ABSTRACT
Chapter 2 begins with a discussion of the formation of the first neutral atoms during the so-called “recombination era.” Shortly after this epoch, the universe entered a “dark age,” which ended with the formation of the first stars. The emergence of stars represented a critical transition in the history of the universe, and an outline of how stars emerged is presented. During the discussion of star formation, the importance of the hydrogen nuclear binding efficiency (ε) is emphasized, and the ability of stars to carry out nucleosynthesis is reviewed. At the end of the chapter, the processes that lead to the death of a star are also considered, and the roles of supernovae and kilonovae in generating the heaviest naturally occurring elements in the universe are discussed. Finally, at the end of the chapter, the important role galaxies have in generating life is highlighted. In addition, the birth of our solar system is presented, and our Sun’s role in generating life-sustaining conditions is introduced.
