The nuclear fusion inside the sun asmain-sequence star only produces helium now. But, there are heavy elements, evenincluding iron, found in solar spectrum. And the earth contains various heavyelements. Where are these heavy elements come from?
Reference viewpoint:
The formation of the earth probably camefrom heavy elements condensate of the supernova ejecta of last generation starin the inner orbit of solar system. The age of the earth is 4.6 billion years.Now the sun is a main sequence star, and experienced approximately 4.57 billionyears. There are various heavy elements, including iron, found on the surfacegas of the sun, while the first generation main sequence stars almost only contain hydrogen and the production of light nuclear fusion——helium.