Hot Jupiters and rocky planets

[E621Keith]

Just watched the 700th S@N. It was mentioned Jupiter may have a rocky core the size of earth. So what are the chances that earth or some of the inner planets were originally cores of Hot Jupiters which had their atmosphere stripped by the young Sun?

[FraserClarke]

The solar radiation isn't strong enough to strip the atmospheres from Jupiter mass planets. We see lots of evidence for gaseous Jupiter mass planets in very close (a few DAYs) orbits around solar-like stars. They are inflated, compared to Jupiter, but they still have their gas atmospheres. There is evidence of the gas being evaporated by the solar radation, but the rates are low compared to the total volume of gas, so the planet lifetimes are comparable with the stellar lifetime I believe.

There may be a population of 'stripped' Jupiter cores, but I'm not sure how/if one could test that with current observations. I'm not sure what the difference would be between something which never had a massive gas atmosphere, and something which did but lost it?

Certainly evidence is emerging from Kepler of a large population of small (<10x earth radius) planets in very close orbits around stars.

[michael.h.f.wilkinson]

Actually, the early sun had far stronger solar winds, and the theory goes it did strip the atmosphere from the inner planets. How thick this shell of gas was is another matter.

Hot Jupiters are thought to migrate inwards after formation.