2009A&A...500..735G


Query : 2009A&A...500..735G

2009A&A...500..735G - Astronomy and Astrophysics, volume 500, 735-747 (2009/6-3)

New constraints on the chemical evolution of the dwarf spheroidal galaxy Leo I from VLT spectroscopy.

GULLIEUSZIK M., HELD E.V., SAVIANE I. and RIZZI L.

Abstract (from CDS):

We present the spectroscopy of red giant stars in the dwarf spheroidal galaxy LeoI, aimed at further constraining its chemical enrichment history. Intermediate-resolution spectroscopy in the CaII triplet spectral region was obtained for 54 stars in LeoI using FORS2 at the ESO Very Large Telescope. The equivalent widths of CaII triplet lines were used to derive the metallicities of the target stars on the [Fe/H] scale of Carretta & Gratton (1997A&AS..121...95C), as well as on a scale tied to the global metal abundance, [M/H]. The metallicity distribution function for red giant branch (RGB) stars in LeoI is confirmed to be very narrow, with mean value [M/H]≃-1.2 and dispersion σ[M/H]≃0.2. By evaluating all contributions to the measurement error, we provide a constraint to the intrinsic metallicity dispersion, σ[M/H],0=0.08. We find a few metal-poor stars (whose metallicity values depend on the adopted extrapolation of the existing calibrations), but in no case are stars more metal-poor than [Fe/H]=-2.6. Our measurements provide a hint of a shallow metallicity gradient of -0.27dex/Kpc among LeoI red giants. The gradient disappears if our data are combined with previous spectroscopic datasets in the literature, so that any firm conclusions about its presence must await new data, particularly in the outer regions. By combining the metallicities of the target stars with their photometric data, we provide age estimates and an age-metallicity relation for a subset of red giant stars in LeoI. Our age estimates indicate a rapid initial enrichment, a slowly rising metal abundance - consistent with the narrowness of the metallicity distribution - and an increase of ∼0.2dex in the last few Gyr. The estimated ages also suggest a radial age gradient in the RGB stellar populations, which agrees with the conclusions of a parallel study of asymptotic giant branch stars in LeoI from near-infrared photometry. Together, these studies provide the first evidence of stellar population gradients in LeoI.

Abstract Copyright:

Journal keyword(s): galaxies: dwarf - galaxies: individual: Leo I - stars: abundances - Local Group - galaxies: stellar content

Nomenclature: Table 1: [GHS2009] NNN (Nos 1-54, 101-103).

