Matthew C. Nixon
A5071706680- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Calibration and Measurement Techniques
- Spacecraft and Cryogenic Technologies
- Gamma-ray bursts and supernovae
- Quantum Chromodynamics and Particle Interactions
- Spacecraft Design and Technology
- Pulsars and Gravitational Waves Research
- Space Exploration and Technology
- Photonic and Optical Devices
- Geophysics and Gravity Measurements
- Geological and Geochemical Analysis
- Thin-Film Transistor Technologies
- Organic Electronics and Photovoltaics
University of Maryland, College Park
2023-2024
University of Cambridge
2020-2022
Osservatorio Astronomico di Palermo
2022
University of Minnesota, Duluth
2015
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 Close-in giant exoplanets with temperatures greater than 2,000 K (‘ultra-hot Jupiters’) have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from Hubble Space Telescope (HST) and Spitzer 1–3 . However, previous studies yielded inconsistent results because small sizes spectral features limited information content data resulted in high sensitivity varying assumptions made treatment instrument systematics retrieval...
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...
Abstract The near-infrared transmission spectrum of the warm sub-Neptune exoplanet GJ 1214 b has been observed to be flat and featureless, implying a high metallicity atmosphere with abundant aerosols. Recent JWST MIRI Low Resolution Spectrometer observations phase curve showed that its is out into mid-infrared. In this paper, we use combined near- mid-infrared constrain atmospheric composition aerosol properties. We generate grid photochemical haze models using an microphysics code for...
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...
Abstract Carbon monoxide was recently reported in the atmosphere of hot Jupiter WASP-39b using NIRSpec PRISM transit observation this planet, collected as part JWST Transiting Exoplanet Community Early Release Science Program. This detection, however, could not be confidently confirmed initial analysis higher-resolution observations with G395H disperser. Here we confirm detection CO data and cross-correlation techniques. We do by searching for signal unbinned transmission spectrum planet...
Abstract We present eclipse maps of the two-dimensional thermal emission from dayside hot-Jupiter WASP-43b, derived an observation a phase curve with JWST MIRI/LRS instrument. The observed shapes deviate significantly those expected for planet emitting uniformly over its surface. fit map to this deviation, constructed spherical harmonics up order <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic">ℓ</mml:mi>...
We report the discovery and characterization of two transiting planets around bright M1 V star LP 961-53 (TOI-776, J = 8.5 mag, M 0.54+-0.03 Msun) detected during Sector 10 observations Transiting Exoplanet Survey Satellite (TESS). Combining TESS photometry with HARPS radial velocities, as well ground-based follow-up transit from MEarth LCOGT telescopes, we measured for inner planet, TOI-776 b, a period 8.25 d, radius 1.85+-0.13 Re, mass 4.0+-0.9 Me; outer c, 15.66 2.02+-0.14 5.3+-1.8 Me....
Understanding the internal structures of planets with a large H$_2$O component is important for characterisation sub-Neptune planets. The finding that mini-Neptune K2-18b could host liquid water ocean beneath mostly hydrogen envelope motivates detailed examination phase water-rich To this end, we present new structure models super-Earths and mini-Neptunes enable planet's component. We use our to explore possible worlds find diverse range interiors are possible, from oceans sandwiched between...
Abstract Atmospheric retrievals of exoplanet transmission spectra allow constraints on the composition and structure day–night terminator region. Such in past have typically assumed one-dimensional (1D) temperature structures which were adequate to explain extant observations. However, increasing data quality expected from spectroscopy with James Webb Space Telescope (JWST) motivates considerations multidimensional atmospheric retrievals. We present Aura-3D , a three-dimensional retrieval...
ABSTRACT Spectroscopic phase curves of hot Jupiters measure their emission spectra at multiple orbital phases, thus enabling detailed characterization atmospheres. Precise constraints on the atmospheric composition these exoplanets offer insights into formation and evolution. We analyse four phase-resolved Jupiter WASP-43b, generated from a curve observed with Mid-Infrared Instrument/Low Resolution Spectrometer onboard JWST, to retrieve its properties. Using parametric 2D temperature model...
Common features of sub-Neptunes atmospheres observed to date include signatures aerosols at moderate equilibrium temperatures (~500-800 K), and a prevalence high mean molecular weight atmospheres, perhaps indicating novel classes planets such as water worlds. Here we present 0.83-5 micron JWST transmission spectrum the sub-Neptune TOI-421 b. This planet is unique among previously counterparts in its temperature ($T_{eq} \approx 920$) Sun-like host star. We find marked differences between...
