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Originally Posted by NEOWatcher
Does this mean that the molecules were formed in a later stage of the universe since it needs these bumpy particles? Any clue as to the formula for when vs how many?
I've always thought it was a more natural state, and the atoms would form the molecule when they met in any circumstance. (I just keep learning)
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Astrophysicists started out expected to find rather little molecular hydrogen (H2) in the interstellar medium, because it's essentially impossible to form one simply from two H atoms bumping into each other (conservation of energy plus the available excitation processes mitigate against it). When H2 started to turn up all over the place, the general association of denser H2 with more dust grains put people on the trail of the role of grains - when one atom is temporarily adsorbed (I think that's the correct description) onto the grain surface, anbother one can join with it and the whole dust grain serves as a sink to satisfy monentum and energy conservation simultaneously. This new work seems to flesh out just how and where this happens in detail.
Indeed we expect less molecular gas in the early Universe, at least until grains form (mostly from supernovae and less violent stellar outbursts). Before that happened, the only known pathways involve the small fraction of free electrons (part per million) left after recombination. These can drive a reaction involving charge exchange that produces a correspondingly small amount of H2, which seems to hjave been crucial in the formation of the first generation of stars. These stars, in turn, would have made quite enough heavy elements, and sprayed them into their surroundings, that succeeding generations of stars would be much more like what we see today.
24-June-2005, 08:41 PM
Hydrogen and stupidity
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