![Dereddened Gaia CMD with PARSEC isochrones overplotted. Black points show Gaia DR3 stars corrected for extinction and reddening using band-specific coefficients. Solid curves show isochrones spanning ages from 1 to 13 Gyr at the reference metallicity. The dotted curves highlight 1 Gyr isochrones computed at the lower (-0.4 dex) and upper (+0.4 dex) metallicity values in the sample, illustrating the range of CMD permitted by the observed metallicity distribution. This comparison demonstrates the impact of metallicity on isochrone placement relative to the data. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Precise.png?resize=1200%2C718&ssl=1)
[astro-ph.EP] Accurate stellar ages are fundamental to interpreting the evolutionary histories of habitable zone (HZ) planets. Because stellar luminosity evolves over time, HZ boundaries migrate outward, meaning that present-day HZ […]
astro-ph.EP
![Schematics of a HAeBe star accreting material from its protoplanetary disc with an ongoing giant planet formation. The giant planet opens a disc gap, preventing the larger dust grains from moving inwards. The HAeBe star has a convective core (red), a radiative envelope (blue), and the stellar photosphere (yellow).-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/The-refractory.png?resize=1200%2C718&ssl=1)
Posted inAstrochemistry
The Refractory Fraction Of Phosphorus In Planet-forming Discs
[astro-ph.EP] Context. Phosphorus (P) is an essential element for life on Earth and a potential tracer of planet formation history. However, there has been no detection of P-bearing molecules in […]
Posted inExoplanets, -moons, -comets
Stellar Flares Rather Than High Tint As Possible Cause For the Missing Methane In Young Exoplanets: The Case Study of V1298-Tau b
[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.
![Bifurcated best-fit solutions. The noisy generated data is shown with gray error bars. The true spectrum of Earth is in black, while the Earth-like solution and thick- -atmosphere solution are shown in blue and orange, respectively. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Impacts.png?resize=1200%2C720&ssl=1)
Posted inExoplanets, -moons, -comets
Impacts Of Correlated Noise On Retrievals Of Exo-Earth Atmospheres
[astro-ph.EP] The Habitable Worlds Observatory (HWO) aims to accomplish high-contrast imaging and spectroscopy of true Earth analogs for the first time. However, high-contrast spectroscopy with HWO may be limited by […]
![Figure showing the structure of pure carbon planets ranging from 0.1 to 20 Earth masses with a surface temperature of 300K. Color bar indicates density in g/cm3 . -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Modeling-Carbon.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
Modeling Carbon-Based Planets with MAGRATHEA
[astro-ph.EP] A planet’s interior structure not only influences its habitability, but it also provides information about the planet’s formation and history.
Posted inExoplanets, -moons, -comets
A Clearer View of HAT-P-1 b: JWST NIRSpec G395H Reveals Water, Carbon Dioxide, and Possibly Hydrogen Sulfide
[astro-ph.EP] As part of JWST’s Exoplanet Grand Tour Survey, we use panchromatic transmission spectroscopy to connect HAT-P-1 b’s previously studied optical and near-infrared atmosphere to the longer-wavelength molecular bands accessible […]
Posted inExoplanets, -moons, -comets
Exploring Long-period Architectures: Four New Planet Candidates from Kepler with Periods >342 days
[astro-ph.EP] The Kepler detection pipeline, as well as the transit method, has a bias towards shorter periods, leaving a dearth of detections at longer orbital periods. This relative lack of […]
![Images acquired on 2019 October 4 (left) and 27 (right) with LDT. The top row show stacks of r and CN images, respectively. The bottom row shows the same images enhanced by subtraction of an azimuthal median profile. The enhanced CN images have been smoothed with a Gaussian profile to better reveal the faint underlying structure. A compass indicating north (N), east (E), the anti-sunward direction (−⊙), and the anti-velocity vector (−v) are overlaid on the r panels, while a scale bar showing a distance at the comet of 20,000 km is given on the CN panels (1 arcsec corresponds to 2134 km on October 4 and 1814 km on October 27). All four panels for a given night have the same orientation and physical scale at the comet. The October 4 image is a single frame and shows several artifacts that could not be removed without a median combination include several bright pixels in the CN frame (yellow) and a bad column in all frames (black diagonal line). On October 4, a bright star is seen near the left edge of the r frames and as a diagonal (yellow) line in the upper right in CN. Two faint trailed stars are visible in the r images on October 27. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Highly.png?resize=1200%2C720&ssl=1)
Posted inComets and Asteroids
The Highly Unusual Behavior And Chemical Composition Of Interstellar Comet 2I/Borisov
[astro-ph.EP]. We report on imaging, spectroscopy, and narrowband photometry of interstellar comet 2I/Borisov obtained at Lowell Observatory from 2019 September 13 to December 16.
Posted inAstrogeology
Volatile Depletion In Rocky Planets As A Chemical Fingerprint Of Hybrid Accretion
[astro-ph.EP] Volatile depletion in rocky planets relative to their host stars is commonplace in both the Solar System and exoplanetary systems, yet the connections between planet formation and composition remain […]
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, […]