoplanets, for four recirculation factors, six metallicities, and six C/O ratios. We find the choice of condensation process (local/rainout) alters the P-T profile and thereby the spectrum substantially, potentially detectable by James Webb Space Telescope. We find H− opacity can contribute to form a strong temperature inversion in ultrahot Jupiters for C/O ratios ≥ 1 and can make transmission spectra features flat in the optical, alongside altering the entire emission spectra. We highlight how adopting different model choices such as thermal ionization, opacities, line-wing profiles and the methodology of varying the C/O ratio, effects the P-T structure, and the spectrum. We show the role of Fe opacity to form primary/secondary inversion in the atmosphere. We use WASP-17b and WASP-121b as test cases to demonstrate the effect of grid parameters across their full range, while highlighting some important findings, concerning the overall atmospheric structure, chemical transition regimes, and their observables. Finally, we apply this library to the current transmission and emission spectra observations of WASP-121b, which shows H2O and tentative evidence for VO at the limb, and H2O emission feature indicative of inversion on the dayside, with very low energy redistribution, thereby demonstrating the applicability of library for planning and interpreting observations of transmission and emission spectrum.

Clouds play a crucial role in shaping the atmospheres of exoplanets, influencing their albedo, heat distribution, and spectrum. While most past studies focused on hot and ultra-hot planets, JWST now allows an in-depth characterisation of warm objects, where the interactions between cloud, circulation, and radiative transfer are yet to be studied in detail.In this study, we integrate physically motivated, radiatively active, tracer-based clouds in General Circulation Models (GCM) (ADAM, former SPARC) to analyze the atmosphere of WASP-80b, a warm Jupiter orbiting an M-dwarf star. This planet, with an equilibrium temperature of ~800 K, is analogous to warm sub-Neptunes, making it a crucial target for understanding sub-Neptune atmospheres. We take advantage of the high-quality dataset from JWST obtained through the MANATEE GTO collaboration, allowing us to jointly interpret both high-quality panchromatic emission and absorption spectra ranging from 2.5 to 12 microns with the outputs from a GCM. We provide an in-depth characterisation of the planet’s atmospheric dynamics and possible cloud distribution. By comparing our models to the data, we constrain the likelihood of different expected cloud species, such as silicate, sulfide, or chloride clouds, on this planet. Figure 1 shows the zonal mean averaged over latitudes and longitudes of the mass mixing ratio distribution of the cloud particles in the atmosphere. The region around 0° latitude (Row: 1, 3, 5) is the region around the equator averaged over all longitudes. The region around 0° longitude (Row: 2, 4, 6) is the dayside region averaged over all latitudes. Figure 2: Emission Spectrum from ADAM-GCM plotted over the JWST observations from the MANATEE-GTO program, with the colored regions indicating the instruments. Figure 3: Transmission Spectrum from ADAM-GCM plotted over the JWST observations from the MANATEE-GTO program, with the colored regions indicating the instruments.While both emission and transmission spectra are very well fitted by cloudless GCMs (Figures 2 and 3), the data also appear compatible with small KCl cloud particles, but Na2S condensates can be ruled out due to the strength of their radiative feedback.Figure 4 shows the dayside average temperature-pressure profiles (Row 1) and the corresponding emission (Row 2) and transmission spectra (Row 3) for different clouds and particle sizes.This showcases the unique insights that can be obtained from global modeling of exoplanet atmospheres. Our results point towards a homogeneous atmosphere with minimal temperature contrast between the day and night sides, suggesting efficient heat redistribution. Additionally, the relatively low abundance of CH4 points to active atmospheric chemistry and the possibility of a high internal heat flux, which can lead to quenching of CH4 in the atmosphere.This work not only provides a comprehensive framework for interpreting JWST observations but also enhances the capabilities of GCMs in characterizing the global atmospheres of exoplanets in the JWST era.

Inverse uncertainty quantification of trace physical model parameters using BFBT benchmark data

The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are expected to be distinct from those of self-luminous objects with similar effective temperatures because hot Jupiters are primarily heated from above by their host stars rather than internally from the release of energy from their formation. Theoretical models predict a continuum of dayside spectra for hot Jupiters as a function of irradiation level, with the coolest planets having absorption features in their spectra, intermediate-temperature planets having emission features due to thermal inversions, and the hottest planets having blackbody-like spectra due to molecular dissociation and continuum opacity from the H- ion. Absorption and emission features have been detected in the spectra of a number of individual hot Jupiters, and population-level trends have been observed in photometric measurements. However, there has been no unified, population-level study of the thermal emission spectra of hot Jupiters such as has been done for cooler brown dwarfs and transmission spectra of hot Jupiters. Here we show that hot Jupiter secondary eclipse spectra centered around a water absorption band at 1.4 microns follow a common trend in water feature strength with temperature. The observed trend is broadly consistent with model predictions for how the thermal structures of solar-composition planets vary with irradiation level. Nevertheless, the ensemble of planets exhibits some degree of scatter around the mean trend for solar composition planets. The spread can be accounted for if the planets have modest variations in metallicity and/or elemental abundance ratios, which is expected from planet formation models. (abridged abstract)

