Niall Whiteford
A5033697639- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Spectroscopy and Laser Applications
- Adaptive optics and wavefront sensing
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Thermodynamic properties of mixtures
- Calibration and Measurement Techniques
- Spectroscopy and Chemometric Analyses
- Planetary Science and Exploration
- Spacecraft and Cryogenic Technologies
- Atmospheric and Environmental Gas Dynamics
- Space Science and Extraterrestrial Life
- Infrared Target Detection Methodologies
- CCD and CMOS Imaging Sensors
- Geophysics and Gravity Measurements
- Methane Hydrates and Related Phenomena
- Meteorological Phenomena and Simulations
American Museum of Natural History
2022-2024
UK Astronomy Technology Centre
2020-2024
University of Edinburgh
2020-2024
Central Park Conservancy
2024
Royal Observatory
2020-2024
We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is $<$20 M$_\mathrm{Jup}$ widely separated ($\sim$8\arcsec, = 150 au), young, companion that shares photometric colors and spectroscopic features with directly imaged exoplanets HR 8799 c, d, e. As an L-to-T transition object, exists along region color-magnitude diagram where substellar atmospheres from cloudy clear. observed 1256~b \textit{JWST}'s NIRSpec IFU MIRI MRS modes for coverage 1 $\mu$m 20 at...
We present JWST Early Release Science (ERS) coronagraphic observations of the super-Jupiter exoplanet, HIP 65426 b, with Near-Infrared Camera (NIRCam) from 2-5 $\mu$m, and Mid-Infrared Instrument (MIRI) 11-16 $\mu$m. At a separation $\sim$0.82" (86$^{+116}_{-31}$ au), b is clearly detected in all seven our observational filters, representing first images an exoplanet to be obtained by JWST, ever direct detection beyond 5 These demonstrate that exceeding its nominal predicted performance up...
We analyse the transmission and emission spectra of ultra-hot Jupiter WASP-76b, observed with G141 grism Hubble Space Telescope's Wide Field Camera 3 (WFC3). reduce fit raw data for each observation using open-source software Iraclis before performing a fully Bayesian retrieval publicly available analysis suite TauRex 3. Previous studies WFC3 WASP-76 b found hints titanium oxide (TiO) vanadium (VO) or non-grey clouds. Accounting fainter stellar companion to WASP-76, we reanalyse this show...
Abstract This paper presents the atmospheric characterization of three large, gaseous planets: WASP-127 b, WASP-79 and WASP-62 b. We analyzed spectroscopic data obtained with G141 grism (1.088–1.68 μ m) Wide Field Camera 3 on board Hubble Space Telescope using Iraclis pipeline TauREx3 retrieval code, both which are publicly available. For is least dense planet discovered so far located in short-period Neptune desert, our results found strong water absorption corresponding to an abundance...
The direct characterization of exoplanetary systems with high contrast imaging is among the highest priorities for broader exoplanet community. As large space missions will be necessary detecting and characterizing exo-Earth twins, developing techniques technology exoplanets a driving focus For first time, JWST directly observe extrasolar planets at mid-infrared wavelengths beyond 5$\mu$m, deliver detailed spectroscopy revealing much more precise chemical abundances atmospheric conditions,...
Abstract We present an atmospheric retrieval analysis of a pair highly variable, ∼200 Myr old, early T type planetary-mass exoplanet analogs SIMP J01365662+0933473 and 2MASS J21392676+0220226 using the Brewster framework. Our analysis, which makes use archival 1–15 μ m spectra, finds almost identical atmospheres for both objects. For targets, we find that data is best described by patchy, high-altitude forsterite (Mg 2 SiO 4 ) cloud above deeper, optically thick iron (Fe) cloud. model...
ABSTRACT Retrieval methods are a powerful analysis technique for modelling exoplanetary atmospheres by estimating the bulk physical and chemical properties that combine in forward model to best fit an observed spectrum, they increasingly being applied observations of directly imaged exoplanets. We have adapted taurex3, Bayesian retrieval suite, near-infrared spectrophotometry from gas giant exoplanets brown dwarfs. demonstrate taurex3’s applicability sub-stellar presenting results dwarf...
Abstract The unprecedented medium-resolution ( R λ ∼ 1500–3500) near- and mid-infrared (1–18 μ m) spectrum provided by JWST for the young (140 ± 20 Myr) low-mass (12–20 M Jup ) L–T transition (L7) companion VHS 1256 b gives access to a catalog of molecular absorptions. In this study, we present comprehensive analysis data set utilizing forward-modeling approach applying our Bayesian framework, ForMoSA . We explore five distinct atmospheric models assess their performance in estimating key...
Context . The MIRI instrument on board JWST is now offering high-contrast imaging capacity at mid-IR wavelengths, thereby opening a completely new field of investigation for characterizing young exoplanetary systems. Aims multiplanet system HR 8799 the first target observed with MIRI’s coronagraph as part MIRI-EC Guaranteed Time Observations (GTO) exoplanet program, launched in November 2022. We obtained deep observations three coronagraphic filters, from ∼10 to 15 µm (F1065C, F1140C,...
Abstract We present results from an atmospheric retrieval analysis of Gl 229B using the Brewster code. find best fit model to be cloud-free, consistent with T dwarf work Line et al.; Zalesky al. and Gonzales Fundamental parameters (mass, radius, log( L Bol / Sun ), g )) determined our agree within 1 σ SED-derived values, except for eff where retrieved is approximately 100 K cooler than evolutionary model-based SED value. a mass <?CDATA ${50}_{-9}^{+12}$?> <mml:math...
