Can there be free electrons in interstellar gas?

[Suekdccia]

TL;DR Summary

Can there be free electrons in interstellar gas? Can they be stable in those conditions?

If I'm not mistaken, in interstellar gas, there can be clouds of free electrons (not "attached" to any atomic nucleus)

But can they stay like that indefinetely? Or will they inevitably end up in atoms?

And how are they holding in interstellar gas inside of galaxies? Are they gravitationally bound to them?

 

[ergospherical]

There are indeed, about 1 every 100 cubic centimeters, because of photoionisation by the interstellar radiation field. The ionized species are neutral metals in dust grains (e.g. C → C⁺ + e^-, etc.) in HI regions, or from hydrogen & helium in HII regions. There'll be some sort of ionization/recombination equilibrium which you can track with a Saha-type equation.

 

[Suekdccia]

There are indeed, about 1 every 100 cubic centimeters, because of photoionisation by the interstellar radiation field. The ionized species are neutral metals in dust grains (e.g. C → C⁺ + e^-, etc.) in HI regions, or from hydrogen & helium in HII regions. There'll be some sort of ionization/recombination equilibrium which you can track with a Saha-type equation.

I see

And as time passes by and stars die out, would those electrons still be free roaming around?

 

[ergospherical]

I don't know, that's a bit too broad for me to say anything meaningful. The interstellar radiation field is dominated by stellar emission. There's also lots of other complications: supernovae, magnetic fields, ...

 

[Vanadium 50]

Can there be free electrons in interstellar gas?

No. By definition this is interstellar plasma. The ISM is a mix of cold gas, warm plasma, and very hot plasma.

And as time passes by and stars die out

By the pendulous yarbles of Zeus, will you please stop starting all these new "fate of the universe" threads? If you want to discuss a topic, discuss it - don't fragment it into a million tiny pieces and expect anyone to make sense of what you are trying to say.

 

[Suekdccia]

No. By definition this is interstellar plasma. The ISM is a mix of cold gas, warm plasma, and very hot plasma.

Oh so then interstellar plasma are free electrons (as well as ionized protons)?

By the pendulous yarbles of Zeus, will you please stop starting all these new "fate of the universe" threads? If you want to discuss a topic, discuss it - don't fragment it into a million tiny pieces and expect anyone to make sense of what you are trying to say.

Hey, I just asked one question! I'm interested about what our models predict about the behaviour of the universe in the future. In this particular case, if interstellar plasma electrons are free because of photoionization, then will electrons attach to ionized atoms again once stars die out and photoionization stops? Or is it more complex than just that? I don't know, it's a simple question that follows from the discussion, I don't see anything wrong

 

[Ken G]

Much of the ionization in the interstellar medium is owed to stars, almost all probably. If that's really all you are asking, then it follows immediately that yes, when stars die out, so will the free electrons, though keep in mind that the stars won't die out as long as there is interstellar medium to make more of them.

 

[DaveE]

Eventually, they will get to the lowest energy state, which will be bound to a proton/atom*. This is the 2nd law of thermodynamics. When? IDK. Are there really enough protons to get every electron? IDK. Does it matter? Not really IMO, it might be the last thing that happens in the universe.

*OK, there are other interactions possible, antimatter, black holes, and such. But really, let's just admit it, it'll really be protons and atoms.