The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Nils Ryde

Nils Ryde

Professor

Nils Ryde

Chemical characterization of the inner Galactic bulge : North-South symmetry

Author

  • G. Nandakumar
  • N. Ryde
  • M. Schultheis
  • B. Thorsbro
  • H. Jönsson
  • P. S. Barklem
  • R. M. Rich
  • F. Fragkoudi

Summary, in English

While the number of stars in the Galactic bulge with detailed chemical abundance measurements is increasing rapidly, the inner Galactic bulge (|b| < 2°) remains poorly studied, due to heavy interstellar absorption and photometric crowding. We have carried out a high-resolution IR spectroscopic study of 72 M giants in the inner bulge using the CRIRES (ESO/VLT) facility. Our spectra cover the wavelength range of 2.0818-2.1444 μm with the resolution of R ~ 50 000 and have signal-to-noise ratio of 50:100. Our stars are located along the bulge minor axis at l = 0°, b= ±0°, ±1°, ±2°, and +3°. Our sample was analysed in a homogeneous way using the most current K-band line list. We clearly detect a bimodal metallicity distribution function with a metal-rich peak at ~ +0.3 dex and a metal-poor peak at ~ -0.5 dex and no stars with [Fe/H] > +0.6 dex. The Galactic Centre field reveals in contrast a mainly metal-rich population with a mean metallicity of +0.3 dex. We derived [Mg/Fe] and [Si/Fe] abundances that are consistent with trends from the outer bulge. We confirm for the supersolar metallicity stars the decreasing trend in [Mg/Fe] and [Si/Fe] as expected from chemical evolution models. With the caveat of a relatively small sample, we do not find significant differences in the chemical abundances between the Northern and the Southern fields; hence, the evidence is consistent with symmetry in chemistry between North and South.

Department/s

  • Lund Observatory - Undergoing reorganization

Publishing year

2018-08-21

Language

English

Pages

4374-4389

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

478

Issue

4

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Galaxy: bulge
  • Stars: abundances
  • Stars: late-type

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711