What is the specific heat of ionised Helium, given as ergs/g/K? This seems to be very difficult find on the internet.

This is in the context calculating the total heat of the Sun which is given as Mass $\times$ Temperature $\times$ Specific Heat.


Specific heat capacity is a measure of the energy required to raise the temperature of 1 kg of material by 1°C.

The SI unit of specific heat capacity is joule per kelvin per kilogram, $J⋅kg^{−1}⋅K^{−1}$

The equivalent definition using cgs units is the amount of heat energy (measured in ergs) required to raise the temperature of one gram of the substance by one Kelvin (erg/(g·K)).

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    $\begingroup$ It might be easier to provide an answer if you give the context for why you ask this question. Are you interested in the plasma phase of ionized Helium? $\endgroup$
    – KF Gauss
    Nov 14, 2021 at 20:41
  • $\begingroup$ @KF Gauss, it's in the context of astronomy, interstellar space and stars. Wait a moment while I check it out, and I will reply with the precise context. $\endgroup$ Nov 14, 2021 at 20:57
  • $\begingroup$ @KF Gauss, the context is that I want to figure out the total heat of the Sun which is given as Mass $\times$ Temperature $\times$ Specific Heat. $\endgroup$ Nov 14, 2021 at 23:22

1 Answer 1


A monoatomic ideal gas has mean energy $\frac 32 kT$ per particle, or a molar heat capacity of $\frac 32 R$, where $R$ is the ideal gas constant. A mole of completely ionized helium will have mass four grams and heat capacity $3\times\frac32 R$, because each free nucleus is accompanied by two free electrons.

You would be amused by this answer, which basically contains the calculation you’re trying to do.

  • $\begingroup$ Thank you that's very helpful! $\endgroup$ Nov 15, 2021 at 0:57

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