2007A&A...476..935F


C.D.S. - SIMBAD4 rel 1.7 - 2020.04.06CEST08:23:38

2007A&A...476..935F - Astronomy and Astrophysics, volume 476, 935-950 (2007/12-3)

First stars. VIII. Enrichment of the neutron-capture elements in the early Galaxy.

FRANCOIS P., DEPAGNE E., HILL V., SPITE M., SPITE F., PLEZ B., BEERS T.C., ANDERSEN J., JAMES G., BARBUY B., CAYREL R., BONIFACIO P., MOLARO P., NORDSTROEM B. and PRIMAS F.

Abstract (from CDS):

Extremely metal-poor (EMP) stars in the halo of the Galaxy are sensitive probes of the production of the first heavy elements and the efficiency of mixing in the early interstellar medium. The heaviest measurable elements in such stars are our main guides to understanding the nature and astrophysical site(s) of early neutron-capture nucleosynthesis. Our aim is to measure accurate, homogeneous neutron-capture element abundances for the sample of 32 EMP giant stars studied earlier in this series, including 22 stars with [Fe/H]←3.0. Based on high-resolution, high S/N spectra from the ESO VLT/UVES, 1D, LTE model atmospheres, and synthetic spectrum fits, we determine abundances or upper limits for the 16 elements Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb in all stars. As found earlier, [Sr/Fe], [Y/Fe], [Zr/Fe] and [Ba/Fe] are below Solar in the EMP stars, with very large scatter. However, we find a tight anti-correlation of [Sr/Ba], [Y/Ba], and [Zr/Ba] with [Ba/H] for -4.5<[Ba/H]←2.5, also when subtracting the contribution of the main r-process as measured by [Ba/H]. Spectra of even higher S/N ratio are needed to confirm and extend these results below [Fe/H]≃-3.5. The huge, well-characterised scatter of the [n-capture/Fe] ratios in our EMP stars is in stark contrast to the negligible dispersion in the [α/Fe] and [Fe-peak/Fe] ratios for the same stars found in Paper V. These results demonstrate that a second (``weak'' or LEPP) r-process dominates the production of the lighter neutron-capture elements for [Ba/H]←2.5. The combination of very consistent [α/Fe] and erratic [n-capture/Fe] ratios indicates that inhomogeneous models for the early evolution of the halo are needed. Our accurate data provide strong constraints on future models of the production and mixing of the heavy elements in the early Galaxy.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: Population II - Galaxy: abundances - Galaxy: halo - nuclear reactions, nucleosynthesis, abundances

Status at CDS:  

CDS comments: HE 1523-0909 is a misprint for HE 1523-0901.

