| Full text | |
| Author(s): Show less - |
Bensby, T.
[1]
;
Feltzing, S.
[1]
;
Gould, A.
[2, 3, 4]
;
Yee, J. C.
[5]
;
Johnson, J. A.
[3]
;
Asplund, M.
[6]
;
Melendez, J.
[7]
;
Lucatello, S.
[8]
;
Howes, L. M.
[1]
;
McWilliam, A.
[9]
;
Udalski, A.
[10]
;
Szymanski, M. K.
[10]
;
Soszynski, I.
[10]
;
Poleski, R.
[10, 3]
;
Wyrzykowski, L.
[10]
;
Ulaczyk, K.
[10, 11]
;
Kozlowski, S.
[10]
;
Pietrukowicz, P.
[10]
;
Skowron, J.
[10]
;
Mroz, P.
[10]
;
Pawlak, M.
[10]
;
Abe, F.
[12]
;
Asakura, Y.
[12]
;
Bhattacharya, A.
[13]
;
Bond, I. A.
[14]
;
Bennett, D. P.
[15]
;
Hirao, Y.
[16]
;
Nagakane, M.
[16]
;
Koshimoto, N.
[16]
;
Sumi, T.
[16]
;
Suzuki, D.
[15]
;
Tristram, P. J.
[17]
;
Collaboration, OGLE
;
Collaboration, MOA
Total Authors: 34
|
| Affiliation: Show less - | [1] Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund - Sweden
[2] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg - Germany
[3] Ohio State Univ, Dept Astron, 140 W 18th Ave, Columbus, OH 43210 - USA
[4] Korea Astron & Space Sci Inst Inst, Daejon 305348 - South Korea
[5] Smithsonian Astrophys Observ, 60 Garden St, Cambridge, MA 02138 - USA
[6] Australian Natl Univ, Res Sch Astron & Astrophys, Cotter Rd, Canberra, ACT 2611 - Australia
[7] Univ Sao Paulo, IAG, Dept Astron, Rua Matao 1226, BR-05508900 Sao Paulo, SP - Brazil
[8] INAF Astron Observ Padova, Vicolo Osservatorio 5, I-35122 Padua - Italy
[9] Carnegie Observ, 813 Santa Barbara St, Pasadena, CA 91101 - USA
[10] Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw - Poland
[11] Univ Warwick, Dept Phys, Gibbet Hill Rd, Coventry CV4 7AL, W Midlands - England
[12] Nagoya Univ, Inst Space Earth Environm Res, Nagoya, Aichi 4648601 - Japan
[13] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA
[14] Massey Univ, Inst Informat & Math Sci, Auckland 1330 - New Zealand
[15] NASA, Goddard Space Flight Ctr, Lab Exoplanets & Stellar Astrophys, Greenbelt, MD 20771 - USA
[16] Osaka Univ, Grad Sch Sci, Dept Earth & Space Sci, Toyonaka, Osaka 5600043 - Japan
[17] Mt John Univ Observ, POB 56, Lake Tekapo 8770 - New Zealand
Total Affiliations: 17
|
| Document type: | Journal article |
| Source: | Astronomy & Astrophysics; v. 605, SEP 2017. |
| Web of Science Citations: | 46 |
| Abstract | |
We 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) a high fraction of intermediate-age to young stars where at {[}Fe/H] > 0 more than 35% are younger than 8 Gyr, and for {[}Fe/H] less than or similar to -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 alpha-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)(0) colour of the bulge red clump should be revised to 1.09. (AU) | |
| FAPESP's process: | 14/18100-4 - Stellar populations in the Milky Way: bulge, halo, disk and star forming regions; instrumentation for high resolution spectroscopy |
| Grantee: | Beatriz Leonor Silveira Barbuy |
| Support Opportunities: | Research Projects - Thematic Grants |