Journal article
HERBS I: Metallicity and alpha enhancement along the Galactic bulge minor axis
Monthly notices of the Royal Astronomical Society, Vol.486(3), pp.3586-3603
07/01/2019
DOI: 10.1093/mnras/stz1104
Abstract
To better understand the origin and evolution of the Milky Way bulge, we have conducted a survey of bulge red giant branch and clump stars using the High Efficiency and Resolution Multi-Element Spectrograph on the Anglo-Australian Telescope. We targeted ARGOS survey stars with predetermined bulge memberships, covering the full metallicity distribution function. The spectra have signal-to-noise ratios comparable to, and were analysed using the same methods as the GALAH survey. In this work, we present the survey design, stellar parameters, distribution of metallicity, and alpha-element abundances along the minor bulge axis at latitudes b = -10 degrees,-7.5 degrees, and -5 degrees. Our analysis of ARGOS stars indicates that the centroids of ARGOS metallicity components should be located approximate to 0.09 dex closer together. The vertical distribution of alpha-element abundances is consistent with the varying contributions of the different metallicity components. Closer to the plane, alpha abundance ratios are lower as themetal-rich population dominates. At higher latitudes, the alpha abundance ratios increase as the number of metal-poor stars increases. However, we find that the trend of alpha-enrichment with respect to metallicity is independent of latitude. Comparison of our results with those of GALAH DR2 revealed that for [Fe/H]approximate to -0.8, the bulge shares the same abundance trend as the high-alpha disc population. However, the metal-poor bulge population ([Fe/H] less than or similar to -0.8) show enhanced alpha abundance ratios compared to the disc/halo. These observations point to fairly rapid chemical evolution in the bulge, and that the metal-poor bulge population does not share the same similarity with the disc as the more metal-rich populations.
Details
- Title: Subtitle
- HERBS I: Metallicity and alpha enhancement along the Galactic bulge minor axis
- Creators
- L. Duong - Australian National UniversityM. Asplund - Australian National UniversityD. M. Nataf - Johns Hopkins UniversityK. C. Freeman - Australian National UniversityM. Ness - Columbia UniversityL. M. Howes - Lund University
- Resource Type
- Journal article
- Publication Details
- Monthly notices of the Royal Astronomical Society, Vol.486(3), pp.3586-3603
- DOI
- 10.1093/mnras/stz1104
- ISSN
- 0035-8711
- eISSN
- 1365-2966
- Publisher
- Oxford Univ Press
- Number of pages
- 18
- Grant note
- Zonta International District 24 Allan C. and Dorothy H. Davis Fellowship CE170100013 / Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D); Australian Research Council National Science Foundation; National Science Foundation (NSF) FL110100012; DP160103747 / Australian Research Council Knut and Alice Wallenberg foundation; Knut & Alice Wallenberg Foundation National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) A/2013B/13; A/2014A/25; A/2015A/19; A/2017A/18 / Australian Astronomical Observatory
- Language
- English
- Date published
- 07/01/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701825602771
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