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Johnson, Christian I; Rich, R Michael; Simion, Iulia T; Young, Michael D; Clarkson, William I; Pilachowski, Catherine A; Michael, Scott; Marchetti, Tommaso; Soto, Mario; Kunder, Andrea; Koch-Hansen, Andreas J; Katherina Vivas, A; Joyce, Meridith; Shen, Juntai; Osmond, Alexis

Blanco DECam Bulge Survey (BDBS) IV: Metallicity distributions and bulge structure from 2.6 million red clump stars

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  • Medientyp: E-Artikel
  • Titel: Blanco DECam Bulge Survey (BDBS) IV: Metallicity distributions and bulge structure from 2.6 million red clump stars
  • Beteiligte: Johnson, Christian I; Rich, R Michael; Simion, Iulia T; Young, Michael D; Clarkson, William I; Pilachowski, Catherine A; Michael, Scott; Marchetti, Tommaso; Soto, Mario; Kunder, Andrea; Koch-Hansen, Andreas J; Katherina Vivas, A; Joyce, Meridith; Shen, Juntai; Osmond, Alexis
  • Erschienen: Oxford University Press (OUP), 2022
  • Erschienen in: Monthly Notices of the Royal Astronomical Society
  • Sprache: Englisch
  • DOI: 10.1093/mnras/stac1840
  • ISSN: 0035-8711; 1365-2966
  • Schlagwörter: Space and Planetary Science ; Astronomy and Astrophysics
  • Entstehung:
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  • Beschreibung: <jats:title>ABSTRACT</jats:title> <jats:p>We present photometric metallicity measurements for a sample of 2.6 million bulge red clump stars extracted from the Blanco DECam Bulge Survey (BDBS). Similar to previous studies, we find that the bulge exhibits a strong vertical metallicity gradient, and that at least two peaks in the metallicity distribution functions appear at b &amp;lt; −5°. We can discern a metal-poor ([Fe/H] ∼ −0.3) and metal-rich ([Fe/H] ∼ +0.2) abundance distribution that each show clear systematic trends with latitude, and may be best understood by changes in the bulge’s star formation/enrichment processes. Both groups exhibit asymmetric tails, and as a result we argue that the proximity of a star to either peak in [Fe/H] space is not necessarily an affirmation of group membership. The metal-poor peak shifts to lower [Fe/H] values at larger distances from the plane while the metal-rich tail truncates. Close to the plane, the metal-rich tail appears broader along the minor axis than in off-axis fields. We also posit that the bulge has two metal-poor populations – one that belongs to the metal-poor tail of the low latitude and predominantly metal-rich group, and another belonging to the metal-poor group that dominates in the outer bulge. We detect the X-shape structure in fields with |Z| &amp;gt; 0.7 kpc and for stars with [Fe/H] &amp;gt; −0.5. Stars with [Fe/H] &amp;lt; −0.5 may form a spheroidal or ‘thick bar’ distribution while those with [Fe/H] $\gtrsim$ −0.1 are strongly concentrated near the plane.</jats:p>
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