2012A&A...540A..98M


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.19CEST05:45:57

2012A&A...540A..98M - Astronomy and Astrophysics, volume 540A, 98-98 (2012/4-1)

Non-LTE effects on the lead and thorium abundance determinations for cool stars.

MASHONKINA L., RYABTSEV A. and FREBEL A.

Abstract (from CDS):

Knowing accurate lead abundances of metal-poor stars provides constraints on the Pb production mechanisms in the early Galaxy. Accurately deriving thorium abundances permits a nucleo-chronometric age determination of the star. We aim to improve the calculation of the PbI and ThII lines in stellar atmospheres based on non-local thermodynamic equilibrium (non-LTE) line formation, and to evaluate the influence of departures from LTE on Pb and Th abundance determinations for a range of stellar parameters by varying the metallicity from the solar value down to [Fe/H]=-3. We present comprehensive model atoms for PbI and ThII and describe calculations of the PbI energy levels and oscillator strengths. The main non-LTE mechanism for PbI is the ultraviolet overionization. We find that non-LTE leads to systematically depleted total absorption in the PbI lines and accordingly, positive abundance corrections. The departures from LTE increase with decreasing metallicity. Using the semi-empirical model atmosphere HM74, we determine the lead non-LTE abundance for the Sun to be logεPb,☉=2.09, in agreement with the meteoritic lead abundance. We revised the Pb and Eu abundances of the two strongly r-process enhanced stars CS 31082-001 and HE 1523-0901 and the metal-poor stellar sample. Our new results provide strong evidence of universal Pb-to-Eu relative r-process yields during the course of Galactic evolution. The stars in the metallicity range -2.3<[Fe/H]←1.4 have Pb/Eu abundance ratios that are, on average, 0.51dex higher than those of strongly r-process enhanced stars. We conclude that the s-process production of lead started as early as the time when Galactic metallicity had reached [Fe/H]=-2.3. The average Pb/Eu abundance ratio of the mildly metal-poor stars, with -1.4≤[Fe/H]≤-0.59, is very close to the corresponding Solar System value, in line with the theoretical predictions that AGB stars with [Fe/H]≃-1 provided the largest contribution to the solar abundance of s-nuclei of lead. The departures from LTE for ThII are caused by the pumping transitions from the levels with Eexc<1eV. Non-LTE leads to weakened ThII lines and positive abundance corrections. Overall, the abundance correction does not exceed 0.2dex when collisions with HI atoms are taken into account in statistical equilibrium calculations.

Abstract Copyright:

Journal keyword(s): line: formation - nuclear reactions, nucleosynthesis, abundances - Sun: abundances - stars: abundances - stars: atmospheres

