astro-ph.EP Archives

Integrated flux for ALMA’s CO(3-2) line measurement. Superposed as black circles on Neptune’s map are the beam positions observed onto the planet and used for the spatially resolved retrievals. The filled red circle in the lower-left corner indicates the size and orientation of the beam. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Neptune, Status Report

Latitudinal Variations In Neptune’s Temperature Profile Observed With ALMA

by Keith CowingMay 26, 2026May 26, 2026

Despite the low solar irradiation it receives, Neptune shows a very active atmosphere with some of the most intense dynamics observed in Solar System atmospheres. Characterizing the atmospheric temperature profiles […]

SFR as a function of stellar mass for equilibrium (left) and non-equilibrium (right) galaxies. The solid red line indicates the SFMS from Renzini & Peng (2015), with dashed lines showing the adopted scatter. Colour maps indicate the number of galaxies per bin in each panel; note that the colour scales differ between the equilibrium and non-equilibrium panels, reflecting the different sample sizes. -- astro-ph.GA

Astrochemistry, Habitable Zones, Status Report

The Habitability Trade-off: Chemical Decoupling And Quenching In Massive Galaxies

by Keith CowingMay 26, 2026May 26, 2026

Massive galaxies experience complex evolutionary processes, including mergers and gas accretion, which can disrupt the chemical equilibrium between their stellar and gaseous components.

ShaneAO/ShARCS high-resolution imaging of HIP 18512 (left), ShaneAO/ShARCS imaging of HIP 45839 (center), and Keck/NIRC2 high-contrast imaging of HIP 45839 (right). Each image is oriented such that north is up and and east is to the left. HIP 18512 shows a binary at a separation of 10. ′′9 and a position angle of 12.7 ◦ . The Keck/NIRC2 imaging of HIP 45839 shows a faint source at 5. ′′3 which is not consistent with the observed RV trend and astrometric acceleration. A zoomed-in 0. ′′4 × 0. ′′4 cutout of the source is shown in the inset panel. Images are displayed with an arcsinh stretch to capture a large dynamic range (Lupton et al. 2004). -- astro-ph.EP

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

Gaia Exoplanet Orbits, Demographics, and Evolution Survey (GEODES): Characteristics of Three Long-Period Companions Accelerating their Host Stars

by Keith CowingMay 26, 2026May 26, 2026

The upcoming release of Gaia DR4 will yield thousands of giant planet candidates, eventually enabling studies of giant planet eccentricities, masses, and occurrence rates across a broad range of stellar […]

Spectral characterization of Chiron’s surface composition. a Comparison of the bestfit spectral model of the surface composition (red) with the measured spectrum (black). The surface is best described by an intimate mixture of water ice in both amorphous and crystalline phases, carbon dioxide ice, and tholin-like materials. b Residuals between the model and the data show an excellent fit, with a root mean square deviation that is just 1% higher than the average scatter in the data. c Zoomed-in view of the complex organic absorption feature spanning 3.3–3.6 µm, with the individual component bands indicated by dashed lines. Comparison between the measured spectrum and synthetic spectra of several candidate species, convolved to the spectral resolution of the data, points to C3H8 and/or ice tholins produced by the irradiation of H2O ice and C2H6 as the most plausible candidates for the observed organic feature. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report

JWST Reveals Anomalously Enhanced Methane Outgassing From Below Chiron’s Water Ice And Carbon Dioxide Bearing Surface

by Keith CowingMay 26, 2026May 26, 2026

Centaurs are inward-scattered Kuiper belt objects, with some exhibiting comet-like activity. The physical mechanisms powering this activity remain poorly understood, with carbon monoxide (CO) sublimation or the crystallization of amorphous […]

A northern polar projection of Jupiter indicating the latitude and longitude ranges adopted for coaddition of individual spectra. The circumference latitude is 40◦ (planetocentric), enclosed concentric circles are spaced by 4◦ in latitude. The magenta line represents the statistical mean position of the auroral oval (Bonfond et al., 2017). Spatial bins in black represent regions that do not overlap in latitude with the auroral oval, blue and red spatial bins represents areas outside and inside the auroral oval, respectively. TEXES achieves diffraction-limited spatial resolutions of 0.7” to 1.4” over the wavelength range adopted in this study, which corresponds to a latitude-longitude footprint of 5-10◦ at 60◦N. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Jupiter, Status Report

Detection Of Propadiene (CH2CCH2), Propene (C3H6) And Non-detection Of Propane (C3H8) In Jupiter’s Northern Polar Stratosphere

by Keith CowingMay 25, 2026May 25, 2026

We report the first detection of stratospheric propadiene (CH2CCH2) and propene (C3H6) at Jupiter’s mid-to-high northern latitudes using IRTF-TEXES measurements recorded on March 5-6, 2025.

