[astro-ph.EP] Sub-Neptunes are the most common short-period (P<100 d) planets known. A major goal for the field is to build a comprehensive understanding of their compositions and evolutionary histories, and […]
sub-Neptune
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 […]
![Planets that will be observed with MIRI in transit, in JWST Cycles 1-5. As mentioned in section 5, we see a wide variety of planet sizes and equilibrium temperatures. The currently published planets are shown in black dots, and listed in Table 1 and Figure 1. We have ommitted the white dwarf planet WD 1856 b (Teq = 160K, Rp = 10.2R⊕, cycle 4), as well as the disintergrating planets K2-22 b (see section 2.1) and BD+05 4868 A b (Teq = 1820K, unknown Rp, cycle 4). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/A-Homogeneous.png?resize=1200%2C720&ssl=1)
Posted inExoplanets, -moons, -comets
A Homogeneous Survey Of JWST MIRI Transmission Spectra Of 10 Exoplanets
[astro-ph.EP] The launch of JWST has enabled unprecedented atmospheric characterization of exoplanets. In particular, the JWST-MIRI instrument in the mid-infrared enables probing of molecular species that are harder to detect […]
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.
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 […]
![Clouds may form via heterogeneous nucleation on top of ‘seed’ photochemical haze particles. Whether or not this pathway dominates over homogeneous nucleation—the process through which ‘pure’ clouds spontaneously form—depends on the microphysical contact angle between the relevant cloud and haze species. Smaller contact angles correspond to stronger cloud-haze interactions due to the increased affinity between the clouds and hazes. While this contact angle is unknown in the absence of lab data, heterogeneous nucleation is the primary cloud-formation pathway across the Solar System. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Wet-Removal.png?resize=1200%2C715&ssl=1)
Posted inAtmospheres, Climate, Weather
Wet Removal and Cloud Enhancement: The Microphysics of Cloud-Haze Interactions on Sub-Neptunes
[astro-ph.EP] Aerosols are a near-ubiquitous feature of sub-Neptune atmospheres, yet their microphysical nature remains poorly understood. Both condensate clouds and photochemical hazes have been proposed to explain observations, but have […]
![Mass-radius diagram of known exoplanets together with model curves taken from A. Aguichine et al. (2021) and L. Zeng et al. (2019). Exoplanet data shown with colored dots were taken from the NASA Exoplanet Archive (J. L. Christiansen et al. 2025) on April 2, 2026. The transiting exoplanets in the HD 191939 system are highlighted with larger markers, error bars and a red outline.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-SPACE.png?resize=1200%2C714&ssl=1)
Posted inExoplanets, -moons, -comets
The SPACE Program II: No Discernible Spectral Features In The Transmission Spectrum Of The sub-Neptune HD 191939 b Observed With HST/WFC3
[astro-ph.EP] The atmospheres of sub-Neptunes provide a window into their internal structure and history, shedding light on the origin of this common, but enigmatic, class of exoplanets.
Posted inExoplanets, -moons, -comets
Exploration Of Exoplanet Atmospheres With The James Webb Space Telescope
[astro-ph.EP] The James Webb Space Telescope (JWST) is providing transformative characterization capabilities for the study of both transiting and directly imaged extrasolar planets. Observations deep into the infrared in the […]
Posted inExoplanets, -moons, -comets
Constraining The Lives And Times Of Exoplanets Through Evolutionary Bayesian Retrievals
[astro-ph.EP] Static retrieval frameworks are leading tools for interpreting exoplanet observations, yet time-independent modelling leaves them prone to degeneracy and unable to resolve exoplanets’ histories.
Posted inStellar Cartography
TESS Photometry and Radial Velocity Analysis of the sub-Neptune Exoplanet π Mensae c and the Wider π Mensae Planetary System
[astro-ph.EP] Exoplanet characterization relies on precise measurements of planetary orbital and physical parameters. This is particularly important for planetary dynamics and atmospheric evolution, as orbital parameters help constrain system evolution, […]