2020A&A...634A..84S


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.27CET08:24:50

2020A&A...634A..84S - Astronomy and Astrophysics, volume 634A, 84-84 (2020/2-1)

Neutron-capture elements in dwarf galaxies. II. Challenges for the s- and i-processes at low metallicity.

SKULADOTTIR A., HANSEN C.J., CHOPLIN A., SALVADORI S., HAMPEL M. and CAMPBELL S.W.

Abstract (from CDS):

The slow (s) and intermediate (i) neutron (n) capture processes occur both in asymptotic giant branch (AGB) stars, and in massive stars. To study the build-up of the s- and i-products at low metallicity, we investigate the abundances of Y, Ba, La, Nd, and Eu in 98 stars, at -2.4<[Fe/H]←0.9, in the Sculptor dwarf spheroidal galaxy. The chemical enrichment from AGB stars becomes apparent at [Fe/H]~=-2 in Sculptor, and causes [Y/Ba], [La/Ba], [Nd/Ba] and [Eu/Ba] to decrease with metallicity, reaching subsolar values at the highest [Fe/H]~=-1. To investigate individual nucleosynthetic sites, we compared three n-rich Sculptor stars with theoretical yields. One carbon-enhanced metal-poor (CEMP-no) star with high [Sr, Y, Zr]>+0.7 is best fit with a model of a rapidly-rotating massive star, the second (likely CH star) with the i-process, while the third has no satisfactory fit. For a more general understanding of the build-up of the heavy elements, we calculate for the first time the cumulative contribution of the s- and i-processes to the chemical enrichment in Sculptor, and compare with theoretical predictions. By correcting for the r-process, we derive [Y/Ba]s/i=-0.85±0.16, [La/Ba]s/i=-0.49±0.17, and [Nd/Ba]s/i=-0.48±0.12, in the overall s- and/or i-process in Sculptor. These abundance ratios are within the range of those of CEMP stars in the Milky Way, which have either s- or i-process signatures. The low [Y/Ba]s/i and [La/Ba]s/i that we measure in Sculptor are inconsistent with them arising from the s-process only, but are more compatible with models of the i-process. Thus we conclude that both the s- and i-processes were important for the build-up of n-capture elements in the Sculptor dwarf spheroidal galaxy.

Abstract Copyright: © Á. Skúladóttir et al. 2020

Journal keyword(s): stars: abundances - stars: chemically peculiar - galaxies: abundances - Galaxy: evolution - galaxies: dwarf - Local Group

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 UCAC4 282-001099 Pe* 00 59 12.099 -33 46 20.87       16.36 15.98 ~ 6 0
2 2MASS J00594641-3341233 RG* 00 59 46.4184190436 -33 41 23.404479563     17.304   15.695 ~ 15 0
3 2MASS J00595563-3333246 RG* 00 59 55.6380234837 -33 33 24.702775226     16.890   15.806 ~ 7 0
4 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1156 4
5 GB07 Scl41 RR* 01 00 12.9547531260 -33 42 03.849749271   18.96 18.029   16.84 ~ 13 0
6 2MASS J01001630-3342371 RG* 01 00 16.2939480511 -33 42 37.233911181   18.86 16.995   15.525 C 16 0
7 SCMS 822 * 01 00 17.0895890704 -33 45 13.860920066   19.14 18.152   17.140 ~ 14 0
8 2MASS J01002076-3347108 RG* 01 00 20.7586004314 -33 47 10.955887678   18.64 17.392   16.068 C 12 0
9 NAME Carina dSph G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 1016 0
10 ALW Carina 8 RB? 06 41 46.2659426758 -50 58 55.998307661   19.173 17.753   16.504 ~ 11 0
11 NAME Leo IV Dwarf Galaxy G 11 32 57.0 -00 32 00     15.1     ~ 330 1
12 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3072 0
13 2MASS J13265076-4733038 RG* 13 26 50.7674358018 -47 33 03.985483634   13.83 12.31   11.037 ~ 16 0
14 NAME UMi Galaxy G 15 09 11.34 +67 12 51.7   13.60 10.6     ~ 1207 0
15 BPS CS 22892-0052 Pe* 22 17 01.6558480594 -16 39 27.051900047   14.03 13.20 13.06 12.19 KIIvw 417 0
16 [SSW2012] Pisces II 10694 * 22 58 25.0765648374 +05 57 20.119791518           ~ 5 0
17 NAME Pisces II G 22 58 31.0 +05 57 09     16.3     ~ 219 0
18 NAME Local Group GrG ~ ~           ~ 7181 0

    Equat.    Gal    SGal    Ecl

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2021.02.27-08:24:50

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