I would like to expand a bit on my previous post by including some reference material. First, I will refer to the book I recommended earlier,
Introduction to Comets by Brandt & Chapman (Cambridge University Press, 2004, 2nd edition), specifically section 6.4.4 (
Cometary X-rays), page 230.
Brandt & Chapman reference
Lisse, et al., 2001, and point out that there are only two plausible sources for cometary X-rays: charge exchange and electron-neutral thermal bremsstrahlung.
Originally Posted by Brandt & Chapman page 230
Lisse, et al. (2001) obtained observations of comet C/LINEAR 1999 S4 using the Chandra X-ray Observatory. Line emission was detected as shown in Fig. 6.24. The fit to the observations contains a six-line charge exchange model plus a thermal bremsstrahlung contribution. The clear peak at 570 eV is caused by charge exchange of O+5. The agreement with the observations is excellent, but the contribution from thermal bremsstrahlung could decrease as spectral resolution imporves
As an example of one common charge exchange reaction, Brandt & Chapman give ...
O6+ + M = O5+* + M+
Where the
M is any one of many different possible neutral molecules or atoms in the cometary coma, most commonly perhaps H
2O, OH, O & H. The '
*' symbol indicates that the O
5+ ion could be either in the ground state (O
5+), or in an excited state (O
5+*). If the latter, then there will be additional X-ray or gamma-ray photons, which are also consistent with astronomical observations.
Also worth noting:
Originally Posted by Brandt & Chapman page 229
Subsequent analysis of 15 comets showed that the emission was confined to the coma volume between the nucleus and the sun. No correlation was found between the X-ray emission and dust or plasma tails or the sun's X-ray flux.
This is noteworthy because the draping of the solar wind magnetic field over he comet would inhibit the build up of charge along the leading edge, where the X-rays are observed to originate, and encourage charge build up either along the sides or through the tail (the latter being the mechanism that our group uncovered to explain the correlation between the solar wind and Jovian radio emission;
Bolton, et al., 1989). So in the EU "model" arcing and X-rays should be generated where the charge builds up, away from the region where the X-rays are actually observed to originate. So one more reason becomes apparent for doubting the EU idea.
A more complete review of cometary X-ray & UV emission can be found in
Krasnopolsky, Greenwood & Stancil, 2004 (not freely available, you will have to look it up the old fashioned way).
I also said that the astronomical observations compared favorably with laboratory observations of charge exchange spectra. See, for instance, the paper
Beiersdorfer, et al., 2005a and the AGU abstract
Beiersdorfer, et al., 2005b.
The emission of X-rays and UV from comets is readily explained via well understood mainstream physics, and supported by agreement between ground based laboratory experiments & astronomical observations. Furthermore, the observed properties of cometary X-rays, while supported by mainstream physics, is simultaneously inconsistent with the expectations of the naieve EU ideas.
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)) try understanding that the x-rays from comet coma have actual scientific explanations. They are so well known that they are even in the textbooks that the thunderbolt cranks have never read.
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