CNO dredge-up in a sample of APOGEE/Kepler red giants: Tests of stellar models and Galactic evolutionary trends of N/O and C/N

Understand

Surface abundances of C, N, and O in red giants are affected by processed material mixed into the stars' convective envelopes.

• Using a sample of $\sim 5100$ stars with elemental abundances from APOGEE and asteroseismic masses from {\it Kepler}, we test theoretical stellar models that predict this mixing, then apply these models to derive birth C, N, and O abundances for these stars.
• Our models with standard mixing can reproduce the observed trends to within plausible uncertainties in the birth abundances.
• Some models with ''extra'' mixing processes fail, predicting trends with surface gravity or evolutionary state that are not observed.