Context. Of the presently known ≈3900 exoplanets, sparse spectral observations are available for ≈100. Ultra-hot Jupiters have recently attracted interest from observers and theoreticians alike, as they provide observationally accessible test cases. Confronting detailed theoretical models with observations is of preeminent importance in preparation for upcoming space-based telescopes. Aims. We aim to study cloud formation on the ultra-hot Jupiter HAT-P-7b, the resulting composition of the local gas phase, and how their global changes affect wavelength-dependent observations utilised to derive fundamental properties of the planet. Methods. We apply a hierarchical modelling approach as a virtual laboratory to study cloud formation and gas-phase chemistry. We utilise 97 vertical 1D profiles of a 3D GCM for HAT-P-7b to evaluate our kinetic cloud formation model consistently with the local equilibrium gas-phase composition. We use maps and slice views to provide a global understanding of the cloud and gas chemistry. Results. The day/night temperature difference on HAT-P-7b (ΔT ≈ 2500 K) causes clouds to form on the nightside (dominated by H2/He) while the dayside (dominated by H/He) retains cloud-free equatorial regions. The cloud particles vary in composition and size throughout the vertical extension of the cloud, but also globally. TiO2[s]/Al2O3[s]/CaTiO3[s]-particles of cm-sized radii occur in the higher dayside-latitudes, resulting in a dayside dominated by gas-phase opacity. The opacity on the nightside, however, is dominated by 0.01…0.1μm particles made of a material mix dominated by silicates. The gas pressure at which the atmosphere becomes optically thick is ~10−4 bar in cloudy regions, and ~0.1 bar in cloud-free regions. Conclusions. HAT-P-7b features strong morning/evening terminator asymmetries, providing an example of patchy clouds and azimuthally-inhomogeneous chemistry. Variable terminator properties may be accessible by ingress/egress transmission photometry (e.g., CHEOPS and PLATO) or spectroscopy. The large temperature differences of ≈2500 K result in an increasing geometrical extension from the night- to the dayside. The H2O abundance at the terminator changes by &lt;1 dex with altitude and ≲0.3 dex (a factor of 2) across the terminator for a given pressure, indicating that H2O abundances derived from transmission spectra can be representative of the well-mixed metallicity at P ≳ 10 bar. We suggest the atmospheric C/O as an important tool to trace the presence and location of clouds in exoplanet atmospheres. The atmospheric C/O can be sub- and supersolar due to cloud formation. Phase curve variability of HAT-P-7b is unlikely to be caused by dayside clouds.

We have developed a physical model of the VLT 2nd generation instrument X-shooter. The parameters of this model, that describe the positions, orientations and other physical properties of the optical components in the spectrograph, are continually updated by an optimisation process that ensures the best possible fit to arc lamp line positions in calibration exposures. Besides its use in driving the wavelength calibration in the data reduction pipeline, the physical model provides us with an insight into physical changes in the optical components and the possibility to correlate these with changing instrument orientation. By utilising a continually growing database of automatic flexure compensation exposures that cover a wide range of instrument orientations, we are able to investigate flexure in terms of physical model parameters.

As a galaxy evolves, its chemical composition changes and the abundance ratios of different elements are powerful probes of the underlying evolutionary processes. Phosphorous is an element whose evolution has remained quite elusive until now, because it is difficult to detect in cool stars. The infrared weak P I lines of the multiplet 1, at 1050-1082 nm, are the most reliable indicators of the presence of phosphorus. The availability of CRIRES at VLT has permitted access to this wavelength range in stellar spectra.We attempt to measure the phosphorus abundance of twenty cool stars in the Galactic disk. The spectra are analysed with one-dimensional model-atmospheres computed in Local Thermodynamic Equilibrium (LTE). The line formation computations are performed assuming LTE. The ratio of phosphorus to iron behaves similarly to sulphur, increasing towards lower metallicity stars. Its ratio with respect to sulphur is roughly constant and slightly larger than solar, [P/S]=0.10+- 0.10. We succeed in taking an important step towards the understanding of the chemical evolution of phosphorus in the Galaxy. However, the observed rise in the P/Fe abundance ratio is steeper than predicted by Galactic chemical evolution model model developed by Kobayashi and collaborators. Phosphorus appears to evolve differently from the light odd-Z elements sodium and aluminium. The constant value of [P/S] with metallicity implies that P production is insensitive to the neutron excess, thus processes other than neutron captures operate. We suggest that proton captures on 30Si and alpha captures on $27Al are possibilities to investigate. We see no clear distinction between our results for stars with planets and stars without any detected planet.

We have analyzed observations with the Chandra X-ray Observatory of the diffuse emission by hot gas in 7 dwarf starburst galaxies, 6 edge-on starburst galaxies, and 9 Ultra Luminous Infrared Galaxies. These systems cover ranges of \~ 10^4 in X-ray luminosity and several thousand in star formation rate and K-band luminosity (a proxy for stellar mass). Despite this range in fundamental parameters, we find that the properties of the diffuse X-ray emission are very similar in all three classes of starburst galaxies. The spectrum of the diffuse emission is well fit by thermal emission from gas with kT ~ 0.25 to 0.8 keV and with several-times-solar abundance ratios of alpha elements to Fe. The ratio of the thermal X-ray to far-infrared luminosity is roughly constant, as is the characteristic surface brightness of the diffuse X-ray emission. The size of the diffuse X-ray source increases systematically with both far-infrared and K-Band luminosity. All three classes show strong morphological relationships between the regions of hot gas probed by the diffuse X-ray emission and the warm gas probed by optical line emission. These findings suggest that the same physical mechanism is producing the diffuse X-ray emission in the three types of starbursts, and are consistent with that mechanism being shocks driven by a galactic superwind'' powered by the kinetic energy collectively supplied by stellar winds and supernovae in the starburst.