The R-Process Alliance: Spectroscopic Follow-up of Low-metallicity Star Candidates from the Best & Brightest Survey

We present results from an observing campaign to identify low- metallicity stars in the Best & Brightest Survey. From medium- resolution (R ̃ 1200-2000) spectroscopy of 857 candidates, we estimate the stellar atmospheric parameters ({T}eff}, {log} g, and [{Fe}/{{H}}]), as well as carbon and α-element abundances. We find that 69% of the observed stars have [{Fe}/{{H}}] ≤ -1.0, 39% have [{Fe}/{{H}}] ≤ -2.0, and 2% have [{Fe}/{{H}}] ≤ -3.0. There are also 133 carbon-enhanced metal-poor (CEMP) stars in this sample, with 97 CEMP Group I and 36 CEMP Group II stars identified in the A(C) versus [Fe/H] diagram. A subset of the confirmed low-metallicity stars were followed- up with high-resolution spectroscopy, as part of the R-process Alliance, with the goal of identifying new highly and moderately r-process- enhanced stars. Comparison between the stellar atmospheric parameters estimated in this work and from high-resolution spectroscopy exhibit good agreement, confirming our expectation that medium-resolution observing campaigns are an effective way of selecting interesting stars for further, more targeted, efforts