2014A&A...565A..93S


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.05CEST13:38:43

2014A&A...565A..93S - Astronomy and Astrophysics, volume 565A, 93-93 (2014/5-1)

High-resolution abundance analysis of very metal-poor r-I stars.

SIQUEIRA MELLO C., HILL V., BARBUY B., SPITE M., SPITE F., BEERS T.C., CAFFAU E., BONIFACIO P., CAYREL R., FRANCOIS P., SCHATZ H. and WANAJO S.

Abstract (from CDS):

Moderately r-process-enriched stars (r-I; +0.3≤[Eu/Fe]≤+1.0) are at least four times as common as those that are greatly enriched in r-process elements (r-II; [Eu/Fe] > +1.0), and the abundances in their atmospheres are important tools for obtaining a better understanding of the nucleosynthesis processes responsible for the origin of the elements beyond the iron peak. The main aim of this work is to derive abundances for a sample of seven metal-poor stars with -3.4≤[Fe/H]≤-2.4 classified as r-I stars, to understand the role of these stars for constraining the astrophysical nucleosynthesis event(s) that is (are) responsible for the production of the r-process, and to investigate whether they differ, in any significant way, from the r-II stars. We carried out a detailed abundance analysis based on high-resolution spectra obtained with the VLT/UVES spectrograph, using spectra in the wavelength ranges 3400-4500Å, 6800-8200Å, and 8700-10000Å, with resolving power R∼40000 (blue arm) and R∼55000 (red arm). The OSMARCS LTE 1D model atmosphere grid was employed, along with the spectrum synthesis code Turbospectrum. We have derived abundances of the light elements Li, C, and N, the α-elements Mg, Si, S, Ca, and Ti, the odd-Z elements Al, K, and Sc, the iron-peak elements V, Cr, Mn, Fe, Co, and Ni, and the trans-iron elements from the first peak (Sr, Y, Zr, Mo, Ru, and Pd), the second peak (Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), the third peak (Os and Ir, as upper limits), and the actinides (Th) regions. The results are compared with values for these elements for r-II and ``normal'' very and extremely metal-poor stars reported in the literature, ages based on radioactive chronometry are explored using different models, and a number of conclusions about the r-process and the r-I stars are presented. Hydrodynamical models were used for some elements, and general behaviors for the 3D corrections were presented. Although the abundance ratios of the second r-process peak elements (usually associated with the main r-process) are nearly identical for r-I and r-II stars, the first r-process peak abundance ratios (probably associated with the weak r-process) are more enhanced in r-I stars than in r-II stars, suggesting that differing nucleosynthesis pathways were followed by stars belonging to these two different classifications.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - stars: abundances

Simbad objects: 13

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Number of rows : 13

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 HE 0057-4541 Pe* 00 59 59.2782844680 -45 24 53.424530705     14.829   13.939 ~ 8 0
2 BPS CS 22953-0003 Pe* 01 02 15.8722809261 -61 43 45.836705614   14.43 13.75 13.339 12.886 KIIvw 54 0
3 HE 0105-6141 Pe* 01 07 37.8491741323 -61 25 17.695190542   14.22 13.64 13.113 12.660 ~ 13 0
4 BPS CS 31082-0001 Pe* 01 29 31.1311330115 -16 00 45.496485322 12.527 12.427 11.642 11.189 10.713 CEMP 244 0
5 HE 0240-0807 Pe* 02 42 57.7257206497 -07 54 35.383862561   15.867 14.971 14.447 13.889 ~ 8 0
6 HE 0516-3820 Pe* 05 18 12.9204318473 -38 17 32.706145391     14.377   13.538 ~ 6 0
7 HE 0524-2055 Pe* 05 27 04.4443497290 -20 52 42.097158461     14.013   12.937 ~ 10 0
8 HD 140283 Pe* 15 43 03.0967798658 -10 56 00.595803430 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 854 0
9 BD+17 3248 HB* 17 28 14.4691668039 +17 30 35.848406966   10.02 9.34     KIIvw 199 0
10 BPS CS 22892-0052 Pe* 22 17 01.6558480594 -16 39 27.051900047   14.03 13.20 13.06 12.19 KIIvw 411 0
11 HE 2229-4153 Pe* 22 32 49.0492627896 -41 38 25.163334842     13.322   12.447 ~ 8 0
12 HE 2323-0256 Pe* 23 26 29.8073543039 -02 39 58.037206596   15.12 14.36   13.358 CEMP-no 171 0
13 BPS CS 30315-0029 Pe* 23 34 26.6960736693 -26 42 14.004570680   14.56 13.64 13.092 12.518 ~ 16 0

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2020.08.05-13:38:43

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