astro-ph.EP Archives

An artist’s rendition of Saturn’s moon Enceladus depicts hydrothermal activity on the seafloor and cracks in the moon’s icy crust that allow material from the watery interior to be ejected into space. New research shows that instruments destined for the next missions could find traces of a single cell in a single ice grain contained in a plume. NASA/JPL-Caltech

Astrochemistry, Astrogeology, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Enceladus, Habitable Zones, Icy Worlds, Status Report

Tidal Rock Grinding As A Source Of H2 On Enceladus

by Keith CowingJune 16, 2026June 16, 2026

The Solar System hosts multiple potentially habitable environments, including the subsurface ocean beneath the icy crust of Saturn’s moon Enceladus.

Schematic diagram of the domain (not to scale). The red line represents the outer boundary of the core; the blue line is the outer boundary of the BMO. (a) 𝑥–𝑧 (meridional) plane. The 𝑧 axis is Earth’s rotation axis and normal to the orbital plane. (b) 𝑥–𝑦 (orbital and equatorial) plane. The blue BMO ellipse always has its long axis aligned with the Moon, but the long axis of the red CMB ellipse can have a non-zero phase lag 𝛥𝜙 relative to the Moon. Throughout the main text, we assume that the solid mantle is static, in which case the BMO outer boundary is undeformed; we consider its deformation in appendix D. -- astro-ph.EP

Astrogeology, Lava / magma ocean / Volcanic Worlds, Moon, Origin & Evolution of Life, Status Report

Resonant Lunar Tides Of Earth’s Core And Basal Magma Ocean

by Keith CowingJune 16, 2026June 16, 2026

Earth’s magnetic field is generated by fluid motion in the liquid-metal core and has been active for billions of year.

The distribution of planetary radius and orbital period of TOIs and new false positives and planet candidates. COUNTESS discovered 38 new planetary signals, with 28 of them being FPs through triceratops validation and LEOVetter pixel-vetting. Note that the square symbols indicate TOI FPs that were successfully recovered as FPs through COUNTESS. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography

COUNTESS I: A Uniformly Vetted Catalog of Known and New Transiting Exoplanets in the TESS Northern Continuous Viewing Zone

by Keith CowingJune 15, 2026June 15, 2026

The Transiting Exoplanet Survey Satellite (TESS) has transformed the study of nearby exoplanetary systems; however, its nominal observing strategy limits sensitivity to planets with orbital periods shorter than ∼10 days […]

Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Desert Worlds, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Mars, Status Report

Coupling Dynamical Accretion And Chemical Differentiation: A Unified Framework For Earth-Mars Diversity

by Keith CowingJune 15, 2026June 15, 2026

The distinct physical and geochemical differences between Earth and Mars provide fundamental constraints on terrestrial planet formation, yet a self-consistent framework linking dynamical and chemical aspects remains elusive.

GLS periodograms of individual wavelength contrast lightcurves. In each of the panels, the light pink, dark pink, and black highlighted lines are the 1st, 2nd, and 3rd 12CO bandheads, respectively. The grey horizontal lines indicate the 1%, 5%, and 10% false alarm probabilities. The black vertical lines indicate the expected rotation period at 8.7 hrs and its first integer harmonic at 4.35 hrs. The top panel shows the uncorrected periodogram, with all wavelengths significantly affected by systematic effects caused by the fibre coupling. The middle panel shows the periodogram after the polynomial correction, while the bottom panel adds Gaussian smoothing to this to highlight strong periodic signals. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Beta Pictoris, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

13CO And Potential Variability In β Pictoris b With GRAVITY+

by Keith CowingJune 14, 2026June 14, 2026

The 12CO/13CO ratio was introduced as an indicator for where in the disk a planet has formed. Previously a lower value compared to the host star’s was suggested to show […]

Locations of the four candidate sites across a 2D map projection of Bennu’s surface captured by the OSIRIS-REx Camera Suite (OCAMS) (Bennett et al., 2021).

