The DECam MAGIC Survey: Spectroscopic Follow-up of the Most Metal-Poor Stars in the Distant Milky Way Halo

2025/06/23 by Vinicius M. Placco, Placco, Vinicius M., Guilherme Limberg +45 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies

paper · pdf · doi:10.48550/arxiv.2506.19163

openalex publication_date 2025/06/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

In this work, we present high-resolution spectroscopic observations for six metal-poor stars with [Fe/H]<-3 (including one with [Fe/H]<-4), selected using narrow-band Ca II HK photometry from the DECam MAGIC Survey. The spectroscopic data confirms the accuracy of the photometric metallicities and allows for the determination of chemical abundances for 16 elements, from carbon to barium. The program stars have chemical abundances consistent with this metallicity range. A kinematic/dynamical analysis suggests that all program stars belong to the distant Milky Way halo population (heliocentric distances 35 < dhelio/kpc < 55), including three with high-energy orbits that might have been associated with the Magellanic system and one, J0026-5445, having parameters consistent with being a member of the Sagittarius stream. The remaining two stars show kinematics consistent with the Gaia-Sausage/Enceladus dwarf galaxy merger. J0433-5548, with [Fe/H]=-4.12, is a carbon-enhanced ultra metal-poor star, with [C/Fe]=+1.73. This star is believed to be a bona fide second-generation star, and its chemical abundance pattern was compared with yields from metal-free supernova models. Results suggest that J0433-5548 could have been formed from a gas cloud enriched by a single supernova explosion from a ~11Mo star in the early universe. The successful identification of such objects demonstrates the reliability of photometric metallicity estimates, which can be used for target selection and statistical studies of faint targets in the Milky Way and its satellite population. These discoveries illustrate the power of measuring chemical abundances of metal-poor Milky Way halo stars to learn more about early galaxy formation and evolution.

Citations

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Cited by

• Discovery of the First Five Carbon-Enhanced Metal-Poor Stars in the LMC
• Ultra-Faint Milky Way Satellites Discovered in Carina, Phoenix, and Telescopium with DELVE Data Release 3
• A second-generation star in a relic dwarf galaxy
• Mapping the Distant and Metal-Poor Milky Way with SDSS-V
• The DECam MAGIC Survey: A Wide-field Photometric Metallicity Study of the Sculptor Dwarf Spheroidal Galaxy

Related

• The DECam MAGIC Survey: A Wide-field Photometric Metallicity Study of the Sculptor Dwarf Spheroidal Galaxy
• Peculiarities of the chemical enrichment of metal-poor Stars in the Milky Way Galaxy
• Spectroscopic Survey of Field stars: A search for Metal-Poor stars
• Ongoing Large Surveys for Metal-Poor Stars in the Galactic Halo
• The Pristine survey