Blanco DECam Bulge Survey (BDBS) IV: Metallicity Distributions and Bulge Structure from 2.6 Million Red Clump Stars
| Autor: | 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, Alexis Osmond |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) FOS: Physical sciences Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics - Astrophysics of Galaxies Astrophysics::Galaxy Astrophysics Solar and Stellar Astrophysics (astro-ph.SR) |
| DOI: | 10.48550/arxiv.2206.14851 |
| Popis: | 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] > -0.1 are strongly concentrated near the plane. 26 pages, 22 figures, accepted for publication in MNRAS; the full data table is very long so only a stub table has been provided here; the full electronic table will be provided through MNRAS upon publication, but early access to the full table will be granted upon request to the authors |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|