2011 Annual Science Report
Arizona State University Reporting | SEP 2010 – AUG 2011
Astrophysical Controls on the Elements of Life, Task 1: High-Precision Isotopic Studies of Meteorites
The elemental abundances of planetary systems potentially are affected by contributions from nearby supernovae. Injection of supernova material can be studied by isotopic analyses of meteorites, especially calcium-rich, aluminum-rich inclusions (CAIs) within them, which reveal the presence in the forming Solar System of short-lived radionuclides. Initial abundances of these radionuclides not only signal contributions from a supernova but also provide a chronometer to date the injection and other formation events. Radionuclides, especially 26Al, also can affect the thermal evolution and volatile retention within planetary bodies. In this task we seek to measure initial abundances of radionuclides in meteorites, especially CAIs, and to constrain the timing of early Solar System events.
The main focus of our efforts under Task 1 during this reporting period has been on placing constraints on the initial abundance of 60Fe in the early Solar System. If present in sufficient abundance (i.e., 60Fe/56Fe >~5 ×10-7), this radionuclide would serve as a “smoking gun” for the late injection of 60Fe by a supernova into the early Solar System, and as a significant heat source for the dehydration/differentiation of planetesimals. This work is being conducted primarily by graduate student Lev Spivak-Birndorf under the supervision of Co-I Meenakshi Wadhwa; two conference abstracts were submitted and a manuscript is currently under preparation.
Another project conducted during this reporting period was the U-Pb and Al-Mg chronology of a unique basaltic achondrite (NWA 2976), which has implications for the homogeneity of the 26Al extinct radionuclide, which played a significant role in the dehydration/differentiation of planetesimals. This work was performed mainly by research associate Audrey Bouvier under the supervision of Co-I Meenakshi Wadhwa, and resulted in the publication of a manuscript in Geochimica Cosmochimica Acta.
Finally, a new project is currently being initiated on identification of refractory inclusions in chondrites with fractionation and unknown Nuclear (FUN) effects. The ultimate goal of this project is to identify FUN inclusions for precise age dating, which would potentially allow us to constrain the timing of 26Al injection into the early Solar System. During this reporting period, we have developed the analytical methodologies for high precision Ti isotope analyses by laser ablation multicollector inductively coupled plasma mass spectrometer, since FUN inclusions are known to contain large mass independent isotope effects in a variety of elements including Ti.