Sensitivity of the C and O production on the 3α rate

We investigate the dependence of the carbon and oxygen production in stars on the 3α rate by varying the energy of the 0⁺ ₂-state of ¹²C and determine the resulting yields for a selection of low-mass, intermediate-mass and massive stars. The yields are obtained using modern stellar evolution codes that follow the entire evolution of massive stars, including the supernova explosion, and consider in detail the 3^rd dredge-up process during the thermally pulsating asymptotic giant branch of low-mass and intermediate-mass stars. Our results show that the C and O production in massive stars depends strongly on the initial mass, and that it is crucial to follow the entire evolution. A rather strong C production during the He-shell flashes compared to quiescent He burning leads to a lower sensitivity of the C and O production in low-mass and intermediate-mass stars on the 3α-rate than predicted in our previous work. In particular, the C production of intermediate-mass stars seems to have a maximum close to the actual value of the 0⁺ ₂ energy level of ¹²C. This revised version was published online in August 2006 with corrections to the Cover Date.