期刊
ASTRONOMY & ASTROPHYSICS
卷 656, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202039030
关键词
stars; abundances; stars; fundamental parameters; Galaxy; center; Galaxy; general; Galaxy; stellar content; Galaxy; structure
资金
- DFG [CH1188/2-1]
- ChETEC COST Action - COST (European Cooperation in Science and Technology) [CA16117]
- European Union [800502 H2020-MSCA-IF-EF-2017]
- FAPESP
- CNPq
- CAPES [001]
- FAPESP [2017/15893-1]
- DGAPA-PAPIIT [IG100319]
- State Research Agency (AEI) of the Spanish Ministry of Science, Innovation and Universities (MCIU)
- European Regional Development Fund (FEDER) [AYA2017-88254-P]
- FONDECYT [3180203, 3180210]
- Becas Iberoamerica Investigador 2019, Banco Santander Chile
- NSF [AST-1801940]
- Laboratorio Interinstitucional de e-Astronomia (LIneA)
- Spanish MICINN [AyA2011-24052]
- Ministerio de Ciencia e Tecnologia (MCT)
- Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ)
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)
- Financiadora de Estudos e Projetos (FINEP)
- Alfred P. Sloan Foundation
- US Department of Energy O ffice of Science
- Center for High-Performance Computing at the University of Utah
- Brazilian Participation Group
- Carnegie Institution for Science
- Chilean Participation Group
- French Participation Group
- Harvard-Smithsonian Center for Astrophysics
- Johns Hopkins University
- Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo
- Lawrence Berkeley National Laboratory
- Max-Planck-Institut fur Astronomie (MPIA Heidelberg)
- Max-Planck-Institut fur Astrophysik (MPA Garching)
- Max-Planck-Institut fur Extraterrestrische Physik (MPE)
- National Astronomical Observatory of China
- New Mexico State University
- New York University
- University of Notre Dame
- Observatario Nacional/MCTI
- Ohio State University
- Pennsylvania State University
- Shanghai Astronomical Observatory
- United Kingdom Participation Group
- Universidad Nacional Autonoma de Mexico
- Univity of Arizona
- University of Colorado Boulder
- University of Oxford
- University of Portsmouth
- University of Utah
- University of Virginia
- University ofWashington
- University of Wisconsin
- Vanderbilt University
- Yale University
- Carnegie Mellon University
- Instituto de Astrofisica de Canarias
- Leibniz-Institut fur Astrophysik Potsdam (AIP)
By using data from APOGEE and Gaia EDR3, we investigated the inner regions of the Milky Way, revealing chemo-dynamical maps of stellar populations and the interaction between different populations with chemical bimodality.
We investigate the inner regions of the Milky Way using data from APOGEE and Gaia EDR3. Our inner Galactic sample has more than 26 500 stars within |X-Gal|< 5 kpc, |Y-Gal|< 3.5 kpc, |Z(Gal)|< 1 kpc, and we also carry out the analysis for a foreground-cleaned subsample of 8000 stars that is more representative of the bulge-bar populations. These samples allow us to build chemo-dynamical maps of the stellar populations with vastly improved detail. The inner Galaxy shows an apparent chemical bimodality in key abundance ratios [alpha/Fe], [C/N], and [Mn/O], which probe different enrichment timescales, suggesting a star formation gap (quenching) between the high- and low-alpha populations. Using a joint analysis of the distributions of kinematics, metallicities, mean orbital radius, and chemical abundances, we can characterize the different populations coexisting in the innermost regions of the Galaxy for the first time. The chemo-kinematic data dissected on an eccentricity-|Z|(max) plane reveal the chemical and kinematic signatures of the bar, the thin inner disc, and an inner thick disc, and a broad metallicity population with large velocity dispersion indicative of a pressure-supported component. The interplay between these different populations is mapped onto the different metallicity distributions seen in the eccentricity-|Z|(max) diagram consistently with the mean orbital radius and V-phi distributions. A clear metallicity gradient as a function of |Z|(max) is also found, which is consistent with the spatial overlapping of different populations. Additionally, we find and chemically and kinematically characterize a group of counter-rotating stars that could be the result of a gas-rich merger event or just the result of clumpy star formation during the earliest phases of the early disc that migrated into the bulge. Finally, based on 6D information, we assign stars a probability value of being on a bar orbit and find that most of the stars with large bar orbit probabilities come from the innermost 3 kpc, with a broad dispersion of metallicity. Even stars with a high probability of belonging to the bar show chemical bimodality in the [alpha/Fe] versus [Fe/H] diagram. This suggests bar trapping to be an efficient mechanism, explaining why stars on bar orbits do not show a significant, distinct chemical abundance ratio signature.
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