Cosmic Chemical Evolution

The formation of the heavy elements is one of the most fascinating topics and it poses one of the remaining open questions in physics. We know that the elements heavier than Fe are mainly formed through neutron-captures and that up to half of all the known isotopes are created by a 'rapid neutron-capture process’, a process that may be associated with supernovae or neutron star mergers

The nature of this process is poorly constrained and can observationally best be explored through chemical tagging of old, metal-poor stars, which we analyse using high-resolution spectroscopy. This research direction is pursued by Camilla Hansen and is outlined by the papers listed below.

"How Many Nucleosynthesis Processes Exist at Low Metallicity?”
Hansen, C. J.; Montes, F.; Arcones, A. (2014)

"Silver and palladium help unveil the nature of a second r-process”
Hansen, C. J.; Primas, F.; Hartman, H.; Kratz, K.-L.; Wanajo, S.; Leibundgut, B.; Farouqi, K.; Hallmann, O.; Christlieb, N.; Nilsson, H. (2012)

"LTE or non-LTE, that is the question. The NLTE chemical evolution of strontium in extremely metal-poor stars”
Hansen, C. J.; Bergemann, M.; Cescutti, G.; François, P.; Arcones, A.; Karakas, A. I.; Lind, K.; Chiappini, C. (2013)

"Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium”
Hansen, C. J.; Andersen, A. C.; Christlieb, N. (2014)