Aguilera-Gómez, C., Jones, M. I. & Chanamé, J.
2023, A&A, 670, 73
https://ui.adsabs.harvard.edu/abs/2023A%26A…670A..73A/abstract
Although not predicted by standard stellar evolution, the surface abundance of light elements, such as lithium (Li), carbon, and nitrogen, changes during the red giant branch (RGB) as a result of extra mixing. This is usually associated with thermohaline mixing acting after the RGB bump.
We measure the Li abundance and carbon isotopic ratio 12C/13C in a sample of 166 field red giants. These abundances act as good diagnostics of mixing inside stellar interiors. The comparison between Li in the RGB and core He-burning giants shows effects of mixing consistent with thermohaline. Our sample shows behavior consistent with additional mixing acting after the RGB bump. The 12C/13C adds new clues which can be used to describe extra mixing, and it could well be the best tool to study mixing in giants. Additional measurements of 12C/13C in field stars would greatly improve our ability to compare data with models and understand mixing mechanisms.