J. K. Barstow
A5056404243- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Nuclear Physics and Applications
- Atmospheric Ozone and Climate
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Spectroscopy and Laser Applications
- Nuclear physics research studies
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Advanced NMR Techniques and Applications
- Methane Hydrates and Related Phenomena
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Medical Imaging Techniques and Applications
- Space Exploration and Technology
- Solid-state spectroscopy and crystallography
- Superconducting Materials and Applications
- Spacecraft and Cryogenic Technologies
- Scientific Research and Discoveries
- Atmospheric and Environmental Gas Dynamics
- Image Processing and 3D Reconstruction
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Molecular Spectroscopy and Structure
The Open University
2020-2025
Indian Institute of Technology Indore
2022
University College London
2016-2021
University College Lahore
2018
University of Oxford
2010-2016
Planetary Science Institute
2016
Clarendon College
2015
University of Leicester
2008-2014
University of California, Berkeley
2009-2010
Centre National de la Recherche Scientifique
2009
A key legacy of the recently launched TESS mission will be to provide astronomical community with many best transiting exoplanet targets for atmospheric characterization. However, time is essence take full advantage this opportunity. JWST, although delayed, still complete its nominal five year on a timeline that motivates rapid identification, confirmation, and mass measurement top characterization from TESS. Beyond future dedicated missions studies such as ARIEL require discovery...
Thousands of exoplanets have now been discovered with a huge range masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface their host star. However, essential nature these remains largely mysterious: there is no known, discernible pattern linking presence, size, or orbital parameters planet its parent We little idea whether chemistry linked formation environment, type star drives physics planet's birth, evolution. ARIEL was conceived observe number...
Detailed characterization of exoplanets has begun to yield measurements their atmospheric properties that constrain the planets' origins and evolution. For example, past observations dayside emission spectrum hot Jupiter WASP-12b indicated its atmosphere a high carbon-to-oxygen ratio (C/O > 1), suggesting it had different formation pathway than is commonly assumed for giant planets. Here we report precise near-infrared transmission based on six transit with Hubble Space Telescope/Wide Field...
We present a consistent optimal estimation retrieval analysis of 10 hot Jupiter exoplanets, each with transmission spectral data spanning the visible to near-infrared wavelength range. Using NEMESIS radiative transfer and tool, we calculate range possible atmospheric states for WASP-6b, WASP-12b, WASP-17b, WASP-19b, WASP-31b, WASP-39b, HD 189733b, 209458b, HAT-P-1b, HAT-P-12b. find that spectra all planets are presence some aerosol; HAT-P-12b fit best by Rayleigh scattering aerosols, whereas...
Transmission spectroscopy1-3 of exoplanets has revealed signatures water vapour, aerosols and alkali metals in a few dozen exoplanet atmospheres4,5. However, these previous inferences with the Hubble Spitzer Space Telescopes were hindered by observations' relatively narrow wavelength range spectral resolving power, which precluded unambiguous identification other chemical species-in particular primary carbon-bearing molecules6,7. Here we report broad-wavelength 0.5-5.5 µm atmospheric...
WASP-39b is a hot Saturn-mass exoplanet with predicted clear atmosphere based on observations in the optical and infrared. Here we complete transmission spectrum of near-infrared (NIR) over three water absorption features Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) G102 (0.8-1.1 microns) G141 (1.1-1.7 spectroscopic grisms. We measure high amplitude H2O feature centered at 1.4 microns, smaller 0.95 1.2 maximum 2.4 planetary scale heights. incorporate these new NIR measurements...
Measuring the abundances of carbon and oxygen in exoplanet atmospheres is considered a crucial avenue for unlocking formation evolution exoplanetary systems. Access to an exoplanet's chemical inventory requires high-precision observations, often inferred from individual molecular detections with low-resolution space-based high-resolution ground-based facilities. Here we report medium-resolution (R$\sim$600) transmission spectrum atmosphere between 3-5 $\mu$m covering multiple absorption...
Abstract Carbon dioxide (CO 2 ) is a key chemical species that found in wide range of planetary atmospheres. In the context exoplanets, CO an indicator metal enrichment (that is, elements heavier than helium, also called ‘metallicity’) 1–3 , and thus formation processes primary atmospheres hot gas giants 4–6 . It one most promising to detect secondary terrestrial exoplanets 7–9 Previous photometric measurements transiting planets with Spitzer Space Telescope have given hints presence but not...
Transmission spectroscopy provides insight into the atmospheric properties and consequently formation history, physics, chemistry of transiting exoplanets. However, obtaining precise inferences from transmission spectra requires simultaneously measuring strength shape multiple spectral absorption features a wide range chemical species. This has been challenging given precision wavelength coverage previous observatories. Here, we present spectrum Saturn-mass exoplanet WASP-39b obtained using...
Abstract Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining dominant chemical processes at work and, if equilibrium, revealing planet formation histories. Transmission spectroscopy (for example, refs. 1,2 ) provides necessary means by abundances of oxygen- carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution high precision, which, together, are not achievable with...
