2012A&A...545A..31H


Query : 2012A&A...545A..31H

2012A&A...545A..31H - Astronomy and Astrophysics, volume 545A, 31-31 (2012/9-1)

Silver and palladium help unveil the nature of a second r-process.

HANSEN C.J., PRIMAS F., HARTMAN H., KRATZ K.-L., WANAJO S., LEIBUNDGUT B., FAROUQI K., HALLMANN O., CHRISTLIEB N. and NILSSON H.

Abstract (from CDS):

The rapid neutron-capture process, which created about half of the heaviest elements in the solar system, is believed to have been unique. Many recent studies have shown that this uniqueness is not true for the formation of lighter elements, in particular those in the atomic number range 38<Z<48. Among these, palladium (Pd) and especially silver (Ag) are expected to be key indicators of a possible second r-process, but until recently they have been studied only in a few stars. We therefore target Pd and Ag in a large sample of stars and compare these abundances to those of Sr, Y, Zr, Ba, and Eu produced by the slow (s-) and rapid (r-) neutron-capture processes. Hereby we investigate the nature of the formation process of Ag and Pd. We study the abundances of seven elements (Sr, Y, Zr, Pd, Ag, Ba, and Eu) to gain insight into the formation process of the elements and explore in depth the nature of the second r-process. By adopting a homogeneous one-dimensional local thermodynamic equilibrium (1D LTE) analysis of 71 stars, we derive stellar abundances using the spectral synthesis code MOOG, and the MARCS model atmospheres. We calculate abundance ratio trends and compare the derived abundances to site-dependent yield predictions (low-mass O-Ne-Mg core-collapse supernovae and parametrised high-entropy winds), to extract characteristics of the second r-process. The seven elements are tracers of different (neutron-capture) processes, which in turn allows us to constrain the formation process(es) of Pd and Ag. The abundance ratios of the heavy elements are found to be correlated and anti-correlated. These trends lead to clear indications that a second/weak r-process, is responsible for the formation of Pd and Ag. On the basis of the comparison to the model predictions, we find that the conditions under which this process takes place differ from those for the main r-process in needing lower neutron number densities, lower neutron-to-seed ratios, and lower entropies, and/or higher electron abundances. Our analysis confirms that Pd and Ag form via a rapid neutron-capture process that differs from the main r-process, the main and weak s-processes, and charged particle freeze-outs. We find that this process is efficiently working down to the lowest metallicity sampled by our analysis ([Fe/H]=-3.3). Our results may indicate that a combination of these explosive sites is needed to explain the variety in the observationally derived abundance patterns.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: Population II - supernovae: general - Galaxy: halo - atomic data

