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

• DOI: 10.1093/mnras/stac1840
• Publication Date: 2022-07-10T01:58:55Z
• Authors: Christian I Johnson; R Michael Rich; Iulia T Simion; Michael D Young; William I Clarkson; Catherine A Pilac...; Scott Michael; Tommaso Marchetti; Mario Soto; Andrea Kunder; Andreas J Koch-Ha...; A Katherina Vivas; Meridith Joyce; Juntai Shen; Alexis Osmond
• Keywords: Red clump

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 exhibits strong vertical gradient, and at least two peaks in distribution functions appear b < -5. can discern metal-poor ([Fe/H] ~ -0.3) metal-rich +0.2) abundance each show clear systematic trends with latitude, may be best understood by changes bulge's star formation/enrichment processes. Both groups exhibit asymmetric tails, as result argue proximity either peak [Fe/H] space is not necessarily an affirmation group membership. The shifts lower values larger distances plane while tail truncates. Close plane, appears broader along minor axis than off-axis fields. also posit has populations -- one belongs low latitude predominantly group, another belonging dominates outer bulge. detect X-shape structure fields |Z| > 0.7 kpc -0.5. Stars -0.5 form spheroidal or "thick bar" those -0.1 are strongly concentrated near plane.