When this light encounters hydrogen atoms still lingering in the stellar nursery that produced the stars, the atoms
become ionised.
The energy released now heats the gas till
it becomes an ionised plasma due to the high Temperature, the escape of this centraally generated energy to the suface of the «cloud», now a proto star will eventually stop the collapse as the outer layers also heat, and the outer plasma will become opaque to the EM radiation generted at the million degree buring interface.
Not exact matches
But when Ilsedore Cleeves at the University of Michigan and her team created a model of the early sun they found this couldn't have happened: once the ice was split, the oxygen
became locked in frozen carbon monoxide and not enough
ionised, deuterium - rich hydrogen was made.
As something spread radially, whether it was a shock wave, the air temperature or
ionised particles or???, the sky very rapidly
became clear, layer by layer starting from the lowest.