2012A&A...541A.143S

Query : 2012A&A...541A.143S

2012A&A...541A.143S - Astronomy and Astrophysics, volume 541A, 143-143 (2012/5-1)

NLTE determination of the calcium abundance and 3D corrections in extremely metal-poor stars.

SPITE M., ANDRIEVSKY S.M., SPITE F., CAFFAU E., KOROTIN S.A., BONIFACIO P., LUDWIG H.-G., FRANCOIS P. and CAYREL R.

Abstract (from CDS):

Calcium is a key element for constraining the models of chemical enrichment of the Galaxy. Extremely metal-poor stars contain the fossil records of the chemical composition of the early Galaxy and it is important to compare Ca abundance with abundances of other light elements, that are supposed to be synthesized in the same stellar evolution phases. The NLTE profiles of the calcium lines were computed in a sample of 53 extremely metal-poor stars with a modified version of the program MULTI, which allows a very good description of the radiation field. With our new model atom we are able to reconcile the abundance of Ca deduced from the CaI and CaII lines in Procyon. This abundance is found to be solar. We find that <[Ca/Fe]≥0.50±0.09 in the early Galaxy, a value slightly higher than the previous LTE estimations. The scatter of the ratios [X/Ca] is generally smaller than the scatter of the ratio [X/Mg] where X is a ``light metal'' (O, Na, Mg, Al, S, and K) with the exception of Al. These scatters cannot be explained by error of measurements, except for oxygen. Surprisingly, the scatter of [X/Fe] is always equal to, or even smaller than, the scatter around the mean value of [X/Ca]. We note that at low metallicity, the wavelength of the CaI resonance line is shifted relative to the (weaker) subordinate lines, a signature of the effect of convection. The Ca abundance deduced from the CaI resonance line (422.7nm) is found to be systematically smaller at very low metallicity than the abundance deduced from the subordinate lines. Our computations of the effects of convection (3D effects) are not able to explain this difference. A fully consistent 3D NLTE model atmosphere and line formation scheme would be necessary to fully capture the physics of the stellar atmosphere.

Abstract Copyright: ∼

Journal keyword(s): line: formation - line: profiles - stars: abundances - supernovae: general - Galaxy: evolution

VizieR on-line data: <Available at CDS (J/A+A/541/A143): tablea1.dat tablea2.dat tablea3.dat tablea4.dat tablea5.dat>

