Researchers found vast, hidden oceans found from Uranus's four large moons.

There are hidden oceans in many moons and dwarf planets including Pluto. Today the hidden oceans are found inside four of Uranus's large moons. And that thing is opening the road to another question. The question is what keeps water liquid on those moons, where nitrogen geysers are filling the air with nitrogen vapor, and the temperature is 190 Kelvin. The vaporization point of nitrogen is 77-124 Kelvin depending on pressure.  

Researchers found water on all of Uranus's large moons except Miranda which is too small to keep water liquid. There is a possibility, that Miranda has no core at all, and its inner structure is homogeneous. And the moon is formed entirely of water. And that makes Miranda-moon the cosmic ice bite. One mystery is what formed Miranda because normally regular, ball-shaped moons and planets form around the nucleus that is heavier than other parts of that planet. That process forms the ball-shaped object. But if there is no heavier nucleus the dwarf planet should be irregular. So why Miranda-moon is a ball-shaped moon without a metallic or stone nucleus?  

Things that affect vaporization are temperature, gravitation, pressure, and magnetic field. In weak gravitation, the water stays liquid in lower temperatures than in a strong gravitational field. And in some visions, the form of the ice on the weak gravitational field is super ionized. That means the water molecules are in lines. And the X-ray emission from Uranus's atmosphere causes thought, could that emission have something to do with the hidden oceans inside the ice shell of those moons? 

"Uranus is surrounded by its four major rings and 10 of its 27 known moons in this color-added view that uses data taken by the Hubble Space Telescope in 1998. A study featuring new modeling shows that four of Uranus’ large moons likely contain internal oceans. Credit: NASA/JPL/STScI" (ScitechDaily.com/Vast, Hidden Oceans Discovered on Four of Uranus’ Large Moons)

"New modeling shows that there likely is an ocean layer in four of Uranus’ major moons: Ariel, Umbriel, Titania, and Oberon. Salty – or briny – oceans lie under the ice and atop layers of water-rich rock and dry rock. Miranda is too small to retain enough heat for an ocean layer.Credit: NASA/JPL-Caltech"(ScitechDaily.com/Vast, Hidden Oceans Discovered on Four of Uranus’ Large Moons)

So the ice on those oceans might not be similar to ice on Earth. The dividing radioactive isotopes can put those water molecules in lines. And super ionized ice can look like a liquid even in extremely low temperatures, especially if the gravitational field is very weak. 

The thing. What makes this water interesting is that Uranus has not so strong gravitational field that could affect those moons very strongly. The hidden oceans can be liquid because of the combination of internal nuclear isotope dividing and the gravitational fields of Uranus and other moons. The temperature on those moons is quite high if we think about their distance from the sun. 

And their size means that the gravitation on those moons is weaker than on our moon. The escaping velocity from the surface of Titania, the largest Uranus moon is 0.759 km/s, and the earth Moon's escaping velocity is 2.38 km/s. That means the water moves far easier than on Earth on those distant moon's icy surfaces. That means tidal waves can keep those moon's oceans liquid. 

https://physicsworld.com/a/x-ray-emissions-from-uranus-are-detected-for-the-first-time/

https://scitechdaily.com/vast-hidden-oceans-discovered-on-four-of-uranus-large-moons/

Earth's moon: https://en.wikipedia.org/wiki/Moon

Uranus's moons

https://en.wikipedia.org/wiki/Ariel_(moon)

https://en.wikipedia.org/wiki/Miranda_(moon)

https://en.wikipedia.org/wiki/Oberon_(moon)

https://en.wikipedia.org/wiki/Titania_(moon)

https://en.wikipedia.org/wiki/Umbriel_(moon)