Fine-tuning carbon-based life in the universe by the triple-alpha process in red giants

Abstract

Through the triple-alpha process occurring in red giant stars the bulk of the carbon existing in our universe is produced. We calculated the change of the triple-alpha reaction rate for slight variations of the nucleon-nucleon force using a microscopic 12-body model. Stellar model calculations for a low-mass, intermediate-mass and massive star using the different triple-alpha reaction rates obtained with different strengths of the N-N interaction have been performed. Even with a change of 0.4% in the strength of N-N force, carbon-based life appears to be impossible, since all the stars then would produce either almost solely carbon or oxygen, but could not produce both elements.

9 pages with 1 figure. Invited talk given at the "The Future of the Universe and the Future of Our Civilization" Conference (July 2-6, 1999, Budapest, Hungary). To appear in the conference proceedings, to be published by World Scientific. The postscript file and more information are available at http://nova.elte.hu/~csoto