James Kirk
A5056640034- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Magnetic Bearings and Levitation Dynamics
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Electric Motor Design and Analysis
- Advanced Radiotherapy Techniques
- Effects of Radiation Exposure
- Atmospheric Ozone and Climate
- Manufacturing Process and Optimization
- Magnetic and Electromagnetic Effects
- Spectroscopy and Laser Applications
- Historical Studies of British Isles
- Scottish History and National Identity
- Tribology and Lubrication Engineering
- Astrophysical Phenomena and Observations
- Advanced machining processes and optimization
- Calibration and Measurement Techniques
- Space Exploration and Technology
- Adaptive optics and wavefront sensing
- Radiation Therapy and Dosimetry
- Pulsars and Gravitational Waves Research
- Power Systems and Renewable Energy
- Mathematical Biology Tumor Growth
Imperial College London
2022-2025
Center for Astrophysics Harvard & Smithsonian
2019-2024
California Institute of Technology
2024
Patient Advocate Foundation
2019-2023
Anna Needs Neuroblastoma Answers
2023
Boston University
2023
Max Planck Society
2012-2019
Max Planck Institute for Astronomy
2019
University of Warwick
2015-2018
University of Southampton
2015
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...
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...
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 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...
Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability. However, no unambiguous photochemical products have been detected in exoplanet to date. Recent observations from JWST Transiting Exoplanet Early Release Science Program found spectral absorption feature at 4.05 $\mu$m arising SO$_2$ atmosphere WASP-39b. WASP-39b 1.27-Jupiter-radii, Saturn-mass (0.28 M$_J$) gas giant orbiting Sun-like star with an equilibrium temperature...
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...
Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun determine or not most favorable worlds detectable Here, present a 2.8-5.2 micron JWST NIRSpec/G395H spectrum warm...
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 We present a JWST/Near Infrared Camera (NIRCam) transmission spectrum from 3.9 to 5.0 μ m of the recently validated sub-Earth GJ 341b ( R P = 0.92 ⊕ , T eq 540 K) orbiting nearby bright M1 star d 10.4 pc, K mag 5.6). use three independent pipelines reduce data JWST visits and perform several tests check for significance an atmosphere. Overall, our analysis does not uncover evidence Our null hypothesis find that none pipelines’ spectra can rule out flat line, although there is weak...
We are entering an era of unprecedented quantities data from current and planned survey telescopes. To maximize the potential such surveys, automated analysis techniques required. Here we implement a new methodology for variable star classification, through combination Kohonen Self-Organizing Maps (SOMs, unsupervised machine learning algorithm) more common Random Forest (RF) supervised technique. apply this method to K2 mission fields 0–4, finding 154 ab-type RR Lyraes (10 newly discovered),...
Abstract We present the detection of helium in extended atmosphere sub-Saturn WASP-107b using high-resolution ( R ≈ 25,000) near-infrared spectra from Keck II/Near Infrared Echelle Spectrograph (NIRSPEC). find peak excess absorption 7.26% ± 0.24% (30 σ ) centered on He i triplet at 10833 Å. The amplitude and shape profile is excellent agreement with previous observations escaping this planet made by CARMENES Hubble Space Telescope . This suggests there no significant temporal variation...
Abstract The search for rocky planet atmospheres with JWST has focused on planets transiting M dwarfs. Such have favorable planet-to-star size ratios, enhancing the amplitude of atmospheric features. Since expected signal strength features is similar to single-transit performance JWST, multiple observations are required confirm any detection. Here, we present two transit GJ 1132 b NIRSpec G395H, covering 2.8–5.2 μ m. Previous Hubble Space Telescope WFC3 were inconclusive, evidence reported...
Scholars warn that partisan divisions in the mass public threaten health of American democracy. We conducted a megastudy (n = 32,059 participants) testing 25 treatments designed by academics and practitioners to reduce Americans’ animosity antidemocratic attitudes. find many reduced animosity, most strongly highlighting relatable sympathetic individuals with different political beliefs or emphasizing common identities shared rival partisans. also identify several support for undemocratic...
