Atmospheres, Climate, Weather Archives

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Status Report, Venus

Stability Of Nucleic Acid Bases In Concentrated Sulfuric Acid: Implications For The Habitability Of Venus’ Clouds

by Keith CowingJuly 3, 2023July 3, 2023

What constitutes a habitable planet is a frontier to be explored and requires pushing the boundaries of our terracentric viewpoint for what we deem to be a habitable environment.

Theoretical stability of subsurface water-ice with respect to diffusion for a) flat surfaces b) 30° pole-facing slopes, using a nominal near-surface humidity. The red curve is the 10% Water-Equivalent Hydrogen contour, which is a good proxy for the presence of water ice in the shallow subsurface (Pathare et al., 2018). White dots indicate exposed water ice along cliff scarps and impact craters as reported in Dundas, Becerra, et al. (2021); Dundas et al. (2023) White diamonds indicate exposed water ice along gullies (Khuller & Christensen, 2021). -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Mars, Status Report

A Reappraisal of Near-Tropical Ice Stability on Mars

by Keith CowingJune 29, 2023June 29, 2023

Two arguments have suggested the presence of subsurface water ice at latitudes lower than 30° Mars.

Comparison between HST and AstroSat-measured SEDs of HIP 23309 in the FUV (1300-1700 A). Top plot shows data in linear y-scale with error bars; bottom plot is identical to top plot except with log y-scale and omission of error bars for easier viewing. The cyan and black data correspond to the unbinned HST and UVIT data, respectively. The blue points correspond to HST data degraded to the approximate quality of the AstroSat data, to enable a closer comparison. The green points correspond to the AstroSat data binned down by a factor of 5, to improve SNR and enable better visual comparison. We assumed Gaussian uncorrelated noise when rebinning the AstroSat data. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

UV Spectral Characterization of Low-Mass Stars With AstroSat UVIT for Exoplanet Applications: The Case Study of HIP 23309

by Keith CowingJune 29, 2023June 29, 2023

Characterizing rocky exoplanet atmospheres is a key goal of exoplanet science, but interpreting such observations will require understanding the stellar UV irradiation incident on the planet from its host star.

TESS target pixel file images of TOI-2084 observed in Sector 16 (left panel) and TOI-4184 observed in Sector 1 (right panel), made by tpfplotter (Aller et al. 2020). Red dots show the location of Gaia DR3 sources, and the red shaded region shows the photometric apertures used to extract the photometric measurements. -- astro-ph.EP

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

TOI-2084 b and TOI-4184 b: Two New Sub-Neptunes Around M Dwarf Stars

by Keith CowingJune 28, 2023June 28, 2023

We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, SED […]

Manifestation of the scattering transparency effect in the transit spectrum of TRAPPIST-1e system having a water cloud with 𝜏=1 and 𝑍c=100 km. The transit spectrum is simulated with MC calculations for cloud particles having an 𝑟eff=20 µm. The dashed lines are the spectra obtained for constant values of 𝑔. The actual spectra, after considering the spectral variations of 𝑔, are shown in bold lines. They are obtained by interpolating among the dashed spectra. The blue curves do not consider the spectral variations of 𝜔 whereas the red curves consider the realistic variation 𝜔 for water clouds which leads to the spectral features of water droplets. Gas absorption is not considered. The spectral rise towards shorter wavelengths in the dashed curves is due to Rayleigh scattering. A color gradient for 𝑓 × 𝜔, which is a measure of scattering transparency, is shown in the background. This gradient of 𝑓 × 𝜔 is same as that shown in figure 3 for TRAPPIST-1e system. -- astro-ph.EP

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

Scattering Transparency of Clouds in Exoplanet Transit Spectra

by Keith CowingJune 27, 2023June 27, 2023

The presence of aerosols in an exoplanet atmosphere can veil the underlying material and can lead to a flat transmission spectrum during primary transit observations.

