Worlds with Eternal Magma Oceans ⚡ экспресс
Sub-Neptunes are the most common exoplanet class; their masses and radii provide ambiguous clues to internal structure. If they are gas dwarfs (rocky core and atmosphere with μ < 3.8 g/mol), the presence of molten interiors would produce observable signatures. Using PROTEUS, a coupled interior‑climate evolution model, a 'solidification shoreline' was determined: an irradiation flux threshold, dependent on the host star's effective temperature, that separates molten from solidified gas dwarfs. 98% of known sub-Neptunes fall into the region where, if they are gas dwarfs, persistent magma oceans must exist. Oxygen fugacity in the mantle and the bulk C/H ratio influence cooling, but planets with oxidized mantles and carbon‑rich atmospheres lie beyond the study's scope due to high μ. Thus, under this hypothesis, nearly all detected sub-Neptunes remain molten, motivating a search for direct evidence of magma–atmosphere interaction.
A star warms its planet like an oven warms a kettle. For most sub-Neptunes (worlds larger than Earth but smaller than Neptune), the heat is enough to keep an ocean of molten rock eternally churning beneath a hydrogen sky. A computer model revealed that 98% of such known planets remain molten inside—provided they truly resemble gas dwarfs with a light atmosphere of hydrogen.
If a planet has a lot of oxygen inside and carbon outside, its atmosphere gets heavier and cools faster. But for most worlds, the internal fire hasn’t gone out. This flips our understanding upside down: we used to think such bodies freeze solid over billions of years, but it turns out their interiors are still blazing.
🎯 Sub-Neptunes are the most common planet type in our galaxy, yet none exist in our Solar System.