In astronomy, nearly everything is hydrogen or helium. Like, over 98% of all matter is H or He. So it’s very useful to be able to talk about H, He, and “everything else”. They call that everything else “metals”.
Some stellar atmosphere models also add “alpha”, which provides an extra knob for the abundance of alpha-capture elements. If you need anything more than that, you’re doing some niche astrophysics.
In astronomy, nearly everything is hydrogen or helium. Like, over 98% of all matter is H or He. So it’s very useful to be able to talk about H, He, and “everything else”. They call that everything else “metals”.
Some stellar atmosphere models also add “alpha”, which provides an extra knob for the abundance of alpha-capture elements. If you need anything more than that, you’re doing some niche astrophysics.
Alpha being the elements up to iron?
Elements formed by alpha capture. Since alpha particles have 2 protons, it’s generally elements with an even number of protons.