Simbad objects: 74

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Number of rows : 74
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 HD 3567 PM* 00 38 31.9473242153 -08 18 33.392826667 9.54 9.70 9.23     F7/8wF3 198 0
2 BD+03 138 PM* 01 00 10.2887788368 +04 44 02.782178520   11.55   10.168   K5V 12 0
3 BPS CS 31082-0001 Pe* 01 29 31.1311443552 -16 00 45.495314460 12.527 12.427 11.642 11.189 10.713 CEMP 274 0
4 BD+42 621 * 02 45 32.4541690680 +42 43 28.889531940   10.60 10.38     A2 9 0
5 HD 19445 PM* 03 08 25.5883873084 +26 19 51.400965175 8.29 8.52 8.06 7.60 7.27 G2VFe-3 756 0
6 HE 0315+0000 Pe* 03 17 39.0100103112 +00 11 04.600281192     15.516   14.506 ~ 13 0
7 BD+20 571 PM* 03 27 39.4522217875 +21 02 34.994793492   11.36   10.8   G0 55 0
8 HD 22879 Pe* 03 40 22.0652879951 -03 13 01.124265616 7.146 7.222 6.667 6.346 6.016 G0VmF2 469 0
9 HD 25704 ** 04 01 44.6317980946 -57 12 24.598726799   8.65 8.10     F7V 143 0
10 HE 0442-1234 Pe* 04 44 51.7052109360 -12 28 45.533823744     12.914   11.672 ~ 14 0
11 CD-33 3337 PM* 06 54 47.8101117384 -33 44 49.024262364   9.56 9.03     F5 91 0
12 CD-57 1633 HV* 07 06 28.9516977109 -57 27 29.118927115   10.04 9.54     F7V 96 0
13 BD+24 1676 PM* 07 30 41.2662525096 +24 05 10.248524088   11.15   10.4   F 118 0
14 CD-45 3283 PM* 07 34 18.5993129322 -45 16 42.883606401   11.08 10.43     G8V-VI 70 0
15 HD 60319 PM* 07 34 35.1077496408 +16 54 04.028098500   9.46   8.6   F8 91 0
16 * 171 Pup PM* 07 45 34.9212542040 -34 10 21.185626324   5.909 5.362     F9V 290 0
17 HD 63598 SB* 07 48 53.5375590480 -24 58 24.162494232   8.47 7.93     G2V 60 0
18 HD 74462 RG* 08 48 20.6518818744 +67 26 59.884515744   9.65 8.69 8.25   G5IV 125 0
19 HD 76932 PM* 08 58 43.9327642391 -16 07 57.817644364 6.47 6.39 5.86     G2VFe-1.8CH-1 382 0
20 BD+09 2190 PM* 09 29 15.5615542183 +08 38 00.467004388   11.54   10.8   sdA5 126 0
21 HD 83212 Pe* 09 36 19.9521173088 -20 53 14.747509716   9.582 9.177 7.83   G6/K0IIIwF7 125 0
22 HD 233666 ** 09 42 19.4747365152 +53 28 26.149112004   9.94 9.30     G2w 68 0
23 HD 88609 Pe* 10 14 28.9853799600 +53 33 39.342740796 9.930 9.540 8.620 7.78 7.15 G5IIIw 196 0
24 HD 298986 PM* 10 17 14.8774744591 -52 29 18.694800089   10.46 10.03   9.48 F5 79 0
25 BD-13 3442 Pe* 11 46 50.6525751264 -14 06 43.458063768   10.662 10.274     CEMP 100 0
26 HD 103723 PM* 11 56 36.0251513496 -21 25 09.829610868   10.554 10.091     F5/6V 75 0
27 HD 105004 PM* 12 05 24.8526164337 -26 35 43.750181317   10.96 10.39     F9 101 0
28 BD-04 3208 PM* 12 07 15.0721580835 -05 44 01.612773628   10.40 9.99     A7 141 0
29 HD 106038 PM* 12 12 01.3688687080 +13 15 40.618559661 10.45 10.630 10.162 9.851 9.539 F6wl 182 0
30 HE 1219-0312 Pe* 12 21 34.1430245160 -03 28 39.636260184     15.940   15.043 ~ 38 0
31 HD 108317 Pe* 12 26 36.8319587208 +05 18 09.023783400       7.7   G2IVm-5 160 0
32 HD 110184 Pe* 12 40 14.0781612216 +08 31 38.057301300 10.20 9.45 8.27 8.52   KIIvw 135 0
33 HD 111980 SB* 12 53 15.0529661499 -18 31 20.013189741 8.80 8.91 8.38     F7V 164 0
34 HD 113679 PM* 13 05 52.8245053407 -38 30 59.990193435   10.342 9.797     G2/3V 94 0
35 HD 115444 Pe* 13 16 42.4590842616 +36 22 52.692135420   9.77 8.97 8.3 7.88 G9V 235 0
36 HD 116064 Pe* 13 21 43.7779908364 -39 18 40.025179966   9.26 8.81     F9IV-Vm-5 128 0
37 Wolf 1492 Pe* 13 40 02.4921849768 -00 02 18.750053436 11.601 11.832 11.451 11.184 10.892 sdF0: 273 0
