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Seminars at FGG

The origin of the heaviest and lightest elements

Speaker: Johannes Andersen (Nordic Optical Telescope)

Date and time: 2013-09-18 12:00

"Textbooks tell us that after the Big Bang, the periodic system got populated with heavier elements from the bottom up. Already at [Fe/H] ~ -3 - long before (in a chemical sense) globular clusters formed - all the elements were in place in precisely defined proportions, essentially the same as those we measure in the Solar System today. But subgroups of such extremely metal-poor stars show dramatic excesses of carbon - the first new product of nucleosynthesis in stars - and the heaviest neutron-capture elements, all the way to Th and U. Theorists ascribe these 'anomalies' to later nucleosynthesis in and mass transfer from a former binary companion to the surface of the star we can still see, so all these peculiar stars should be in binary systems. We have have monitored a sample of these stars with FIES@NOT since 2007 to test this hypothesis, and first results of this programme will be described."