Prof. Satoshi Yamamoto (Department of Physics, The University of Tokyo)
Star and planet formation is one of the basic physical processes in the universe, and has extensively been studied observationally and theoretically over more than 30 years. It is not only a structure-formation process, but also a chemical-evolution process of interstellar matter toward stars and planets. Observational understanding of the chemical evolution is an important target for modern astronomy, which would possibly be related to an origin of life. On the other hand, chemical compositions of the star forming clouds are sensitive to physical conditions and evolutionary history. Hence, they can be useful tools to investigate physical processes of star and planet formation.
With these in mind, we are studying chemical evolution of molecular clouds mainly by millimeter- and submillimeter-wave observations. In this talk, I am going to introduce our continuous study on the chemical evolution from starless cores to star-forming cores. In particular, we have recently found star forming cores, L1527 and IRAS15398-3359, which have different chemical compositions from others. In these sources, various carbon-chain molecules are extremely abundant in the vicinity of the protostars (Warm Carbon Chain Chemistry: WCCC). Discovery of the WCCC sources means that star-forming cores have a significant chemical variation, even if they look similar in physical properties. An origin of the chemical variation is discussed in relation to the difference in star-formation processes.