Expert: James Gort - 1/8/2009

Question
Hello again Professor Gort

Thank you for your help. Professor Gort, in your reply to my last question (small cold sun) you said:
charged particles from the sun collide with the earth's atmosphere (or Saturn's or Venus') and excite the atoms to produce a glow.
And you also said: The electrical current in the water (which are fast moving electrons) collides with the water molecules and ionizes them.

My question regards these collisions.

Do we no how fast the charged particles are travelling inside the magnetic field loops on the sun?
If they are travelling at great speed, could they somehow be involved in collisions, and could this produce hot plasma?
And lastly, wouldn't this better explain how fast moving particles hit the earth's atmosphere after the loops snap? (Not that the particles are accelerated on there journey, but were already moving at great speed inside the loop before the loop broke).


Thanks again
David

Answer
Hello David,

Yes, we have a pretty good idea of how fast these particles are travelling.  In some types of stars, they are travelling nearly at the velocity of light.  Not quite as fast in our sun's atmosphere, but they are definitely involved with collisions which produce plasma and cause emission of light.  In some stars (again, not our sun), this is a major factor, and it produces strong "emussion lines" in the spectra of their light.  In our sun, most light we see comes from the hotter interior, through the cooler astmosphere (so we mainly see an "absorportion spectrum"), but there is certainly some emission going on from the hot plasma.  And lastly, the fast particles hitting the earth's atmosphere do interact with atmospheric molecules and produce plasmas.  Not sure if that answers your last question, but hope it helps.

Prof. James Gort