Photochemistry Archives

UV absorption cross sections for the phosphorus species in the network that undergo photolysis reactions. The photolysis threshold wavelength for each species is indicated by the coloured arrows. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Jupiter, Saturn, Status Report, Water/Hycean Worlds & Oceanography

A Photochemical PHO Network For Hydrogen-dominated Exoplanet Atmospheres

by Keith CowingSeptember 13, 2024September 13, 2024

Due to the detection of phosphine PH3 in the Solar System gas giants Jupiter and Saturn, PH3 has long been suggested to be detectable in exosolar substellar atmospheres too. However, […]

An international team of researchers led by the University of Bern has used observation-based computer modelling to find an explanation for how macromolecules can form in a short time in disks of gas and dust around young stars. These findings could be crucial for understanding how habitability develops around different types of exoplanets and stars.

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Interstellar, Meteorites & Asteroids, Press Release

Astronomers Clarify How Organic Macromolecules Are Formed

by Keith CowingJuly 31, 2024July 31, 2024

An international team of researchers led by the University of Bern has used observation-based computer modelling to find an explanation for how macromolecules can form in a short time in […]

Contribution functions at selected wavenumbers calculated for the best-fitting models (Fig. 5) of CIRS (red lines) and TEXES (blue lines) observations. These contribution functions, which have been normalized at each wavenumber, are Jacobians that give the rate of change of spectral flux with temperature (Panel A), logarithm of C2H2 mole fraction (Panel B), and logarithm of C2HD mole fraction (Panel C). -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report, Titan

The D/H Ratio in Titan’s Acetylene From High Spectral Resolution IRTF/TEXES Observations

by Keith CowingJuly 31, 2024July 31, 2024

We report observations of deuterated acetylene (C2HD) at 19.3 μm (519 cm−1) with the Texas Echelon Cross Echelle Spectrograph on the NASA Infrared Telescope Facility in July 2017.

The detections of H2O, CO, and total atmospheric signal in the atmosphere of WASP-127 b. The CC maps shown here are generated by cross-correlating the residual data with solar composition RCTE models with opacity from H2O alone, CO alone, and all absorbers respectively. The tellurics have been masked and the out-of-transit frames have been cropped in the residual data. The white dashed lines in these maps denote the literature reported values of Vsys0 and Kp0 for the WASP-127 b system. The red cross indicates the peak value of the SNR within each map. Similar to the trail, the peak signal in these maps can be seen blue shifted. The bottom red curves under each panel shows the row/cross-section of the CC SNRs at the peak Kp. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

IGRINS Observations of WASP-127 b: H2O, CO, and Super-Solar Atmospheric Metallicity in the Inflated sub-Saturn

by Keith CowingJune 21, 2024June 21, 2024

High resolution spectroscopy of exoplanet atmospheres provides insights into their composition and dynamics from the resolved line shape and depth of thousands of spectral lines. WASP-127 b is an extremely […]

Three independent reductions of the NIRCam F322W2 and F444W data agree within their uncertainties The top panel shows the F322W2 and F444W transmission spectra, as reduced using the Pegasus, Eureka, and tshirt pipelines, plotted with their associated 1 σ uncertainties using constant 0.015µm-wide spectral bins. All of the F322W2 spectra have been offset down by 163 ppm to correct for a bias offset in the F322W2 transit depths compared to the F444W and Spitzer data (see Appendix B.3). All three reductions agree on the shape of the transmission spectrum and show features due to H2O (2.5–3.2µm), CH4 (3.2–3.5µm), SO2 (3.9–4.1µm), and CO2 (2.6–2.9µm and 4.2–4.5µm). The absorption cross sections of the prominent species in this wavelength range, many of which are visually identifiable in the bottom panel. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Sulfur Dioxide and Other Molecular Species in the Atmosphere of the Sub-Neptune GJ 3470 b

by Keith CowingJune 11, 2024June 11, 2024

We report observations of the atmospheric transmission spectrum of the sub-Neptune exoplanet GJ 3470 b taken using the Near-Infrared Camera (NIRCam) on JWST. Combined with two archival HST/WFC3 transit observations […]

Weighting function distribution for nadir and limb viewing geometries for the 2017 observation. Beam locations were placed such that the top-of-atmosphere latitudes matched for both locations for each observation, taking into account Titan’s tilt. Weighting distributions are not coadded, as plotted, but calculated individually for each extraction region. Titan’s solid body radius (2575 km; dashed circle), top of atmosphere (1200 km above the surface; solid circle), and top-of-atmosphere latitudes are shown. The FWHM of the ALMA beam is denoted by the dashed ellipses. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Status Report, Titan

