The Age, Formation and Evolution of the Elements

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

AST 0307279 Cowan, John J. The P.I. is continuing his research on the age, formation and evolution of the heavy elements, specifically, those formed in the s(low) and r(apid) neutron-capture nuclear processes, in the interiors of the oldest stars in our Galaxy. The detection by the P.I. and his collaborators of the long-lived radioactive element thorium in several, and uranium in one, of these Galactic halo stars has provided an exciting, and perhaps unique, opportunity to directly determine the ages of the oldest stars. Employing extensive, new and far more accurate data, the P.I. will first extend and expand his studies of stellar radioactive ages by determining the abundances for a number of metal-poor stars (i.e., old, with low levels of elements such as iron). These new thorium and uranium detections will be necessary to reduce any observational uncertainties and confirm earlier stellar and Galactic age estimates. Utilizing the newly determined abundance distributions in the metal-poor stars, the P.I. will calculate the initial abundance values of the radioactive elements Th and U (also known as nuclear chronometers or clocks) and make new age determinations of other low-metallicity stars, based upon their observed (i.e., decayed) thorium abundances. These studies result in more accurate age estimates for the oldest stars than previously possible and will help to answer the fundamental questions of just how old are the Galaxy and the Universe. Broader impacts. Both graduate and undergraduate students are involved in the research activities of the P.I., including female and underrepresented minority students who are being trained and mentored by the P.I. The P.I. also teaches voluntarily in one of the local elementary schools (sixth grade), and regularly gives public lectures on astronomy to the general community.In addition, the P.I. maintains a web site that includes research papers available to the community. Also included on the web site are examples of technology innovation, such as how they are utilizing the capabilities of the Internet 2 to transfer large amounts of astronomical data. Educational images, produced to illustrate the results of NSF-supported activities (such as the P.I.'s observations of supernovae and black holes), are available on the site for students and the general public. Finally, the P.I. includes and maintains databases on his web site that can be accessed by the astronomical community.