2024-03-29T06:10:09Zivo://CDS.VizieR/J/ApJ/862/1742022-11-04T00:00:00ZJ.ApJ10.26093/cds/vizier.18620174Gull M.Frebel A.Cain M.G.Placco V.M.Ji A.P.Abate C.Ezzeddine R.,Karakas A.I.Hansen T.T.Sakari C.Holmbeck E.M.Santucci R.M.,Casey A.R.Beers T.C.Spectroscopy obs. of RAVE J094921.8-161722CDS2019Chemically peculiar starsGiant starsLine intensitiesChemical abundancesRadial velocityOptical astronomystellar-astronomyobservational-astronomyexoplanet-astronomyinterdisciplinary-astronomyCDS support team <cds-question@unistra.fr>ivo://CDS.VizieR/J/ApJ/862/174https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/862/174http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/862/1742018ApJ...862..174Gtext/xml+votablehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlWe present a high-resolution (R~35000), high signal-to-noise ratio (S/N>200) Magellan/MIKE spectrum of the star RAVE J094921.8-161722, a bright (V=11.3) metal-poor red giant star with [Fe/H]=-2.2, identified as a carbon-enhanced metal-poor (CEMP) star from the RAVE survey. We report its detailed chemical abundance signature of light fusion elements and heavy neutron-capture elements. We find J0949-1617 to be a CEMP star with s-process enhancement that must have formed from gas enriched by a prior r-process event. Light neutron-capture elements follow a low-metallicity s-process pattern, while the heavier neutron-capture elements above Eu follow an r-process pattern. The Pb abundance is high, in line with an s-process origin. Thorium is also detected, as expected from an r-process origin, as Th is not produced in the s-process. We employ nucleosynthesis model predictions that take an initial r-process enhancement into account, and then determine the mass transfer of carbon and s-process material from a putative more massive companion onto the observed star. The resulting abundances agree well with the observed pattern. We conclude that J0949-1617 is the first bonafide CEMP-r+s star identified. This class of objects has previously been suggested to explain stars with neutron-capture element patterns that originate from neither the r- nor the s-process alone. We speculate that J0949-1617 formed in an environment similar to those of ultra-faint dwarf galaxies like TucanaIII and ReticulumII, which were enriched in r-process elements by one or multiple neutron star mergers at the earliest times.