A5009504510- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Advanced Combustion Engine Technologies
- Scientific Research and Discoveries
- Planetary Science and Exploration
- Calibration and Measurement Techniques
- Atmospheric chemistry and aerosols
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- High-pressure geophysics and materials
- Energy Load and Power Forecasting
- SAS software applications and methods
- Hydrocarbon exploration and reservoir analysis
- Astronomical Observations and Instrumentation
- Geology and Paleoclimatology Research
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Advanced Chemical Physics Studies
Max Planck Institute for Astronomy
2023-2025
University of Exeter
2021-2024
University of Chicago
2024
University of Virginia
2013-2023
University of Florida
2017
University of Illinois Urbana-Champaign
2010
We present the first exoplanet phase curve measurement made with JWST NIRSpec instrument, highlighting exceptional stability of this newly-commissioned observatory for climate studies. The target, WASP-121b, is an ultrahot Jupiter orbital period 30.6 hr. analyze two broadband light curves generated NRS1 and NRS2 detectors, covering wavelength ranges 2.70-3.72 micron 3.82-5.15 micron, respectively. Both exhibit minimal systematics, approximately linear drifts in baseline flux level 30 ppm/hr...
With sizable volatile envelopes but smaller radii than the solar system ice giants, sub-Neptunes have been revealed as one of most common types planet in galaxy. While spectroscopic characterization larger (2.5-4R$_\oplus$) has hydrogen-dominated atmospheres, (1.6--2.5R$_\oplus$) could either host thin, rapidly evaporating hydrogen-rich atmospheres or be stable metal-rich "water worlds" with high mean molecular weight and a fundamentally different formation evolutionary history. Here, we...
Even though sub-Neptunes likely represent the most common outcome of planet formation, their natures remain poorly understood. In particular, planets near 1.5-2.5$\,R_\oplus$ often have bulk densities that can be explained equally well with widely different compositions and interior structures, resulting in grossly divergent implications for formation. Here, we present full 0.6-5.2$\,\mu \mathrm{m}$ JWST NIRISS/SOSS+NIRSpec/G395H transmission spectrum 2.2$\,R_\oplus$ TOI-270d...
This paper presents a detailed hydrostatic model of the upper atmosphere HD 189733b, with goal constraining its temperature, particle densities, and radiation field over pressure range $10^{-4}-10\, \mu \rm bar$, where observed H$\alpha$ transmission spectrum is produced. The atomic hydrogen level population computed including both collisional radiative transition rates. Ly$\alpha$ resonant scattering using Monte-Carlo simulation. spectra are in broad agreement data. Excitation H(2$\ell$)...
We investigate giant molecular cloud (GMCs) collisions and their ability to induce gravitational instability thus star formation. This mechanism may be a major driver of formation activity in galactic disks. carry out series three dimensional, magnetohydrodynamics (MHD), adaptive mesh refinement (AMR) simulations study how trigger dense filaments clumps. Heating cooling functions are implemented based on photo-dissociation region (PDR) models that span the atomic transition can return...
Transport-induced quenching, i.e., the homogenisation of chemical abundances by atmospheric advection, is thought to occur in atmospheres hot gas giant exoplanets. While some numerical modelling this process exists, three-dimensional nature transport-induced chemistry underexplored. Here we present results 3D cloud- and haze-free simulations HAT-P-11b, HD 189733b, 209458b, WASP-17b including coupled hydrodynamics, radiative transfer chemistry. Our were performed with two schemes: a kinetics...
Abstract Radiative transfer (RT) is a key component for investigating atmospheres of planetary bodies. With the 3D nature exoplanet being important in giving rise to their observable properties, accurate and fast methods are required be developed meet future multidimensional temporal data sets. We develop an open-source GPU RT code, gCMCRT, Monte Carlo forward model general use atmosphere problems. aim automate post-processing pipeline, starting from direct global circulation (GCM) output...
It has been suggested that hot stellar wind gas in a bow shock around an exoplanet is sufficiently opaque to absorb photons and give rise observable transit depth at optical UV wavelengths. In the first part of this paper, we use cloudy plasma simulation code model absorption from X-ray radio wavelengths by 1D slabs coronal equilibrium with varying densities (104–108 cm−3) temperatures (2000–106 K) illuminated solar spectrum. For (106 even orders magnitude larger than expected for compressed...
Gas giant exoplanets orbiting at close distances to the parent star are subjected large radiation and stellar wind fluxes. In this paper, hydrodynamic simulations of planetary upper atmosphere its interaction with carried out understand possible flow regimes how they affect Lyman-alpha transmission spectrum. Following Tremblin Chiang, charge exchange reactions included explore role energetic atoms as compared thermal particles. order tail leading edge gas, were under axisymmetry,...
We present results of 3D hydrodynamical simulations HD209458b including a coupled, radiatively-active cloud model ({\sc EddySed}). investigate the role mixing by replacing default convective treatment used in previous works with more physically relevant ($K_{zz}$) based on global circulation. find that uncertainty efficiency sedimentation through factor $f_\mathrm{sed}$ plays larger shaping thickness and its radiative feedback local gas temperatures -- e.g. hot spot shift day-to-night side...
ABSTRACT Transport-induced quenching in hot Jupiter atmospheres is a process that determines the boundary between part of atmosphere at chemical equilibrium and thermochemical (but not photothermochemical) disequilibrium. The location this boundary, quench level, depends on interplay dynamical time-scales atmosphere, with occurring when these are equal. We explore sensitivity level position to an increase planet’s atmospheric metallicity using aerosol-free 3D general circulation model...
