September 22nd
when: Tuesday 22/09/2020, 12:45
where: KE D201 and Zoom meeting!
speaker: Ann-Cecilie Larsen
Title: A bright-matter mystery: the quest for the origin of heavy elements
abstract:
All elements found in our Universe, except for the very lightest ones, have been created during stars' lives and/or deaths. Life as we know it would not be possible without elements such as carbon, oxygen, and iron. Nuclear processes in stars provide the energy that makes them shine, and the same processes contribute to the "cooking" of lighter elements up to the iron group. However, elements heavier than iron cannot be reached through fusion. Burbidge, Burbidge, Fowler and Hoyle, and independently Cameron, realized that the only way to create heavy elements as observed in the solar system is via neutron-induced reactions. Two main processes were identified: the slow neutron-capture (s-) and the rapid neutron-capture (r-) process. For the latter, a huge flux of neutrons are needed in the astrophysical environment in order to explain the abundance pattern found in the solar system. For long, it was thought that core-collapse supernovae could do the trick, but recent state-of-the-art simulations show that the necessary conditions are not reached. On the other hand, simulations of colliding neutron stars seemed very promising. The neutron-star merger discovery in 2017 with its observed “afterglow” is the best proof that r-process elements are made in such extreme events, although many details are still not fully understood. In this talk, heavy-element nucleosynthesis will be discussed, with particular emphasis on the nuclear-physics input crucial for realistic abundance calculations. Also, recent experimental efforts on the nuclear-physics side will be presented, focussing on the research performed at the Oslo Cyclotron Laboratory and at Michigan State University.
Here for Seminar slides.