How are photons produced when hydrogen atoms collide in the core of sun?
Through Nuclear interactions, like Carbon, Nitrogen and Oxygen which under some physical processes release gamma radiation. I don't know the processes off-hand, but I am sure you could find it with a search! Ęthelwulf, Mon, 2nd Apr 2012
Isn't our sun, at it's current stage, only fusing Hydrogen to Helium at the moment? I think it's not old enough yet to fuse Helium to higher order atoms. They may be present in the core, but not active at the moment. So I'm saying: Hydrogen + Hydrogen -> Helium + Energy Nizzle, Mon, 2nd Apr 2012
Basically it is just because it is a lot of hot gas radiating thermally into space. All the nuclear stuff is way down inside and invisible apart from the neutrinos. OK it is thge driver that keeps the surface nice and hot. the radiation is just because as the molecules collide they exchange photons and some of these escape into empty space.