Abstract We present a transmission spectrum of the misaligned hot Jupiter WASP-15b from 2.8–5.2 microns observed with JWST’s NIRSpec/G395H grating. Our high signal to noise data, which has negligible red noise, reveals significant absorption by H2O (4.2σ) and CO2 (8.9σ). From independent data reduction atmospheric retrieval approaches, we infer that WASP-15b’s metallicity is super-solar (≳ 15 × solar) its C/O consistent solar, together imply planetesimal accretion. GCM simulations for...
Magnetic fields are expected to influence the atmospheric dynamics of hot and ultra-hot Jupiters; however, due disparate conditions between day night sides, modelling their impact can be difficult.  To make problem tractable, interactions with magnetic field often reduced inclusion a drag term.  In this talk,  I will demonstrate vertical meridional from background dipole on flows in Jupiter atmospheres show that limit over poles create relatively static dayside...
Abstract The formation and migration history of a planet is expected to be imprinted in its atmosphere, particular carbon-to-oxygen (C/O) ratio metallicity. BOWIE-ALIGN programme performing comparative study JWST spectra four aligned misaligned hot Jupiters, with the aim characterising their atmospheres corroborating link between observables history. In this work, we present 2.8 − 5.2 micron transmission spectrum TrES-4 b, Jupiter an orbit rotation axis F-type host star. Using free chemistry...
Recent observations of column densities in molecular clouds find lognormal distributions with power-law high-density tails. These results are often interpreted as indications that supersonic turbulence dominates the dynamics observed clouds. We calculate and present column-density three clouds, modelled very different techniques, none which is dominated by turbulence. The first star-forming cloud simulated using smoothed particle hydrodynamics; this case gravity, opposed only...
We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. further develop our three dimensional magnetized, turbulent, colliding GMC simulations by implementing formation sub-grid models. Two such models are explored: (1) "Density-Regulated," i.e., fixed efficiency per free-fall time above a set density threshold; (2) "Magnetically-Regulated," in regions that magnetically supercritical. Variations of parameters associated with these also explored....
ABSTRACT General circulation models are a useful tool in understanding the three dimensional structure of hot Jupiter and sub-Neptune atmospheres; however, validity results from these simulations requires an artificial dissipation required for numerical stability. In this paper, we investigate impact longitudinal filter vertical ‘sponge’ used Met Office’s unified model when simulating gaseous exoplanets. We demonstrate that excessive can result counter-rotating jets catastrophic failure to...
Absorption of stellar H\alpha\ by the upper atmosphere planet HD189733b has recently been detected Jensen et al. Motivated this observation, we have developed a model for atomic hydrogen in n=2 state and compared resulting line profile to observations. The is hydrostatic balance, as well thermal photoionization equilibrium. Collisional radiative transitions are included determination level population. We find that absorption dominated an optical depth \tau\ ~ 1 shell, composed metastable 2s...
ABSTRACT We investigate the impact of clouds on atmosphere GJ 1214b using radiatively coupled, phase-equilibrium cloud model EddySed coupled to Unified Model general circulation model. find that, consistent with previous investigations, high metallicity (100 × solar) and large vertical extents (a sedimentation factor fsed = 0.1) are required best match observations, although metallicities even higher than those investigated here may be improve agreement further. additionally that in our case...
We investigate collisions between giant molecular clouds (GMCs) as potential generators of their internal turbulence. Using magnetohydrodynamic (MHD) simulations self-gravitating, magnetized, turbulent, GMCs, we compare kinematic and dynamic properties dense gas structures formed when such collide compared to those that form in non-colliding self-gravity overwhelms decaying explore the nature turbulence these via distribution functions density, velocity dispersions, virial parameters,...
We investigate the formation of stars within giant molecular clouds (GMCs) evolving in environments different global magnetic field strength and large-scale dynamics. Building upon a series magnetohydrodynamic (MHD) simulations non-colliding colliding GMCs, we employ density- magnetically-regulated star sub-grid models which range from moderately magnetically supercritical to near critical. examine gas cluster morphologies, strengths relative orientations, pre-stellar core densities,...
Abstract With an increased focus on the observing and modeling of mini-Neptunes, there comes a need to better understand tools we use model their atmospheres. In this Paper, present protocol for Comparing Atmospheric Models Extrasolar Mini-Neptunes Building Envisioning Retrievals Transits, CAMEMBERT, project, intercomparison general circulation models (GCMs) used by exoplanetary science community simulate atmospheres mini-Neptunes. We two targets well studied both observationally...
ABSTRACT Compression in giant molecular cloud (GMC) collisions is a promising mechanism to trigger the formation of massive star clusters and OB associations. We simulate colliding non-colliding magnetized GMCs examine properties pre-stellar cores, selected from projected mass surface density maps, including after synthetic ALMA observations. then core properties, mass, size, density, velocity, velocity dispersion, temperature, magnetic field strength. After 4 Myr, ∼1000 cores have formed...
With observatories such as JWST, astronomers are now attempting to better understand the previously inscrutable atmospheres of mini-Neptunes, smaller and often cooler cousins better-studied hot Jupiters. General circulation models (GCMs) an essential part toolset used improve that understanding, from both perspective theoretical investigations in support observation. It is only recently, however, exoplanet community has begun benchmark study behaviour our GCMs through intercomparisons, a...