NOAO >   Observing Info >   Approved Programs >   2018A-0445

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Program Information for 2018A-0445


PI: Jeffrey Gerber, Indiana U., jemigerb@indiana.edu
Address: Astronomy Department, 727 E. 3rd St, Bloomington, IN 47405 USA

CoI: Zachary Maas, Indiana U.
CoI: Eileen Friel, Indiana U.
CoI: Catherine A Pilachowski, Indiana U.
CoI: Enrico Vesperini, Indiana U.
CoI: Alex Deibel, Indiana U.

Title: Li Abundance in M10: Using Light Element Abundances to Constrain Deep Mixing

Abstract: Decades ago the abundances of C and N were found to decrease and increase, respectively, as the stars in globular clusters evolved past the luminosity function bump and climbed the red giant branch. The surface abundance measurements led to the discovery of a secondary, non- canonical stellar mixing phenomenon occurring in solar mass stars. The current favored mechanism for what has been referred to as deep or extra mixing is a process called thermohaline mixing. While non-canonical, thermohaline mixing has been theorized to be the cause of deep mixing for quite some time, there is still uncertainty about how the process operates. More observational samples of stars covering large ranges of magnitude and multiple elements affected by thermohaline mixing, such as lithium, are required to constrain theoretical models, so we can determine how this process fits into the current canonical model of stellar evolution. We propose spectroscopic observations using the Hydra, fiber-fed spectrograph of the WIYN 3.5-m to determine the Li abundances for a sample of red giant branch stars covering a range of magnitudes in M10. We will then be able to use the data from this sample in combination with our already determined C and N abundances, and $^{12}$C/$^{13}$C ratios to further constrain models on thermohaline mixing by considering all four abundance profiles.

Program Type: ITAC

Scheduled Nights:
Run 1 (2018A):  WIYN/HYDR -- 2n on May 23 - May 24 2018


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