2014A&A...572A..88L

Query : 2014A&A...572A..88L

2014A&A...572A..88L - Astronomy and Astrophysics, volume 572A88-88 (2014/12-1)

VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy.

LEMASLE B., DE BOER T.J.L., HILL V., TOLSTOY E., IRWIN M.J., JABLONKA P., VENN K., BATTAGLIA G., STARKENBURG E., SHETRONE M., LETARTE B., FRANCOIS P., HELMI A., PRIMAS F., KAUFER A. and SZEIFERT T.

Abstract (from CDS):

Fornax is one of the most massive dwarf spheroidal galaxies in the Local Group. The Fornax field star population is dominated by intermediate age stars but star formation was going on over almost its entire history. It has been proposed that Fornax experienced a minor merger event. Despite recent progress, only the high metallicity end of Fornax field stars ([Fe/H]>-1.2dex) has been sampled in larger number via high resolution spectroscopy. We want to better understand the full chemical evolution of this galaxy by better sampling the whole metallicity range, including more metal poor stars. We use the VLT-FLAMES multi-fibre spectrograph in high-resolution mode to determine the abundances of several α, iron-peak and neutron-capture elements in a sample of 47 individual red giant branch stars in the Fornax dwarf spheroidal galaxy. We combine these abundances with accurate age estimates derived from the age probability distribution from the colour-magnitude diagram of Fornax. Similar to other dwarf spheroidal galaxies, the old, metal-poor stars of Fornax are typically α-rich while the young metal-rich stars are α-poor. In the classical scenario of the time delay between Type II (SNe II) and Type Ia Supernovae (SNe Ia), we confirm that SNe Ia started to contribute to the chemical enrichment at [Fe/H] between -2.0 and -1.8dex. We find that the onset of SNe Ia took place between 12-10Gyr ago. The high values of [Ba/Fe], [La/Fe] reflect the influence of SNe Ia and AGB stars in the abundance pattern of the younger stellar population of Fornax. Our findings of low [α/Fe] and enhanced [Eu/Mg] are compatible with an initial mass function that lacks the most massive stars and with star formation that kept going on throughout the whole history of Fornax. We find that massive stars kept enriching the interstellar medium in α-elements, although they were not the main contributor to the iron enrichment.

Abstract Copyright: ∼

Journal keyword(s): stars: abundances - galaxies: individual: Fornax - galaxies: evolution

VizieR on-line data: <Available at CDS (J/A+A/572/A88): tablea3.dat table7.dat table3.dat tablea5.dat>

Nomenclature: Table A.3: [LDH2014] Fnx-memNNNN N=45 among (Nos 0514-0779), [LDH2014] Fnx-rgbNNNN N=13 among (Nos 0507-0614).

CDS comments: Star ET228 not identified.

