2018A&A...611A..30S


Query : 2018A&A...611A..30S

2018A&A...611A..30S - Astronomy and Astrophysics, volume 611A, 30-30 (2018/3-1)

Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars.

SPITE F., SPITE M., BARBUY B., BONIFACIO P., CAFFAU E. and FRANCOIS P.

Abstract (from CDS):


Aims. The abundance patterns of the neutron-capture elements in metal-poor stars provide a unique record of the nucleosynthesis products of the earlier massive primitive objects.
Methods. We measured new abundances of so-called light neutron-capture of first peak elements using local thermodynamic equilibrium (LTE) 1D analysis; this analysis resulted in a sample of 11 very metal-poor stars, from [Fe/H]=-2.5 to [Fe/H]=-3.4, and one carbon-rich star, CS 22949-037 with [Fe/H]=-4.0. The abundances were compared to those observed in two classical metal-poor stars: the typical r-rich star CS 31082-001 ([Eu/Fe]>+1.0) and the r-poor star HD 122563 ([Eu/Fe]<0.0), which are known to present a strong enrichment of the first peak neutron-capture elements relative to the second peak.
Results. Within the first peak, the abundances are well correlated in analogy to the well-known correlation inside the abundances of the second-peak elements. In contrast, there is no correlation between any first peak element with any second peak element. We show that the scatter of the ratio of the first peak abundance over second peak abundance increases when the mean abundance of the second peak elements decreases from r-rich to r-poor stars. We found two new r-poor stars that are very similar to HD 122563. A third r-poor star, CS 22897-008, is even more extreme; this star shows the most extreme example of first peak elements enrichment to date. On the contrary, another r-poor star (BD-18 5550) has a pattern of first peak elements that is similar to the typical r-rich stars CS 31082-001, however this star has some Mo enrichment.
Conclusions. The distribution of the neutron-capture elements in our very metal-poor stars can be understood as the combination of at least two mechanisms: one that enriches the forming stars cloud homogeneously through the main r-process and leads to an element pattern similar to the r-rich stars, such as CS 31082-001; and another that forms mainly lighter, first peak elements.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: abundances - stars: population II - galaxy: halo

Simbad objects: 21

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Number of rows : 21
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 BPS CS 29497-0004 Pe* 00 28 06.9155612016 -26 03 04.269055032   14.76 14.07 13.583 13.116 ~ 50 0
2 HD 2796 Pe* 00 31 16.9147531152 -16 47 40.790991624 9.58 9.28 8.50 8.14 8.67 Fw 188 0
3 BPS CS 22953-0003 Pe* 01 02 15.8723379360 -61 43 45.836012208   14.43 13.75 13.339 12.886 KIIvw 63 0
4 BPS CS 29518-0051 Pe* 01 24 10.0049733024 -28 15 21.115362312 13.567 13.62 13.02 12.594 12.162 ~ 31 0
5 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
6 2MASS J03142084-1035112 Pe* 03 14 20.8495451808 -10 35 11.277788028   13.54 12.73 12.204 11.693 KIIvw 65 0
7 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
8 UCAC2 7177623 Pe* 19 42 26.8926894816 -56 58 34.059037980   14.27 13.63     ~ 48 0
9 HD 186478 Pe* 19 45 14.1409752672 -17 29 27.071239056   10.116 9.302 8.527 7.961 K2III 144 0
10 UCAC2 5726991 Pe* 19 53 49.7804195664 -59 40 00.163242192   13.592 12.620   11.48 KIIvw 46 0
11 BD-18 5550 Pe* 19 58 49.7371417608 -18 12 11.140126164 10.18 10.03 9.35 9.04 8.74 CEMP-no 170 0
12 BPS CS 22873-0166 Pe* 20 19 22.0362485016 -61 30 15.119987544   12.818 11.802 11.52 10.57 KIIvw 51 0
13 BPS CS 22885-0096 Pe* 20 20 51.1730095656 -39 53 30.234972840   14.02 13.33     CEMP-no 84 0
14 UCAC2 31779418 Pe* 20 38 43.1848979784 -00 23 32.761814352   13.726 12.731 12.51 11.57 CEMP 17 0
15 BPS CS 22897-0008 Pe* 21 03 11.8565397504 -65 05 08.852220600   14.02 13.33     CEMP-no 68 0
16 HE 2139-5432 Pe* 21 42 42.4478261040 -54 18 42.968447028   15.9       CEMP-no 28 0
17 2MASS J22045836+0401321 Pe* 22 04 58.3605927288 +04 01 32.135832984 14.503 14.25 13.36 12.805 12.259 ~ 31 0
18 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 432 0
19 BPS CS 29516-0041 Pe* 22 21 48.8262598080 +02 28 44.867730936 13.291 13.4 12.74 12.325 12.013 ~ 38 0
20 HE 2323-0256 Pe* 23 26 29.8073738880 -02 39 58.036383180   15.12 14.36   13.358 CEMP-no 175 0
21 BPS CS 22966-0057 Pe* 23 48 57.7540034928 -29 39 22.824085392 14.759   14.32   13.512 ~ 33 0

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2022.12.08-08:07:22

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