Oops, I must have missed this earlier, sorry!
With big planets ending up close in, could they have captured moons on their way?
Possibly, I guess. Capture is really hard to do though - it's probably more likely that they have any moons that they formed with.
How quickly would an ice ball melt when it was falling in below the snow line?
Um... can't really answer that accurately beyond saying it'd take a very long time, since it'd start outside the snow line, and then slowly get warmer as it moved inwards, and it has to get hot enough to lose the vapour form of its volatiles (e.g. water vapour, CO2 gas, methane gas), and then it would have to get hotter and hotter to lose it faster. It'd be millions of years, probably hundreds of millions of years, maybe billions of years - depends on the size of the body and the type of volatile it's losing.
On what sort of timescale does insolation heat a planet size body?
. Solar insolation is what heats up the Earth on a day to day basis.
I recall that the earth gets a big chunk of its heat budget from radioactive decay inside its guts. Enough heat to drive the plate tectonics.
It gets way more energy from the sun than it does from its interior (take the sun away, and earth would freeze pretty quickly. The internal heat wouldn't warm the surface much at all, except at volcanic areas). Internal heat does drive the plate tectonics though - solar heating isn't involved in that at all.
What is thought about all these torch orbit Supiters? Are they all expanding and boiling off? I seem to recall one of them was tracked in its transit as being very expanded.
A few are. But jovians are massive planets, and most can retain hydrogen even in really hot conditions. When you get that close to the star though I think other processes can also enhance atmosphere loss (stripping by solar wind, for example), more so than they do further out.
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