2013A&A...549A.147B


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.14CET19:01:55

2013A&A...549A.147B - Astronomy and Astrophysics, volume 549A, 147-147 (2013/1-1)

Chemical evolution of the Galactic Bulge as traced by microlensed dwarf and subgiant stars. V. Evidence for a wide age distribution and a complex MDF.

BENSBY T., YEE J.C., FELTZING S., JOHNSON J.A., GOULD A., COHEN J.G., ASPLUND M., MELENDEZ J., LUCATELLO S., HAN C., THOMPSON I., GAL-YAM A., UDALSKI A., BENNETT D.P., BOND I.A., KOHEI W., SUMI T., SUZUKI D., SUZUKI K., TAKINO S., TRISTRAM P., YAMAI N. and YONEHARA A.

Abstract (from CDS):

Based on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. Combined with the sample of 26 stars from the previous papers in this series, we now have 58 microlensed bulge dwarfs and subgiants that have been homogeneously analysed. The main characteristics of the sample and the findings that can be drawn are: (i) the metallicity distribution (MDF) is wide and spans all metallicities between [Fe/H]=-1.9 to +0.6; (ii) the dip in the MDF around solar metallicity that was apparent in our previous analysis of a smaller sample (26 microlensed stars) is no longer evident; instead it has a complex structure and indications of multiple components are starting to emerge. A tentative interpretation is that there could be different stellar populations at interplay, each with a different scale height: the thin disk, the thick disk, and a bar population; (iii) the stars with [Fe/H]≲-0.1 are old with ages between 10 and 12Gyr; (iv) the metal-rich stars with [Fe/H]>-0.1 show a wide variety of ages, ranging from 2 to 12Gyr with a distribution that has a dominant peak around 4-5Gyr and a tail towards higher ages; (v) there are indications in the [α/Fe]-[Fe/H] abundance trends that the ``knee'' occurs around [Fe/H]=-0.3 to -0.2, which is a slightly higher metallicity as compared to the ``knee'' for the local thick disk. This suggests that the chemical enrichment of the metal-poor bulge has been somewhat faster than what is observed for the local thick disk. The results from the microlensed bulge dwarf stars in combination with other findings in the literature, in particular the evidence that the bulge has cylindrical rotation, indicate that the Milky Way could be an almost pure disk galaxy. The bulge would then just be a conglomerate of the other Galactic stellar populations (thin disk, thick disk, halo, and ...?), residing together in the central parts of the Galaxy, influenced by the Galactic bar.

Abstract Copyright:

Journal keyword(s): gravitational lensing: micro - Galaxy: bulge - Galaxy: formation - Galaxy: evolution - stars: abundances

VizieR on-line data: <Available at CDS (J/A+A/549/A147): table2.dat table3.dat table4.dat table5.dat>

CDS comments: Table 5 MACH-1999-BLG-022 is a probable misprint for MOA 2012-BLG-022.

