Calcium atoms can't withstand extreme heat according to this link. http://abyss.uoregon.edu/~js/ast122/lectures/lec09.html "Why do some stars have strong lines of hydrogen, others strong lines of calcium? The answer was not composition (all stars are 95% hydrogen) but rather surface temperature.

As temperature increases, electrons are kicked up to higher levels (remember the Bohr model) by collisions with other atoms. Large atoms have more kinetic energy, and their electrons are excited first, followed by lower mass atoms.

If the collision is strong enough (high temperatures) then the electron is knocked off the atom and we say the atom is ionized. So as we go from low temperatures in stars (couple 1,000K) we see heavy atoms, like calcium and magnesium, in the stars spectrum. As the temperature increases, we see lighter atoms, such as hydrogen (the heavier atoms are all ionized by this point and have no electrons to produce absorption lines)."

So, everything including heavier elements such as calcium will be reduced to helium and hydrogen in the ground zero of nuclear explosions because the temperature at ground zero reach millions of degree Celsius. Correct?

  • $\begingroup$ all stars are 95% hydrogen what? where did that fake statistic come from? $\endgroup$
    – Kyle Kanos
    Dec 20, 2019 at 11:35
  • $\begingroup$ @KyleKanos Not sure, that's what was said in the link. $\endgroup$
    – SnoopyKid
    Dec 20, 2019 at 17:00
  • $\begingroup$ Well that's clearly not at all true. Neutron stars, for instance, are not made of hydrogen. $\endgroup$
    – Kyle Kanos
    Dec 20, 2019 at 17:32
  • $\begingroup$ @KyleKanos during the supernovae explosion, only nuclei in the core of the supernovae get destroyed while nuclei on the surface get ejected, correct? $\endgroup$
    – SnoopyKid
    Dec 21, 2019 at 3:59
  • $\begingroup$ how are you defining "destroyed"? And which class of SNe are you considering I(a|b|c)? II? PISNe? Other? $\endgroup$
    – Kyle Kanos
    Dec 21, 2019 at 4:11

1 Answer 1


The temperature of a nuclear explosion won’t cause the nuclei of calcium atoms to come apart into helium and hydrogen nuclei. That process needs even more extreme conditions, because the transition the other way (toward heavier nuclei) is energetically preferred: fusion liberates energy by colliding lighter nuclei and turning them into heavier ones.

What the high temperature will do is excite and largely strip the electrons from those nuclei. That’s what’s causing the behavior of the spectral lines.

  • $\begingroup$ Gotcha. So maybe by bombarding calcium with alpha particles so the protons of the calcium or basically nuclei will get scattered and shattered? This is one of the answer I got when I asked how to change calcium atoms into wholly different entities. What are other processes that can turn calcium atoms into different elements, others, etc.? $\endgroup$
    – SnoopyKid
    Dec 19, 2019 at 4:16
  • $\begingroup$ @MohamedObeidallah A lot of energy is involved and the only way is scattering with high energy particles in accelerators, and the reslult is probabilistic. $\endgroup$
    – anna v
    Dec 19, 2019 at 5:40
  • $\begingroup$ @anna v Probabilistic? This article said they successfully break calcium and neon journals.aps.org/pr/abstract/10.1103/PhysRev.51.8 $\endgroup$
    – SnoopyKid
    Dec 19, 2019 at 6:03
  • $\begingroup$ @Bob Jacobsen so even in the star's core which temperature is millions of degree, there are calcium nuclei? $\endgroup$
    – SnoopyKid
    Dec 19, 2019 at 6:40
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    $\begingroup$ @MohamedObeidallah A quasar is a type of Active Galactic Nucleus. They are large structures, and the temperature varies over the structure. Certainly, the hottest parts are hot enough for photodisintegration, but the spectra of AGN show emission lines from a variety of light elements, upto iron. However, comments aren't a good place for discussion, chat is much better for that. $\endgroup$
    – PM 2Ring
    Dec 19, 2019 at 17:25

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