Nuclear Astrophysics

How old are the oldest stars?

How old are the oldest stars? Using DSL, scientists have helped astrophysicists narrow-in on a key cosmic mystery: the age of the oldest stars in the Milky Way. To infer a star's age from its starlight, astrophysicists need to know the rates of nuclear reactions powering it, in particular the rate of the reaction when 14N captures a proton to become 15O. It's the slowest reaction, and thus determines the overall pace, of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As reported in Physical Review C (2014), using the DSL facility, scientists measured the 6.79 MeV energy state and others in 15O and constrained its lifetime to be less than 1.8 femtoseconds, or quadrillionths of a second. The researchers believe that even more precise reaction rates could come from coupling the DSL facility to TRIUMF's new recoil spectrometer EMMA.