[astro-ph.EP] Recent observations of V1298-Tau b, a warm sub-Neptune (R=9.85±0.3R⊕, M=13.1±5.3,M⊕, Teq=670K) orbiting a young (10-30Myr) K star, show depleted methane and surprising abundances of CO2 in its atmosphere.
Space Weather & Heliophysics
![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)
Posted inHabitable Zones
Panchromatic Spectra of Nearby Low-mass and Sun-like Stars with Directly Imageable Habitable Zones
[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.
![Keck/NIRSPEC M -band spectrum of TRAPPIST-1 (black) with best-fit model (red). Top: echelle order 16 (λ ≈ 4.63–4.73 µm). Bottom: order 15 (λ ≈ 4.93–5.04 µm). Residuals (data minus model) are shown beneath each panel. Gray shading indicates the relative telluric transmission (dimensionless, 0–1). Masked pixels are omitted from the retrieval. -- [astro-ph.SR]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Isotopic.png?resize=1200%2C721&ssl=1)
Posted inTRAPPIST-1
The Isotopic And Elemental Abundances of Planet-Host Star TRAPPIST-1
[astro-ph.SR]. Elemental and isotopic abundances are key tracers of planet formation, stellar evolution, and Galactic chemical evolution. Very low-mass stars are particularly interesting in this regard, because unlike more massive […]
Posted inSpace Weather & Heliophysics
Preparing For The Early eVolution Explorer: The Impact of Flare Temperature on Ozone Column Depth in Earth-Like Atmospheres
[astro-ph.EP] Atmospheric photochemical models incorporating the impacts of stellar flares often assume a ∼9,000 K spectrum at ultraviolet-optical wavelengths.
![Differences in the TLS effect for the TRAPPIST-1 planets for our minimal two-zone model. The left panel shows a representative diagram of the stellar surface with increased spottedness in the polar regions. Lines are drawn to represent the center of the transit chord for each of the TRAPPIST-1 planets. As a representative example, the width of planet b’s transit chord is shaded in blue. In the right panel, the relative transit depth is shown assuming only stellar heterogeneity made up of cooler regions (upper) and hotter regions (lower) with no contribution from a planetary atmosphere over the wavelength range relevant to JWST NIRSpec/PRISM. The higher impact parameter planets (f, g, and h) are less impacted by the TLS effect than the lower impact parameter planets given our choice of zonal boundary. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Leveraging-Impact.png?resize=1200%2C717&ssl=1)
Posted inTRAPPIST-1
Leveraging Impact Parameter to Mitigate the Transit Light Source Effect: Early Insights from TRAPPIST-1
[astro-ph.EP] Stellar activity complicates exoplanet transmission spectra, particularly for smaller planets around M dwarfs with JWST.
Posted inSpace Weather & Heliophysics
Intense but Harmless: Exo-Space Weather Around an M Dwarf with a Single-Hemisphere Dynamo
[astro-ph.SR] M dwarfs are among the most promising host stars in the search for habitable exoplanets. However, their active atmospheres drive intense magnetic activity, including energetic flares and possibly coronal […]
![TiO absorption variation during 8 years on surface of proxima centauri. Vertical lines depicts regions were used to measure B index. -- [astro-ph.SR]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Titanium-Oxide.png?resize=1200%2C715&ssl=1)
Posted inProxima Centauri
Titanium Oxide Absorption as a Proxy to Detect Long term Variation and Activity Cycle in Proxima Centauri
[astro-ph.SR] Stellar activity cycles on magnetically active stars can be estimated by molecular absorption bands.
![Average ion velocity and magnetic field distributions near the ICB. (A) The center-of-mass velocity of heavy ions in the XZMSE plane, averaged over −1 RM < YMSE < 1 RM. (B) Proton velocity. (C) Velocity shear between protons and heavy ions. (D) Magnetic field strength. (E) Angle between the magnetic field and the X�⃗ MSEin the YZMSE plane, averaged over −1.5 RM < XMSE < 0.5 RM. Black arrows in (A) to (C) indicate velocity directions. Black curves in (A) to (D) mark the nominal locations of the bow shock and ICB. The black shaded sphere in (E) denotes the planetary shadow. -- [physics.space-ph]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Simultaneous.png?resize=1200%2C720&ssl=1)
Posted inSpace Weather & Heliophysics
Simultaneous Mars-orbit Observations Reveal Kelvin-Helmholtz Instability-driven Bulk Atmospheric Ion Escape
[physics.space-ph] Atmospheric ion escape driven by the solar wind is a key process controlling the long-term loss of the Martian atmosphere. Localized plasma clouds can carry substantial fluxes of planetary […]
Posted inImaging & Spectroscopy
Proba-3 Views Its Coronagraph – And Our Home World
[ESA]. At first glance, this is just another image of Earth. But look closely, and you will be able to make out Proba-3’s Coronagraph spacecraft hiding in plain sight, covering […]
![Stellar influence on planetary habitability. Figure credit: solar images from NASA/ESA and KPNO/NSO/AURA/NSF, background pictures generated through OpenAI’s image-generation system (i.e., Adobe Firefly and ChatGPT Images 2.0). Illustration: K. Herbst - [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/StellarActivity.jpg?resize=1200%2C720&ssl=1)
Posted inHabitable Zones
Stellar Activity, Exoplanet, Habitability, Planetary Atmospheres
[astro-ph.EP] This chapter will review the deep connection of planetary habitability and stellar irradiation. We present the long-term stellar evolution as one of the drivers of atmospheric escape and climate […]