2018MNRAS.478.4374N -
Mon. Not. R. Astron. Soc., 478, 4374-4389 (2018/August-3)
Chemical characterization of the inner Galactic bulge:North-South symmetry.
NANDAKUMAR G., RYDE N., SCHULTHEIS M., THORSBRO B., JONSSON H., BARKLEM P.S., RICH R.M. and FRAGKOUDI F.
Abstract (from CDS):
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 ∼+0.3dex and a metal-poor peak at ∼-0.5dex 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 +0.3dex. 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.
Abstract Copyright:
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
stars: abundances - stars: late-type - Galaxy: bulge
Nomenclature:
Table 1: [NRS2018] bp3-NN N=15 among (Nos 1-17), [NRS2018] bp2-NN (Nos 1-15), [NRS2018] bp1-NN (Nos 1-14).
Status at CDS
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