Simbad objects: 106

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Number of rows : 106
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16530 1
2 [GHS2009] 101 * 10 07 51.18 +12 17 36.6   21.08 19.56     ~ 1 0
3 [GHS2009] 26 RG* 10 07 55.8111365160 +12 17 54.101409576   21.62 20.449   19.309 ~ 3 0
4 [GHS2009] 33 RG* 10 07 57.31 +12 18 25.2   21.14 19.74   18.44 ~ 2 0
5 [GHS2009] 37 RG* 10 07 59.36 +12 18 35.7   21.35 19.75     ~ 1 0
6 [BSS2007b] Leo I 2488 RG* 10 08 01.8691905000 +12 17 55.397866812   21.25 19.794   18.416 ~ 4 0
7 [GHS2009] 8 RG* 10 08 03.60 +12 16 46.2   21.24 19.74   18.64 ~ 2 0
8 [GHS2009] 102 * 10 08 05.23 +12 18 13.5   21.01 19.96     ~ 1 0
9 [MOW2008] 217 RG* 10 08 06.23 +12 17 45.4   21.44 20.16   19.08 ~ 3 0
10 [GHS2009] 19 RG* 10 08 07.4860351584 +12 17 34.204815528   21.41 20.079   18.827 ~ 3 0
11 [GHS2009] 10 RG* 10 08 08.79 +12 17 05.9   21.07 20.00     ~ 1 0
12 [BSS2007b] Leo I 4173 RG* 10 08 10.61 +12 17 08.0   21.25 20.05     ~ 2 0
13 [GHS2009] 17 RG* 10 08 11.82 +12 17 29.4   21.36 20.31     ~ 1 0
14 [GHS2009] 49 RG* 10 08 13.33 +12 20 13.6   20.91 19.64   18.38 ~ 2 0
15 [MOW2008] 115 RG* 10 08 14.14 +12 17 36.4   21.01 19.90   18.88 ~ 3 0
16 [GHS2009] 52 RG* 10 08 14.9299740792 +12 20 43.596806928   21.05 19.468   18.022 ~ 4 0
17 [GHS2009] 21 RG* 10 08 15.34 +12 17 38.6   20.91 19.48   18.22 ~ 2 0
18 [GHS2009] 32 RG* 10 08 15.96 +12 18 25.3   21.42 20.25     ~ 1 0
19 [GHS2009] 2 RG* 10 08 16.46 +12 15 59.5   21.07 19.510   18.116 ~ 4 0
20 2MASS J10081756+1216147 RG* 10 08 17.5595209944 +12 16 15.485237652   21.16 19.420   17.855 ~ 6 0
21 [GHS2009] 54 RG* 10 08 18.2058820056 +12 20 54.220192656   21.29 19.925   18.670 ~ 3 0
22 [BSS2007b] Leo I 8203 RG* 10 08 19.1434416792 +12 20 48.549783408   21.25 19.771   18.410 ~ 5 0
23 [HW78] V21 Ce* 10 08 19.40 +12 16 32.2   21.38 20.70     ~ 4 0
24 [GHS2009] 41 RG* 10 08 20.19 +12 18 46.2   21.03 19.62   18.24 ~ 2 0
25 2MASS J10082050+1217451 RG* 10 08 20.4840610584 +12 17 44.773389564   21.25 19.529   18.006 ~ 6 0
26 [MOV98] 7 RG* 10 08 21.1240326408 +12 19 43.183631316   21.24 19.645   18.174 ~ 5 0
27 [GHS2009] 50 RG* 10 08 22.17 +12 20 14.9   20.53 19.15     ~ 1 0
28 [SMM2007] 60019 RG* 10 08 24.2000077080 +12 18 52.948832616   21.31 19.862   18.551 ~ 5 0
29 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1151 1
30 [GHS2009] 1 RG* 10 08 28.41 +12 15 54.0   21.01 19.62   18.23 ~ 3 0
31 [MOV98] 3 RG* 10 08 28.4603248464 +12 20 26.020252788   21.12 19.716   18.488 ~ 6 0
32 [GHS2009] 18 RG* 10 08 29.8498298064 +12 17 31.426339812   20.97 19.553   18.287 ~ 3 0
33 [SMM2007] 22567 RG* 10 08 30.6443376168 +12 19 29.754777684   21.34 20.305   19.103 ~ 4 0
