RAVE J203843.2–002333: The First Highly R-process-enhanced Star Identified in the RAVE Survey

Abstract

We report the discovery of RAVE J203843.2-002333, a bright (V = 12.73), very metal-poor ([Fe/H] = -2.91), r-process-enhanced ([Ba/Eu] = +1.64 and = -0.81) star selected from the RAVE survey. This star was identified as a metal-poor candidate based on its medium-resolution (R ∼ 1600) spectrum obtained with the KPNO/Mayall Telescope, and followed up with high-resolution (R ∼ 66,000) spectroscopy with the Magellan/Clay Telescope, allowing for the determination of elemental abundances for 24 neutron-capture elements, including thorium and uranium. RAVE J2038-0023 is only the fourth metal-poor star with a clearly measured U abundance. The derived chemical abundance pattern exhibits good agreement with those of other known highly r-process-enhanced stars, and evidence suggests that it is not an actinide-boost star. Age estimates were calculated using U/X abundance ratios, yielding a mean age of 13.0 ± 1.1 Gyr.