Measurement of stellar age from uranium decay.

摘要: The ages of the oldest stars in Galaxy indicate when star formation began, and provide a minimum age for Universe. Radioactive dating meteoritic material relies on comparing present abundance ratios radioactive stable nuclear species to theoretically predicted their production. radioisotope 232Th (half-life 14 Gyr) has been used date Galactic stars, but it decays by only factor two over lifetime 238U 4.5 is principle more precise indicator, even its strongest spectral line, from singly ionized uranium at wavelength 385.957 nm, previously not detected stars. Here we report measurement this line very metal-poor CS31082-001, which strongly overabundant heavy elements. derived abundance, log(U/H) = -13.7 +/- 0.14 0.12 yields an 12.5 3 Gyr, though still model dependent. observation cosmochronometer gives most direct determination Galaxy. Also, with improved theoretical laboratory data, will highly lower limit