astro-ph.EP Archives

Lower-triangular Pearson correlation matrix of the final feature set used in this study. Each cell shows the Pearson correlation coefficient between a pair of planetary or stellar properties, with the color scale ranging from −1 (strong negative correlation) to +1 (strong positive correlation). The diagonal elements represent self-correlations. To improve readability, only moderate to strong correlations (|r| ≥ 0.5) are annotated. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Mapping, Geodesy, Cartography, Bathymetry, Nomenclature, Systematics, Natural History, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

Active Learning For Planet Habitability Classification Under Extreme Class Imbalance

by Keith CowingMarch 10, 2026March 10, 2026

The increasing size and heterogeneity of exoplanet catalogs have made systematic habitability assessment challenging, particularly given the extreme scarcity of potentially habitable planets and the evolving nature of their labels.

Planetary system of GJ 1137 relative to the conservative habitable zone (cHZ; green) and the optimistic habitable zone (oHZ; yellow), respectively. Black orbital bands come from our 1σ posteriors of the orbital parameters of GJ 1137 b and GJ 1137 c.-- astro-ph.EP

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

Long-period Magnetic Activity In The K Dwarf GJ 1137 And A New Super-Earth On A 9-day Orbit

by Keith CowingMarch 9, 2026March 9, 2026

Aims: We investigate long-term radial velocity (RV) variability in the K-dwarf star GJ 1137 (HD 93083, HIP52521), a known Saturn-mass exoplanet host, and assess the role of stellar activity in […]

The absorption cross sections of common absorbers in exoplanet atmospheres considered in this work, shown at a pressure and temperature of 0.1 mbar and 1000 K. The wavelength coverage of Pandora’s NIR detector (NIRDA), JWST’s NIRCam F322W2 and F444W filters, and HST’s WFC3 instrument (for the G141 grism) are shown. Pandora/NIRDA covers absorption bands of H2O, CH4, NH3 and the wing of the K doublet, making it most sensitive to these absorbers. -- NASA

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

NASA’s Pandora SmallSat Mission: Simulated Modeling and Retrieval of Near-Infrared Exoplanet Transmission Spectra

by Keith CowingMarch 9, 2026March 9, 2026

Pandora is a SmallSat mission dedicated to understanding exoplanets and their host stars by disentangling the impact of stellar heterogeneity on exoplanet transmission spectra.

Snapshots of mantle temperature and melt fraction (top row) and basalt fraction (bottom row) at 6.5 Gyr for each interior model of K2-141 b. All models show a shallow magma ocean on the dayside (left hemisphere) and a solid nightside (right hemisphere). Models without plastic yielding (MixCC, MBasal, MixIntr), exhibit upwellings at the substellar and antistellar points, with downwellings forming at the day-night terminators. MPlastic, which includes plastic yielding (lithospheric weakening), displays a more asymmetric pattern, with downwellings forming on the nightside and upwellings rising preferentially on the dayside. Videos for these model runs are available online and on Zenodo (Meier 2025). -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Lava / magma ocean / Volcanic Worlds, Status Report

Mantle Convection And Nightside Volcanism On Lava World K2-141 b

by Keith CowingMarch 8, 2026March 8, 2026

Ultra-short period lava worlds offer a unique window into the coupled evolution of planetary interior and atmospheres under extreme irradiation.

Additional analysis for the tentative cross-correlation signal observed for H2S. We show the cross-correlation S/N as a function of the orbital parameters of the planet. In each case, the expected parameters are marked with crosshairs. Left: The S/N is shown as a function of planetary velocity space, parameterised by 𝐾p and 𝑉sys, reproduced from the top panel of Figure 3 but with a more zoomed in colorscale. A tentative peak with a S/N of 1.7 is observed at the expected systemic velocity. Right: the time duration of the observed H2S cross-correlation signal is constrained with a value that is consistent with the literature value for the transit duration of the planet. This is measured by varying the number of spectra considered to be in-transit (𝑁in) when calculating the cross-correlation S/N, with 𝐾p fixed to that expected for this planet. -- astro-ph.EP

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

Ground-based Atmospheric Characterization of Super-Earth L 98-59 d at High Spectral Resolution

by Keith CowingMarch 8, 2026March 8, 2026

Atmospheric characterization of exoplanets using ground-based high-resolution transmission spectroscopy has traditionally focussed on large and close-in planets, such as hot Jupiters.

