I just read the Wiki article on calcium isotopes and it said the stable calcium isotopes such as 40Ca have never been observed to decay. Then, despite the high temperature of stars such as Sun there are calcium ions floating on the chromosphere of Sun. I thought calcium will be vaporized or even turned into plasma if it is exposed to extreme heat.

My main question is, is calcium for example 40Ca II is indestructible or at least can't be change to something different? If 40Ca II can indeed be change to something different like maybe carbon, helium, potassium, etc. what is the level of temperature that is required to achieve that?

  • $\begingroup$ Those calcium ions observed in stars are already vaporized. Vaporization has nothing to do with radioactive decay, nor do ions in a plasma state. When water molecules vaporize from the liquid state, the vapor still consists of water molecules. $\endgroup$
    – Bill Watts
    Dec 16, 2019 at 19:07
  • $\begingroup$ Is it possible to change ionized 40Ca into something that is no longer a calcium perhaps by extreme force, etc.? $\endgroup$
    – SnoopyKid
    Dec 17, 2019 at 1:38
  • $\begingroup$ I saw one article on the internet that they got Ca to emit protons by bombarding it with alpha particles. But that is not spontaneous decay with a rise in temperature. $\endgroup$
    – Bill Watts
    Dec 17, 2019 at 1:50
  • $\begingroup$ But the Ca still remain, right? How about if there is no longer anything that is related to calcium? How about in the core of stars? $\endgroup$
    – SnoopyKid
    Dec 17, 2019 at 1:58
  • 2
    $\begingroup$ If Ca emits protons, it is no longer Ca. $\endgroup$
    – Bill Watts
    Dec 17, 2019 at 2:59

1 Answer 1


You should distinguish the significantly different energy scales at which the phenomena take place. Vaporisation happens near melting temperature. Ca melts at 842C and boils at 1484C. Plasma formation requires ionisation that is 6.11 eV or 70.000 C/K. Thermal fusion of 40Ca with for example 4He requires even much higher temperatures combined with very high pressure.

  • $\begingroup$ Is it possible to change 40Ca II to smaller nuclei that it is no longer 40Ca II but wholly different kind of something that is no longer calcium? $\endgroup$
    – SnoopyKid
    Dec 17, 2019 at 1:37
  • $\begingroup$ It can be neutron activated to give 37Ar. See google.com/amp/s/www.researchgate.net/figure/… $\endgroup$
    – my2cts
    Dec 17, 2019 at 8:24
  • $\begingroup$ That's fusion, how about if splitting any calcium including 40Ca ii into different elements? $\endgroup$
    – SnoopyKid
    Dec 17, 2019 at 8:37

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