The main topics of the workshop are:

R-process sites: mergers vs. supernovae

We will discuss the astrophysical production site of r-process elements. This will focus on nu- merical models of the various sites and mass ejection channels believed to contribute to the r-process enrichment in the Galaxy. The workshop will include contributions discussing com- pact star mergers and core-collapse supernovae including magneto-rotational supernovae and collapsars. We will address the following key questions:

• What are the exact conditions in the outflows from neutron star mergers and what are the current challenges to model the different ejecta components?

• Which range of elements can be produced by different types of supernovae?

• What are the relevant reactions shaping the final r-process abundance pattern?

Nuclear physics input: theory and experiment

Nuclear physics is crucial to determine the exact nucleosynthetic yields from a given r-process site. Because the r-process involves many exotic neutron-rich nuclei, nuclear network calculations rely on theoretical predictions of the reaction rates. It is well known that, for instance, the mass model has a strong impact on the final r-process abundance pattern for fixed thermodynamical outflow conditions. Understanding r-process element formation relies on advances in theoretical modelling and new measurements of neutron-rich nuclei to benchmark these modes. We will address the following key questions:

• What is the sensitivity of the r-process abundance pattern to the nuclear physics input like mass model, beta decay rates, and fission properties?

• Which experiments are most crucial to advance r-process predictions?

Observations: kilonova and elemental abundances

Electromagnetic emission from the first kilonova AT2017gfo was studied extensively in visible and near-infrared bands. The shape and evolution timescale of the kilonova light curve suggest that at least some heavy r-process material was produced. So far, several tentative identifications of mostly lighter r-process elements have been made through radiative transfer modelling, though more quantitative abundance measurements have proven to be challenging. In this section, we will discuss current and future kilonova observations as well as radiative transfer models and how to improve them for future determinations of r-process elemental abundances, and also draw in information from indirect stellar observations. In this context, we will focus on the following key questions:

• How important are multidimensional and non-LTE radiative transfer effects for placing constraints on the inferred r-process abundances?

• Which observations are required from future kilonova events?

• How can we best use the information from indirect stellar abundances to improve our knowledge of the r-process?

Galactic chemical evolution

The primary astrophysical site responsible for the r-process is still a topic of debate, with potential candidates including mergers of compact objects and peculiar types of supernovae. While observations suggest that mergers are likely the primary sources of r-process material in the Universe, simulations of chemical evolution struggle to accurately reproduce the abundance patterns of typical r-process elements like Europium if mergers are the sole contributors. This part of the meeting will delve into the origins of r-process elements as explored through various Galactic chemical evolution models. Our focus will be on addressing the following key questions:

• How do different astrophysical sites impact the evolution of r-process element abundances within the Galaxy?

• In what ways does this evolution vary across different metallicities and environmental conditions?

•  Which insights can be derived from different chemical evolution simulations?