![Comparisons between the theoretical transmission spectra generated by EPACRIS (solid lines) and the JWST observations for (Top) H2:H2O=50:50 and [C+N+S]=100×solar metallicity scenario of K2-18 b assuming Ab = 0.3 corresponding to the left panel of Figure 4, and (Bottom) H2:H2O=75:25 and [C+N+S]=100×solar metallicity scenario of TOI-270 d assuming Ab = 0 corresponding to the right panel of Figure 4. The grey symbols with error bars indicate JWST observations of corresponding exoplanets taken from Madhusudhan et al. (2023) for K2-18 b (Top), and Benneke et al. (2024) for TOI-270 d (Bottom). Each color represents a spectrum generated by excluding specific species: green for no CH4, red for no CO2, light blue for no OCS, blue for no H2O, teal for no CO, light brown for no NH3, and black for all species included. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/06/Chemical-Mapping-of.png?resize=1200%2C720&ssl=1)
Understanding the envelope composition of sub-Neptune-type exoplanets is challenging due to the inherent degeneracy in their interior composition scenarios. Particularly, the H2O/H2 ratio, or can be expressed as the O/H […]
We update the PlanetS catalog of transiting planets with precise and robust mass and radius measurements and use this comprehensive catalog to explore Mass-Radius (M-R) diagrams.
![Mass–radius diagram of confirmed exoplanets with mass and radius precision better than 3σ and 10σ, respectively. Planetary parameters (black dots) are taken from the NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu), and updated to October 2023. HD 73344b is represented by the red dot. The red arrow represents the upper 10σ limit on its mass. Composition models calculated from Aguichine et al. (2021) with a core mass fraction of 30% and various H2O mass fraction (from 10% to 80%) are represented by coloured lines (see text). Composition models calculated from Lopez & Fortney (2014) for a 1 Gyr-old system, Teq,b ∼ 900 K, and an envelope mass fraction fenv = [1, 2, 3, 4, 5] % are shown in gray. For comparison, the relation for an Earth-like composition (32.5% core, 67.5% mantle) from Brugger et al. (2017) is shown by the green dashed curve, and some solar system planets (Venus, the Earth, Uranus and Neptune) are displayed. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/05/A-Low-mass-Sub-Neptune-Planet.png?resize=1200%2C719&ssl=1)
Context. Planets with radii of between 2-4 RE closely orbiting solar-type stars are of significant importance for studying the transition from rocky to giant planets.
Sub-Neptunes with 2−3R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of […]
Exoplanet discoveries have revealed a dramatic diversity of planet sizes across a vast array of orbital architectures. Sub-Neptunes are of particular interest; due to their absence in our own solar […]
The characterization of Super-Earth-to-Neptune sized exoplanets relies heavily on our understanding of their formation and evolution.
![Cumulative XUV irradiation vs. planetary escape velocity for a range of rocky exoplanets (grey squares and colored circles) and solar system planets (blue stars). The cumulative lifetime XUV is thought to be the driving force behind planetary evaporation. Atmospheres can be found where gravity is high and solar irradiation is low. The light blue colored line represents the proposed “cosmic shoreline” which follows a power law, IXUV ∝ vesc4 , following [15]. Rocky planets around M dwarfs can be studied with JWST to assess the validity of this shoreline. Plot adapted from [16]. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/05/Characterizing-Exoplanetary-Atmospheres.png?resize=1200%2C725&ssl=1)
I review the major open science questions in exoplanet atmospheres. These are mainly focused in the areas of understanding atmospheric physics, the atmosphere as a window into other realms of […]
Small planets transiting bright nearby stars are essential to our understanding of the formation and evolution of exoplanetary systems. However, few constitute prime targets for atmospheric characterization, and even fewer […]
The TOI-421 planetary system contains two sub-Neptune-type planets and is a prime target to study the formation and evolution of planets and their atmospheres.
M dwarf stars are not only the most promising hosts for detection and characterization of small and potentially habitable planets, they provide leverage relative to solar-type stars to test models […]
