Rubidium-Rich Asymptotic Giant Branch Stars

Garcia-Hernandez, D. A.; Garcia-Lario, P.; Plez, B.; D'Antona, F.; Manchado, A.; Trigo-Rodriguez, J. M.

Rubidium-Rich Asymptotic Giant Branch Stars

Authors

Garcia-Hernandez, D. A.

Trigo-Rodriguez, J. M.

Description

A long debated issue concerning the nucleosynthesis of neutron-rich elements in Asymptotic Giant Branch (AGB) stars is the identification of the neutron source. We report intermediate-mass (4 to 8 solar masses) AGB stars in our Galaxy that are rubidium-rich owing to overproduction of the long-lived radioactive isotope 87Rb, as predicted theoretically 40 years ago. This represents a direct observational evidence that the 22Ne(alpha,n)25Mg reaction must be the dominant neutron source in these stars. These stars then challenge our understanding of the late stages of the evolution of intermediate-mass stars and would promote a highly variable Rb/Sr environment in the early solar nebula.
17 pages, 2 figures and 1 table. 3 figures of supporting online material are also included. Accepted 2006 Oct 19 for publication in Science; Published online in 2006 Nov 9 edition of Science Express