Stellar Fusion Requirements

Fusion	Fusion By-product	Minimum Core Temperature	Minimum Core Density	Minimum Stellar Mass*
Hydrogen	He	13 million K	100 gm/cc	0.08 solar masses
Helium	C, O	100 million K	100,000 gm/cc	0.5 solar masses
Carbon	O, Ne, Mg, Na	500 million K	200,000 gm/cc	4 solar masses
Neon	O, Mg	1.2 billion K	4 million gm/cc	about 8 solar masses
Oxygen	Mg, Si, S, P	1.5 billion K	10 million gm/cc	about 8 solar masses
Silicon	Si, S, Ar, Ca, Ti, Cr, Fe, Ni	around 3 billion K	30 million gm/cc	about 8 solar masses

*Stars with masses less than this will not able to reach the temperature and density criteria for the fusion to begin. For the neon, oxygen and silicon fusion, the mass estimates are very approximate and uncertain.