Research project The making of the heaviest elements in the Universe
About 14 billion years ago, the Universe began with the Big Bang. A few minutes later, hydrogen, helium, and traces of lithium were formed during the Big Bang Nucleosynthesis. However, the Universe expanded and cooled, leading to the end of this process after 20 minutes. Where, when, and how were the remaining elements of the periodic table produced?
The answer is in the stars. All elements heavier than lithium, including the essential ingredients for planets and life as we know it, are formed during the life and death of stars.
This project seeks to understand the formation and evolution of the heaviest elements, like silver, gold, and uranium, in the Universe. Using high-quality data from telescopes worldwide, our international team will map the chemical composition of thousands of the oldest stars in our Galaxy, thereby gaining insights into where and how elements like silver and gold formed.
Project description
About half the elements heavier than iron in the Universe, including silver, gold and uranium, are created in the so-called rapid neutron-capture (r-)process. Yet, more than 60 years after the theoretical framework for this process was described, it is still debated in which astrophysical site(s) this process can take place. The main candidates are rare explosive events in the Universe like supernovae and neutron star mergers. Unfortunately, signatures of heavy element production are very hard to directly observe in these types of events. Likewise, it is difficult for nuclear physicists to recreate and study the nuclear process in the laboratory. Hence to make progress, we need to look for clues concerning the details of the r-process in other places. An ideal place is the abundances of the oldest and most metal-poor stars in the Milky Way. The chemical composition of these stars, mapped through detailed abundance analysis, is a direct fingerprint of the elements produced in the stellar generation before them. In 2016, the R-Process Alliance (RPA), a small team of international experts, initiated a successful search to uncover bright metal-poor stars in the Milky Way halo containing large amounts of elements produced in the r-process. To date, the RPA has collected spectra of ~2000 stars, and this project will use this extensive new dataset to explore the nature and astrophysical site of the r-process. For example, abundances for 12 so-called light r-process elements in the region from gallium to tin can be derived from the highly r-process enhanced stars in the sample, facilitating an in-depth investigation of this largely unexplored region of the r-process.
Project members
Project managers
Terese Thidemann Hansen
Researcher
Members
Mila Racca
PhD student
Terese Thidemann Hansen
Researcher