![Cumulative oxygen loss for planets at the habitable zone of each sample star over 1 Gyr, assuming constant stellar XUV flux at the HZ and no replenishment of oxygen. The curves are calculated using the energy-limited O2 loss prescription from V. S. Airapetian et al. 2017. Colored lines show individual stars, with solid segments representing the earliest ages (for stars with age ranges) and dashed segments extending beyond the minimum age. The black solid line shows the solar reference. Horizontal lines indicate the present-day Earth atmospheric O2 content (∼0.2 bars; dotted) and the total mass of Earth’s oceans (∼240 bars; dashed), providing reference levels for planetary habitability. -- [astro-ph.SR]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Panchromatic.png?resize=1200%2C720&ssl=1)
[astro-ph.SR] Characterizing the high-energy radiation environments of stars plays a critical role in determining which systems’ planets are capable of retaining atmospheres and sustaining habitable conditions.
atmosphere
Posted inExoplanets, -moons, -comets
Hidden Worlds: A Non-transiting Candidate Planet In The Neptunian Desert Around The Solar-type Pulsator KIC 9139163
[Astronomy & Astrophysics] Close-in substellar companions experience strong tidal and magnetic interactions with their host stars and are therefore subject to fast orbital evolution.
Posted inExoplanets, -moons, -comets
An Evolving Cosmic Shoreline and Sandbar Bounding the Rocky Airless Valley
[astro-ph.EP] Recent JWST observations challenge the traditional ‘cosmic shoreline’ from both sides, revealing thick volatile atmospheres on the hottest close-in ‘lava worlds,’ where irradiation should drive the most extreme escape, […]
![Example weighting functions for selected microwave frequencies (logarithmically spaced between 3 mm - 3 m) corresponding to the model atmospheres for Saturn (top) and Uranus (bottom) from Figure 1. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Microwave-Remote-.png?resize=1200%2C715&ssl=1)
Posted inAtmospheres, Climate, Weather
Microwave Remote Sensing Of Giant Planet Atmospheres: Considerations For Saturn And Uranus Orbiter Missions
[astro-ph.EP] Microwave radiometer instruments are uniquely capable of studying volatile element abundances and heat/mass transport within the deep atmospheres of giant planets.
![Normalized magnetospheric standoff distance rM/rpl as a function of the planetary magnetic field and the total stellar pressure for Modern Earth (left panel) and Early Earth (right panel) across the HZ of the host star. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-impact-of.png?resize=1200%2C714&ssl=1)
Posted inExoplanets, -moons, -comets
The Impact Of Tidal Locking On Earth-like Planetary Dynamos
[astro-ph.EP] We investigate how tidal locking affects the planetary dynamo and the magnetospheres of Earth-like planets orbiting the habitable zones of M dwarfs.
Posted inMars
Quasi-diurnal Kelvin Wave Observed in the Atmosphere of Mars by the Pressure Sensor on the InSight Lander
[astro-ph.EP]. During the initiation phase of Martian dust storms, a spectral signature of a zonal wavenumber 1 normal mode Kelvin wave (K1) has been observed in several surface pressure records.
Posted inBiosignatures & Paleobiology
The Effects of M Star Age Dependent Ultraviolet Emission on Detecting and Interpreting Exoplanet Biosignatures
[astro-ph.EP] Given their abundance and observational advantages, M stars will arguably be the best candidates for characterizing and searching for biosignatures on terrestrial exoplanets in the near future.
![The best-fit chemical equilibrium models to our co-added data performed with three different retrieval suites. For all chemical equilibrium fits, the models produced poor fits to several features on the spectrum, namely near 3 µm and between 4 − 5 µm region. For the 4.3 micron region, the differences between features are due to a combination of differences in the retrieval framework (namely prior constraints) and chemical networks used (FastChem vs GGChem) for each retrieval suite. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/GEMS-JWST.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
GEMS JWST: HATS(-6 b): A Sub-solar Metallicity Giant Planet With Water, Methane And Ammonia In Its Atmosphere
[astro-ph.EP] HATS-6 b is one of several recently discovered Giant Exoplanets orbiting M-dwarf Stars (GEMS) and is part of a JWST survey that aims to compare bulk and atmospheric properties […]
![HZ and planetary orbits in the GJ 12 system. The extent of the HZ is shown in green, where light green and dark green indicate the CHZ and OHZ, respectively. The solid line shows the orbit with the nominal eccentricity of 0.24, and the dashed lines represent 1σ boundaries (Turner et al. 2026). The scale of the figure is 0.2 AU along each side with a 0.02 AU grid.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Tidal-.png?resize=1200%2C712&ssl=1)
Posted inExoplanets, -moons, -comets
The Tidal Venus Phenomenon: Demographics and Case Studies
[astro-ph.EP] The demographics of terrestrial planets and their orbits reveal a vast diversity in overall planetary energy budgets.
Posted inAtmospheres, Climate, Weather
A Search for Helium in the Atmospheres of Three Sub-Neptunes and a Super-Earth Around M-dwarfs
[astro-ph.EP] Thousands of sub-Neptunes have been discovered mainly through space-based surveys such as Kepler and TESS. Their bulk compositions and internal structures are thought to reflect their formation and evolutionary […]