Simbad objects: 61

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Number of rows : 61

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 EWS 2012-BLG-270 * 17 14 42.460 -29 35 50.40           ~ 3 0
2 EWS 2011-BLG-1410 * 17 32 49.610 -29 23 10.60           ~ 3 0
3 NAME OGLE-2012-BLG-0026L * 17 34 18.700 -27 08 33.90           ~ 24 1
4 EWS 2012-BLG-1274 * 17 45 00.650 -34 32 49.50           ~ 4 0
5 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11045 0
6 MOA 2009-BLG-456 * 17 48 56.40 -34 13 29.7           ~ 5 0
7 MOA 2011-BLG-191 * 17 51 40.150 -29 53 26.15           ~ 3 0
8 MOA 2010-BLG-78 * 17 52 01.650 -30 24 25.63           ~ 4 0
9 MOA 2006-BUL-99 * 17 54 10.99 -35 13 38.0           G 11 0
10 NAME OGLE 2011-BLG-012N * 17 54 11.320 -30 05 21.56           ~ 4 0
11 MOA 2008-BLG-310 * 17 54 14.53 -34 46 41.0           GV 39 1
12 MOA 2011-BLG-104 * 17 54 22.480 -29 50 01.67           ~ 9 0
13 EWS 2011-BLG-1105 * 17 54 48.480 -31 25 57.86           ~ 3 0
14 EWS 2012-BLG-617 * 17 54 53.870 -31 08 19.10           ~ 4 0
15 MOA 2009-BLG-493 * 17 55 46.13 -28 48 25.5           ~ 6 0
16 MOA 2010-BLG-285 * 17 56 48.160 -30 00 39.47           ~ 5 0
17 EWS 2012-BLG-1279 * 17 56 52.400 -31 46 54.12           ~ 3 0
18 MOA 2008-BLG-311 * 17 56 53.65 -31 23 49.9           ~ 13 0
19 EWS 2011-BLG-1072 * 17 56 53.940 -28 50 53.31           ~ 3 0
20 MOA 2010-BLG-523 RS* 17 57 08.870 -29 44 58.40           ~ 9 0
21 MOA 2011-BLG-336 * 17 57 16.620 -32 39 57.15           ~ 6 0
22 MOA 2011-BLG-174 * 17 57 20.620 -30 22 47.57           ~ 3 0
23 MOA 2012-BLG-22 * 17 57 40.970 -27 29 56.49           ~ 3 0
24 MOA 2009-BLG-489 * 17 57 46.67 -28 38 56.9           ~ 6 0
25 MOA 2009-BLG-259 * 17 57 57.51 -29 11 39.4           ~ 6 0
26 EWS 2007-BUL-514 * 17 58 03.09 -27 31 05.7           ~ 12 0
27 EWS 2012-BLG-816 * 17 58 15.980 -29 57 21.45           ~ 3 0
28 EWS 2009-BLG-76 * 17 58 31.93 -29 12 17.9           ~ 10 0
29 MOA 2012-BLG-532 * 17 58 41.130 -30 02 11.80           ~ 5 0
30 MOA 2012-BLG-391 * 17 58 56.670 -31 26 30.82           ~ 3 0
31 EWS 2012-BLG-1156 * 18 00 35.950 -28 11 15.20           ~ 3 0
32 EWS 2012-BLG-1534 * 18 00 46.350 -28 01 00.30           ~ 3 0
33 MOA 2009-BLG-174 * 18 02 07.70 -31 25 26.4           FV 7 0
34 MOA 2009-BLG-475 * 18 02 27.46 -27 26 49.4           ~ 6 0
35 MOA 2012-BLG-291 * 18 02 43.080 -28 23 00.86           ~ 4 0
36 NAME Baade Window reg 18 03.5 -30 01           ~ 516 3
37 MOA 2011-BLG-445 * 18 04 45.630 -28 35 44.06           ~ 3 0
38 EWS 2008-BUL-209 * 18 04 49.84 -29 42 33.2           ~ 11 0
39 MOA 2010-BLG-49 * 18 05 07.020 -26 46 12.79           ~ 4 0
40 MOA 2010-BLG-37 * 18 05 17.930 -27 56 13.21           ~ 4 0
41 OGLE BLG241.6 137439 ** 18 05 24.43 -26 25 18.8           ~ 29 1
42 EWS 2012-BLG-521 * 18 05 36.740 -25 45 47.42           ~ 3 0
43 MOA 2012-BLG-288 * 18 05 57.720 -27 42 43.20           ~ 7 0
44 MOA 2009-BLG-133 * 18 06 32.85 -31 30 11.4           ~ 6 0
45 MOA 2010-BLG-446 * 18 07 04.250 -28 03 57.77           ~ 4 0
46 EWS 2006-BUL-265 * 18 07 18.88 -27 47 42.7           G 14 0
47 MOA 2012-BLG-187 * 18 08 02.160 -29 28 11.45           ~ 3 0
48 MOA 2010-BLG-311 * 18 08 49.980 -25 57 04.27           ~ 9 0
49 MOA 2011-BLG-58 * 18 09 00.360 -29 14 12.66           ~ 4 0
50 EWS 2011-BLG-969 * 18 09 41.130 -31 11 04.70           ~ 3 0
51 EWS 2012-BLG-1526 * 18 09 43.130 -28 48 45.20           ~ 3 0
52 EWS 2012-BLG-211 * 18 10 10.960 -25 01 40.20           ~ 4 0
53 MOA 2011-BLG-34 * 18 10 12.230 -27 32 02.39           ~ 5 0
54 EWS 2012-BLG-1217 * 18 10 16.850 -27 37 59.00           ~ 3 0
55 MOA 2012-BLG-410 * 18 10 22.620 -25 10 16.83           ~ 3 0
56 MOA 2011-BLG-90 * 18 10 29.850 -26 38 43.03           ~ 6 0
57 MOA 2011-BLG-234 * 18 10 56.780 -26 33 48.59           ~ 3 0
58 MOA 2010-BLG-167 * 18 11 27.370 -29 41 02.54           ~ 4 0
59 MOA 2012-BLG-202 * 18 12 34.840 -25 02 59.79           ~ 3 0
60 NAME Galactic Bulge reg ~ ~           ~ 3247 0
61 NAME Galactic Bar reg ~ ~           ~ 827 0

    Equat.    Gal    SGal    Ecl

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2019.11.14-19:01:55

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