A consistent explanation for ${}^{12}$C/${}^{13}$C, ${}^7$Li, and ${}^3$He anomalies in red giant stars

The observations of carbon isotopic ratios in evolved stars suggest that non standard mixing is acting in low mass stars as they are ascending the red giant branch. We propose a simple consistent mechanism, based on the most recent developments in the description of rotation-induced mixing by Zahn (1992), which simultaneously accounts for the low ${}^{12}$C/${}^{13}$C ratios in globular cluster and field Pop II giants and for the lithium abundances in metal-poor giant stars. It also leads to the destruction of ${}^3$He produced on the main sequence in low mass stars. This should both naturally account for the recent measurements of ${}^3$He/H in galactic HII regions and allow for high values of ${}^3$He observed in some planetary nebulae.