Planet in the habitable zone of a later F-class star

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

Activity Time Series Of Old Stars From Late F To Early K VI. Exoplanet Mass Characterisation And Detectability In Radial Velocity

by Keith CowingJune 26, 2023June 26, 2023

Stellar variability impacts radial velocities at various timescales and therefore the detectability of exoplanets and the mass determination based on this technique. It is necessary to implement systematic studies, to […]

Model transmission spectrum of our canonical Hycean world K2-18 b. The model spectrum with all the molecules included is shown in grey. The spectra with the individual contributions of the different molecular species are shown as denoted in the legend. The synthetic JWST observations corresponding to the full model are shown as the gold-centered black points with error bars binned to a resolution of R= 40. The observations include one transit with NIRISS SOSS, three transits with NIRSpec G395H and two transits with MIRI LRS, as discussed in section 4. -- astro-ph.EP

Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Chemical Conditions On Hycean Worlds

by Keith CowingJune 26, 2023June 26, 2023

Traditionally, the search for life on exoplanets has been predominantly focused on rocky exoplanets. Hycean worlds are a class of habitable sub-Neptunes with planet-wide oceans and H2-rich atmospheres. Their broad […]

Artist impression showing the exoplanet LP 890-9c’s potential evolution from a hot Earth to a desiccated Venus. Carl Sagan Institute/R. Payne

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release, TRAPPIST-1, Venus, Water/Hycean Worlds & Oceanography

Exoplanet LP 890-9c May Reveal Secrets About The Edge Of Habitability

by Keith CowingJune 21, 2023June 21, 2023

How close can a rocky planet be to a star, and still sustain water and life? A recently discovered exoplanet may be key to solving that mystery.

Time-mean vertically-integrated cloud water amount (including both liquid and ice) simulated by the three models. Left panels are for TRAPPIST-1e, and right panels are for K2-72e. The global-mean values are listed in the top left corner of each panel. The red cross marks the substellar point. The blue dashed line is the morning terminator and the blue dotted line is the evening terminator, used for transmission spectra calculations (Fig. 6 below). SAM has less total cloud water path. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Imaging & Spectroscopy, Status Report

Cloud Behaviour On Tidally Locked Rocky Planets From Global High-resolution Modeling

by Keith CowingJune 21, 2023June 21, 2023

Determining the behaviour of convection and clouds is one of the biggest challenges in our understanding of exoplanetary climates.

Top: Predicted fundamental frequency distribution for all molecules in the CHNOPS2743-HARMONIC dataset of potential biosignatures. Please note that this plot is not a spectrum but a histogram of the all calculated frequencies. Bottom-left: Distribution of calculated vibrational transition intensities. Bottom-right: Comparison between the strongest vibrational transition intensity per molecule with its corresponding predicted fundamental frequency. Note that only intensities with up to 500 km/mol and frequencies above 2000 cm−1 are consider for the sake of readability. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

High-throughput Quantum Chemistry: Empowering The Search For Molecular Candidates Behind Unknown Spectral Signatures In Exoplanetary Atmospheres

by Keith CowingJune 21, 2023June 21, 2023

The identification of molecules in exoplanetary atmospheres is only possible thanks to the availability of high-resolution molecular spectroscopic data. However, due to its intensive and time-consuming generation process, at present, […]

Atmospheres, Climate, Weather

Stability Of Nucleic Acid Bases In Concentrated Sulfuric Acid: Implications For The Habitability Of Venus’ Clouds

A Reappraisal of Near-Tropical Ice Stability on Mars

UV Spectral Characterization of Low-Mass Stars With AstroSat UVIT for Exoplanet Applications: The Case Study of HIP 23309

TOI-2084 b and TOI-4184 b: Two New Sub-Neptunes Around M Dwarf Stars

Scattering Transparency of Clouds in Exoplanet Transit Spectra

Activity Time Series Of Old Stars From Late F To Early K VI. Exoplanet Mass Characterisation And Detectability In Radial Velocity

Chemical Conditions On Hycean Worlds

Exoplanet LP 890-9c May Reveal Secrets About The Edge Of Habitability

Cloud Behaviour On Tidally Locked Rocky Planets From Global High-resolution Modeling

High-throughput Quantum Chemistry: Empowering The Search For Molecular Candidates Behind Unknown Spectral Signatures In Exoplanetary Atmospheres

Astrobiologist Dale Andersen’s Antarctic Field Report: 9 November 2026: Lake Untersee Basecamp Update

Astrochemistry: Hubble and JWST Observe Star Formation in The Carina Nebula

Mapping the Historical Roots of Astrobiology: A Reference Publication Year Spectroscopy (RPYS) Analysis

The Agentic Observer Hackathon: Autonomous Decision-making in Simulated Astronomical Surveys

Tracking The Evolution of sub-Neptunes. I. Gyrochronology of Planet Hosting Stars