[extropy-chat] [ASTRO] Stars and X-Rays

[Robert Bradbury]

Amara can correct me if I am wrong, but I believe the O- and B-class
stars (but not M-stars?) would have higher X-ray output simply due to
their higher overall energy output (and therefore higher
temperatures).  Another facter would be because they are simply more
massive and have more atoms to whose electrons can be excited to
higher energy levels.

I would be curious to know at what energy level all atoms become
completely ionized.  At that point presumably one isn't generating
X-rays by ones own electrons dropping to lower energy levels but by
random electrons from the electron "cloud" being captured.

A related question would be how are very high energy gamma rays
generated?  Do you have to have an electron coming in at very high
velocity and be captured by the atom to have its energy converted
completely to a gamma ray photon (I'm using particle analogies here --
I'm sure the electromagnetic wave approach to these questions would be
somewhat different).

Robert


On 5/30/06, Damien Sullivan <phoenix at ugcs.caltech.edu> wrote:
> Amara (or anyone else): I think I've read, somewhere, that the Sun is
> fairly low in X-ray output, not just compared to M-stars or O-stars but
> even to other G-stars, though I've never seen why.  Does this sound
> familiar, and you expand upon or correct it?  It's probably come up in
> the context of colonizing other star systems, but I thought it might
> also have a role in the Great Filter, in the category Robin didn't talk
> about his essay: mass extinctions, or the things which didn't happen on
> Earth, vs. the hard (or not) things whihc did.