2017/08/03 by K. Youakim, E. Starkenburg, D. S. Aguado +13 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stx2005
14 pages, 6 figures, 4 tables, full version of Table 1 available on-line only, accepted for publication in MNRAS
arxiv created 2017/08/03 · arxiv updated 2017/08/07
The Pristine survey is a narrow-band, photometric survey focused around the wavelength region of the Ca II H & K absorption lines, designed to efficiently search for extremely metal-poor stars. In this work, we use the first results of a medium-resolution spectroscopic follow-up to refine the selection criteria for finding extremely metal-poor stars (\textrm[Fe/H] ≤ -3.0) in the Pristine survey. We consider methods by which stars can be selected from available broad-band and infrared photometry plus the additional Pristine narrow-band photometry. The spectroscopic sample presented in this paper consists of 205 stars in the magnitude range 14 < V < 18. Applying the photometric selection criteria cuts the sample down to 149 stars, and from these we report a success rate of 70% for finding stars with \textrm[Fe/H] ≤ -2.5 and 22% for finding stars with \textrm[Fe/H] ≤ -3.0. These statistics compare favourably with other surveys that search for extremely metal-poor stars, namely an improvement by a factor of ∼ 4-5 for recovering stars with \textrm[Fe/H] ≤ -3.0. In addition, Pristine covers a fainter magnitude range than its predecessors, and can thus probe deeper into the Galactic halo.