NOAO >   Observing Info >   Approved Programs >   2006A-0174

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Proposal Information for 2006A-0174


PI: Jeremy King, Clemson University, jking2@clemson.edu
Address: Department of Physics and Astronomy, 118 Kinard Lab, Clemson, SC 29634-0978, USA

Title: Lithium Isotope Ratios in T Tauri Stars

Abstract: The cosmic evolution of ^6Li and the gamma-ray fluence are inextricably linked, and trace the Galactic cosmic ray history. Recent work has shown that the pre-solar ^6Li abundance requires a gamma-ray flux which is ~4 times larger than the entire extragalactic gamma- ray background! This discrepancy may necessitate a pre-Galactic source of cosmic rays, which also would have significant implications for the post-Big Bang production of ^7Li and, thus, the interpretation of ^7Li in halo stars. Surprisingly, meteoritic ^6Li/^7Li measurements are the only “stellar” estimate of this important isotopic ratio at solar-metallicity; ISM measurements show huge variations along different lines of sight. Here, we propose to exploit the large aperture of Gemini-S and the very high resolving power of bHROS to determine the first present-day stellar estimates of undepleted ^6Li at solar-metallicity by obtaining high resolution and S/N spectra of young, warm, slowly-rotating T Tauri stars.


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