Simbad objects: 53

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Number of rows : 53

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 V* CM Cet LP? 00 33 14.3107315285 -10 43 42.728505105   10.66 9.48 8.84 9.06 G3/5V 86 0
2 HD 6755 SB* 01 09 43.0595349996 +61 32 50.293373799 8.48 8.40   7.3   G5 226 0
3 HD 6833 * 01 09 52.2649551382 +54 44 20.273398737 8.81 7.91 6.74     K0IIIbFe-2 186 0
4 HD 8724 PM* 01 26 17.5944981072 +17 07 35.123836665   9.29 8.34     G5 104 0
5 BPS CS 31082-0001 Pe* 01 29 31.1311330115 -16 00 45.496485322 12.527 12.427 11.642 11.189 10.713 CEMP 244 0
6 HD 20039 SB* 03 18 38.4963249803 +72 16 30.444784368       8.4   G6 50 0
7 HD 23798 Pe* 03 46 45.7222019530 -30 51 13.332706976   9.35 8.32     G8/K1(III)wF0/3 63 0
8 HD 23439A EB* 03 47 02.1134213149 +41 25 38.104505984   8.89 8.12 7.7   K2:V_Fe-1.3 218 0
9 HD 26297 Pe* 04 09 03.4179730777 -15 53 27.057216777   8.55 7.47 7.09   G5/6IVw 140 0
10 HD 29907 SB* 04 38 22.4006754245 -65 24 57.599417729   10.52 9.91     F8V 87 0
11 V* HP Eri LP* 04 38 55.7330333369 -13 20 48.133826226 10.91 9.72 8.33     G8/K0IIIwF7 125 0
12 HD 246132 SB* 05 40 09.7461619343 +12 10 41.057014518       9.8   G5 64 0
13 HD 37828 Pe* 05 40 54.6448086996 -11 12 00.190392856   7.988 6.869     G8III 87 0
14 HD 247297 PM* 05 45 40.3823971357 +14 41 20.112422752       8.7   G0 32 0
15 HD 250792 ** 06 03 14.8634898007 +19 21 38.692248180 9.89 9.898 9.310 8.954 8.547 G1 145 0
16 HD 44007 Pe* 06 18 48.5271098810 -14 50 43.424752212   8.85 8.06 7.69   G5(IV)wF3/5 170 0
17 HD 63791 PM* 07 54 28.7246905383 +62 08 10.775561430   8.81 7.90     G0 105 0
18 BD+00 2245 PM* 08 16 57.7755569201 +00 01 03.598095093   10.36 9.76 9.55   G0 32 0
19 HD 74462 PM* 08 48 20.6518837664 +67 26 59.887115014   9.65 8.69 8.25   G5IV 121 0
20 G 47-12 PM* 08 57 59.2550581600 +24 28 22.528335572   12.52   11.9   ~ 39 0
21 HD 94028 PM* 10 51 28.1254469804 +20 16 38.965521484 8.51 8.69 8.22 7.82 7.54 F8 330 0
22 HD 103095 PM* 11 52 58.7683801554 +37 43 07.240082865 7.38 7.20 6.45 5.80 5.35 K1V_Fe-1.5 749 1
23 BD+22 2442 ** 12 08 54.6643032916 +21 47 19.446132546       9.0   G2V 55 1
24 HD 105755 PM* 12 10 15.8755100459 +54 29 17.314317646   9.14 8.59     G0Vw 69 0
25 HD 105861 PM* 12 10 55.3588777075 +44 00 11.824039480       9.9   G5 22 0
26 HD 106516 SB* 12 15 10.55731 -10 18 44.6354 6.44 6.57 6.11     F9VFe-1.7CH-0.7 388 0
27 HD 108317 Pe* 12 26 36.8316698542 +05 18 09.021203658       7.7   G2IVm-5 145 0
28 BD+29 2356 Pe* 13 01 52.4292964485 +29 11 17.935248118   12.27 11.50     ~ 18 0
29 HD 121135 * 13 53 33.5447662743 +02 41 41.186221790   10.14 9.37     KIIvw 59 0
30 HD 122956 PM* 14 05 13.0245301143 -14 51 25.455585497   8.18 7.25 6.88   G6IV/VwF6 142 0
31 BD+01 2916 Pe* 14 21 45.2616002321 +00 46 59.172388634   10.93 9.65     KIIvw 81 0
32 BD+30 2611 * 15 06 53.8283818900 +30 00 36.942401309 11.50 10.37 9.13     G8III 122 0
33 BD+33 2560 PM* 15 14 26.1847280372 +33 00 38.276815654   11.5   10.1   G3 27 1
34 HE 1523-0901 Pe* 15 26 01.0697794752 -09 11 38.882076152   12.37 11.50 10.476 9.863 CEMP 61 0
35 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 857 0
36 HD 141531 PM* 15 49 16.4995136367 +09 36 42.408762912   10.31 9.08 8.720   M1V 60 0
37 HD 166161 PM* 18 09 40.6841408875 -08 46 45.602722086 9.53 9.13 8.16     G0wF0 129 0
38 BD+05 3640 PM* 18 12 21.8775881607 +05 24 04.403971434   11.16   9.9   G8 76 0
39 HD 171496 * 18 36 07.4934207098 -24 26 11.312599970   9.59 8.52     G8IV 65 1
40 HD 175305 Pe* 18 47 06.4424234462 +74 43 31.448124921 8.07 7.93 7.18 6.52 6.03 G5III 193 0
41 HD 187111 Pe* 19 48 39.5745673482 -12 07 19.741286114   8.92 7.75     G8wF8III/IV 130 0
42 HD 201891 PM* 21 11 59.0322335571 +17 43 39.888647667 7.74 7.88 7.37 6.91 6.59 G5V_Fe-2.5 368 0
43 HD 204543 * 21 29 28.2127594590 -03 30 55.356028557   9.17 8.30 7.99   F6/8(V) 124 0
44 HD 206739 PM* 21 44 23.9463878252 -11 46 22.846895572   9.45 8.60 8.14   G5V 74 0
45 BD+19 4788 PM* 21 48 19.2877532861 +19 58 30.633926083       9.6   ~ 33 0
46 HD 210295 PM* 22 09 41.4458820463 -13 36 19.476747948   10.49 10.10     Gwl 79 0
47 HD 235766 PM* 22 14 47.1706585813 +50 47 15.411971639   10.03 9.01     G5 11 0
48 HD 214925 Pe* 22 41 59.4325476504 -20 47 03.712271392   10.77 9.30     (F) 30 0
49 BD-00 4470 Pe* 23 09 32.9438722600 +00 42 39.756464995   10.66   9.6   sdG2 90 2
50 BD+20 5292 PM* 23 13 17.1487473552 +20 56 33.928346593       9.4   G5 25 0
51 G 29-25 PM* 23 22 18.1564482938 +12 09 33.605505286   11.48   10.6   G8: 28 0
52 HD 220838 * 23 27 16.4823484588 -26 58 58.178452827   10.50 9.39     G6/8(III)w 48 0
53 HD 221170 Pe* 23 29 28.8087923676 +30 25 57.847432750 9.43 8.74 7.66     G2IV 264 0

    Equat.    Gal    SGal    Ecl

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2020.09.19-05:45:57

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