astro-ph.EP Archives

Poynting flux divergence in (a) the bow shock nose and (b) magnetopause reconnection regions. Simulation with southward IMF orientation, |B|IMF = 30 nT and Pd = 1.2 nPa. Black lines indicate the region of the bow shock (n > 20 cm−3 ), the red lines the exoplanet magnetic field lines and the pink iso-surface the reconnection region in the XZ plane (|B| < 5 nT). -- -astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biophysics, Exoplanets, -moons, -comets, Habitable Zones, Radiation, Space Weather & Heliophysics, Water/Hycean Worlds & Oceanography

MHD Study Of Extreme Space Weather Conditions For Exoplanets With Earth-like Magnetospheres: On Habitability Conditions And Radio-emission

by Keith CowingApril 18, 2023April 27, 2023

The present study aims at characterizing the habitability conditions of exoplanets with an Earth-like magnetosphere inside the habitable zone of M stars and F stars like tau Boo, caused by […]

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 […]

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 […]

Covariance matrices computed for X and Ka band atmospheric absorptivity from RO simulations for the Set 1 model atmosphere. The corresponding 1σ uncertainties are shown in context bracketing the absorptivity profiles. -- astro-ph.EP

Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report, Venus

Approaches for Retrieving Sulfur Species Abundances from Dual X/Ka Band Radio Occultations of Venus with EnVision and VERITAS

by Keith CowingApril 17, 2023April 17, 2023

The EnVision and VERITAS missions to Venus will fly with X and Ka band telecommunications channels which can be used to conduct radio occultation studies of Venus’ atmosphere.

Water production rate in comet C/2021 A1 (Leonard) as a function of time from perihelion. The points give the water production rate in s-1 from single images. The error bars give the 1-s formal random fitting errors for each value. There is a ~30% uncertainty from the model parameters and calibration. -- astro-ph.EP

Astrochemistry, Comets and Asteroids, Status Report

Water Production Rates from SOHO/SWAN Observations of Comets C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS)

by Keith CowingApril 11, 2023April 11, 2023

In 2021 and 2022 the hydrogen comae of three long period comets, C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS) were observed with the Solar Wind ANisotropies (SWAN) […]

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.

Two example cases comparing the outputs of one of the NN models with the corresponding TEA outputs. Left: Case where the NN’s predictions closely match the outputs of TEA, at a temperature of ∼1053 K, log C/H of -3.57, log N/H of -4.17, and log O/H of -3.31 over the full range of pressures considered in Table 1. Right: Case where the NN performs less accurately, at a temperature of ∼2112 K, M/H of 2.5, and C/O of 0.9 (log C/H of -0.956, log N/H of -1.556, and log O/H of -0.910). Despite the less accurate performance, the NN’s predictions are within an order of magnitude of the true values except for H2O, CO2, and HCN at the lowest pressures. Only abundances ≥ 10−15 are shown for clarity. -- astro-ph.EP

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

Towards 3D Retrieval of Exoplanet Atmospheres: Assessing Thermochemical Equilibrium Estimation Methods

by Keith CowingApril 4, 2023April 4, 2023

Characterizing exoplanetary atmospheres via Bayesian retrievals requires assuming some chemistry model, such as thermochemical equilibrium or parameterized abundances. The higher-resolution data offered by upcoming telescopes enables more complex chemistry models […]

Representation of the adopted strategy for the network-based approach, where the ANN component has been redesigned with respect to the DL model derived from PHOENIX-ACES spectra (to be compared with Fig. 1 of Passegger et al. 2020). -- astro-ph.IM

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

The CARMENES Search For Exoplanets Around M Dwarfs — A Deep Transfer Learning Method To Determine Teff And [M/H] Of Target Stars

by Keith CowingApril 4, 2023April 4, 2023

The large amounts of astrophysical data being provided by existing and future instrumentation require efficient and fast analysis tools.

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 […]

astro-ph.EP

MHD Study Of Extreme Space Weather Conditions For Exoplanets With Earth-like Magnetospheres: On Habitability Conditions And Radio-emission

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

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

Earth Was Shaped By Primordial Hydrogen Atmospheres

Approaches for Retrieving Sulfur Species Abundances from Dual X/Ka Band Radio Occultations of Venus with EnVision and VERITAS

Water Production Rates from SOHO/SWAN Observations of Comets C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS)

The Runaway Greenhouse Effect on Hycean Worlds

Towards 3D Retrieval of Exoplanet Atmospheres: Assessing Thermochemical Equilibrium Estimation Methods

The CARMENES Search For Exoplanets Around M Dwarfs — A Deep Transfer Learning Method To Determine Teff And [M/H] Of Target Stars

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

Relevance of the Avalon Assemblage as an Astrobiological Analog for Icy Ocean Worlds

The Climate and Potential Habitability of a Warm and Oxygenated Mars

Variable X-ray flux May Explain Variable Helium Escape From The Habitable-zone Exoplanet LHS 1140b

Spacetime Contactability in Galactic Civilization Networks: Contact Counts and Percolation

Surprisingly Enriched CO and CH4 in Halley-type Comet 13P/Olbers: Clues to Its Interstellar Heritage