astro-ph.EP Archives

Variation of the planetary radius, expressed as transit depth, as a function of wavelength.

Long-term Monitoring Of WASP-19 b: Signs Of Apsidal Precession And Molecular Signatures

by Keith CowingMarch 17, 2026March 17, 2026

With more than 6000 exoplanets discovered so far, about 12 percent are hot Jupiters. Their large sizes and short orbital periods make them valuable targets for studying planetary formation, atmospheres, […]

Mg/Si ratios of JWST-observed hot Jupiter host stars versus separation (semi-major axis).

Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Imaging & Spectroscopy, Status Report

Bridging the Gap: Using Brown Dwarfs to Examine Silicate Clouds in Giant Exoplanet Atmospheres

by Keith CowingMarch 17, 2026March 17, 2026

We present results from examining the silicate cloud modeling of four JWST-observed hot Jupiters in the context of brown dwarf theory to further explore signatures of formation in present-day atmospheres.

Velocity and line-width residuals derived from discminer models applied to synthetic observations of planet-disc interaction (q = 2 × 10−3 , ϕp = −45◦ ) and disc instabilities. Details of the simulation setups are provided in Sect. 3.1. All discs are inclined by −30◦ , and the residuals from all mechanisms are shown on the same color scale indicated on the left. Semi red-blue circles in the bottom left corners of the top-row panels indicate the locations of the redshifted and blueshifted sides of the simulated disc, which are useful to understand the velocity structure of the non-Keplerian flows -- astro-ph.EP

Astrogeology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

exoALMA XX: Tomographic Detection of Embedded Planets in Protoplanetary Disks

by Keith CowingMarch 16, 2026March 16, 2026

The exoALMA Large Program has revealed a wealth of substructures in the dust and molecular line emission of several protoplanetary discs, suggesting that planet formation may unfold within highly dynamic […]

Numerical ocean-induction setup for Ganymede in a deep-ocean scenario with Re m = 1.77. Ganymede’s internal structure is depicted, featuring the ice crust, the deep ocean with its simulated zonal flow, the internal ice layer, the silicate mantle, and the metallic core. Yellow tubes visualize the magnetic field lines. The bottom-right panel shows how magnetic field lines are sheared by the zonal (east–west) jet flow in the ocean (blue/red denote westward/eastward jets, respectively), thereby reflecting the secondary magnetic field induced by such dynamics. -- astro-ph.EP

Astrogeology, Ganymede, Icy Worlds, Jupiter, Magnetic Fields, Electromagnetism, bioelectricity,, Mapping, Geodesy, Cartography, Bathymetry, Status Report, Water/Hycean Worlds & Oceanography

Motional Induction In Ganymede’s Ocean

by Keith CowingMarch 14, 2026March 14, 2026

We investigate the magnetic signature of oceanic circulation in Ganymede’s subsurface ocean using kinematic induction modeling. Our approach couples zonal jet flows from rotating thermal convection simulations with magnetic field […]

Stacked images of 3I/ATLAS acquired by HiRIC CMOS camera onboard Tianwen-1 spacecraft (upper row) and the corresponding 1/ρ divided images (lower row) from the three epochs. All images are displayed north up and east to the left. The stacked images are displayed with logarithmic brightness stretch, and the enhanced images are displayed with a linear brightness stretch. The arrows in the upper panels mark the projected directions of the Sun and the heliocentric velocity vector. The scalebars are 10,000 km. The bright star trails are visible in each stack due to the apparent movement of 3I in the sky background during each 30-second observation epoch. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Interstellar Object 3I/ATLAS Observed from Mars by China’s Tianwen-1 Spacecraft

by Keith CowingMarch 14, 2026March 14, 2026

China’s Tianwen-1 Mars orbiter successfully imaged the third interstellar object, 3I/ATLAS, during its close encounter with Mars using the onboard HiRIC CMOS camera. This is China’s first deep-space observation of […]

Mars-like Exoplanet -- Grok via Astrobiology.com

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

Oxygenated False Positive Biosignatures in Mars-like Exoplanet Atmospheres

by Keith CowingMarch 14, 2026March 14, 2026

Oxygen is a well-studied biosignature. Studying potential abiotic pathways for O2 build-up in exoplanet atmospheres is essential for evaluating whether the detection of O2 would constitute a biosignature detection on […]

Blue and red Shane/Kast optical spectrum of TOI-4616 (black line) compared to the best-fit M4 SDSS spectral template from Bochanski et al. (2007, magenta line). Key spectral features are indicated, including regions of strong telluric absorption (⊕). The inset box shows the 6520–6770 ˚𝐴 region encompassing the strong 6563 ˚𝐴 H𝛼 emission line and absent 6708 ˚𝐴 Li i absorption. -- astro-ph.EP

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

TOI-4616 b: A Benchmark Earth-sized Planet Transiting A Nearby M4 Dwarf

by Keith CowingMarch 14, 2026March 14, 2026

Rocky exoplanets are particularly abundant around M-type stars. Their small radii and low luminosities provide favourable conditions for detecting transiting terrestrial planets and probing their atmospheric properties.

