Speaker
Marc Pinsonneault
(Ohio State University, Dept. of Astronomy)
Description
Asteroseismology permits us to infer masses for large samples of evolved red giant stars, which have also been the subject of comprehensive spectroscopic surveys. There is a strong correlation between the C/N ratio, mass and metallicity; this permits us to assign spectroscopic ages linked to a physical mechanism (the first dredge-up), as opposed to being a correlation. In this talk I critically analyze the strengths and weaknesses of this approach. I demonstrate the importance of an absolute asteroseismic mass calibration for reliable ages. Independent chemical evolution checks on C/N in unevolved stars are important for constraining the mass dependence of the first dredge up. Mixing on the RGB is an important confounding factor in metal-poor giants, and I discuss its impact for solar abundance stars. Finally, I discuss the prospects for using C/N as an age diagnostic in core He burning stars, where the current mass need not reflect the initial one.
Primary author
Marc Pinsonneault
(Ohio State University, Dept. of Astronomy)
Co-authors
Jennifer Johnson
(Ohio State University, Dept. of Astronomy)
Matthew Shetrone
(University of Texas at Austin)
