Stellar production rates of carbon and its abundance in the universe

The bulk of the carbon in our universe is produced in the triple-alpha proc ess in helium-burning red giant stars. We calculated the change of the trip le-alpha reaction rate in a microscopic 12-nucleon model of the C-12 nucleu s and Looked for the effects of minimal variations of the strengths of the underlying interactions. Stellar model calculations were performed with the alternative reaction rates. Here, we show that outside a narrow window of 0.5 and 4% of the values of the strong and Coulomb forces, respectively, th e stellar production of carbon or oxygen is reduced by factors of 30 to 100 0.