Simbad objects: 55

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Number of rows : 55
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 2MASS J00203619+2347376 Pe* 00 20 36.1923434544 +23 47 37.617775440   14.84 14.5     ~ 27 0
2 BPS CS 29527-0015 Pe* 00 29 10.6814565504 -19 10 07.305102624   14.61 14.24     CEMP-no 57 0
3 HE 0027-3613 Pe* 00 30 15.9610744584 -35 56 51.229784760     14.74     ~ 30 0
4 HD 2796 Pe* 00 31 16.9147531152 -16 47 40.790991624 9.58 9.28 8.50 8.14 8.67 Fw 193 0
5 CD-38 245 Pe* 00 46 36.1954514592 -37 39 33.555030480   12.733 11.929 13.39 10.996 KIIvw 225 0
6 BPS CS 22953-0003 Pe* 01 02 15.8723379360 -61 43 45.836012208   14.43 13.75 13.339 12.886 KIIvw 70 0
7 BPS CS 29518-0020 * 01 12 13.2160928832 -31 00 05.358952296 14.164 14.41 14.00     ~ 19 0
8 2MASS J01183829-3041026 Pe* 01 18 38.3021768400 -30 41 02.851310832 14.730 14.94 14.6     ~ 25 0
9 BPS CS 29518-0051 Pe* 01 24 10.0049733024 -28 15 21.115362312 13.567 13.62 13.02 12.594 12.162 ~ 32 0
10 BPS CS 22953-0037 Pe* 01 25 06.6508649808 -59 16 00.742176912   14.01 13.64   13.13 CEMP-no 42 0
11 BD-16 251 RG* 01 29 31.1311443552 -16 00 45.495314460 12.527 12.427 11.642 11.189 10.713 CEMP 291 0
12 BPS CS 31061-0032 Pe* 02 38 43.3009378608 +03 19 02.563623012   14.30 13.90 13.581 13.290 ~ 26 0
13 HE 0239-1340 Pe* 02 41 42.3721546152 -13 28 10.603797240   14.73 13.97 13.566 13.080 CEMP-no 59 0
14 HE 0305-5442 Pe* 03 06 29.5014981984 -54 30 32.498486568   14.44 13.70 13.212 12.715 KIIvw 75 0
15 2MASS J03142084-1035112 Pe* 03 14 20.8495451808 -10 35 11.277788028   13.54 12.73 12.204 11.693 KIIvw 67 0
16 BPS CS 22177-0009 Pe* 04 07 40.6490981040 -25 02 43.970266068   14.67 14.27     ~ 33 0
17 HE 0409-1212 Pe* 04 12 13.8814287960 -12 05 05.075250072   13.843 12.897   11.764 ~ 65 0
18 BPS CS 22186-0025 Pe* 04 24 32.7982834272 -37 09 02.518136460   14.99 14.24 13.740 13.269 ~ 36 0
19 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1865 0
20 BPS BS 16467-0062 Pe* 13 42 00.6326009568 +17 48 40.826539260   14.69 14.09 13.665 13.216 ~ 47 0
21 2MASS J14005447+2246423 Pe* 14 00 54.4740571128 +22 46 42.087313956 14.317 14.548 14.2     ~ 23 0
22 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 854 0
23 BPS BS 16477-0003 Pe* 14 32 56.9231765928 +06 46 06.974256288   14.94 14.22 13.727 13.224 ~ 35 0
24 2MASS J14543927+0421380 Pe* 14 54 39.2685981792 +04 21 38.099145888   13.02 12.32 11.849 11.376 ~ 47 0
25 BPS BS 16968-0061 Pe* 15 01 06.1171458744 +03 42 45.573411168   13.73 13.22 13.39   ~ 32 0
26 UCAC2 31517587 Pe* 15 08 29.6579865432 -00 35 59.273507796   13.37 12.95   12.37 ~ 26 0
27 HD 140283 Pe* 15 43 03.0971190219 -10 56 00.595693188 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 938 0
28 BPS CS 22878-0101 Pe* 16 45 31.4513454168 +08 14 45.470265900   14.59 13.79   12.673 KIIvw 60 0
29 BD+17 3248 HB* 17 28 14.4690179544 +17 30 35.847574776   10.02 9.34     KIIvw 224 0
30 BPS CS 22891-0209 Pe* 19 42 02.1802427088 -61 03 44.534898612   13.03 12.18     KIIvw 57 0
31 UCAC2 7177623 Pe* 19 42 26.8926894816 -56 58 34.059037980   14.27 13.63     ~ 51 0
32 HD 186478 SB* 19 45 14.1409752672 -17 29 27.071239056   10.116 9.302 8.527 7.961 K2III 154 0
33 UCAC2 5726991 Pe* 19 53 49.7804195664 -59 40 00.163242192   13.592 12.620   11.48 KIIvw 47 0
34 BD-18 5550 Pe* 19 58 49.7371417608 -18 12 11.140126164 10.18 10.03 9.35 9.04 8.74 CEMP-no 173 0
35 BPS CS 22873-0166 Pe* 20 19 22.0362485016 -61 30 15.119987544   12.818 11.802 11.52 10.57 KIIvw 56 0
36 BPS CS 22885-0096 Pe* 20 20 51.1730095656 -39 53 30.234972840   14.02 13.33     CEMP-no 88 0
37 BPS CS 22897-0008 Pe* 21 03 11.8565397504 -65 05 08.852220600   14.02 13.33     CEMP-no 70 0
38 BPS CS 29506-0007 Pe* 21 20 28.6541822328 -20 46 22.955304144     14.18     ~ 31 0
39 BPS CS 29506-0090 Pe* 21 30 28.8706762776 -22 10 41.578379040     14.33     ~ 29 0
40 BPS CS 29495-0041 Pe* 21 36 33.2900452248 -28 18 48.440793960 14.111 14.15 13.34   12.222 ~ 32 0
41 HE 2141-3741 RG* 21 44 51.1647807408 -37 27 55.017356112   14.10 13.47     CEMP-no 55 0
42 BPS CS 22948-0093 Pe* 21 50 31.5180047928 -41 07 49.355148468   15.54 15.18     ~ 36 0
43 BPS CS 22956-0050 Pe* 21 58 05.8340681280 -65 13 27.160682772   14.95 14.25 13.745 13.211 CEMP-no 40 0
44 BPS BS 17569-0049 Pe* 22 04 58.3605927288 +04 01 32.135832984 14.503 14.263 13.126 13.122 12.259 ~ 34 0
45 BPS CS 22965-0054 Pe* 22 06 30.2933030688 -02 32 34.433318220   15.69 15.07 14.732 14.072 CEMP-no 36 0
46 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 448 0
47 BPS CS 29516-0041 Pe* 22 21 48.8262598080 +02 28 44.867730936 13.291 13.4 12.74 12.325 12.013 ~ 39 0
48 2MASS J22261535+0251462 Pe* 22 26 15.3575269416 +02 51 46.326341232   14.43 13.57 13.011 12.416 ~ 36 0
49 BPS CS 29491-0053 Pe* 22 36 56.2965716592 -28 31 06.577096368   13.76 12.92 12.380 11.812 ~ 34 0
50 BPS CS 22888-0031 Pe* 23 11 32.4788498208 -35 26 42.872735796   15.31 14.90     CEMP-no 36 0
51 HE 2323-0256 Pe* 23 26 29.8073738880 -02 39 58.036383180   15.12 14.36   13.358 CEMP-no 180 0
52 2MASS J23350705-3022543 Pe* 23 35 07.0484945928 -30 22 54.278132700 14.694 14.97 14.6     ~ 29 0
53 HE 2334-0604 RG* 23 37 28.6873103640 -05 47 56.594641632   14.03 13.28 12.768 12.249 KIIvw 70 0
54 2MASS J23485776-2939228 Pe* 23 48 57.7540034928 -29 39 22.824085392 14.759   14.3   13.512 ~ 35 0
55 SB 966 Pe* 23 53 40.2978963936 -26 58 43.988391156   13.50 13.050     sdF/G? 37 0

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