TOI-3686 hosts a hot Jupiter and a smaller sub-Neptune that orbit in a 2:1 resonance: the outer planet takes almost exactly twice as long to orbit as the inner one. Both planets show large shifts in their transit timings, and TOI-3686 is the only kno...

Simulations show that ammonia and hydrogen can separate into distinct layers under some planetary conditions. The boundary between mixing and separation crosses expected temperature profiles inside Uranus and Neptune, suggesting ammonia may be rainin...