34 [BSS2007b] Leo I 18214 RG* 10 08 31.00 +12 16 40.6   21.17 19.85     ~ 2 0
35 [GHS2009] 9 RG* 10 08 32.56 +12 16 54.9   21.64 20.45     ~ 1 0
36 [GHS2009] 42 RG* 10 08 33.75 +12 18 47.0   20.49 19.23     ~ 1 0
37 [GHS2009] 31 RG* 10 08 34.85 +12 18 22.6   21.22 19.98     ~ 1 0
38 [GHS2009] 13 RG* 10 08 34.90 +12 17 17.8   21.17 20.01     ~ 1 0
39 [GHS2009] 36 RG* 10 08 35.99 +12 18 32.5   20.88 19.58   18.36 ~ 2 0
40 [GHS2009] 3 RG* 10 08 36.37 +12 16 02.1   21.35 19.89   18.64 ~ 2 0
41 [KWK2007] 351 RG* 10 08 37.2666145392 +12 20 11.800722912   21.12 19.856   18.516 ~ 7 1
42 [GHS2009] 29 RG* 10 08 38.58 +12 18 21.0   20.65 19.71     ~ 1 0
43 [GHS2009] 47 RG* 10 08 39.4014622992 +12 20 05.502665976   20.90 19.689   18.402 ~ 3 0
44 [KWK2007] 195 RG* 10 08 39.6262787952 +12 17 19.601635920   21.05 19.582   18.244 ~ 5 0
45 [BSS2007b] Leo I 25113 RG* 10 08 40.4320747176 +12 16 37.674697152   21.13 19.667   18.354 ~ 5 0
46 [GHS2009] 44 RG* 10 08 40.5767327520 +12 19 02.420421996   20.91 19.631   18.291 ~ 3 0
47 [BSS2007b] Leo I 25820 RG* 10 08 41.9076423240 +12 18 39.278562444   21.38 20.191   18.926 ~ 4 0
48 [GHS2009] 34 RG* 10 08 44.09 +12 18 29.0   20.79 19.66     ~ 1 0
49 [GHS2009] 28 RG* 10 08 45.2273658840 +12 17 57.420119976   21.36 19.981   18.672 ~ 4 0
50 [GHS2009] 22 RG* 10 08 46.36 +12 17 41.3   21.65 20.32     ~ 1 0
51 [GHS2009] 35 RG* 10 08 47.86 +12 18 29.6   21.16 19.70   18.48 ~ 2 0
52 [SMM2007] 30538 RG* 10 08 49.4285400576 +12 17 13.750105812   21.62 20.380   19.215 ~ 4 0
53 [KWK2007] 677 RG* 10 08 50.7124802736 +12 17 45.802902156   21.46 20.300   19.069 ~ 4 0
54 [GHS2009] 40 RG* 10 08 51.7414453608 +12 18 44.532975924   21.51 20.143   18.855 ~ 3 0
55 [GHS2009] 103 * 10 08 53.43 +12 18 27.4   21.24 19.88     ~ 1 0
56 [GHS2009] 16 RG* 10 08 55.4830442808 +12 17 20.865257016   21.40 20.100   18.896 ~ 4 0
57 [GHS2009] 30 RG* 10 08 56.58 +12 18 22.4   21.35 20.22     ~ 1 0
58 [KWK2007] 833 RG* 10 08 57.3937850736 +12 17 19.785996168   21.62 20.416   19.228 ~ 6 0
59 [SMM2007] 20345 RG* 10 08 58.7280952872 +12 18 35.953488828   21.29 19.724   18.367 ~ 5 0
60 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 804 0
61 NGC 4372 GlC 12 25 45.43 -72 39 32.7   10.86 9.85     ~ 289 0
62 Cl* NGC 4590 HAR 130 RG* 12 39 17.0048908872 -26 45 38.599156332   15.183 14.231     ~ 12 0
63 Cl* NGC 4590 ALC 66 RG* 12 39 18.2334625752 -26 46 40.418097600   15.581 14.684     ~ 14 0
64 Cl* NGC 4590 HAR 1119 RG* 12 39 27.0710087040 -26 47 51.184492224   14.67 13.659     ~ 10 0
65 M 68 GlC 12 39 27.98 -26 44 38.6     7.96     ~ 952 0
66 Cl* NGC 4590 ALC 53 * 12 39 30.8380890720 -26 47 52.674381456   14.09 12.76     ~ 17 0
