I have asked questions like this before, relating to a phenomenon on my planet that is called pseudo-aurorae.


X-rays of the [O VII] forbidden line in my star are constantly forming due to MCWS (magnetically confined wind shocks) in the star. These amounts of radiation are rarely significant, but every once in a while, a flare happens and massive amounts of x-rays are released. These x-rays excite atoms in the planet's atmosphere directly and also secondary particles that also excite atoms in the planet's atmosphere indirectly.

I have already figured out that this sky-glow will be visible and that is not my question. My question is for how long will the sky glow be dominant.

Some Info

The planet's atmosphere is roughly composed of:

  • Nitrogen ($\ce{N_2}$) - 61.5%
  • Oxygen ($\ce{O_2}$) - 21%
  • Neon ($\ce{Ne}$) - 15.5% (very dominant in the high atmosphere, as it is quite light)
  • Xenon ($\ce{Xe}$) - 1% (since it is heavy, it's almost completely in the lower atmosphere, so it doesn't really affect the upper atmosphere much)
  • Water Vapor ($\ce{H_2O}$) - 0.5%
  • Argon ($\ce{Ar}$) - 0.479%
  • Carbon Dioxide ($\ce{CO_2}$) - 0.02%
  • Trace - the rest (this includes the ozone)

Here is some other information you may find useful.

  • Atmospheric Pressure - 1.13 atm
  • Temperature at Sea Level - 290.78 K


For some time, I have one problem, I want to know how long the molecules will remain ionized and create a dominant sky-glow like an aurora.

To help you, the starting ionizations of the molecules are fully ionized nitrogen, fully ionized oxygen, $\ce{Ne^9+}$ , $\ce{Ar^16+}$, fully ionized carbon, fully ionized hydrogen, and fully ionized helium.

The only element I couldn't find the ionization info on was xenon, due to limited information being there beyond its third ionization level, but that is fine, because since most of the xenon is in the lower atmosphere, very little would be ionized anyways.

  • $\begingroup$ If the question is taken verbatim, the answer is trivially zero time, because there is no such thing as a fully ionized nitrogen, oxygen etc. $\rightarrow$molecule$\leftarrow$. And anyway, I would be mildly interested to learn how you plan to make significant amounts of fully ionized oxygen, $\ce{O^8+}$, without using tremendous amounts of energy. $\endgroup$
    – AlexP
    Nov 18 at 23:47
  • $\begingroup$ I know that the ionized molecules would dissappear quickly, but they would release a sky glow. I want to know how long that sky glow would last. $\endgroup$
    – Neil Iyer
    Nov 19 at 0:53
  • $\begingroup$ And the ionized atoms come from significant amounts of x-rays and secondary particles from the flare. $\endgroup$
    – Neil Iyer
    Nov 19 at 18:09
  • $\begingroup$ If your giant death laser of a star is radiating enough energy to strip 16 electrons out of the core shells of Argon, your question is purely academic, cause no life form will be there to see any of it. Those are not significant amounts of x-rays; those are apocalyptic amounts of x-rays. I'd also like to point out that after a quick look at the NIST database, most of the crazy ionization states that you expect are predicted based on purely theoretical/extrapolated ionization energies. It doesn't look like anyone ever measured the 16th ionization of Argon, which is not too surprising $\endgroup$ Nov 21 at 6:42
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    $\begingroup$ As an aside, those extreme ionized states are not directly relevant to the coloration of your sky. Much like they needed x-rays to form in the first place, they will emit in the x-ray range as they recombine $\endgroup$ Nov 21 at 6:52


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