Atmospheres, Climate, Weather Archives

Column density maps for H2 (top left), H (top right), and O (bottom) from the torus model (Smith et al. 2019, 2022) in a plane through Jupiter and corresponding to the viewing geometry of the first torus-centered exposure le2oa1010 (Table 1) from 2020. For O, the tori of Europa-genic (left) and Io-genic (right) material are shown separately. Jupiter (large black circle) is centered and Io (white, behind Jupiter) and Europa (black) are shown by the smaller disks to the right (west of Jupiter). The densities are higher closer to the moons (here, west of Jupiter) and the HST/COS observations scanned over the densest regions of the Europa-genic neutrals from 8.0 RJ to 12.5 RJ. (Note that the viewing geometry in Figure 1 corresponds to an 1.5-hour earlier exposure). -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Europa, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Constraints On Europa’s Water Group Torus From HST/COS Observations

by Keith CowingApril 18, 2023April 18, 2023

In-situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter provide indirect evidence that an enhancement of neutral gas is present near the orbit of the […]

Mass–radius for USP planets, with mass–radius measurements better than 25 per cent from http://www.astro.keele.ac.uk/jkt/tepcat/ and for our USP TESS candidates (see Table 1), colour coded by their equilibrium temperature. Two-layer models from Zeng et al. (2016) are displayed with different lines and colours. ‘Earth-like’ here means a composition of 30 per cent Fe and 70 per cent MgSiO3, whereas ‘100 per cent Rock’ means a composition of 100 per cent MgSiO3. Earth and Venus are identified in this plot as pale blue and orange circles, respectively -- astro-ph.EP

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

Surface Pressure Impact On Nitrogen-dominated USP Super-Earth Atmospheres

by Keith CowingApril 18, 2023April 18, 2023

In this paper, we compare the chemistry and the emission spectra of nitrogen-dominated cool, warm, and hot ultra-short-period (USP) super-Earth atmospheres in and out of chemical equilibrium at various surface […]

While metal-poor stars emit more UV radiation overall than metal-rich ones, for metal-poor stars the ratio of ozone-generating UV-C radiation to ozone-destroying UV-B radiation allows for the formation of a thicker protective ozone-layer around the orbiting planets. Therefore, the planets belonging to metal-poor stars provide more favourable conditions for the emergence of complex life. CREDIT MPS/hormesdesign.de

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Press Release, Space Weather & Heliophysics

Metal-Poor Stars Are More Life-Friendly

by Keith CowingApril 18, 2023April 18, 2023

Stars that contain comparatively large amounts of heavy elements provide less favourable conditions for the emergence of complex life than metal-poor stars, as scientists from the Max Planck Institutes for […]

The sequence of events leading to formation of water, light elements in metal, and increases in oxygen fugacity for Earth’s progenitor embryos in this work. Stage 1 is the embryo where surface temperatures are too high to retain primary atmospheres of hydrogen. Stage 2 is the initial condition for our calculations in which the molten embryos accrete and retain primary atmospheres of H2. Metalsilicate differentiation may have already begun at this stage. Stage 3 is the result of chemical equilibration of the silicate and metal melts with the evolved atmospheres. Annotations show the changes in oxygen fugacity and metal density deficits. Reactions shown are simplifications of the full set, for illustration purposes. Two or more such embryos combine to form the final Earth. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

Earth Was Shaped By Primordial Hydrogen Atmospheres

by Keith CowingApril 17, 2023April 17, 2023

Earth’s water, intrinsic oxidation state, and metal core density are fundamental chemical features of our planet. Studies of exoplanets provide a useful context for elucidating the source of these chemical […]

Living stromatolites at Shark Bay, Western Australia. Oxygen produced by ancient stromatolites may have left its mark on Earth's environment as early as 2.5 billion years ago. Photo courtesy Ariel Anbar

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Origin & Evolution of Life, Press Release

ASU-led Team Defends Molecular Oxygen Findings

by Keith CowingApril 12, 2023April 12, 2023

When did molecular oxygen, the gas that all large and complex forms of life on Earth today require to function, first appear on Earth?

An artist's impression of the 'light curve' produced by a star passing behind Titan. The spike at the center of the light curve represents the central flash produced by Titan's atmosphere acting as a lens and refracting the starlight toward a single focal point. Credit: NASA/ESA/C.Carreau

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Imaging & Spectroscopy, Press Release, Titan

Using Stars To Study Titan’s Atmosphere

by Keith CowingApril 11, 2023April 11, 2023

With its thick atmosphere and mysterious weather patterns, Saturn’s largest moon, Titan, is an alien world ripe with discovery potential.

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 […]

Surface temperature as a function of incoming instellation for different hydrogen-helium inventories. The introduction of layers with convective inhibition when the moisture content at the bottom of the atmosphere (BOA) is high enough (orange region) causes a rapid increase in surface temperature (and moisture content). Once the bottom of the atmosphere is pure steam (pink region), the atmosphere becomes optically thick and increasing surface temperature is no longer linked with an increase in cooling, causing a runaway state. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, Water/Hycean Worlds & Oceanography

The Runaway Greenhouse Effect on Hycean Worlds

by Keith CowingApril 11, 2023April 11, 2023

Hycean worlds are a proposed subset of sub-Neptune exoplanets with substantial water inventories, liquid surface oceans and extended hydrogen-dominated atmospheres that could be favourable for habitability.

Potential energy surface of the CN + toluene reaction at the level of CCSD(T)/CBS//M06–2X-D3/6-311+G(d,p) in this work. The energetically favorable pathways are represented in red. Energies in parentheses are the results calculated at the level of M06-2X/aug-cc-pVTZ from Messinger et al. (Messinger et al. 2020). astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Imaging & Spectroscopy, Interstellar, Status Report, Titan

Reaction Kinetics Of CN + Toluene And Its Implication On The Productions Of Aromatic Nitriles In The Taurus Molecular Cloud And Titan’s Atmosphere

by Keith CowingApril 10, 2023April 10, 2023

Reactions between cyano radical and aromatic hydrocarbons are believed to be important pathways for the formation of aromatic nitriles in the interstellar medium (ISM) including those identified in the Taurus […]

Structure and genetics of the nitrogenase G-subunit. A) Left, crystallographic structure of the extant A. vinelandii Vnf nitrogenase complex (VnfH, PDB 6Q9336; VnfDGK, PDB 5N6Y22 ) containing the G-subunit (dark blue). The Anf nitrogenase is inferred to be comparable in its multimeric structure, binding FeFe-co instead of FeV-co. Right, crystallographic structure of the extant Nif nitrogenase complex (NifH, PDB 1M3437; NifDK, PDB 3U7Q38) lacking the G subunit. B) Secondary structure of the Vnf G-subunit. C) Arrangement of the Nif, Vnf, and Anf structural genes in A. vinelandii. Vnf/AnfG (dark blue) is located between Vnf/AnfD and Vnf/AnfK genes. -- biorxiv.org

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Microbiology & Virology, Plant Biology, Status Report

An Orphan Protein Drove The Ecological Expansion Of Nitrogen Fixation

by Keith CowingApril 10, 2023April 10, 2023

Nitrogenases have catalyzed biological nitrogen fixation for billions of years and revolutionized planet Earth by supplying essential nitrogen to the biosphere.