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Missions & Hardware, Sample Return, Status Report

Quantifying Surface Heterogeneity Across Asteroid (101955) Bennu using Candidate Site Remote Sensing Data

by Keith CowingJune 13, 2026June 13, 2026

The OSIRIS-REx mission acquired spatially resolved (2-10 m spot sizes) visible-near infrared (VNIR) and thermal infrared (TIR) spectra across four candidate sampling sites on asteroid (101955) Bennu: Nightingale, Osprey, Sandpiper, […]

Carbon isotope ratio as a function of the semi-major axis for young, directly-imaged companions. Measurements in the HR 8799 system for planets e, b, and c (Ruffio et al. 2026) are shown with squares and connected with a dotted line. The other measurements are for HD 984 b (Costes et al. 2024), GQ Lup b (González Picos et al. 2025b), VHS 1256 b (Gandhi et al. 2023), YSES 1 b (Zhang et al. 2024), AB Pic b (Gandhi et al. 2025), and DH Tau b and HIP 79098 b (Xuan et al. 2024a). The present-day local ISM (12C/13C = 68±14; Milam et al. 2005) and solar photospheric value (12C/13C⊙ = 91.4 ± 1.3; Lyons et al. 2018) are overlaid. The horizontal line spans the typical CO snow-line location for a solar-type host star (22–36 au). For stars hotter than the Sun, the CO snow line is expected at distances greater than 30 au, so β Pic b is located interior to the CO snow line. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report

The Carbon Isotope Ratio Of β Pic b With High-resolution Spectroscopy

by Keith CowingJune 13, 2026June 13, 2026

Isotopic ratios trace the formation and evolution of planets and link their atmospheres to the chemistry of their natal protoplanetary discs.

NIRSpec average spectrum of Titan (black) compared with a radiative transfer calculation in which the surface albedo decreases smoothly with wavelength beyond 4.9 µm (red). The blue line shows the difference between the observed and synthetic spectra, shifted by 0.005 for clarity. The 5.11-µm absorption is clearly missing in the model. The small mismatch below 4.93 µm is due to a component of the non-LTE CO emission not included in the model. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Pluto, Status Report, Titan

An Unidentified Absorption Feature At 5.11 μm On The Surface Of Titan And Pluto From JWST Spectroscopy

by Keith CowingJune 12, 2026June 12, 2026

Titan possesses a thick N2-CH4 atmosphere that makes it difficult to study its surface spectroscopically. The chemical composition of the solid surface of Titan thus remains very uncertain.

New fall lines for the Pust'e U'lany meteorite fall. Red lines correspond assuming a spherical shape (eastern extremities correspond to ∼5 g), with four WRF models (labels correspond to initialisation time). Two of the models match the find quite well laterally. Along the fall line, a higher drag shape (cylinder option in the code of M. C. Towner et al. (2022)) provides a somewhat better fit (yellow line). This figure is adapted from Fig. 8 of L. Shrben´y et al. (2026). -- astro-ph.EP

Away Teams & Field Reports, Meteorites & Asteroids, Planetary Protection & Biosafety, Sample Return, Status Report

Freo Doctor: Atmospheric Modelling for Meteorite Falls and Spacecraft Re-Entries

by Keith CowingJune 10, 2026June 10, 2026

How much does the wind affect the path of meteorite falls? We finely model the lower ~30 km of the atmosphere using Weather Research and Forecasting open source tools at […]

Simulated Ariel single-epoch spectral observations of 3 targets from our sample.

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

Assessing Ariel’s Capabilities To Observe Free-floating Brown Dwarfs

by Keith CowingJune 10, 2026June 10, 2026

The primary goal of the Ariel space telescope is to conduct the biggest spectroscopic survey of transiting exoplanets to characterize their atmospheres and weather.

astro-ph.EP

Tidal Rock Grinding As A Source Of H2 On Enceladus

Resonant Lunar Tides Of Earth’s Core And Basal Magma Ocean

COUNTESS I: A Uniformly Vetted Catalog of Known and New Transiting Exoplanets in the TESS Northern Continuous Viewing Zone

Coupling Dynamical Accretion And Chemical Differentiation: A Unified Framework For Earth-Mars Diversity

13CO And Potential Variability In β Pictoris b With GRAVITY+

Quantifying Surface Heterogeneity Across Asteroid (101955) Bennu using Candidate Site Remote Sensing Data

The Carbon Isotope Ratio Of β Pic b With High-resolution Spectroscopy

An Unidentified Absorption Feature At 5.11 μm On The Surface Of Titan And Pluto From JWST Spectroscopy

Freo Doctor: Atmospheric Modelling for Meteorite Falls and Spacecraft Re-Entries

Assessing Ariel’s Capabilities To Observe Free-floating Brown Dwarfs

A Martian Horizon Last Monday Afternoon

Habitable-zone Earths At The Detection Frontier: Measured Completeness And False-alarm Rate Of A Transit Pipeline For The PLATO M-dwarf Sample

A Homogeneous Survey Of JWST MIRI Transmission Spectra Of 10 Exoplanets

Retrieving Ocean Glint Reflectance Signatures From Directly Imaged Earth-like Exoplanets

Analytical Platform (Microsampling, Catapulting, Trapping, and LIBS) for the Characterization of Discrete Domains in Samples of Astrochemical Interest