We present an atmospheric transmission spectrum of the ultra-hot Jupiter WASP-76 b by analyzing archival data obtained with Space Telescope Imaging Spectrograph (STIS) on board Hubble (HST). The dataset spans three transits, two a wavelength coverage between 2900 and 5700 Armstrong, third one 5250 10300 Armstrong. From one-dimensional, time dependent spectra we constructed white chromatic light curves, latter typical integration band widths ~200 computed planet-to-star radii ratios taking...
Abstract Exoplanets orbiting M-dwarfs present a valuable opportunity for their detection and atmospheric characterization. This is evident from recent inferences of H 2 O in such atmospheres, including that the habitable-zone exoplanet K2-18b. With bulk density between Earth Neptune, K2-18b may be expected to possess H/He envelope. However, extent an envelope thermodynamic conditions interior remain unexplored. In work, we investigate properties based on its transmission spectrum. We...
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 5-12 $μ$m JWST's Mid-Infrared Instrument (MIRI). The spectra reveal large day-night temperature contrast (with...
Abstract A key goal of exoplanet spectroscopy is to measure atmospheric properties, such as abundances chemical species, in order connect them our understanding physics and planet formation. In this new era high-quality JWST data, it paramount that these measurement methods are robust. When comparing models observations, multiple candidate may produce reasonable fits the data. Typically, conclusions reached by selecting best-performing model according some metric. This ignores uncertainty...
Atmospheric retrieval of exoplanets from spectroscopic observations requires an extensive exploration a highly degenerate and high-dimensional parameter space to accurately constrain atmospheric parameters. Retrieval methods commonly conduct Bayesian estimation statistical inference using sampling algorithms such as Markov Chain Monte Carlo (MCMC) or Nested Sampling. Recently several attempts have been made use machine learning either complement replace fully methods. While much progress has...
Abstract Recent JWST observations of the sub-Neptune GJ 1214 b suggest that it hosts a high-metallicity (≳100× solar), hazy atmosphere. Emission spectra planet show molecular absorption features, most likely due to atmospheric H 2 O. In light this new information, we conduct thorough reevaluation planet’s internal structure. We consider interior models with mixed H/He/H O envelopes varying composition, informed by constraints from phase curve, in order determine possible bulk compositions...
Close-in giant exoplanets with temperatures greater than 2,000 K (''ultra-hot Jupiters'') have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from Hubble and Spitzer Space Telescopes. However, previous studies yielded inconsistent results because small sizes spectral features limited information content data resulted in high sensitivity varying assumptions made treatment instrument systematics retrieval analysis. Here we...
Context. Despite being a prominent subset of the exoplanet population discovered in past three decades, nature and provenance sub-Neptune-sized planets are still one open questions science. Aims. For orbiting bright stars, precisely measuring orbital planet parameters system is best approach to distinguish between competing theories regarding their formation evolution. Methods. We obtained 69 new radial velocity observations mid-M dwarf G 9-40 with CARMENES instrument measure for first time...
Abstract Kepler-51 is a ≲1 Gyr old Sun-like star hosting three transiting planets with radii ≈6–9 R ⊕ and orbital periods ≈45–130 days. Transit timing variations (TTVs) measured past Kepler Hubble Space Telescope (HST) observations have been successfully modeled by considering gravitational interactions between the planets, yielding low masses mean densities (≲0.1 g cm −3 ) for all planets. However, transit time of outermost planet Kepler-51d recently James Webb 10 yr after significantly...
A numerical investigation of an array consisting SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> fibers to generate whispering gallery modes (WGMs) and lensing effects atop organic solar cell (OSC) enhance optical absorption efficiency is reported. calibrated the optimal WGM resonator (WGMR) antireflection coating for broadband light account increases in integrated up 16% when compared with its flat-OSC counterpart. The overall...
Spectroscopic phase curves of hot Jupiters measure their emission spectra at multiple orbital phases, thus enabling detailed characterisation atmospheres. Precise constraints on the atmospheric composition these exoplanets offer insights into formation and evolution. We analyse four phase-resolved Jupiter WASP-43b, generated from a curve observed with MIRI/LRS onboard JWST, to retrieve its properties. Using parametric 2D temperature model assuming chemically homogeneous atmosphere within...