Buchumschlag

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

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 d...

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Hauptverfasser: Johnson, Christian I. (VerfasserIn) , Rich, R Michael (VerfasserIn) , Simion, Iulia T (VerfasserIn) , Young, Michael D (VerfasserIn) , Clarkson, William I (VerfasserIn) , Pilachowski, Catherine A (VerfasserIn) , Michael, Scott (VerfasserIn) , Marchetti, Tommaso (VerfasserIn) , Soto, Mario (VerfasserIn) , Kunder, Andrea (VerfasserIn) , Koch-Hansen, Andreas (VerfasserIn) , Katherina Vivas, A (VerfasserIn) , Joyce, Meridith (VerfasserIn) , Shen, Juntai (VerfasserIn) , Osmond, Alexis (VerfasserIn)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 09 July 2022
In: Monthly notices of the Royal Astronomical Society
Year: 2022, Jahrgang: 515, Heft: 1, Pages: 1469-1491
ISSN:1365-2966
DOI:10.1093/mnras/stac1840
Online-Zugang:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1093/mnras/stac1840
Volltext
Verfasserangaben:Christian I. Johnson, R. Michael Rich, Iulia T. Simion, Michael D.Young, William I. Clarkson, Catherine A. Pilachowski, Scott Michael, Tommaso Marchetti, Mario Soto, Andrea Kunder, Andreas J. Koch-Hansen, A.Katherina Vivas, Meridith Joyce, Juntai Shen and Alexis Osmond
Beschreibung
Zusammenfassung: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 < −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| > 0.7 kpc and for stars with [Fe/H] > −0.5. Stars with [Fe/H] < −0.5 may form a spheroidal or ‘thick bar’ distribution while those with [Fe/H] $\gtrsim$ −0.1 are strongly concentrated near the plane.
Beschreibung:Gesehen am 14.09.2022
Beschreibung:Online Resource
ISSN:1365-2966
DOI:10.1093/mnras/stac1840

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