[The Astrophysical Journal Letters]. Primordial, or Population III (Pop III), supernovae (SNe) were the first nucleosynthetic engines in the Universe, forging the heavy elements required for the later formation of […]
Exoplanets, -moons, -comets
Posted inBiosignatures & Paleobiology
The Long-term Persistence Of Microbial Biospheres Introduces A Temporal Bias 1 Into The Drake Equation: Implications For The Search For Extraterrestrial Life
[eartharxiv.org] The Drake equation was designed to estimate the number of communicative technological civilisations, not the prevalence of life. Its lifetime term therefore describes a detectable technological phase that may […]
![The black line shows the empirical high-S/N template spectrum of Proxima Centauri (left) and Barnard’s Star (right). In the top panel, the green curve shows the median spectrum obtained by taking the median flux at each wavelength across the full grid of PHOENIX M-dwarf spectra, while the shaded region denotes the corresponding 1σ envelope. Comparing this range of model spectra with the empirical M-dwarf spectra demonstrates that the PHOENIX models do not adequately reproduce the observed spectra. The middle and bottom panels show either empirical templates or postellar spectral samples constructed from synthetic SPIRou observations of the respective stars at different S/N regimes. For the postellar spectra, the 1σ, 2σ, and 3σ intervals are shown, highlighting the uncertainties recovered on individual spectral feature. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/POSTELLAR.png?resize=1200%2C721&ssl=1)
Posted inExoplanets, -moons, -comets
POSTELLAR: Posterior Stellar Spectrum Sampling – An Alternative to Approximate Stellar Spectra for Exoplanetary Analysis
[astro-ph.EP] We present a novel approach to perform posterior sampling of the underlying stellar spectrum in high-resolution spectroscopic observations.
![Left: Average ocean fraction, calculated assuming a seawater freezing point of −1.8°𝐶 for Cases 1 and 3 and 0°𝐶 for Case 2. White shows the ice, and blue ocean. Middle: The mean near-surface air temperatures. Shown within the black contours are the regions where these vary between above and below freezing over the course of a single Earth year. Right: The mean surface temperatures. Also shown within the black contours are the regions where these vary between above and below freezing over the course of a single Earth year: these regions are narrower than the air ‘perifreezing zone’.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Sea-Ice.png?resize=1200%2C720&ssl=1)
Posted inWater/Hycean Worlds & Oceanography
Sea Ice As An Origin Of Life Location For Hycean And Ocean Worlds
[astro-ph.EP] Water worlds with potential deep oceans are at the forefront of currently observable exoplanetary habitability.
![RMS vs bin-size of the residuals from our TTV fits (see Section 4.1). The four panels show the 2x2 different reduction-likelihood pairings considered in this work. The two jitter treatments find binning behavior worse than that expected from pure Gaussian noise (dashed line), and instead have a slope of ∼ − 1/3, similar to other NIRSpec PRISM results (e.g. Kipping et al. 2025). The inclusion of a GP to absorb time-correlated noise greatly reduces the slopes, as again expected.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/JWST-Excludes.png?resize=1200%2C720&ssl=1)
Posted inExoplanets, -moons, -comets
JWST Excludes Exomoons Down to 0.1 Earth Radii Around a Rocky, Temperate Exoplanet
[astro-ph.EP] To date, even with JWST, it has not been possible to test for exomoons as small as the Moon. Only two reported searches for exomoons around bound planets have […]
Posted inExoplanets, -moons, -comets
The Metallicity Of Giant Exoplanets Around Low-mass Stars And How Ariel Can Help
[astro-ph.EP] Giant planets orbiting low-mass stars represent a unique population of giant planets that can be studied to constrain planet formation theory. Surveys of transiting giant exoplanets around M-dwarfs (GEMS) […]
Posted inExoplanets, -moons, -comets
Two Extremely Irradiated Volatile-rich Sub-Neptunes With Companions In The TOI-426 And TOI-1839 Systems: Insights Into Arrival And Survival Near The Lower Edge Of The Neptunian Desert
[astro-ph.EP] Using TESS photometry and 147 HARPS radial velocities, we confirm two extremely irradiated, volatile-rich sub-Neptunes near the lower edge of the Neptunian desert: TOI-426 b and TOI-1839 b, orbiting […]
![Zoomed-in 12CO J = 3 − 2 channel maps. Contours are 3, 6 and 10σ. The isovelocity contours are calculated with a flat surface. The planet locations are marked with white dots. The beam is given in the bottom right corner while the velocity of the channel is provided in the bottom left corner. Fig. F.5 shows the channel maps over the full extent of the disk.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Mapping.png?resize=1200%2C717&ssl=1)
Posted inExoplanets, -moons, -comets
Mapping the WISPIT2 Planet-Hosting Cavity at Sub-Hill-Radius scales
[astro-ph.EP] We present new deep, very high angular resolution observations of the sub-mm continuum (19×13 mas) and 12CO (67×52 mas) emission from the disk surrounding the planet host WISPIT2. Our […]
Posted inAtmospheres, Climate, Weather
Contrasting C/O Ratios in Uranus and Neptune From Disequilibrium Chemistry: A Clue To Distinct Evolutionary Pathways?
[astro-ph.EP] The formation of Uranus and Neptune remains poorly constrained largely due to uncertain deep elemental abundances. Carbon monoxide (CO), a disequilibrium species in the upper troposphere, provides an indirect […]
![[TOP] Marginal posterior probability distribution functions of the Bayesian fit to Eq. 1 when [X/H] is the mean abundance of iron-peak elements (left), volatile elements (middle), and α elements (right). The vertical line indicates the mean of the distribution. [BOTTOM] Same as above but considering only the stars with a spectral type earlier than F5. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Signatures.png?resize=1200%2C718&ssl=1)
Posted inExoplanets, -moons, -comets
Signatures Of Rocky Debris Accretion In AF-Type Planet Hosts
[astro-ph.EP] The gas-giant planet-metallicity correlation plays a fundamental role in our understanding of planet formation.