astro-ph.EP Archives

Free retrieval results (top two panels) and cross sections of considered chemical species (bottom two panels) from our investigation of the 3.17 µm feature. Free retrievals were conducted on the combined Tiberius (top, blue) and Eureka! (middle-top, pink) reductions. The 1σ range in retrieved spectra are shown in the colored bands for all considered species (red), all species except C2H2 and C2H4 (yellow), all species except for C2H2, C2H4, and C3 (green), all species except for C2H2, C2H4, C3, and NH3 (dark blue), and only the common species (H2O, CH4, CO2, CO, SO2, and H2S; light pink). -- astro-ph.EP

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

JWST COMPASS: A NIRSpec G395H Transmission Spectrum of Radius Valley-Dweller TOI-260 b

by Keith CowingFebruary 28, 2026February 28, 2026

We present a JWST/NIRSpec G395H transmission spectrum of TOI-260 b, a Teq∼490 K, Rp=1.76R⊕ planet.

A heatmap of Planck-weighted correlated-k tables to complement Figure 5 of PICASO 3.0 release in order to show any major differences between opacity and chemistry updates. The four panels correspond to Gauss points 1, 3, 5, and 7 (shown in the title of each panel). The dashed black lines correspond to Sonora-bobcat pressure-temperature profiles at increasing effective temperatures for reference (as labeled in the upper left panel) (Marley et al. 2021). All major features of the correlated-k tables remain the same between v3 and v4. -- astro-ph.EP

Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

PICASO 4.0: Clouds And Photochemistry In Climate Models Of Brown Dwarfs And Exoplanets

by Keith CowingFebruary 28, 2026February 28, 2026

We present a major update to the open-source atmospheric modeling package PICASO, designed for simulating the thermal structure and spectra of hydrogen-rich atmospheres of brown dwarfs and exoplanets.

Schematic representation of the effect of stellar contamination (TLS) with actual examples of the effect of TLS in simulated signals.

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

Efficient Reduction Of Stellar Contamination And Noise In Planetary Transmission Spectra Using Neural Networks

by Keith CowingFebruary 27, 2026February 27, 2026

Context: JWST has enabled transmission spectroscopy at unprecedented precision, but stellar heterogeneities (spots and faculae) remain a dominant contamination source that can bias atmospheric retrievals if uncorrected.

Spectral flux and exergy at the top of the atmosphere for three blackbody models, all normalized to the same bolometric flux 𝐹bol = 1361 W m2.Solid curves show 𝐹TOA,𝜆 and dashed curves 𝜂ex𝐹TOA,𝜆. The vertical line marks a PSII-like threshold at 𝜆thr = 690 nm, illustrating how the shortwavelength band available for high-Δ𝐺 photochemistry shrinks for M-type hosts. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Habitable Zones, Plant Biology, Status Report

Photosynthetic Exergy I. Thermodynamic Limits For Habitable-zone Planets

by Keith CowingFebruary 26, 2026June 11, 2026

Photosynthesis is central to Earth’s biosphere and a prime candidate for sustaining complex life on habitable exoplanets, yet a thermodynamically consistent treatment of the work potential of stellar radiation at […]

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Radiation, Status Report

Topography-Induced Stationary Waves And The Onset Of Nightside Warming On Rocky Planets Around M-dwarf Stars

by Keith CowingFebruary 26, 2026February 26, 2026

Among potentially habitable worlds, rocky planets orbiting M dwarfs offer the most favorable prospects for atmospheric characterization, yet their climates may differ substantially from those of Earth analogs.

One hour stacked HATPI subtracted images of 3I/ATLAS from each of the nights on which 3I/ATLAS is formally detected with 3σ confidenc

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

HATPI Pre-Perihelion Time-series Photometry of the Interstellar Comet 3I/ATLAS

by Keith CowingFebruary 26, 2026February 26, 2026

HATPI is a recently commissioned time-domain facility at Las Campanas Observatory, Chile, that uses 64 wide-angle, 9.6 cm diameter lenses and back-illuminated CCDs, yielding a mosaic field-of-view of 7,100 square […]

Overview and performance of the LUMOS framework for biogenicity assessment. a, The LUMOS (Life Unveiled using Molecular Orbital Signatures) framework integrates amino acid abundance measurements with quantum chemical descriptors to evaluate biogenicity. First, the abundance of a set of amino acids is estimated, followed by the computation of molecular descriptors (e.g., HOMO–LUMO gap). These descriptors are then weighted by abundance using statistical features such as weighted variance. The resulting value is used to assess the confidence in biogenicity, informed by additional contextual data and environmental provenance. b, Heatmap of P(B|E), the confidence that a sample is biotic (B) given the observed weighted variance (evidence E) as a function of the number of amino acids measured. The prior P(B) is taken as 0.01. Color intensity reflects the biogenicity probability as determined by Bayesian inference applied to simulated distributions of biotic and abiotic samples. c, Criteria met by the LUMOS framework for distinguishing biotic from abiotic amino acid systems. -- astro-ph.EP

