Ages^2: taking stellar ages to the next power

Th and U as cosmo-chronometers for old stars

18 Sept 2017, 10:00

15m

La Biodola, Isola d'Elba

talk Ages of the oldest stars and the connection to the halo and accretion

Speaker

Vanessa Hill (Université de la Côte d'Azur)

Description

We report on the abundance of 31 neutron-capture elements (including Thorium and Uranium) in the highly r-process-enhanced metal-poor giant CS~29497-004 (Hill et al. 2016, arXiv:1608.07463). Combining the various elemental chronometer pairs that are available for this star, and different theoretical yields for the r-process (Waiting-Point approximation, High Entropy Wind models), we derive ages for the star ranging from 12 to 14Gyrs. The U/Th nuclei-chronometer is confirmed to be the most resilient to theoretical production ratio. Beyond the case of CS~29497-004, I will discuss the benefits of using cosmo-chonometers to set the clock at the oldest ages, thanks to the fact that they are largely insensitive to stellar evolution or stellar interior models, and highlight where progress is expected in the coming decade on the observational side (large surveys of metal-poor stars) and on the theoretical side (better understanding of the r-process).