One of the long-lasting open questions in Astrophysics, "Where does the rapid neutron-capture process occurs?", still does not have a complete answer. While the optical counterpart AT 2017gfo of the kilonova GW 170817 did provide evidence of the r-process in neutron star mergers, important details are still unsolved. Neutron star mergers alone seem to be unable to explain r-process enrichment in the Universe, and there are still open questions with respect to their time scale. Variations in observed r-process abundance patterns have been detected both in actinides as well as in mid-atomic number range (30 < Z < 50). These variations suggest the existence of multiple astrophysical sources for the r-process in addition to neutron star mergers, like magnetohydrodynamic supernovae. Using high-quality UVES spectra (R ~40,000) of more than 50 metal-poor stars (-3.2 < [Fe/H] < -1.7), we investigate abundance patterns in elements with atomic numbers around Hf (Z = 72), predicted to be sensitive to different scenarios of production of r-process elements. That region of the periodic table is difficult to observe because it manifests itself mostly in the blue/near-UV part of spectrum, a region severely affected by line crowding and by relatively low S/N in observations of late-type stars. In this presentation we discuss our results and their significance for the proposed r-process scenarios.
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