Upper panels: Equatorial rotational velocity (veq) vs. projected rotational velocity (v sin i) for stars in Tiers 1, 2, and 3. The v sin i values are taken directly from the ARC and the veq values are calculated using Prot from the ARC and R⋆ from the HPIC. Several stars in each tier fall in a region of parameter space that is mathematically forbidden, i.e., requiring sin i > 1. Lower Panels: Expected and observed inclination distributions for stars in Tiers 1, 2, and 3. The observed distributions are systematically distinct from the expected distributions. Not only do they predict undefined stellar inclinations, but the results favor face-on orbits (i = 0◦ ) rather than edge-on orbits (i = 90◦) as one would expect if stellar spin axes were drawn from an isotropic distribution. -- astro-ph.SR

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

HWO Target Stars and Systems: Activity and Rotation Catalog (ARC) of Potential Target Stars for the Habitable Worlds Observatory

by Keith CowingMay 24, 2026May 24, 2026

A major goal of the Habitable Worlds Observatory (HWO) is to precisely characterize exoplanets and their atmospheres.

ExoCAM simulations of Earth from the present up to 2.0 Gyr in the future, assuming CO2 remains fixed at 400 ppm. The top row shows surface temperature, the middle row shows precipitation minus evaporation, and the bottom row shows the habitability metric developed by Woodward et al. (2025) (Eqs. (D1) and (D2)). All quantities are 20-year averages after the model has reached a steady-state. Increases in temperature due to a brightening sun cause an increase in habitability up to 1.5 Gyr due to the greening of the poles, but habitability decreases significantly by 2.0 Gyr as Earth becomes too hot for complex vegetative life. This corresponds to a weak temperature dependence of weathering, in which Earth’s CO2 levels do not change even as the climate warms (c.f., Graham et al., 2024). -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Desert Worlds, Gaia - Planetary Perspectives, Imaging & Spectroscopy, Space Agriculture, Status Report, Terraforming & Geoengineering, Water/Hycean Worlds & Oceanography

Maximum Lifetime Of The Vegetative Biosphere

by Keith CowingMay 23, 2026May 23, 2026

We use a three-dimensional model to calculate steady-state climates at various intervals in Earth’s future, across a parameter space of increasing insolation and decreasing CO2 mixing ratio.

A demonstration of the limitations of the PSPT data processing pipeline, which did not process the limb uniformly with the rest of the Solar disc. The solid blue line is the stated extent of the solar disk in the original dataset, and the dashed red line is the extent to which the data has been cleaned. Note between the red and blue lines there exists a slight intensity increase — an example of the difference between the processed and unprocessed data separated by this boundary. -- astro-ph.SR

Astronomy & Telescopes, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report, Stellar Cartography

Astrometric Exoplanet Detection Survives Solar-like Stellar Contamination

by Keith CowingMay 23, 2026May 23, 2026

Astrometric monitoring of stars provides a promising method for discovery of low-mass planets around nearby Sun-like stars.

Protoplanetary disk images (top row) and scattered-/transmitted-light spectra (bottom-left and bottom-middle) obtained from the radiative-transfer simulations, together with the crystallinity dependence of their Fresnel-feature heights (bottom-right). For the edge-on case, the Fresnel-feature height is measured in absolute value of feature depth. Alt text: Theoretical images, spectra, and Fresnel feature height of the protoplanetary disks. -- astro-ph.EP

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

Constraints On The Crystallinity Of Water Ice In Planet-forming Disks From Infrared Scattered-Light Spectra

by Keith CowingMay 23, 2026May 23, 2026

The crystallinity of water ice not only records the thermal history experienced by an astronomical body, but also affects the composition of forming planets by controlling the trapping of volatile […]

(Top) A simulated transit depth spectrum showing SF6 and NF3 in the atmosphere of terrestrial exoplanets of different atmospheric compositions orbiting an M Dwarf star. The concentrations of SF6 and NF3 are at 1 ppm. (Bottom) Absorption cross sections for various atmospheric molecules, including the industrial produced SF6 and NF3. It is noted that concentrations of 1 ppm for both SF6 and NF3 are orders of magnitude above that of present-day Earth’s abundances of these two industrial gases. The high concentrations of SF6 and NF3 could exist in so-called “service worlds”. Figure from (Seager et al. 2023). -- astro-ph.EP

Astronomy & Telescopes, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, SETI & Technosignatures, Status Report

The Search For Technosignatures: A Review Of Possibilities

by Keith CowingMay 22, 2026May 22, 2026

This paper aims to review the diverse range of technosignatures that have been proposed in the literature.

astro-ph.EP

Latitudinal Variations In Neptune’s Temperature Profile Observed With ALMA

The Habitability Trade-off: Chemical Decoupling And Quenching In Massive Galaxies

Gaia Exoplanet Orbits, Demographics, and Evolution Survey (GEODES): Characteristics of Three Long-Period Companions Accelerating their Host Stars

JWST Reveals Anomalously Enhanced Methane Outgassing From Below Chiron’s Water Ice And Carbon Dioxide Bearing Surface

Detection Of Propadiene (CH2CCH2), Propene (C3H6) And Non-detection Of Propane (C3H8) In Jupiter’s Northern Polar Stratosphere

HWO Target Stars and Systems: Activity and Rotation Catalog (ARC) of Potential Target Stars for the Habitable Worlds Observatory

Maximum Lifetime Of The Vegetative Biosphere

Astrometric Exoplanet Detection Survives Solar-like Stellar Contamination

Constraints On The Crystallinity Of Water Ice In Planet-forming Disks From Infrared Scattered-Light Spectra

The Search For Technosignatures: A Review Of Possibilities

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