The neon-burning process is a set of nuclear fusion reactions that take place in evolved massive stars with at least 8 Solar masses. Neon burning requires high temperatures and densities (around 1.2 billion K or 100 keV and 4 billion kg/m<sup>3</sup>).
Process
Formulae
At such high temperatures photodisintegration becomes a significant effect, so some neon nuclei decompose, absorbing 4.73 MeV and releasing alpha particles. This free helium nucleus can then fuse with neon to produce magnesium, releasing 9.316 MeV.
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Ne-20 + y -> O-16 + He - 4.73 MeV
Ne-20 + He -> Mg-24 + y + 9.32 MeV
-->:{| border="0"
|- style="height:2em;"
|Neon-20| ||+ ||γ ||→ ||Oxygen-16| ||+ ||Helium|
|- style="height:2em;"
|Neon-20| ||+ ||Helium| ||→ ||Magnesium-24| ||+ ||γ
|}
Alternatively:
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Ne-20 + n -> Ne-21 + y
Ne-21 + He -> Mg-24 + n
-->:{| border="0"
|- style="height:2em;"
|Neon-20| ||+ ||n ||→ ||Neon-21| ||+ ||γ
|- style="height:2em;"
|Neon-21| ||+ ||Helium| ||→ ||Magnesium-24| ||+ ||n
|}
where the neutron consumed in the first step is regenerated in the second.
A secondary reaction causes helium to fuse with magnesium to produce silicon: