OCEAN WORLDS: Might planets replete with liquid water bedew the galaxy?

The article focuses on the study and characterization of ocean worlds—exoplanets with significant water content—highlighting the example of LHS 1140b, a planet initially thought to be a dense super-Earth but later found to possibly contain 10% to 20% water by mass. Researchers use measurements of planetary mass, radius, and transmission spectroscopy, particularly with the James Webb Space Telescope (JWST), to infer atmospheric composition and distinguish between rocky, mini-Neptune, and water-rich scenarios, though degeneracies in data interpretation remain a challenge. The concept of "hycean worlds," planets with deep liquid oceans beneath hydrogen-rich atmospheres, is introduced as a novel class of ocean worlds that may exist under specific conditions. Future missions like the proposed Habitable Worlds Observatory (HWO) aim to improve direct observations of exoplanet atmospheres and surfaces to better assess their potential habitability and presence of liquid water. [Extracted from the article]