  Some young, massive stars can be found in the Galactic halo. As star
formation is unlikely to occur in the halo, they must have been formed in the
disk and been ejected shortly afterwards. One explanation is a supernova in a
tight binary system. The companion is ejected and becomes a runaway star.
HD\,271791 is the kinematically most extreme runaway star known (Galactic
restframe velocity $725 \pm 195\, \rm km\,s^{-1}$, which is even larger than
the Galactic escape velocity). Moreover, an analysis of the optical spectrum
showed an enhancement of the $\alpha$-process elements. This indicates the
capture of supernova ejecta, and therefore an origin in a core-collapse
supernova. As such high space velocities are not reached by the runaway stars
in classical binary supernova ejection scenarios, a very massive but compact
primary, probably of Wolf-Rayet type is required. HD\,271791 is therefore a
perfect candidate for studying nucleosynthesis in a supernova of probably type
Ibc. The goal of this project is to determine the abundances of a large number
of elements from the $\alpha$-process, the iron group, and heavier elements by
a quantitative analysis of the optical and UV spectral range. Detailed
line-formation calculations are employed that account for deviations from local
thermodynamic equilibrium (non-LTE). We intend to verify whether core-collapse
supernova are a site of r-process element production. Here, we state the
current status of the project.