Abstract We present two transit observations of the ∼870 K, 1.7 R ⊕ super-Earth TOI-836b with JWST NIRSpec/G395H, resulting in a 2.8–5.2 μ m transmission spectrum. Using different reduction pipelines, we obtain median depth precision 34 ppm for Visit 1 and 36 2, leading to combined 25 spectroscopic channels 30 pixels wide (∼0.02 m). find that spectrum from both visits is well fit by zero-sloped line, fitting sloped lines as step functions our data. Combining visits, are able rule out...
Abstract Planets between the sizes of Earth and Neptune are most common in Galaxy, bridging gap terrestrial giant planets our solar system. Now that we firmly era JWST, can begin to measure, more detail, atmospheres these ubiquitous better understand their evolutionary trajectories. The two TOI-836 system ideal candidates for such a study, as they fall on either side radius valley, allowing direct comparisons present-day formed same environment but had different ultimate end states. We...
Observing exoplanets through transmission spectroscopy supplies detailed information on their atmospheric composition, physics, and chemistry. Prior to JWST, these observations were limited a narrow wavelength range across the near-ultraviolet near-infrared, alongside broadband photometry at longer wavelengths. To understand more complex properties of exoplanet atmospheres, improved coverage resolution are necessary robustly quantify influence broader absorbing molecular species. Here we...
The primary effect of irradiation on self-renewing normal tissues is sterilisation their proliferative cells, but how this translates into failure tissue function depends the mode organisation concerned. It has recently been suggested (Michalowski, 1981) that may be classed as "hierarchical" (like haemopoietic tissues) or "flexible" liver parenchyma) and radiation injury to develops by different pathways in these tissues. Mathematical model studies confirm responses differently organized...
We have created a catalogue of variable stars found from search the publicly available K2 mission data Campaigns 1 and 0. This provides identifiers 8395 stars, including 199 candidate eclipsing binaries with periods up to 60d 3871 periodic or quasi-periodic objects, 20d for Campaign 15d Lightcurves are extracted detrended data. These searched using combination algorithmic human classification, leading classifier each object as an binary, sinusoidal periodic, quasi aperiodic variable. The...
Photometric surveys such as Kepler have the precision to identify exoplanet and eclipsing binary candidates from only a single transit. K2, with its 75d campaign duration, is ideally suited detect significant numbers of single-eclipsing objects. Here we develop Bayesian transit-fitting tool ("Namaste: An Mcmc Analysis Single Transit Exoplanets") extract orbital information transit events. We achieve favourable results testing this technique on known planets, apply 7 identified targeted...
K2-19 is the second multi-planetary system discovered with K2 observations. The composed of two Neptune size planets close to 3:2 mean-motion resonance. To better characterise we obtained additional transit observations K2-19b and five radial velocity These were combined data fitted simultaneously dynamics (photo-dynamical model) which increases precision time measurements. higher allows us detect chopping signal dynamic interaction that in turn permits uniquely system. Although reflex...
This is a catalogue of ∼70 X-ray emitting binary systems in the Small Magellanic Cloud (SMC) that contain Be star as mass donor system and clear pulse signature from neutron star. The are generally referred to Be/X-ray binaries. It lists all their known characteristics (orbital period, eccentricity), measured spin period compact object, plus (spectral type, size circumstellar disc, evidence for non-radial pulsations behaviour). For first time data Spitzer Observatory combined with...
We have performed ground-based transmission spectroscopy of the hot Jupiter HAT-P-18b using ACAM instrument on William Herschel Telescope (WHT). Differential over an entire night was carried out at a resolution R ≈ 400 nearby comparison star. detect blueward slope extending across our optical spectrum that runs from 4750 to 9250 Å. The is consistent with Rayleigh scattering equilibrium temperature planet (852 K). do not enhanced sodium absorption, which indicates high-altitude haze masking...
Abstract We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b ( <?CDATA ${T}_{\mathrm{eq}}=2484$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mi>eq</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>2484</mml:mn> </mml:math> K). Our is result combining five transits from ACCESS survey and two LRG-BEASTS with reanalysis three archival Gemini/GMOS one VLT/FORS2...