Chemical characterization of the inner Galactic bulge : North-South symmetry
(2018) In Monthly Notices of the Royal Astronomical Society 478(4). p.4374-4389- Abstract
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... (More)
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.
(Less)
- author
- Nandakumar, G. LU ; Ryde, N. LU ; Schultheis, M. ; Thorsbro, B. LU ; Jönsson, H. LU ; Barklem, P. S. ; Rich, R. M. and Fragkoudi, F.
- organization
- publishing date
- 2018-08-21
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Galaxy: bulge, Stars: abundances, Stars: late-type
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 478
- issue
- 4
- pages
- 16 pages
- publisher
- Oxford University Press
- external identifiers
-
- scopus:85050822268
- ISSN
- 0035-8711
- DOI
- 10.1093/mnras/sty1255
- language
- English
- LU publication?
- yes
- id
- 5e78f73c-5457-4640-bd1c-88c6cc3d4503
- date added to LUP
- 2018-08-15 15:08:11
- date last changed
- 2024-04-16 14:35:20
@article{5e78f73c-5457-4640-bd1c-88c6cc3d4503, abstract = {{<p>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.</p>}}, author = {{Nandakumar, G. and Ryde, N. and Schultheis, M. and Thorsbro, B. and Jönsson, H. and Barklem, P. S. and Rich, R. M. and Fragkoudi, F.}}, issn = {{0035-8711}}, keywords = {{Galaxy: bulge; Stars: abundances; Stars: late-type}}, language = {{eng}}, month = {{08}}, number = {{4}}, pages = {{4374--4389}}, publisher = {{Oxford University Press}}, series = {{Monthly Notices of the Royal Astronomical Society}}, title = {{Chemical characterization of the inner Galactic bulge : North-South symmetry}}, url = {{http://dx.doi.org/10.1093/mnras/sty1255}}, doi = {{10.1093/mnras/sty1255}}, volume = {{478}}, year = {{2018}}, }