JWST observations of WASP-107 b (colored vertical bars) along with the best fit model (black line; Kzz = 109 cm2 s −1 ), resulting in a χ˜ 2 red = 3.4. The NIRISS observations are shifted vertically by 130 ppm to match the NIRCam data at the wavelengths where they overlap. The runs with higher and lower Kzz are shown with blue and brown lines, respectively, to illustrate the spectroscopic effects of varying the turbulent diffusivity. The simulated spectrum of a cloudless atmosphere is plotted in gray -- astro-ph.EP

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

A Cloudy Fit To The Atmosphere of WASP-107 b

by Keith CowingMarch 13, 2026March 13, 2026

Context. WASP-107 b has been observed comprehensively by JWST in the near- and mid-IR bands, making it an ideal planet to probe the composition and internal dynamics. Recent analysis reveals […]

(Left) Predicted concretion diameter for different nucleation density scaling exponents α. For α ≤ 1, diffusion controls at the Mars dust grain size and predictions match observations (green band). For α ≥ 1.5, nucleation dominates even at 3 µm, predicting concretions well below the observed range, ruled out by the data. (Right) Crossover grain size as a function of α (log scale). Green region: diffusion-limited zone (crossover above Mars dust at 3 µm). Pink region: nucleation-limited zone. The graincontact derivation (dotted line, α = 1) sits within the diffusion-limited zone, consistent with observations. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Mars, Status Report

Martian Concretion Sizes Predicted From Two Independently Constrained Inputs: Atmospheric Dust Grain Size And Obliquity-forced Wetting Duration

by Keith CowingMarch 13, 2026March 13, 2026

Diagenetic concretions have been identified at multiple widely separated sites on Mars, including Meridiani Planum (Opportunity), Gale crater (Curiosity), and Jezero crater (Perseverance).

CH3OH/H2O column density ratio found in the literature for a wide range of clouds, YSOs and Solar System comets (see Sect 4.1 for the references). The values for molecular clouds, LYSOs and MYSOs reflect the ice composition, while the ratio was measured in the gas-phase for protoplanetary disks and comets. We used open symbols for the protoplanetary disks in which the upper/lower limit on the methanol-to-water column density ratio was estimated combining measurements taken at different wavelength ranges. The upward triangles for the HD 100546 and the IRS 48 disks indicate a lower limit, whereas the downward triangles for DG Tau A and HL Tau indicate a upper limit. The values for HL Tau are taken dividing the 3σ upper limit on the NCH3OH for the three different assumed excitation temperature in Table 2 for the water column density measured by Facchini et al. (2024). -- astro-ph.SR

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Status Report

Hunting For Methanol In The Water Rich, Planet Forming Disk Aaround HL Tau

by Keith CowingMarch 13, 2026March 13, 2026

Methanol, the simplest complex organic molecule found in space, is considered a key compound necessary for the formation of chemical species of prebiotic interest. Methanol detections in protoplanetary disks remain […]

astro-ph.EP

Long-term Monitoring Of WASP-19 b: Signs Of Apsidal Precession And Molecular Signatures

Bridging the Gap: Using Brown Dwarfs to Examine Silicate Clouds in Giant Exoplanet Atmospheres

exoALMA XX: Tomographic Detection of Embedded Planets in Protoplanetary Disks

Motional Induction In Ganymede’s Ocean

Interstellar Object 3I/ATLAS Observed from Mars by China’s Tianwen-1 Spacecraft

Oxygenated False Positive Biosignatures in Mars-like Exoplanet Atmospheres

TOI-4616 b: A Benchmark Earth-sized Planet Transiting A Nearby M4 Dwarf

A Cloudy Fit To The Atmosphere of WASP-107 b

Martian Concretion Sizes Predicted From Two Independently Constrained Inputs: Atmospheric Dust Grain Size And Obliquity-forced Wetting Duration

Hunting For Methanol In The Water Rich, Planet Forming Disk Aaround HL Tau

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