Variability in Titan’s Mesospheric HCN and Temperature Structure as Observed by ALMA

by Keith CowingFebruary 6, 2024February 6, 2024

The temperature structure of Titan’s upper atmosphere exhibits large variability resulting from numerous spatially and temporally irregular external energy sources, seasonal changes, and the influence of molecular species produced via […]

Ternary diagrams depicting the porosity levels required for selected ices to float on the ternary mixture. The light blue and pink diamond symbols indicate observed compositions of Titan’s northern and southern polar lakes, with diamond-shaped boxes showing the uncertainty (Poggiali et al., 2020). -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Saturn, Status Report, Titan

The Fate of Simple Organics on Titan’s Surface: A Theoretical Perspective

by Keith CowingJanuary 8, 2024January 8, 2024

Atmospheric photochemistry on Titan continuously transforms methane and nitrogen gases into various organic compounds.

Schematic diagram demonstrating interstellar ices within dark clouds made of molecular hydrogen being processed by photochemistry involving the production of electronically excited water and radiation chemistry involving the production of ionized water and secondary electrons. This work focuses on the interaction depicted in the second of the two CRs (blue lines) in which a CR interacts in the ice mantle to produce secondary electrons. Reproduced from Ref. 4. Copyright 2019, The Royal Society of Chemistry. -- astro-ph.HE

Astrochemistry, Status Report

The Role of Low-energy (< 20 eV) Secondary Electrons in the Extraterrestrial Synthesis of Prebiotic Molecules

by Keith CowingDecember 6, 2023December 6, 2023

We demonstrate for the first time that Galactic cosmic rays with energies as high as 1e10 eV can trigger a cascade of low-energy (< 20 eV) secondary electrons that could […]

Comparison of measured and simulated absorbances of C2H6 (top) and C2H2 (bottom) for a spectral resolution of 0.45 cm-1 in the case of the H2:CH4:N2 gas mixture after 24 hr of irradiation at 473 K. The simulated spectra were obtained following the procedure described in Section 2.2. -- astro-ph.EP

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Experimental Investigation of the Photochemical Production of Hydrocarbons in Warm Gas Giant Exoplanet Atmospheres

by Keith CowingOctober 19, 2023October 19, 2023

In warm (equilibrium temperature <1000 K) gas giant exoplanet atmospheres, the observation of trace species in abundances deviating from thermochemical equilibrium predictions could be used as an indicator of disequilibrium […]

The left panel shows the synthetic transmission spectra of the evening and morning limbs of WASP-39b with a resolution of R = 300. The atmospheric structure and chemical composition are based on 2D VULCAN, incorporating temperature and wind profiles obtained from the Exo-FMS GCM. The models excluding horizontal transport are labelled 1D for comparison. The right panel shows the morning-evening averaged transmission spectra when assuming different atmospheric metallicities within 2D VULCAN. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Status Report

Day-night Transport Induced Chemistry And Clouds On WASP-39b I: Gas-phase Composition

by Keith CowingJune 14, 2023June 14, 2023

JWST has recently detected the first robust photochemical product on an exoplanet: sulfur dioxide (SO2) on WASP-39b (Rustamkulov et al. 2023; Alderson et al. 2023; Tsai et al. 2023b).

Photochemistry

A Photochemical PHO Network For Hydrogen-dominated Exoplanet Atmospheres

Astronomers Clarify How Organic Macromolecules Are Formed

The D/H Ratio in Titan’s Acetylene From High Spectral Resolution IRTF/TEXES Observations

IGRINS Observations of WASP-127 b: H2O, CO, and Super-Solar Atmospheric Metallicity in the Inflated sub-Saturn

Sulfur Dioxide and Other Molecular Species in the Atmosphere of the Sub-Neptune GJ 3470 b

Variability in Titan’s Mesospheric HCN and Temperature Structure as Observed by ALMA

The Fate of Simple Organics on Titan’s Surface: A Theoretical Perspective

The Role of Low-energy (< 20 eV) Secondary Electrons in the Extraterrestrial Synthesis of Prebiotic Molecules

Experimental Investigation of the Photochemical Production of Hydrocarbons in Warm Gas Giant Exoplanet Atmospheres

Day-night Transport Induced Chemistry And Clouds On WASP-39b I: Gas-phase Composition

How High-pressure Ices On Large Ocean Worlds Can Support Habitability: The Compatibility Of Amino Acids Into Ice VI And VII

Ice Drives The Emergence Of Functional Protocells

Chemical Abundance Patterns at z=1-7: Carbon, Nitrogen, Neon, Sulphur, and Argon Abundances From JWST Spectroscopy

Optimization of Petal-Shaped Occulters for Exo-Earth Observation

Topographically Forced Stationary Waves Can Explain The Near-Surface Zonal Winds Observed By Huygens On Titan