system
Given the following post, respond as if you're commenting on Reddit:
human
Are there chemical reactions on the Sun?

Most of the layman's descriptions describe the fusion of the Sun, but today I heard a person misspeak of a chemical reaction.  I thought "Well, why not?  There's still matter up there, even though it's superheated".  Is it meaningful to describe chemical reactions on the Sun?
gpt
Not the Sun, but in the atmospheres of low mass stars! Chemical reactions are all about the relationship between electrons and nuclei of various atoms. The bonds the electrons create have some threshhold energy (or temperature), above which the bond is too weak to hold. The surface of the Sun is too hot for these molecular bonds to exist. Only a little deeper in the Sun, it's so hot that electrons don't even stay with the hydrogen nucleus anymore. If you move to cooler stars, though, the surface gets cool enough that molecules like carbon monoxide (CO), titanium oxide (TiO), or cyanogen (CN) can form. (Add an electron to neutral cyanogen and you have cyanide. At least, astronomers call neutral CN "cyanogen", chemists may say different - but then, we also call carbon a metal so don't think we're changing it.) These molecules are visible as broad absorption bands in stellar spectra as they absorb a range of wavelengths (energies) of light, in contrast to plain atoms which absorb only very specific energies.