Simbad objects: 65

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Number of rows : 65
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
2 2MASS J02372020-3446458 RG* 02 37 20.2055116752 -34 46 46.016190984   20.200 18.59   17.11 ~ 7 0
3 [LDH2014] Fnx-mem0738 * 02 37 22.0694795160 -34 55 20.883948780   19.834 18.490   16.901 ~ 1 0
4 [LDH2014] Fnx-mem0654 RG* 02 37 22.5410645280 -34 49 04.573203456   19.949 18.67   17.29 ~ 5 0
5 [WMO2009] For-1353 RG* 02 37 23.6730255318 -34 43 21.040792536   19.832 18.56   17.28 ~ 5 0
6 2MASS J02372424-3448367 RG* 02 37 24.2653041864 -34 48 37.345765068   20.007 18.54   17.13 ~ 5 0
7 [LDH2014] Fnx-mem0528 * 02 37 32.4704932704 -34 39 53.522270388   19.743 18.43   16.94 ~ 4 0
8 2MASS J02373287-3440420 RG* 02 37 32.8750534440 -34 40 42.022468020   20.096 18.54   17.02 ~ 9 0
9 2MASS J02373448-3456088 RG* 02 37 34.4965054992 -34 56 08.816996724   20.120 18.61   17.25 ~ 6 0
10 2MASS J02374255-3458304 RG* 02 37 42.5460534216 -34 58 30.394614180   19.777 18.3   17.04 ~ 5 0
11 [KHI2013] III-84 * 02 37 44.4915592224 -34 45 58.887060552   19.741 18.607   17.293 ~ 2 0
12 [LDH2014] Fnx-rgb0614 RG* 02 37 47.300 -34 54 30.50   19.841 18.448   16.592 ~ 1 0
13 2MASS J02374746-3454527 RG* 02 37 47.4842947680 -34 54 52.699910040   19.943 18.25   16.89 ~ 5 0
14 2MASS J02374841-3436219 RG* 02 37 48.4154920368 -34 36 21.925986120   20.287 18.33   16.75 ~ 7 0
15 [LDH2014] Fnx-mem0675 RG* 02 37 55.7611682352 -34 50 25.259159580     18.756   17.354 ~ 4 0
16 2MASS J02375588-3447160 RG* 02 37 55.8848223048 -34 47 16.038093120   20.157 18.41   16.78 ~ 10 0
17 2MASS J02380004-3444219 RG* 02 38 00.0356937480 -34 44 22.086378744   20.340 18.562   16.702 ~ 6 0
18 2MASS J02380051-3452334 RG* 02 38 00.5350569120 -34 52 34.019487804   19.869 18.6   17.23 ~ 5 0
19 2MASS J02380140-3440114 RG* 02 38 01.3998362352 -34 40 11.651514708   20.218 18.71   17.17 ~ 6 0
20 2MASS J02380246-3441008 RG* 02 38 02.4569856624 -34 41 00.826153296   20.140 18.43   16.86 ~ 10 0
21 [LDH2014] Fnx-rgb0522 RG* 02 38 02.6914978752 -34 37 03.529448616   19.807 18.517   17.154 ~ 4 0
22 [LDH2014] Fnx-mem0538 RG* 02 38 03.8537208744 -34 40 39.085618368   19.893 18.561     ~ 2 0
23 DK 4 RG* 02 38 09.0567945672 -34 51 07.095620556   20.268 18.50   16.92 ~ 12 0
24 [LDH2014] Fnx-mem0715 RG* 02 38 11.1117356520 -34 53 20.642206200   20.257 18.722   17.245 ~ 4 0
25 [WMO2009] For-1401 RG* 02 38 13.9378369416 -34 46 55.578924660   20.057 18.705   17.36 ~ 6 0
26 2MASS J02381557-3454228 RG* 02 38 15.5537001648 -34 54 22.623040044   20.062 18.69   17.48 ~ 4 0
27 2MASS J02381791-3449535 RG* 02 38 17.9045604552 -34 49 53.472562860   19.859 18.63   17.37 ~ 6 0
28 2MASS J02381931-3436008 RG* 02 38 19.3173720768 -34 36 00.867356064   19.971 18.4   17.02 ~ 3 0
29 DK 16 RG* 02 38 19.7695106208 -34 38 54.143704320   20.508 18.41   16.90 ~ 9 0
30 FBW J023821.3-343618 RG* 02 38 21.3337513392 -34 36 18.281970864   20.142 18.335   16.393 ~ 8 0
31 2MASS J02382200-3446368 RG* 02 38 22.0137234888 -34 46 37.015779864   20.119 18.62   17.14 ~ 10 0
32 2MASS J02382246-3445061 RG* 02 38 22.4564152056 -34 45 06.389078976   20.123 18.576   17.014 ~ 8 0
