A Laboratory Investigation of the Formation of Pre-Solar Oxide Grains and Grains in the Early Solar System
Abstract
Our research on the stoichiometry, structure, and nucleation of silicon oxide clusters and their application to cosmic oxide grain formation and nucleation will be presented. The role of clusters in the chemical pathways leading to the formation of grains in cooling outflows of circumstellar shells in evolved stars, and possible oxygen isotope effects in grains will be illustrated. Our recent experimental data on silicon oxide clusters have implications relevant to recent observations by the Infrared Space Observatory (ISO) indicating the presence of crystalline forms of oxide grains in oxygen-rich shells of evolved late- type stars. The silicon oxide clusters were produced in a laser vaporization source and either the cationic or anionic clusters were investigated by pulsed field extraction in a time-of-flight mass spectrometer, or the neutral clusters were probed by multiphoton ionization with a femtosecond laser ( 50 fs @ 800 nm ). This is the first detailed specific experimental study of the role of clusters on the formation of cosmic grains. The study has become feasible as a result of long-term investigation of the development of atomic and molecular beam methods. The experimental results have implications for the chemical origin of the formation of our solar system.
- Publication:
-
IAU Joint Discussion
- Pub Date:
- 2000
- Bibcode:
- 2000IAUJD...1E..42L