Chemicals in the Sun's Atmosphere

Where did these elements come from? Hydrogen and helium are primordial: They were produced in the big bang in roughly the same amounts, relative to each other, as are seen today. Helium is also produced in the nuclear burning process that occurs on the interiors of all stars. But, during its normal lifetime, so little of a star's hydrogen is converted to helium, that it doesn't change the relative abundances of these two elements in the star's atmosphere by very much at

all. In fact, much of the helium produced by nuclear burning remains in the core of the star, and much is further converted in the thermonuclear reactions to form heavier elements. That brings us to all the other elements seen in the solar spectrum. Some of them are produced in the core of the star, by fusing lighter atomic nuclei. More than that, the Sun formed in a region of space where there have been other stars burning, and some supernova explosions (which produce huge amounts of heavy elements, including those that cannot be produced any other way), which have left behind a gas fairly abundant in these heavier elements. Thus, when the gas gathered to form the sun, it already had many of these metals in it. It turns out that this greatly accelerates star formation, compared to a gas with very small amounts of heavy elements. The sun is a fairly "dirty" star. Some stars have almost no detectable elements heavier than helium. However, since they are slow to form, they are much less common than dirty stars.