Galaxies contained only light elements such as H, He, Li, Be, and B immediately after they formed. All the other elements we are familiar with have been synthesized through nuclear fusion taking place in stars. Stars more than 10 times massive than the sun explodes as supernovae at the end of their lives, and ejects elements synthesized. Stars of the next generations were formed from the gas that contains these elements. The repetition of these processes eventually leads to the elemental abundance patterns seen in the present solar system.

Evolution of first stars and origin of elements

The objective of this project is to construct a quantitative model to describe the dynamical and chemical evolution of galaxies. Quasars at cosmological distances emit photons including information on the early universe. In addition, there are many stars older than the sun in our galaxy. The emission of these stars also contains fossil information on the galaxy when these stars formed. In particular, the emissions both from quasars and old stars encode fruitful information on how elements were synthesized by nuclear fusion operating in stars. In our project, we will simulate the evolution of galaxies by numerical models. The processes to be calculated include the formation of galaxies in the early universe, the evolution of the first stars formed from the gas with the primordial elemental abundances, supernova explosion, the subsequent evolution of a supernova, the formation of stars of the next generation, and the recycle of these processes. By comparing results of the simulations with information in emissions from quasars and old stars, we will explore the origin of elements in the universe. Through these studies, we will learn how a supernova explodes and how different nearby celestial objects are from those at cosmological distances. It will help to probe the geometry of the universe with distant supernovae, for example.