A curious question

[Chattiestspike2]

--==Please feel free to correct any premise I propose, because I am almost certain I have something wrong.==--

Can we see plasma? The reason I ask is because, to my understanding, plasma is a state of matter where it is so hot that it is stripped of electrons. Since light and all other electromagnetic energy is detectable when it passes through a medium of electrons (correct me please, I know I got something wrong so far), if plasma does not have electrons, would it still be able to emit some sort of electromagnetic energy?

I am sure I missed a bunch of vital points and I can almost hear the facepalms of physicists and the sort, but remember, I am just asking a question, and not asserting anything as truth.

 

[Nelson]

Interesting question. So I believe the answer is yes. There a number of ways we can see radiation from a source that is made mostly of plasma (such as a star). The biggest is:

Black Body Radiation

A large collection of ionized particles that is being heated due to friction from its own gravitational collapse will emit a thermal spectrum. This is what we see from stars. On top of this black body spectrum we can also see absorption and emission lines from molecules in the outer atmosphere of the star that are not fully ionized (not a plasma).

Then, there are a couple of more exotic types of radiation that we can observe, such as:

Synchrotron Radiation

This is radiation that is emitted by highly energetic particles in the presence of strong magnetic fields. We see this sort of thing in active galactic nuclei, which is basically a very active accretion disk around a supermassive black hole. You need a huge energy source, as well as very strong magnetic fields.

The last type that I can think of is not actually emission, it is:

Thomson Scattering

This is light that scatters off of free charged particles. The cool thing about this is that the particles will oscillate with the electric field of the incoming radiation, which causes them to accelerate and then re-emit photons perpendicular to their oscillations. Because of this, you can learn something about the direction of the original radiation source based on the polarization of the radiation you observe from the scattering source.

I hope this answered the question. Perhaps there are some other mechanisms I forgot as well?

Edit:

A bit of background on absorption/emission in a regular gas.

A plasma still has electrons, they are just no longer bound to nuclei. The regular sort of absorption and emission you see in a hot gas is from electrons transitioning between different orbitals in a bound atomic state. If a photon is absorbed at the correct quantized energy, an electron can jump to a higher energy orbital in the atom. But, the electron doesn't like to stay in this higher energy state unless the rest of the molecules in the gas are also this hot, so it will eventually (in a very short amount of time) transition back down to a lower energy state, or sometimes through a series of transitions. When it does this it emits photons equal to the discrete amount of energy lost in the orbital transitions. This is how absorption and emission lines are produced.

Some every day examples:

A fluorescent light bulb is emitting in this way, at a few discrete wavelengths. The color we see is a combination of all of these wavelengths that fall within the visible range. An incandescent bulb on the other hand is actually a filament being heated. This emits a black body spectrum that is continuous, and the shape is determined by the temperature.

 

[Crazyfist]

That, my friend, is the perfect answer, for a good question.