Examinando por Autor "Queiroz A."

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    A Perspective on the Milky Way Bulge Bar as Seen from the Neutron-capture Elements Cerium and Neodymium with APOGEE
    (Institute of Physics, 2024-04-01) Sales-Silva J.V.; Cunha K.; Smith V.V.; Daflon S.; Souto D.; Guerço R.; Queiroz A.; Chiappini C.; Hayes C.R.; Masseron T.; Hasselquist, Sten; Horta D.; Prantzos N.; Zoccali M.; Allende Prieto C.; Barbuy B.; Beaton R.; Bizyaev D.; Fernández-Trincado J.G.; Frinchaboy P.M.; Holtzman J.A.; Johnson J.A.; Jönsson, Henrik; Majewski S.R.; Minniti D.; Nidever D.L.; Schiavon R.P.; Schultheis M.; Sobeck J.; Stringfellow G.S.; Zasowski G.
    This study probes the chemical abundances of the neutron-capture elements cerium and neodymium in the inner Milky Way from an analysis of a sample of ∼2000 stars in the Galactic bulge bar spatially contained within ∣X Gal∣ < 5 kpc, ∣Y Gal∣ < 3.5 kpc, and ∣Z Gal∣ < 1 kpc, and spanning metallicities between −2.0 ≲ [Fe/H] ≲ +0.5. We classify the sample stars into low- or high-[Mg/Fe] populations and find that, in general, values of [Ce/Fe] and [Nd/Fe] increase as the metallicity decreases for the low- and high-[Mg/Fe] populations. Ce abundances show a more complex variation across the metallicity range of our bulge-bar sample when compared to Nd, with the r-process dominating the production of neutron-capture elements in the high-[Mg/Fe] population ([Ce/Nd] < 0.0). We find a spatial chemical dependence of Ce and Nd abundances for our sample of bulge-bar stars, with low- and high-[Mg/Fe] populations displaying a distinct abundance distribution. In the region close to the center of the MW, the low-[Mg/Fe] population is dominated by stars with low [Ce/Fe], [Ce/Mg], [Nd/Mg], [Nd/Fe], and [Ce/Nd] ratios. The low [Ce/Nd] ratio indicates a significant contribution in this central region from r-process yields for the low-[Mg/Fe] population. The chemical pattern of the most metal-poor stars in our sample suggests an early chemical enrichment of the bulge dominated by yields from core-collapse supernovae and r-process astrophysical sites, such as magnetorotational supernovae.