disequilibrium chemistry Archives - Page 2 of 2 - Astrobiology

Top: The full spectrum of VHS 1256 b using JWST’s NIRSpec IFU and MIRI MRS observation modes. Bandpasses are highlighted with different colors and error bar are displayed in grey. A single photometric point for MIRI MRS Channel 4A is shown because there is little to no signal in the MIRI MRS 4B, and 4C channels. Error bars are plotted in a light grey. Bottom: The wavelength overlap region between JWST’s NIRSpec IFU (black) and MIRI MRS (red) observation modes with errors plotted in light gray. The flux calibrated NIRSpec IFU spectra agree well with the MIRI MRS extracted spectra in the overlap region. -- astro-ph.EP

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

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b

by Keith CowingJuly 23, 2024July 22, 2024

We present the highest fidelity spectrum to date of a planetary-mass object. VHS 1256 b is a <20 MJup widely separated (∼8 arcsec, a = 150 au), young, planetary-mass companion […]

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 […]

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 […]

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

An Extensively Validated C/H/O/N Chemical Network For Hot Exoplanet Disequilibrium Chemistry

by Keith CowingOctober 13, 2023October 13, 2023

We aimed to build a new and updated C0-C2 chemical network to study the CHON disequilibrium chemistry of warm and hot exoplanet atmospheres that relies on extensively validated and recent […]

The LSTM predicted mixing ratios plotted against the actual mixing ratios (left) and the LSTM mixing ratio prediction error in log space (right). The dashed diagonal line in the left plot shows the performance of a perfectly predicting model and the colour of each bin represents the number of predictions. The solid line in the right plot shows the median value, and the dashed lines show the 5th and 95th percentiles. -- astro-ph.EP

AI - Data - Apps - Cybernetics, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Using A Neural Network Approach To Accelerate Disequilibrium Chemistry Calculations In Exoplanet Atmospheres

by Keith CowingJune 14, 2023June 14, 2023

In this era of exoplanet characterisation with JWST, the need for a fast implementation of classical forward models to understand the chemical and physical processes in exoplanet atmospheres is more […]

Molecular volume mixing ratios comparing the equilibrium and disequilibrium abundances as a function of pressure altitude. The significant presence of CO in the disequilibrium model is highlighted with a thick curve. Molecules are roughly grouped into color families and labels are constrained to the same y-coordinate in both panels. Additional species noticeably affected by the disequilibrium chemistry include N2, NH3, CO2, and HCN. -- astro-ph.EP

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

The Infrared Colors Of 51 Eridani b: Micrometereoid Dust Or Chemical Disequilibrium?

by Keith CowingApril 11, 2023April 11, 2023

We reanalyze near-infrared spectra of the young extrasolar giant planet 51 Eridani b which was originally presented in (Macintosh et al. 2015) and (Rajan et al. 2017) using modern atmospheric […]

Relative contributions of major opacity sources in Y dwarf atmospheres. 400 K and 1 bar correspond to the photosphere for our clear, equilibrium model with Teff = 350, log10(g) = 4.25, and Z/Z = 1. CO is negligible at 400 K, but we have enhanced its abundance in the figure, as one might expect in cases of strong vertical mixing, in order to illustrate which wavelengths are affected. -- astro-ph.EP

Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Self-consistent Models of Y Dwarf Atmospheres With Water Clouds And Disequilibrium Chemistry

by Keith CowingMarch 29, 2023

Y dwarfs are the coolest spectral class of brown dwarf. They have effective temperatures less than 500 K, with the coolest detection as low as ~250 K. Their spectra are […]