67 2MASS J12393762-2645155 RG* 12 39 37.6268792376 -26 45 15.557633604   15.211 14.277     ~ 14 0
68 2MASS J12394022-2647374 RG* 12 39 40.2216702672 -26 47 37.435920144   16.043 15.186     ~ 8 0
69 M 5 GlC 15 18 33.22 +02 04 51.7     5.95     ~ 1907 0
70 NGC 5927 GlC 15 28 00.69 -50 40 22.9           ~ 439 0
71 2MASS J16322112-1302516 RG* 16 32 21.1205417160 -13 02 51.610357356   15.12 13.40     ~ 23 0
72 M 107 GlC 16 32 31.86 -13 03 13.6           ~ 758 0
73 Cl* NGC 6171 SK I * 16 32 41.5188287904 -13 04 34.988755764   15.38 13.93     ~ 7 0
74 NGC 6397 428 RG* 17 40 15.2617950648 -53 40 15.042604836 10.14 12.56 11.48 11.247   ~ 33 0
75 NGC 6397 GlC 17 40 42.09 -53 40 27.6     5.17     ~ 1912 0
76 NGC 6528 GlC 18 04 49.61 -30 03 20.8   12.12 10.65     ~ 505 0
77 NGC 6752 5 RG* 19 10 48.6380923344 -60 01 55.414478928   14.402 13.743 13.633   ~ 13 0
78 NGC 6752 GlC 19 10 52.11 -59 59 04.4           ~ 1928 0
79 2MASS J19105326-6002037 RG* 19 10 53.2773937224 -60 02 03.672736152   13.06 12.060     ~ 24 0
80 2MASS J19111115-6000169 RG* 19 11 11.1684637896 -60 00 16.942232952   14.07 13.33     ~ 14 0
81 NGC 6752 29 RG* 19 11 14.3927402376 -60 00 32.223800196   13.006 11.867     ~ 31 0
82 NGC 6752 30 RG* 19 11 19.4663098272 -60 00 34.729621596   13.27 12.195     ~ 25 0
83 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1512 0
84 Cl* NGC 4372 ALC 74 * ~ ~   15.57 14.17     ~ 2 0
85 Cl* NGC 6528 VD I-42 * ~ ~   18.08 16.46     ~ 1 0
86 Cl* NGC 5904 ARPH II-80 * ~ ~   15.22 14.31     ~ 1 0
87 Cl* NGC 5904 ARPH 2074 * ~ ~   14.83 13.82     ~ 1 0
88 Cl* NGC 4372 ALC 89 * ~ ~   15.78 14.49     ~ 2 0
89 Cl* NGC 4372 ALC 77 * ~ ~   15.47 14.19     ~ 2 0
90 Cl* NGC 6397 ALC 326 * ~ ~   13.67 12.78     ~ 3 0
91 Cl* NGC 5927 MEN 133 * ~ ~   16.72 14.75     ~ 2 0
92 Cl* NGC 5904 ARPH 1002 * ~ ~   14.89 13.87     ~ 1 0
93 Cl* NGC 4372 ALC 91 * ~ ~   15.78 14.45     ~ 2 0
94 Cl* NGC 4372 ALC 10 * ~ ~   15.11 13.82     ~ 2 0
95 Cl* NGC 6397 ALC 361 * ~ ~   12.75 11.67     ~ 6 0
96 Cl* NGC 5927 MEN 65 * ~ ~   16.56 14.64     ~ 3 0
97 Cl* NGC 5904 ARPH I-71 * ~ ~   14.30 13.01     ~ 2 0
98 Cl* NGC 4372 ALC 14 * ~ ~   15.58 14.29     ~ 2 0
99 Cl* NGC 5904 ARPH 2045 * ~ ~   15.57 14.75     ~ 1 0
100 NAME Local Group GrG ~ ~           ~ 7909 0
101 Cl* NGC 5927 MEN 372 * ~ ~   16.77 14.66     ~ 3 0
102 Cl* NGC 6528 VD II-41 * ~ ~   17.94 16.30     ~ 1 0
103 Cl* NGC 4372 ALC 76 * ~ ~   15.48 14.18     ~ 2 0
104 Cl* NGC 6397 ALC 328 * ~ ~   13.00 12.07     ~ 3 0
105 Cl* NGC 5904 ARPH 1050 * ~ ~   14.88 13.91     ~ 1 0
106 Cl* NGC 4372 ALC 95 * ~ ~   15.78 14.48     ~ 2 0

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2023.02.08-01:11:40

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