Simbad objects: 34

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Number of rows : 34

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 2796 Pe* 00 31 16.9149599675 -16 47 40.792690842 9.58 9.28 8.50 8.14 8.67 Fw 177 0
2 CD-38 245 Pe* 00 46 36.1954714218 -37 39 33.555736375   12.733 11.929 13.39 10.996 KIIvw 200 0
3 BPS CS 22953-0003 Pe* 01 02 15.8722809261 -61 43 45.836705614   14.43 13.75 13.339 12.886 KIIvw 53 0
4 BPS CS 29518-0051 Pe* 01 24 10.0046408484 -28 15 21.119402152 13.567 13.62 13.02 12.594 12.162 ~ 30 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 239 0
6 HE 0239-1340 Pe* 02 41 42.3721693746 -13 28 10.604872550   14.73 13.97 13.566 13.080 CEMP-no 53 0
7 HE 0305-5442 Pe* 03 06 29.5014936276 -54 30 32.498352902   14.44 13.70 13.212 12.715 KIIvw 72 0
8 HE 0311-1046 Pe* 03 14 20.8495240680 -10 35 11.279671787   13.54 12.73 12.204 11.693 KIIvw 64 0
9 HE 0409-1212 Pe* 04 12 13.8814170981 -12 05 05.075798490   13.843 12.897   11.764 ~ 59 0
10 BPS CS 22186-0025 Pe* 04 24 32.7982638728 -37 09 02.518352449   14.99 14.24 13.740 13.269 ~ 33 0
11 BPS BS 16467-0062 Pe* 13 42 00.6325668250 +17 48 40.825137829   14.69 14.09 13.665 13.216 ~ 45 0
12 BPS BS 16477-0003 Pe* 14 32 56.9230863125 +06 46 06.975505394   14.94 14.22 13.727 13.224 ~ 34 0
13 BPS CS 30325-0094 Pe* 14 54 39.2685324873 +04 21 38.098655567   13.02 12.32 11.849 11.376 ~ 43 0
14 HE 1523-0901 Pe* 15 26 01.0697794752 -09 11 38.882076152   12.37 11.50 10.476 9.863 CEMP 60 0
15 BPS CS 22878-0101 Pe* 16 45 31.4514010341 +08 14 45.471045094   14.59 13.79   12.673 KIIvw 55 0
16 BD+17 3248 HB* 17 28 14.4691668039 +17 30 35.848406966   10.02 9.34     KIIvw 196 0
17 BPS CS 22891-0209 Pe* 19 42 02.1800028329 -61 03 44.536144090   13.03 12.18     KIIvw 53 0
18 UCAC2 7177623 Pe* 19 42 26.8930018981 -56 58 34.061929902   14.27 13.63     ~ 45 0
19 HD 186478 Pe* 19 45 14.1410795461 -17 29 27.071420634   10.116 9.302 8.527 7.961 K2III 128 0
20 UCAC2 5726991 Pe* 19 53 49.7800945675 -59 40 00.163969151   13.592 12.620   11.48 KIIvw 42 0
21 BD-18 5550 Pe* 19 58 49.7370363913 -18 12 11.142309703 10.18 10.03 9.35 9.04 8.74 CEMP-no 161 0
22 BPS CS 22873-0166 Pe* 20 19 22.0361305437 -61 30 15.121053020   12.818 11.802 11.52 10.57 KIIvw 46 0
23 BPS CS 22885-0096 Pe* 20 20 51.1729562140 -39 53 30.235406812   14.02 13.33     CEMP-no 81 0
24 BPS CS 22897-0008 Pe* 21 03 11.8563237064 -65 05 08.852932036   14.02 13.33     CEMP-no 62 0
25 BPS CS 29495-0041 Pe* 21 36 33.2901533828 -28 18 48.439267198 14.111 14.15 13.34   12.222 ~ 30 0
26 HE 2141-3741 Pe* 21 44 51.1647173336 -37 27 55.017357431   14.10 13.47     CEMP-no 51 0
27 BPS CS 22956-0050 Pe* 21 58 05.8339798575 -65 13 27.160917994   14.95 14.25 13.745 13.211 CEMP-no 35 0
28 BPS BS 17569-0049 Pe* 22 04 58.3605638072 +04 01 32.135813469 14.503 14.25 13.36 12.805 12.259 ~ 27 0
29 BPS CS 22892-0052 Pe* 22 17 01.6558480594 -16 39 27.051900047   14.03 13.20 13.06 12.19 KIIvw 405 0
30 BPS CS 29516-0041 Pe* 22 21 48.8261125099 +02 28 44.864481048 13.291 13.4 12.74 12.325 12.013 ~ 35 0
31 BPS CS 29516-0024 Pe* 22 26 15.3575399312 +02 51 46.325239449   14.43 13.57 13.011 12.416 ~ 32 0
32 BPS CS 29491-0053 Pe* 22 36 56.2964405478 -28 31 06.577841168   13.76 12.92 12.380 11.812 ~ 31 0
33 HE 2334-0604 Pe* 23 37 28.6873335486 -05 47 56.594686365   14.03 13.28 12.768 12.249 KIIvw 67 0
34 BPS CS 22966-0057 Pe* 23 48 57.7535714010 -29 39 22.828517864 14.759   14.32   13.512 ~ 31 0

    Equat.    Gal    SGal    Ecl

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2020.04.06-08:23:38

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