Geographic locations of the observatories from which photometric data were obtained. Colors correspond to observatory names and telescope apertures given in the legend. Insets indicate regions with clustered sites. -- astro-ph.EP

Astrochemistry, Astrogeology, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report

Time-Domain Photometry and Activity Evolution of Interstellar Comet 3I/ATLAS with BHTOM

by Keith CowingMarch 7, 2026March 7, 2026

Time-domain photometric monitoring is essential for characterizing cometary evolution, particularly for rare interstellar objects with limited observing opportunities.

Chemical structures of selected ILs and DES.

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Origin & Evolution of Life, Status Report

Ionic Liquid Biospheres

by Keith CowingMarch 6, 2026March 6, 2026

Liquid is a fundamental requirement for life as we understand it, but whether that liquid has to be water is not known.

Mars topographic map showing the inventory of observed data relating to water flow effects.

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Mapping, Geodesy, Cartography, Bathymetry, Mars, Status Report, Water/Hycean Worlds & Oceanography

A Global High-Resolution Hydrological Model to Simulate the Dynamics of Surface Liquid Reservoirs: Application on Mars

by Keith CowingMarch 6, 2026March 6, 2026

Surface runoff shapes planetary landscapes, but global hydrological models often lack the resolution and flexibility to simulate dynamic surface water bodies beyond Earth. Recent studies of Mars have revealed abundant […]

Schematic structure of the planet in our model. From top to bottom, the planet consists of four layers: a nebular-composition envelope (pure H2), a vapor-mixed envelope (H2 + H2O), a reactive magma layer, and a non-reactive (inert) magma layer. Only the vapor-mixed envelope and the reactive magma are assumed to interact. If the radiative–convective boundary (RCB) lies within the nebular– composition layer, its convective part is assumed to mix with the vapor-mixed layer. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Status Report

Water Enrichment Of Forming Sub-Neptune Envelopes Limited By Oxygen Exhaustion

by Keith CowingMarch 6, 2026March 6, 2026

The interaction between a magma ocean and a primordial atmosphere is increasingly recognized as a key process in shaping planetary envelope compositions.

Distribution of companions in semi-major axis and mass, along with the occurrence rate density of subsamples. (a), Detection efficiency-weighted KDE and distribution of our sample (white points). We divide the sample into low-mass and high-mass subsamples, with the division marked by a dashed red line at 30MJ. Detection efficiencies of 20% is outlined by a black contour. (b), The occurrence rate density vs companion mass (dN/d ln m per 100 stars). The best-fit log-normal plus power-law model with its uncertainty is overplotted. The uncertainties correspond to the 16th and 84th percentiles of the posterior distributions. (c), The occurrence rate density vs semi-major axes (dN/d ln a per 100 stars), when companion mass above 30MJ. (d), similar to c but for companions with m < 30MJ.

Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Status Report, Stellar Cartography

A Universal Brown Dwarf Desert Formed Between Planets And Star

by Keith CowingMarch 5, 2026March 5, 2026

Giant planets and brown dwarfs play a crucial role in star and planet formation, as they are situated at the boundary between planets and stars with uncertain formation mechanisms.

astro-ph.EP

Active Learning For Planet Habitability Classification Under Extreme Class Imbalance

Long-period Magnetic Activity In The K Dwarf GJ 1137 And A New Super-Earth On A 9-day Orbit

NASA’s Pandora SmallSat Mission: Simulated Modeling and Retrieval of Near-Infrared Exoplanet Transmission Spectra

Mantle Convection And Nightside Volcanism On Lava World K2-141 b

Ground-based Atmospheric Characterization of Super-Earth L 98-59 d at High Spectral Resolution

Time-Domain Photometry and Activity Evolution of Interstellar Comet 3I/ATLAS with BHTOM

Ionic Liquid Biospheres

A Global High-Resolution Hydrological Model to Simulate the Dynamics of Surface Liquid Reservoirs: Application on Mars

Water Enrichment Of Forming Sub-Neptune Envelopes Limited By Oxygen Exhaustion

A Universal Brown Dwarf Desert Formed Between Planets And Star

Direct Dating Of 3.5 Ga Biogenic Carbon In A Microbial Mat Remnant, Singhbhum Craton, India

The VLA and High-Frequency SETI: Expanding The Search for Life

GEMS JWST: HATS(-6 b): A Sub-solar Metallicity Giant Planet With Water, Methane And Ammonia In Its Atmosphere

The Tidal Venus Phenomenon: Demographics and Case Studies

RNA Droplets May Have Helped Start life on Earth