Abstract Study Analysis Group 21 (SAG21) of NASA’s Exoplanet Exploration Program was organized to study the effect stellar contamination on space-based transmission spectroscopy, a method for studying exoplanetary atmospheres by measuring wavelength-dependent radius planet as it transits its star. Transmission spectroscopy relies precise understanding spectrum star being occulted. However, stars are not homogeneous, constant light sources but have temporally evolving photospheres and...
The recent inference of sulfur dioxide (SO2) in the atmosphere hot (approximately 1,100 K), Saturn-mass exoplanet WASP-39b from near-infrared JWST observations1-3 suggests that photochemistry is a key process high-temperature atmospheres4. This because low (<1 ppb) abundance SO2 under thermochemical equilibrium compared with produced H2O and H2S (1-10 ppm)4-9. However, was made single, small molecular feature transmission spectrum at 4.05 μm and, therefore, detection other absorption bands...
Abstract Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on nightside molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum hot Jupiter WASP-43b measured from 5 μm to 12 JWST’s Mid-Infrared Instrument. The spectra reveal large day–night temperature contrast (with...
Observations of transiting gas giant exoplanets have revealed a pervasive depletion methane, which has only recently been identified atmospherically. The is thought to be maintained by disequilibrium processes such as photochemistry or mixing from hotter interior. However, the interiors are largely unconstrained along with vertical strength and upper limits on CH$_4$ available. warm Neptune WASP-107 b stands out among an unusually low density, reported core mass, temperatures amenable though...
Abstract The recent discovery of three Earth-sized, potentially habitable planets around a nearby cool star, TRAPPIST-1, has provided key targets for the upcoming James Webb Space Telescope (JWST). Depending on their atmospheric characteristics and precise orbit configurations, it is possible that any may be in liquid water zone, meaning they capable supporting life. We find present-day Earth levels ozone, if present, would detectable JWST observes 60 transits innermost planet 1b 30 1c 1d.
We present a secondary eclipse observation for the hot Jupiter HD189733b across wavelength range 290-570nm made using Space Telescope Imaging Spectrograph on Hubble Telescope. measure geometric albedos of Ag = 0.40 \pm 0.12 290-450nm and < 450-570nm at 1-sigma confidence. The albedo decrease toward longer wavelengths is also apparent when six bins over same range. This can be interpreted as evidence optically thick reflective clouds dayside hemisphere with sodium absorption suppressing...
We report Gemini-South GMOS observations of the exoplanet system WASP-29 during primary transit as a test case for differential spectrophotometry. use multi-object spectrograph to observe target star and comparison simultaneously produce multiple light curves at varying wavelengths. The 'white' curve fifteen 'spectral' are analysed refine parameters transmission spectrum from 515 720nm. All exhibit time-correlated noise, which we model using variety techniques. These include simple noise...
We report Gemini-North GMOS observations of the inflated hot Jupiter HAT-P-32b during two primary transits. simultaneously observed comparison stars and used differential spectro-photometry to produce multi-wavelength light curves. 'White' curves 29 'spectral' were extracted for each transit analysed refine system parameters transmission spectra from 520-930nm in ~14nm bins. The contain time-varying white noise as well time-correlated noise, we a Gaussian process model fit this complex...
Here we present a publicly available database of opacities for molecules astrophysical interest named ExoMolOP that has been compiled over 80 species, and is based on the latest line list data from ExoMol, HITEMP, MoLLIST databases. These are generally suitable characterising high-temperature exoplanet or cool stellar substellar atmospheres, have computed at variety pressures temperatures, with few included room temperature only HITRAN database. The formatted in different ways four...
The James Webb Space Telescope (JWST) is predicted to make great advances in the field of exoplanet atmospheres. Its 25 m2 mirror means that it can reach unprecedented levels precision observations transit spectra, and thus characterise atmospheres planets orbiting stars several hundred pc away. coverage infrared spectral region between 0.6 28 {\mu}m allows abundances key molecules be probed during a planet front host star, when same eclipsed constraints placed on its temperature structure....
The James Webb Space Telescope (JWST) will likely revolutionize transiting exoplanet atmospheric science, due to a combination of its capability for continuous, long duration observations and larger collecting area, spectral coverage, resolution compared existing space-based facilities. However, it is unclear precisely how well JWST perform which myriad instruments observing modes be best suited studies. In this article, we describe prefatory Early Release Science (ERS) Cycle 1 program that...
We present an analysis of Spitzer/Infrared Array Camera primary transit and secondary eclipse light curves measured for HD 209458b, using Gaussian process models to marginalize over the intrapixel sensitivity variations in 3.6 4.5 μm channels ramp effect 5.8 8.0 channels. The main advantage this approach is that we can account a broad range degeneracies between planet signal systematics without actually having specify deterministic functional form latter. Our results do not confirm previous...