In this chapter we discuss how, when, and during which processes the chemical
elements have been formed in the universe. A short review about the origin of the universe
is given The most abundant chemical element in the universe is hydrogen. This was formed
during the first phases of the Big Bang and all other elements such as He, Carbon, Oxygen
were formed by thermonuclear reactions (expect elements heavier than Fe). These processes
are discussed in the chapter on stellar evolution where a distinction has to be done between
low mass and massive stars. Therefore, it took several generations of stars before the universe
contained a certain amount of these elements so that solid planets and complex molecules
could originate.
The main message of this chapter is that the chemical elements necessary for life are the products
of thermonuclear reaction that took place in the center of stars (with few exceptions),
so that we consist of stellar dust.
Keywords: Universe: Origin; Primordial composition; stellar evolution; white dwarfs; red
giants; neutron stars; black holes; supernovae; origin of elements; nucleosyntheis
