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Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way

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dc.abstract.enWe present a detailed elemental abundance study of 90 F and G dwarf, turn-off, and subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages and abundances for 11 elements (Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Zn, Y and Ba) have been determined. Four main findings are presented: (1) a wide metallicity distribution with distinct peaks at [Fe/H] = -1.09, -0.63, -0.20, + 0.12, + 0.41; (2) ahigh fraction of intermediate-age to young stars where at [Fe/H] > 0 more than 35% are younger than 8 Gyr, and for [Fe/H] ≲ -0.5 most stars are 10 Gyr or older; (3) several episodes of significant star formation in the bulge has been identified: 3, 6, 8, and 11 Gyr ago; (4) tentatively the knee in the α-element abundance trends of the sub-solar metallicity bulge is located at a slightly higher [Fe/H] than in the local thick disk. These findings show that the Galactic bulge has complex age and abundance properties that appear to be tightly connected to the main Galactic stellar populations. In particular, the peaks in the metallicity distribution, the star formation episodes, and the abundance trends, show similarities with the properties of the Galactic thin and thick disks. At the same time, the star formation rate appears to have been slightly faster in the bulge than in the local thick disk, which most likely is an indication of the denser stellar environment closer to the Galactic centre. There are also additional components not seen outside the bulge region, and that most likely can be associated with the Galactic bar. Our results strengthen the observational evidence that support the idea of a secular origin for the Galactic bulge, formed out of the other main Galactic stellar populations present in the central regions of our Galaxy. Additionally, our analysis of this enlarged sample suggests that the (V-I)<SUB>0</SUB> colour of the bulge red clump should be revised to 1.09. Based on data obtained with the European Southern Observatory telescopes (Proposal ID:s 87.B-0600, 88.B-0349, 89.B-0047, 90.B-0204, 91.B-0289, 92.B-0626, 93.B-0700, 94.B-0282), the Magellan Clay telescope at the Las Campanas observatory, and the Keck I telescope at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration.Full Tables A.1 and A.2 are only available at the CDS via anonymous ftp to <A href=http://cdsarc.u-strasbg.fr>http://cdsarc.u-strasbg.fr</A> (<A href=http://130.79.128.5>http://130.79.128.5</A>) or via <A href=http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A89>http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A89</A>
dc.affiliationUniwersytet Warszawski
dc.contributor.authorBensby, T.
dc.contributor.authorFeltzing, S.
dc.contributor.authorGould, A.
dc.contributor.authorYee, J. C.
dc.contributor.authorJohnson, J. A.
dc.contributor.authorAsplund, M.
dc.contributor.authorMeléndez, J.
dc.contributor.authorLucatello, S.
dc.contributor.authorHowes, L. M.
dc.contributor.authorMcWilliam, A.
dc.contributor.authorUdalski, Andrzej
dc.contributor.authorSzymański, Michał
dc.contributor.authorSoszyński, Igor
dc.contributor.authorPoleski, Radosław
dc.contributor.authorWyrzykowski, Łukasz
dc.contributor.authorUlaczyk, Krzysztof
dc.contributor.authorKozłowski, Szymon
dc.contributor.authorPietrukowicz, Paweł
dc.contributor.authorSkowron, Jan
dc.contributor.authorMróz, Przemysław
dc.contributor.authorPawlak, Michał
dc.contributor.authorAbe, F.
dc.contributor.authorAsakura, Y.
dc.contributor.authorBhattacharya, A.
dc.contributor.authorBond, I. A.
dc.contributor.authorBennett, D. P.
dc.contributor.authorHirao, Y.
dc.contributor.authorNagakane, M.
dc.contributor.authorKoshimoto, N.
dc.contributor.authorSumi, T.
dc.contributor.authorSuzuki, D.
dc.contributor.authorTristram, P. J.
dc.date.accessioned2024-01-24T19:12:58Z
dc.date.available2024-01-24T19:12:58Z
dc.date.copyright2017-02-09
dc.date.issued2017
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeNie dotyczy
dc.description.versionORIGINAL_AUTHOR
dc.description.volume605
dc.identifier.doi10.1051/0004-6361/201730560
dc.identifier.issn0004-6361
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/102978
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2017A&A...605A..89B
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofAstronomy and Astrophysics
dc.relation.pagesA89
dc.rightsOther
dc.sciencecloudnosend
dc.titleChemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
dc.typeJournalArticle
dspace.entity.typePublication