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


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.26CET18:18:09

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 - 2020
#notes
1 HD 3567 PM* 00 38 31.9476246205 -08 18 33.395481958 9.54 9.70 9.23     F7/8wF3 189 0
2 BD+03 138 PM* 01 00 10.2887646371 +04 44 02.781133620   11.55   10.168   K5V 10 0
3 BPS CS 31082-0001 Pe* 01 29 31.1311330115 -16 00 45.496485322 12.527 12.427 11.642 11.189 10.713 CEMP 239 0
4 BD+42 621 * 02 45 32.4543650848 +42 43 28.885148550   10.60 10.38     A2 7 0
5 HD 19445 PM* 03 08 25.5884 +26 19 51.400 8.29 8.52 8.06 7.60 7.27 G2VFe-3 735 0
6 HE 0315+0000 Pe* 03 17 39.0098946532 +00 11 04.598852939     15.516   14.506 ~ 10 0
7 BD+20 571 PM* 03 27 39.4524583375 +21 02 34.997258945   11.36   10.8   G0 51 0
8 HD 22879 Pe* 03 40 22.0654223510 -03 13 01.124769689 7.146 7.222 6.667 6.346 6.016 G0VmF2 426 0
9 HD 25704 ** 04 01 44.6318109883 -57 12 24.595289561   8.65 8.10     F7V 132 0
10 HE 0442-1234 Pe* 04 44 51.7051525378 -12 28 45.536189519     12.914   11.672 ~ 12 0
11 CD-33 3337 PM* 06 54 47.8102286237 -33 44 49.020854453   9.56 9.03     F5 84 0
12 CD-57 1633 HV* 07 06 28.9517777029 -57 27 29.118056344   10.04 9.54     F7V 85 0
13 BD+24 1676 PM* 07 30 41.2663867705 +24 05 10.250742299   11.15   10.4   F 103 0
14 CD-45 3283 PM* 07 34 18.5967102074 -45 16 42.875165214   11.08 10.43     G8V-VI 64 0
15 HD 60319 PM* 07 34 35.1080318077 +16 54 04.031855106   9.46   8.6   F8 83 0
16 * 171 Pup PM* 07 45 34.9191268687 -34 10 21.283643355   5.95 5.37     F9V 278 0
17 HD 63598 PM* 07 48 53.5379266143 -24 58 24.217788534   8.47 7.93     G2V 55 0
18 HD 74462 PM* 08 48 20.6518837664 +67 26 59.887115014   9.65 8.69 8.25   G5IV 120 0
19 HD 76932 PM* 08 58 43.9328634171 -16 07 57.805389219 6.47 6.39 5.86     G2VFe-1.8CH-1 364 0
20 BD+09 2190 PM* 09 29 15.5616421382 +08 38 00.469417390   11.54   10.8   sdA5 115 0
21 HD 83212 Pe* 09 36 19.9520860588 -20 53 14.744519420   9.582 9.177 7.83   G6/K0IIIwF7 117 0
22 HD 233666 ** 09 42 19.4747877938 +53 28 26.150908010   9.94 9.30     G2w 64 0
23 HD 88609 Pe* 10 14 28.9854651931 +53 33 39.345145786 9.930 9.540 8.620 7.78 7.15 G5IIIw 183 0
24 HD 298986 PM* 10 17 14.8775103392 -52 29 18.691601582   10.46 10.03   9.48 F5 72 0
25 BD-13 3442 Pe* 11 46 50.6526364381 -14 06 43.453858029   10.662 10.274     CEMP 89 0
26 HD 103723 PM* 11 56 36.0250188318 -21 25 09.826660968   10.554 10.091     F5/6V 67 0
27 HD 105004 PM* 12 05 24.8526214531 -26 35 43.746369085   10.96 10.39     F9 91 0
28 BD-04 3208 PM* 12 07 15.0719832426 -05 44 01.609304815   10.40 9.99     A7 132 0
29 HD 106038 PM* 12 12 01.3690548564 +13 15 40.620671155 10.45 10.630 10.162 9.851 9.539 F6wl 167 0
30 HE 1219-0312 Pe* 12 21 34.1430157283 -03 28 39.635608057     15.940   15.043 ~ 30 0
31 HD 108317 Pe* 12 26 36.8316698542 +05 18 09.021203658       7.7   G2IVm-5 142 0
32 HD 110184 Pe* 12 40 14.0784174924 +08 31 38.056629204 10.20 9.45 8.27 8.52   KIIvw 125 0
33 HD 111980 SB* 12 53 15.0528185218 -18 31 20.009066873 8.80 8.91 8.38     F7V 152 0
34 HD 113679 PM* 13 05 52.8243888123 -38 30 59.990798799   10.342 9.797     G2/3V 81 0
35 HD 115444 Pe* 13 16 42.4591800169 +36 22 52.695481224   9.77 8.97 8.3 7.88 G9V 222 0
36 HD 116064 Pe* 13 21 43.7823913103 -39 18 39.998476883   9.26 8.81     F9IV-Vm-5 122 0
37 Wolf 1492 Pe* 13 40 02.4921790616 -00 02 18.750321114 11.601 11.832 11.451 11.184 10.892 sdF0: 259 0