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Status Report

Distinguishing Life From Non-life Via Molecular Frontier Orbital Energy Gaps

by Keith CowingFebruary 25, 2026February 26, 2026

Amino acids (AAs) are a key target in the search for life beyond Earth due to their extensive role in the machinery of all known life, persistence over geologic timescales, […]

Subsurface ice final depth interpolated map for latitudes 40-55 North, assuming ice was emplaced 630 kyr ago for 1% dust fraction scenario and no lag layer porosity. The red line represents MONS 7.5% Water-Equivalent Hydrogen contour. The white circles and crosses are locations where ice-exposing craters and maybe ice-exposing craters are found, respectively. The black circles are locations where non-ice-exposing craters are found. The numbers next to the circles indicate the assumed crater depths. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Desert Worlds, Habitable Zones, Icy Worlds, Mars, Status Report

The Martian Mid-latitude Subsurface Ice Is The Remnant Of A Past Ice Sheet

by Keith CowingFebruary 25, 2026February 25, 2026

On Mars, a relatively pure water ice layer lies beneath several centimeters of dry soil at mid-latitudes. Its widespread presence poleward of 60° latitude was detected by remote neutron spectroscopy […]

Illustration of liposome protection from UV. The top panel shows a drawing of the crater. The top- and sideview photographs show the intensity distribution of the blue color after UV exposure. When subjected to UV radiation, the liposomes go through a color change from the original white to blue, with the color intensity correlated with the level of physical destruction of the liposomes. Furthermore, the liposomes change to red when exposed to high heat. The experiment shows that liposomes located at the edges and not covered by the solution turn to blue and then to red within the first few seconds of UV exposure, likely due to the combined effects of UV and heat emitted from the lamp. Liposomes covered by the solution demonstrate a gradual change of the blue color from deep-blue for those at the edge to less intense and almost transparent, deeper toward the center. Even after more than two hours of UV exposure, the liposomes in the crater’s center stayed intact. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Caves, Craters, Mountains, Subsurface, Lava Tubes, Genomics, Proteomics, Bioinformatics, Habitable Zones, Impact events, Origin & Evolution of Life, Panspermia, Sample Return, Status Report

Experimental And Numerical Modeling Of Liposome Congregation In Meteorite Craters Of Early Earth

by Keith CowingFebruary 25, 2026February 25, 2026

This paper provides experimental and numerical evidence supporting the occurrence of liposome congregation at the floors of meteor craters on Early Earth.

Orbital eccentricity (in e2) versus semi-major axis for the planet sample with eccentricities constrained to better than 40% for clarity (or if e < 0.1). Colors denote sub-Neptunes (1–4 R⊕, blue), sub-Saturns (4–8 R⊕, purple), and Jovians (8–16 R⊕, orange). Overlaid curves show theoretical formation channels from R. I. Dawson & J. A. Johnson (2018) for a fiducial planet of ∼6 R⊕ and ∼80 M⊕: high-eccentricity migration (red shaded region) and planet-planet scattering (gray dashed line, gray shaded region). The concentration of larger planets at high eccentricities and small semi-major axes is consistent with high-eccentricity migration. -- astro-ph.EP

Exoplanets, -moons, -comets, Status Report, Stellar Cartography

The Orbital Eccentricity–Radius Distribution for Warm, Single Planets in TESS

by Keith CowingFebruary 25, 2026February 25, 2026

We characterize the radius-dependent eccentricity distribution of 347 warm (P = 8-200 days) systems with only one transiting planetary candidate identified during Sectors 1-69 of the TESS mission.

astro-ph.EP

JWST COMPASS: A NIRSpec G395H Transmission Spectrum of Radius Valley-Dweller TOI-260 b

PICASO 4.0: Clouds And Photochemistry In Climate Models Of Brown Dwarfs And Exoplanets

Efficient Reduction Of Stellar Contamination And Noise In Planetary Transmission Spectra Using Neural Networks

Photosynthetic Exergy I. Thermodynamic Limits For Habitable-zone Planets

Topography-Induced Stationary Waves And The Onset Of Nightside Warming On Rocky Planets Around M-dwarf Stars

HATPI Pre-Perihelion Time-series Photometry of the Interstellar Comet 3I/ATLAS

Distinguishing Life From Non-life Via Molecular Frontier Orbital Energy Gaps

The Martian Mid-latitude Subsurface Ice Is The Remnant Of A Past Ice Sheet

Experimental And Numerical Modeling Of Liposome Congregation In Meteorite Craters Of Early Earth

The Orbital Eccentricity–Radius Distribution for Warm, Single Planets in TESS

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