A Waterfall of Planets: The Mystery of the Vanishing Water Worlds ⚡ экспресс
To explain the radius valley in Kepler planets, a scenario based on primordial differences in bulk density is proposed. Using refined interior models of water worlds with adiabatic steam atmospheres and migration models from the Genesis library, a Bayesian hierarchical mixture model is constructed for planets with periods under 100 days. It combines rocky planets and water worlds without hydrogen-helium envelopes. The recovered mass distributions peak at ~2.6 M⊕ for rocky and ~7 M⊕ for water planets, with a peak water fraction of ~41% in water worlds. Water worlds match the Kepler sub-Neptune population well: the prevalence drop (radius cutoff) manifests as a sharp decline dubbed the “waterfall.” However, mass–radius analysis shows that planets with R ≳ 3 R⊕ cannot be explained by water alone, and at least 20% of the sub-Neptunes in the sample must contain a hydrogen-helium admixture.
The Kepler telescope William Borucki's caught the faint twinkling of distant stars and discovered thousands of planets around other suns. Among them gapes a gap: almost no worlds sized between rocky balls and puffy water giants. This 'radius valley' was explained by a new model: planets initially divide into rocky and water ones. Water worlds with a steam atmosphere fill the gap, but at three times Earth's size they abruptly cut off — like a stream plunging over a waterfall.
Upon reaching a critical mass, such a planet captures hydrogen and helium and becomes a gas giant. Large water worlds simply don't get a chance to appear — they transform earlier. But inside them lies a surprise: water under immense pressure turns into hot ice — solid but scorching. Light measurements from Kepler show that the oceans there have no bottom. And although such water worlds are common in the galaxy, our Solar System is just one possible recipe.
🎯 On water planets, water turns into hot ice under incredible pressure — a solid substance that remains red-hot. So the oceans there can be liquid on top and icy deep down at the same time.
🎬 In 'Interstellar,' the characters visit Miller's planet, covered by a shallow ocean. But real water worlds are more like giant droplets without a solid surface, far deeper than any Earthly seas.