The Principal Investigator proposes to derive the abundances of carbon (C), nitrogen (N), and oxygen (O) in the atmospheres of cool stars and stars at the turn-off region in the Hertzsprung-Russel diagram of globular clusters. (Globular star clusters are aggregates of about 100,000 to 1,000,000 stars and among the oldest objects in our and other galaxies.) The tools for this research are computer codes for stellar atmospheres and a large file of data of atomic and molecular spectral lines. The models are flux constant and include the effects of convection and line absorption. The theoretical results will be compared with observations with the aim of determining the ages of globular clusters, the mechanisms of mixing in red giant stars, the primordial CNO abundances and how they were produced, and the difference between globular clusters in our Galaxy and the Andromeda galaxy.