Abstract Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs 1,2 . Within giant planets auroral emission with signatures across the electromagnetic spectrum including infrared H 3 + and methane. Isolated in searched for corresponding features, but only null detections reported CWISEP J193518.59-154620.3. (W1935 short) is an dwarf a temperature approximately 482 K. Here we report James Webb Space Telescope strong methane W1935 at 3.326 μm....
T-type brown dwarfs present an opportunity to explore atmospheres teeming with molecules such as H2O, CH4 and NH3, which exhibit a wealth of absorption features in the mid-infrared. With JWST, we can finally this chemistry detail, including for coldest that were not yet discovered Spitzer era. This allows precise derivations molecular abundances, turn informs our understanding vertical transport these provide clues about formation cold exoplanets. study presents first JWST/MRS mid-IR...
With a temperature of ∼285 K, WISEJ0855–0714 (hereafter, WISE 0855) is the coldest brown dwarf observed thus far. Studying such cold gas giants allows us to probe atmospheric physics and chemistry evolved objects that resemble Solar System giants. Using James Webb Space Telescope (JWST), we obtained observations characterize 0855's atmosphere, focusing on vertical variation in water steam abundance, measuring trace abundances, obtaining bulk parameters for this object. We ultra-cool 0855...
Abstract Isolated planetary-mass objects share their mass range with planets but do not orbit a star. They lack the necessary to support fusion in cores and thermally radiate heat from formation as they cool, primarily at infrared wavelengths. Many isolated show variations brightness consistent nonuniform atmospheric features modulated by rotation. SIMP J013656.5+093347.3 is rapidly rotating object, previous monitoring suggests complex out of view. The physical nature these well understood,...
Abstract T-type brown dwarfs present an opportunity to explore atmospheres teeming with molecules such as H 2 O, CH 4 , and NH 3 which exhibit a wealth of absorption features in the mid-infrared. With JWST, we can finally this chemistry detail, including for coldest that were not yet discovered Spitzer era. This allows precise derivations molecular abundances, turn inform our understanding vertical transport these provide clues about formation cold exoplanets. study presents first JWST/MRS...
We present an atmospheric characterization study of two medium sized planets bracketing the radius Neptune: HD 106315 c (R$_{\rm{P}}$=4.98 $\pm$ 0.23 R$_{\oplus}$) and 3167 (R$_{\rm{P}}$=2.740$_{-0.100}^{+0.106}$ R$_{\oplus}$). analyse spatially scanned spectroscopic observations obtained with G141 grism (1.125 - 1.650 $\mu$m) Wide Field Camera 3 (WFC3) onboard Hubble Space Telescope. use publicly available Iraclis pipeline TauREx3 retrieval code we detect water vapor in atmosphere both...
The Medium Resolution Spectrometer on board JWST/MIRI will give access to mid-IR spectra while retaining spatial information. With the unparalleled sensitivity of JWST and MIRI detectors, MRS has potential revolutionise our understanding giant exoplanet atmospheres. Molecular mapping is a promising detection characterisation technique used study directly imaged exoplanets. We aim examine feasibility application this observations. instrument simulator MIRISIM create mock observations resolved...
We report results from 8 hours of JWST/MIRI LRS spectroscopic monitoring directly followed by 7 JWST/NIRSpec prism the benchmark binary brown dwarf WISE 1049AB, closest, brightest dwarfs known. find water, methane, and CO absorption features in both components, including 3.3 $\mu$m methane feature a tentative detection small grain ($<$ 1$\mu$m) silicate at $>$8.5 1049A. Both components vary significantly ($>$1$\%$), with 1049B displaying larger variations than Using K-means clustering, we...
ABSTRACT We present a photometric variability survey of young planetary-mass objects using the New Technology Telescope in JS and KS bands. Surface gravity plays an important role atmospheric structure brown dwarfs, as low-gravity L dwarfs have higher rate than field dwarfs. In this study, we extend studies to T-type investigate effects surface on T across large sample. conduct continuous monitoring for 18 with spectral types from L5 T8 detect four new variables two variable candidates....
Context . Mid-infrared imaging of exoplanets and disks is now possible with the coronographs Mid-InfraRed Instrument (MIRI) on James Webb Space Telescope (JWST). This wavelength range unveils new features young directly imaged systems allows us to obtain constraints for characterizing atmosphere giant associated disks. Aims These observations aim characterize planet HD 95086 b by adding mid-infrared information so that various hypotheses about its atmospheric parameters values can be...
Abstract We present the analysis of hot-Jupiter KELT-7 b using transmission and emission spectroscopy from Hubble Space Telescope, both taken with Wide Field Camera 3. Our study uncovers a rich spectrum that is consistent cloud-free atmosphere suggests presence H 2 O − . In contrast, extracted does not contain strong absorption features and, although it simple blackbody, can be explained by varying temperature–pressure profile, collision induced absorption, had also been studied other...
Although the search for habitability is a much-vaunted objective in study of planetary environments, material requirements an environment to be habitable can met with relatively few ingredients. In this hypothesis paper, minimum are first re-evaluated, necessarily based on life "as we know it." From vantage point, explore examples number conditions arise environment, which illustrate "minimum diagrams." These raise that may common throughout universe. If was accepted, then discovery would...