2007A&A...469..319N


Query : 2007A&A...469..319N

2007A&A...469..319N - Astronomy and Astrophysics, volume 469, 319-330 (2007/7-1)

Sulphur and zinc abundances in Galactic halo stars revisited.

NISSEN P.E., AKERMAN C., ASPLUND M., FABBIAN D., KERBER F., KAEUFL H.U. and PETTINI M.

Abstract (from CDS):

Based on a new set of sulphur abundances in very metal-poor stars and an improved analysis of previous data, we aim at resolving current discrepancies on the trend of S/Fe vs. Fe/H and thereby gain better insight into the nucleosynthesis of sulphur. The trends of Zn/Fe and S/Zn will also be studied. High resolution VLT/UVES spectra of 40 main-sequence stars with -3.3<[Fe/H]←1.0 are used to derive S abundances from the weak λ8694.6 SI line and the stronger λλ9212.9,9237.5 pair of SI lines. For one star, the S abundance is also derived from the SI triplet at 1.046µm recently observed with the VLT infrared echelle spectrograph CRIRES. Fe and Zn abundances are derived from lines in the blue part of the UVES spectra, and effective temperatures are obtained from the profile of the Hβ line. Comparison of sulphur abundances from the weak and strong SI lines provides important constraints on non-LTE effects. The high sulphur abundances reported by others for some metal-poor stars are not confirmed; instead, when taking non-LTE corrections into account, the Galactic halo stars distribute around a plateau at [S/Fe]~+0.2dex with a scatter of 0.07dex only. [Zn/Fe] is close to zero for metallicities in the range -2.0<[Fe/H]←1.0 but increases to a level of [Zn/Fe]~+0.1 to +0.2dex in the range -2.7<[Fe/H]←2.0. At still lower metallicities [Zn/Fe] rises steeply to a value of [Zn/Fe]~+0.5dex at [Fe/H]=-3.2. The trend of S/Fe vs. Fe/H corresponds to the trends of Mg/Fe, Si/Fe, and Ca/Fe and indicates that sulphur in Galactic halo stars has been made by α-capture processes in massive SNe. The observed scatter in S/Fe is much smaller than predicted from current stochastic models of the chemical evolution of the early Galaxy, suggesting that either the models or the calculated yields of massive SNe should be revised. We also examine the behaviour of S/Zn and find that departures from the solar ratio are significantly reduced at all metallicities if non-LTE corrections to the abundances of these two elements are adopted. This effect, if confirmed, would reduce the usefulness of the S/Zn ratio as a diagnostic of past star-formation activity, but would bring closer together the values measured in damped Lyman-alpha systems and in Galactic stars.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: atmospheres - Galaxy: halo - galaxies: abundances - galaxies: high-redshift

CDS comments: Table C.1: SDSS1116+4118A could be SDSS J111610.68+411814.4 or SDSS J111611.73+411821.5 QSOs.