38 HD 120559 PM* 13 51 40.3897554726 -57 26 08.293465228 8.679 8.647 7.982 7.605 7.217 G7VFe-1.4CH-1 135 0
39 HD 121004 PM* 13 53 58.1163515488 -46 32 19.526169178   10.112 9.522     G2V 124 0
40 HD 122196 PM* 14 01 02.1244272306 -38 03 03.297565043   9.19 8.75     F0(V)w 106 0
41 Ross 841 Pe* 14 02 30.0901582051 -05 39 05.181328144   11.508 11.149 10.866 10.576 sdA3 136 0
42 HD 122563 Pe* 14 02 31.8456299772 +09 41 09.942736952 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 733 0
43 HD 122956 PM* 14 05 13.0245301143 -14 51 25.455585497   8.18 7.25 6.88   G6IV/VwF6 141 0
44 HD 124002 * 14 10 58.4880986653 -02 40 28.023267981   8.74 7.67     K0III 10 1
45 BD+08 2856 * 14 23 58.1664117100 +08 01 33.336508723   10.90 10.08     KIIvw 57 0
46 HD 126238 Pe* 14 25 29.9570911985 -43 38 36.947126248   8.44 7.68 7.44   G3/8wF0/2 101 1
47 HD 126587 Pe* 14 27 00.3636840211 -22 14 38.991614082   9.88 9.60 8.75   CEMP-no 121 0
48 HD 126681 PM* 14 27 24.9096361739 -18 24 40.457119166   9.939 9.535     G3V 163 0
49 HD 128279 Pe* 14 36 48.5106582134 -29 06 46.610625293 8.64 8.63 8.00     Gw 170 0
50 HD 132475 PM* 14 59 49.7649807130 -22 00 45.814964574 8.98 9.11 8.55     F5/6V 222 1
51 BD+30 2611 * 15 06 53.8283818900 +30 00 36.942401309 11.50 10.37 9.13     G8III 122 0
52 BPS CS 22890-0024 Pe* 15 16 05.4007854507 -00 03 57.928698172   13.98 13.41     ~ 7 0
53 BPS CS 30312-0059 Pe* 15 34 48.8386734596 -01 23 37.343657126   13.85 13.14 12.596 12.065 ~ 22 0
54 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 848 0
55 BPS CS 30312-0100 Pe* 15 43 31.6556092098 +02 01 17.340471826   13.629 12.916 12.444 11.995 ~ 16 0
56 BD+17 3248 HB* 17 28 14.4691668039 +17 30 35.848406966   10.02 9.34     KIIvw 196 0
57 HD 160617 PM* 17 42 49.3235999900 -40 19 15.505712142   9.18 8.73 8.394 8.065 G0 182 0
58 BD+20 3603 PM* 17 54 43.2306261669 +20 16 16.443521966   10.13   9.6   F0 145 0
59 V* V2564 Oph LP? 18 04 40.0713993238 +03 46 44.716089845 9.53 8.59 7.30 6.24 5.43 F6/7V 241 0
60 BD+01 3597 PM* 18 07 56.5964043216 +01 52 32.700438137   11.53   10.8   sdF5 56 0
61 HD 166161 PM* 18 09 40.6841408875 -08 46 45.602722086 9.53 9.13 8.16     G0wF0 129 0
62 HD 166913 PM* 18 16 25.6833261555 -59 24 11.241154880   8.66 8.23     F5/7Vw 121 0
63 HD 175305 Pe* 18 47 06.4424234462 +74 43 31.448124921 8.07 7.93 7.18 6.52 6.03 G5III 190 0
64 HD 175179 PM* 18 54 23.2030233107 -04 36 18.624524830 9.56 9.61 9.03     G5V 103 0
65 HD 186478 Pe* 19 45 14.1410795461 -17 29 27.071420634   10.116 9.302 8.527 7.961 K2III 128 0
66 HD 188510 PM* 19 55 09.6783577203 +10 44 27.395091177 9.30 9.41   8.5   G5V: 232 0
67 HD 189558 PM* 20 01 00.2452564415 -12 15 20.355884232   8.27 7.72     F8/G2V 169 1
68 HD 195633 PM* 20 32 23.9917031781 +06 31 03.251333868 9.05 9.03 8.52     G0Vw 125 0
69 CD-30 18140 PM* 20 44 06.2871219229 -30 00 07.598765502   10.326 9.932     F8 73 0
70 HD 204543 * 21 29 28.2127594590 -03 30 55.356028557   9.17 8.30 7.99   F6/8(V) 124 0
71 HD 205650 PM* 21 37 26.0309417494 -27 38 06.697112156   9.59 9.00     F6V 93 0
72 BPS CS 22892-0052 Pe* 22 17 01.6558480594 -16 39 27.051900047   14.03 13.20 13.06 12.19 KIIvw 403 0
73 BPS CS 29512-0073 Pe* 22 28 36.7001192788 -12 24 44.112909323   14.71 14.14 13.76 13.384 CEMP-s 17 0
74 HD 213657 PM* 22 33 47.0565944504 -42 03 13.792590617   10.08 9.66     (G0)w(A) 82 0

    Equat.    Gal    SGal    Ecl

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2020.01.26-18:18:09

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