33 [LDH2014] Fnx-rgb0553 RG* 02 38 25.2111651888 -34 41 24.258880824   20.284 18.655   17.033 ~ 4 0
34 2MASS J02382648-3442367 RG* 02 38 26.4947315256 -34 42 36.875745756   20.291 18.606   16.979 ~ 7 0
35 2MASS J02383024-3445030 RG* 02 38 30.2416943040 -34 45 03.134040120   20.464 18.324   16.449 ~ 9 0
36 [MOW91] 103 RG* 02 38 30.8864860224 -34 47 44.436872256   19.847 18.697   17.383 ~ 4 0
37 2MASS J02383095-3456544 RG* 02 38 30.9502123872 -34 56 54.274188048   20.178 18.48   16.91 ~ 10 0
38 [WMO2009] For-2122 RG* 02 38 35.0324152944 -34 42 40.665347532   20.039 18.42   16.93 ~ 8 0
39 [WMO2009] For-1095 RG* 02 38 35.0341735680 -34 41 38.125612608   20.254 18.56   17.09 ~ 6 0
40 2MASS J02383555-3444024 RG* 02 38 35.5497063384 -34 44 02.616618768   20.190 18.47   16.96 ~ 9 0
41 [LDH2014] Fnx-mem0610 * 02 38 36.7333878360 -34 45 21.040303500   20.006 18.537   16.526 ~ 1 0
42 2MASS J02383716-3453103 RG* 02 38 37.1550321048 -34 53 10.476838824   19.855 18.53   17.13 ~ 4 0
43 [WMO2009] For-1097 RG* 02 38 40.1836241568 -34 39 12.095578980   20.056 18.3   16.67 ~ 10 0
44 2MASS J02384060-3453308 * 02 38 40.6017221640 -34 53 30.806323548   20.175 18.5   16.95 ~ 9 0
45 [WMF2009] F 31013 RG* 02 38 41.1151886592 -34 44 20.558729004   19.672 18.157   16.653 ~ 8 0
46 DK 9 RG* 02 38 42.1786995120 -34 47 40.480134576   20.125 18.415   16.791 ~ 10 0
47 2MASS J02384297-3450564 RG* 02 38 42.9886796592 -34 50 56.333753232   20.316 18.62   17.07 ~ 10 0
48 2MASS J02384461-3442334 RG* 02 38 44.6103869736 -34 42 33.440355180   20.185 18.55   17.1 ~ 6 0
49 [LDH2014] Fnx-mem0556 RG* 02 38 45.5685554664 -34 41 45.309482916   20.159 18.666   17.171 ~ 5 0
50 2MASS J02384635-3441147 RG* 02 38 46.3487515392 -34 41 14.899686648   20.132 18.62   17.25 ~ 7 0
51 2MASS J02384682-3439250 RG* 02 38 46.8191885280 -34 39 25.136188452   20.082 18.37   16.83 ~ 4 0
52 2MASS J02384789-3439397 RG* 02 38 47.8923633984 -34 39 39.734023824   20.149 18.44   16.77 ~ 9 0
53 [LDH2014] Fnx-mem0571 * 02 38 49.4730962544 -34 42 29.650578552   19.802 18.40   16.94 ~ 2 0
54 2MASS J02385026-3453195 RG* 02 38 50.2704929400 -34 53 19.563238284   19.641 18.211   16.727 ~ 4 0
55 2MASS J02385092-3445351 RG* 02 38 50.9226962424 -34 45 35.382414456   19.887 18.47   17.06 ~ 6 0
56 DK 13 RG* 02 38 52.2848238864 -34 44 55.359484368   19.78 18.14   16.41 ~ 7 0
57 2MASS J02385297-3447013 RG* 02 38 52.9645447128 -34 47 01.407091596   19.677 18.14   16.73 ~ 9 0
58 2MASS J02385552-3447211 RG* 02 38 55.5159454344 -34 47 21.150630420   20.238 18.63   17.2 ~ 6 0
59 DK 12 RG* 02 38 59.5388746776 -34 45 36.363132684   20.029 18.38   16.46 ~ 9 0
60 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
61 * alf Cet LP? 03 02 16.77307 +04 05 23.0596 6.10 4.17 2.53 1.18 0.02 M1.5IIIa 480 1
62 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
63 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2417 1
64 * gam Sge PM* 19 58 45.4282303572 +19 29 31.726069716 6.97 5.04 3.47 2.27 1.35 M0-III 276 0
65 NAME Local Group GrG ~ ~           ~ 9325 0

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