2021/03/30 by Anirudh Chiti, Anna Frebel, Mohammad K. Mardini +4 · 43 citations
Physics and Astronomy · #Astronomical and nuclear sciences #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Galaxy #Metallicity #Milky Way #Photometric system #Photometry (optics) #Physics #Stars #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/1538-4365/abf73d
published in The Astrophysical Journal Supplement Series 254(2), 31 (Institute of Physics) · 15 pages, 9 figures, 2 tables; submitted to ApJS and revised after one round of referee feedback. Full version of Table 2 in source
arxiv created 2021/03/30 · openalex created_date 2021/04/13 · openalex publication_date 2021/06/01 · arxiv updated 2021/06/09 · openalex updated_date 2026/08/06
Abstract The Milky Way’s metal-poor stars are nearby ancient objects that are used to study early chemical evolution and the assembly and structure of the Milky Way. Here we present reliable metallicities of ∼280,000 stars with −3.75 ≲ [Fe/H] ≲ −0.75 down to g = 17 derived using metallicity-sensitive photometry from the second data release of the SkyMapper Southern Survey. We use the dependency of the flux through the SkyMapper v filter on the strength of the Ca ii K absorption features, in tandem with SkyMapper u , g , i photometry, to derive photometric metallicities for these stars. We find that metallicities derived in this way compare well to metallicities derived in large-scale spectroscopic surveys, and we use such comparisons to calibrate and quantify systematics as a function of location, reddening, and color. We find good agreement with metallicities from the APOGEE, LAMOST, and GALAH surveys, based on a standard deviation of σ ∼ 0.25 dex of the residuals of our photometric metallicities with respect to metallicities from those surveys. We also compare our derived photometric metallicities to metallicities presented in a number of high-resolution spectroscopic studies to validate the low-metallicity end ([Fe/H] < −2.5) of our photometric metallicity determinations. In such comparisons, we find the metallicities of stars with photometric [Fe/H] < −2.5 in our catalog show no significant offset and a scatter of σ ∼ 0.31 dex level relative to those in high-resolution work when considering the cooler stars ( g − i > 0.65) in our sample. We also present an expanded catalog containing photometric metallicities of ∼720,000 stars as a data table for further exploration of the metal-poor Milky Way.