38 HD 120559 PM* 13 51 40.3987847839 -57 26 08.350982731 8.679 8.647 7.982 7.605 7.217 G7VFe-1.4CH-1 149 0
39 HD 121004 PM* 13 53 58.1163626566 -46 32 19.522719077   10.112 9.522     G2V 143 0
40 HD 122196 PM* 14 01 02.1249985961 -38 03 03.313496920   9.19 8.75     F0(V)w 115 0
41 Ross 841 Pe* 14 02 30.0900761861 -05 39 05.181979951   11.508 11.149 10.866 10.576 sdA3 147 0
42 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 808 0
43 HD 122956 PM* 14 05 13.0244442888 -14 51 25.455804480   8.18 7.25 6.88   G6IV/VwF6 148 0
44 HD 124002 * 14 10 58.4877899472 -02 40 28.022741688   8.74 7.67     K0III 13 1
45 BD+08 2856 * 14 23 58.1664038424 +08 01 33.333124908   10.90 10.08     KIIvw 61 0
46 HD 126238 Pe* 14 25 29.9571431040 -43 38 36.948515460   8.44 7.68 7.44   G3/8wF0/2 107 1
47 HD 126587 Pe* 14 27 00.3636631296 -22 14 38.992940592   9.88 9.60 8.75   CEMP-no 129 0
48 HD 126681 PM* 14 27 24.9094012952 -18 24 40.454425566   9.939 9.535     G3V 179 0
49 HD 128279 Pe* 14 36 48.5108525999 -29 06 46.612858494 8.64 8.63 8.00     Gw 188 0
50 HD 132475 PM* 14 59 49.7651173448 -22 00 45.815162806 8.98 9.11 8.55     F5/6V 232 1
51 BD+30 2611 * 15 06 53.8282684752 +30 00 36.941373756 11.50 10.37 9.13     G8III 133 0
52 BPS CS 22890-0024 Pe* 15 16 05.4008489928 -00 03 57.930271128   13.98 13.41     ~ 9 0
53 BPS CS 30312-0059 Pe* 15 34 48.8386814136 -01 23 37.343777064   13.85 13.14 12.596 12.065 ~ 25 0
54 HD 140283 Pe* 15 43 03.0971190219 -10 56 00.595693188 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 899 0
55 BPS CS 30312-0100 Pe* 15 43 31.6557531288 +02 01 17.338042560   13.629 12.916 12.444 11.995 ~ 22 0
56 BD+17 3248 HB* 17 28 14.4690179544 +17 30 35.847574776   10.02 9.34     KIIvw 210 0
57 HD 160617 PM* 17 42 49.3234249010 -40 19 15.503834657   9.18 8.73 8.394 8.065 G0 196 0
58 BD+20 3603 PM* 17 54 43.2306198848 +20 16 16.444611703   10.13   9.6   F0 155 0
59 V* V2564 Oph LP? 18 04 40.0713763656 +03 46 44.716990584 9.53 8.59 7.30 6.24 5.43 F6/7V 252 0
60 BD+01 3597 PM* 18 07 56.5963171590 +01 52 32.701833212   11.53   10.8   sdF5 62 0
61 HD 166161 PM* 18 09 40.6841536776 -08 46 45.603012144 9.53 9.13 8.16     G0wF0 136 0
62 HD 166913 PM* 18 16 25.6832938176 -59 24 11.239435980   8.66 8.23     F5/7Vw 128 0
63 HD 175305 RG* 18 47 06.4416868934 +74 43 31.451436187 8.07 7.93 7.18 6.52 6.03 G5III 208 0
64 HD 175179 PM* 18 54 23.2029803432 -04 36 18.621907480 9.56 9.61 9.03     G5V 114 0
65 HD 186478 Pe* 19 45 14.1409752672 -17 29 27.071239056   10.116 9.302 8.527 7.961 K2III 144 0
66 HD 188510 PM* 19 55 09.6782304000 +10 44 27.398607828 9.30 9.41   8.5   G5V: 244 0
67 HD 189558 PM* 20 01 00.2452184673 -12 15 20.353638621   8.28 7.73     F8/G2V 181 0
68 HD 195633 PM* 20 32 23.9917043856 +06 31 03.255667608 9.05 9.03 8.52     G0Vw 138 0
69 CD-30 18140 PM* 20 44 06.2872647830 -30 00 07.597192977   10.326 9.932     F8 85 0
70 HD 204543 * 21 29 28.2126852216 -03 30 55.353564216   9.17 8.30 7.99   F6/8(V) 131 0
71 HD 205650 PM* 21 37 26.0286639804 -27 38 06.697265704   9.59 9.00     F6V 99 0
72 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 432 0
73 BPS CS 29512-0073 Pe* 22 28 36.7002065736 -12 24 44.113375440   14.71 14.14 13.76 13.384 CEMP-s 20 0
74 HD 213657 PM* 22 33 47.0565175200 -42 03 13.790346516   10.08 9.66     (G0)w(A) 91 0

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2022.11.30-00:57:14

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