[astro-ph.EP] The long-term stability of exoplanetary atmospheres depends critically on the extreme-ultraviolet (EUV) photon and high-energy particle fluxes from the host star, which are poorly constrained.
Astronomy & Telescopes
![Schematic overview of instability-inducing mechanisms through which planets may be ejected from a system. These mechanisms, each discussed throughout this work, include close approaches between neighboring planets (top left; Section 2), binary-induced instabilities (top center and right, and bottom left; Section 3), flyby encounters (bottom center; Section 4), and post-main-sequence orbital evolution (bottom right; Section 5).-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Dynamics.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
The Dynamics Of Planetary Ejection
[astro-ph.EP] The ubiquity of free-floating planets inferred from microlensing and direct imaging surveys suggests that planetary ejection—a process in which planets initially born encircling a stellar host become gravitationally unbound—is […]
![Computed abundance maps of ammonium cyanate, ammonium formate, ammonium acetate, ammonium hydrosulfide and ammonium carbamate in the solid phase for r < 50 au and computed after 1 Myr and 10 Myrs. We also show the ratio of the vertically integrated abundances of these salts relative to water ice. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Ammonium-salt-.png?resize=1200%2C720&ssl=1)
Posted inAstrochemistry
Ammonium Salt Formation And Abundance In Protoplanetary Disks
[astro-ph.EP] Ammonium salts may represent an important reservoir of volatile species in Solar system primitive bodies, but the question of how and when these salts can form during the star […]
![Pollux optical layout. The exact sequence in the optical path of the retractable polarimeters and fiber link connections of the OPT and NIR is still to be discussed and what shown here is not representative of the final configuration. -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Pollux.png?resize=1200%2C715&ssl=1)
Posted inExoplanets, -moons, -comets
Pollux: High-resolution Precision Spectroscopy And Polarimetry For The Habitable Worlds Observatory
[astro-ph.IM] Pollux is a high-resolution spectrograph and spectropolarimeter (R from 65000 to 100000) covering a spectral range from 100 nm to 1750 nm, proposed by a European consortium to equip […]
Posted inComets and Asteroids
A JWST Study of Stardust. I. Infrared Spectroscopy of Comet 81P/Wild 2 and Overall Composition
[astro-ph.EP] We report observations of comet 81P/Wild 2, target of the Stardust sample return mission, on UT 2023 March 20 and 24 at a heliocentric distance (rH) of 1.85 au […]
![Left: Orbital separations of inspiralling planets over time. Right: Mass accreted onto planets over time. For each initial planet mass, we show results for 𝜀 ∈ [0.01, 0.1, 0.3, 0.5, 1.0], with an increasing efficiency denoted by an increasing opacity. We also allow the accretion to increase up to 10× the Eddington limit, denoted by the dotted lines. Accretion stops when 𝑅𝐵 < 𝑅Jup (see §2.3). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Atmospheric-Signatures.png?resize=1200%2C722&ssl=1)
Posted inExoplanets, -moons, -comets
Atmospheric Signatures of Common Envelope Evolution in White Dwarf Planets
[astro-ph.EP] The majority of confirmed exoplanets orbit within 1 au of a main-sequence (MS) star. When their stellar hosts evolve off the MS, many of these planets will be engulfed […]
![Top: Hexagonal segmented primary mirror designs with no central obscuration with different number of rings and varying segment sizes (flat-to-flat (m) 1-Hex: 2.64, 2-Hex: 1.45, 3-Hex: 1.19, 4-Hex: 0.85, 5-Hex: 0.66), all designs have an inscribed diameter of ∼6 m. Middle: Binary apodizer masks optimized for their respective aperture design. Bottom: Respective coronagraphic PSFs with an annular dark hole ranging from 3.4λ/D - 12λ/D, and a spatial average contrast floor of ∼4 × 10−11 inside the dark hole. -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Segmentlevel.png?resize=1200%2C720&ssl=1)
Posted inAstronomy & Telescopes
Segment-level Thermal Sensitivity Analysis For Exo-Earth Coronagraphy With Segmented Space Telescopes
[astro-ph.IM] Direct imaging and characterization of Earth-like planets require ultra-stable wavefronts to achieve a starlight suppression level of 100 parts per trillion (ppt) in the coronagraphic dark region of the […]
![Schematic diagram of our spectral line stacking and matched filtering procedures. First, (a) shows relevant spectral regions of the (synthetic) observational data (black) and an initial spectral simulation (red). Each spectral window is then weighted based on the signal-to-noise ratio of each region to create a velocity stack of all relevant molecular rotational transitions (b). Finally, the stacked simulation is used as a matched filter and is cross-correlated with the stacked data to visualize the statistical significance of a given detection (c). -- [astro-ph.GA]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Exploring-the-Limits.png?resize=1200%2C720&ssl=1)
Posted inAstrochemistry
Exploring the Limits of Spectral Line Stacking in Spectral Line Data and Application Toward the Detection of Bulk 13C Enrichment of Aromatics in TMC-1
[astro-ph.GA] The formation history of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium remains a topic of active debate, with proposed mechanisms ranging from high-temperature stellar ejecta processes to low-temperature […]
Posted inSETI & Technosignatures
Nondetection of Narrowband Radio Technosignatures from LHS 1140 b at 1–12 GHz
[Research Notes of the AAS] LHS 1140b, a rocky exoplanet in its host star’s habitable zone, was recently shown to have an escaping helium atmosphere.
![Helicity asymmetries of the primordial (left panel) and late-time (right panel) density fields for parity asymmetric (blue curves) and symmetric (red curves) simulations. The shaded regions indicate the standard deviation (1σ) of the ensemble-average. The red markers highlight the asymmetries exceeding a statistical significance of 3σ. - [astro-ph.CO]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Probing.png?resize=1200%2C718&ssl=1)
Posted inAstrochemistry
Probing Primordial Chirality in the Matter Distribution
[astro-ph.CO] Whether parity symmetry was violated in the early universe remains one of the fundamental open questions in cosmology. If so, it may leave an intrinsic handedness in the large-scale […]