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 - 2023
#notes
1 QSO J0003-2603 QSO 00 03 22.9531962024 -26 03 18.304471908   18 17.53     ~ 285 0
2 LBQS 0013-0029 QSO 00 16 02.4050159808 -00 12 25.077257064   18.67 18.36     ~ 190 0
3 PHL 957 QSO 01 03 11.2741573824 +13 16 17.809871484   16.97 16.57     ~ 340 0
4 BD+02 263 SB* 01 45 13.8130 +03 30 49.253   11.14 10.61 10.54   sdF6 29 0
5 7C 020156.39+363507.00 QSO 02 04 55.5959081688 +36 49 17.992097868     18.1     ~ 119 1
6 HD 15315 * 02 30 08.7909173400 +58 38 35.292098580   8.91 8.72     A0V 17 0
7 LP 651-4 PM* 02 44 11.7179917488 -05 27 00.003085992   12.35 11.97     ~ 24 0
8 G 4-37 PM* 02 44 35.0876406984 +08 28 50.094009408   11.90   11.0   F7 80 0
9 QSO J0407-4410 QSO 04 07 18.0880236912 -44 10 13.983623724   17.6 17.6     ~ 95 0
10 QSO B0528-2505 QSO 05 30 07.9627395840 -25 03 29.900044512   18.17 17.34 17.7   ~ 412 0
11 QSO B0551-36 QSO 05 52 46.1824785360 -36 37 27.608212524   17.72 17.57     ~ 93 0
12 QSO J0812+32 QSO 08 12 40.6859242632 +32 08 08.579336496   18.16 17.75     ~ 99 0
13 QSO B0841+129 BLL 08 44 24.2445546984 +12 45 46.526286780   18.28 18.5     ~ 116 0
14 Ross 889 Pe* 09 40 43.2053340378 +01 00 29.511836741       10.39   sdA4 159 0
15 HD 84937 Pe* 09 48 56.0992891997 +13 44 39.326709913 8.49 8.68 8.32 7.97 7.70 F8Vm-5 767 0
16 Ross 892 PM* 10 27 24.2460060626 +01 24 00.190284079   11.55   10.8   sdF8 66 0
17 BD-13 3442 Pe* 11 46 50.6525751264 -14 06 43.458063768   10.662 10.274     CEMP 101 0
18 BD-04 3208 PM* 12 07 15.0721580835 -05 44 01.612773628   10.40 9.99     A7 142 0
19 Ross 453 PM* 12 10 55.7733238889 +00 23 54.332076195   11.53   10.9   F2 105 0
20 HD 106038 PM* 12 12 01.3688687080 +13 15 40.618559661 10.45 10.630 10.162 9.851 9.539 F6wl 182 0
21 LBQS 1210+1731 QSO 12 13 03.0135468360 +17 14 23.237180160   18.21 18.03     ~ 82 0
22 HD 108177 PM* 12 25 34.9568267745 +01 17 02.259553591 9.87 10.09 9.66 9.21 8.89 F0V 244 0
23 BD+28 2137 SB* 12 36 39.4525105848 +27 28 28.155760104   11.29   10.4   sdF2 88 0
24 HD 110621 PM* 12 43 43.2215753256 -44 40 31.562765508   10.34 9.92     Fpw 73 0
25 QSO B1331+170 Bla 13 33 35.7827544072 +16 49 04.013500728   16.84 16.71 16.41   ~ 435 0
26 Wolf 1492 Pe* 13 40 02.4921849768 -00 02 18.750053436 11.601 11.832 11.451 11.184 10.892 sdF0: 274 0
27 Ross 841 Pe* 14 02 30.0900761861 -05 39 05.181979951   11.508 11.149 10.866 10.576 sdA3 147 0
28 V* BU Cir bC* 14 45 10.9595976864 -55 36 05.906309508 5.23 6.016 6.089     B2III 93 0
29 Wolf 550 SB* 14 50 07.8032346714 +00 50 27.127840325   11.47   10.8   sd:F5 76 0
30 BD+26 2621 PM* 14 54 10.7123241110 +25 33 48.927279437   11.40   10.7   F0 41 0
31 HD 140283 Pe* 15 43 03.0971190219 -10 56 00.595693188 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 905 0
32 CD-71 1234 Pe* 16 07 44.6410532021 -71 21 01.360284611   10.81 10.44     ~ 37 0
33 BD+02 3375 PM* 17 39 45.5948675731 +02 24 59.606824535 10.18 10.40 9.92 9.47 9.12 A5 192 0
34 HD 160617 PM* 17 42 49.3234249010 -40 19 15.503834657   9.18 8.73 8.394 8.065 G0 197 0
35 HD 166197 V* 18 10 55.3486784976 -33 48 00.251316684 5.16 6.02 6.16     B2II/III 50 0
36 HD 179626 PM* 19 13 20.7189797919 -00 35 42.325251766   9.701 9.187 8.844 8.489 F5V 124 0
37 HD 181743 PM* 19 23 42.7454702782 -45 04 56.914961207   10.13 9.71     F4 103 0
38 CD-42 14278 PM* 19 32 19.1474936380 -42 12 43.711761026   10.76 10.29     F5Vwl 36 0
39 HD 338529 PM* 19 32 31.9104668184 +26 23 26.117367216   9.72   9.2   B5 204 0
40 HD 188031 PM* 19 54 58.6573602356 -42 38 43.395207211   10.54 10.17     F0V 63 0
41 G 24-3 Pe* 20 05 44.3170407024 +04 02 52.812418452   10.92   10.2   sdF8 89 0
42 HD 193901 PM* 20 23 35.8471605389 -21 22 14.226959304 9.08 9.22 8.67 8.17 7.87 F7V 274 0
43 HD 340279 PM* 20 24 45.4125969504 +25 03 07.109969040   11.23   10.7   A5 99 0
44 HD 194598 PM* 20 26 11.9183775668 +09 27 00.429558608 8.62 8.82 8.34 7.90 7.56 F8 295 0
45 LP 635-14 PM* 20 26 46.8302881512 -00 37 15.175129512 11.57 11.76 11.33     OB- 39 0
46 BPS CS 22943-0095 Pe* 20 27 29.9870188056 -46 50 56.315093100 11.857 12.063 12.62     ~ 24 0
47 LP 815-43 PM* 20 38 13.2998605176 -20 26 10.850795808   11.31 10.72     ~ 74 0
48 CD-30 18140 PM* 20 44 06.2872647830 -30 00 07.597192977   10.326 9.932     F8 85 0
49 CD-35 14849 PM* 21 33 49.7524989129 -35 26 14.228198341   10.95 10.56 10.59   B8 70 0
50 G 126-52 PM* 22 04 13.3810303392 +19 32 54.335372892       10.7   sd:F2 36 0
51 BD+17 4708 SB* 22 11 31.3756832854 +18 05 34.177983548 9.73 9.91 9.46 9.03 8.70 sdF8 558 0
52 BD+07 4841 PM* 22 18 36.5059714907 +08 26 44.962089682   10.84   10.1   G0 109 0
53 KODIAQ J223235+024755 QSO 22 32 35.2154152488 +02 47 55.814764596   18.387 18.038     ~ 92 0
54 KODIAQ J223408+000001 QSO 22 34 08.9971751592 +00 00 01.703853180   18.09 17.39 17.3   ~ 130 0
55 QSO J2246-6015 QSO 22 47 08.9258659440 -60 15 45.299400480           ~ 66 0
56 HD 215801 PM* 22 48 29.4254660444 -46 03 50.538724185   10.46 10.05     F0w 62 0
57 CD-24 17504 Pe* 23 07 20.2534619736 -23 52 35.954286096   12.51 12.18     CEMP-no 84 0
58 QSO B2314-409 QSO 23 16 46.91990359 -40 41 21.0863175   17.9 17.9     ~ 67 1
59 BD+02 4651 PM* 23 19 40.4500387773 +03 22 16.694733495   10.67   9.9   sdF6 107 0
60 QSO J2346+1247 QSO 23 46 25.4308096896 +12 47 43.873268928           ~ 19 0
61 QSO B2343+125 QSO 23 46 28.200 +12 49 00.00     17.5     ~ 133 2

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2023.02.04-09:54:00

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