2003A&A...404..291V


C.D.S. - SIMBAD4 rel 1.7 - 2021.02.24CET22:11:13

2003A&A...404..291V - Astronomy and Astrophysics, volume 404, 291-299 (2003/6-2)

More lead stars.

VAN ECK S., GORIELY S., JORISSEN A. and PLEZ B.

Abstract (from CDS):

The standard model for the operation of the s-process in asymptotic giant branch (AGB) stars predicts that low-metallicity ([Fe/H]≲-1) AGB stars should exhibit large overabundances of Pb and Bi as compared to other s-elements. The discovery of the first three such ``lead stars'' (defined as stars enriched in s-elements with [Pb/hs]>1, hs being any of Ba, La or Ce) among CH stars has been reported in a previous paper (Van Eck et al., 2001Natur.412..793V). Five more CH stars (with [Fe/H] ranging from -1.5 to -2.5) are studied in the present paper, and two of them appear to be enriched in lead (with [Pb/Ce]≃0.7). The PbI line at λ4057.812Å is detected and clearly resolved thanks to high-resolution spectra (R=λ/Δλ=135000). The abundances for these two stars (HD 198269 and HD 201626) are consistent with the predictions for the s-process operating in low-metallicity AGB stars as a consequence of the ``partial mixing'' of protons below the convective hydrogen envelope. Another two stars (HD 189711 and V Ari) add to a growing number of low-metallicity stars (also including LP 625-44 and LP 706-7, as reported by Aoki et al., 2001ApJ...561..346A) which do not conform to these predictions. Variations on the canonical proton-mixing scenario for the operation of the s-process in low-metallicity stars, that could account for these discrepant stars, are briefly discussed.

Abstract Copyright:

Journal keyword(s): nuclear reactions, nucleosynthesis, abundances - stars: carbon - stars: evolution - stars: population II

Simbad objects: 14

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Number of rows : 14

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 HD 224959 Pe* 00 02 08.0224361239 -02 49 12.239963584   10.6 9.55     C1,1_CH4 88 0
2 HD 26 Pe* 00 05 22.2077761394 +08 47 16.096990670 9.80 9.29 8.25 7.49 7.03 C-H1.5 165 0
3 SB 960 Pe* 00 44 03.5698517387 -13 55 26.270588506   12.69 12.15 11.806 11.483 CEMP-s 104 0
4 CD-26 304 Pe* 00 57 18.1376089543 -25 26 09.699477820   13.57 12.69 12.198 11.759 CEMP-s 63 1
5 V* V Ari Pe* 02 15 00.0771486824 +12 14 23.613348802   10.8 9.80     C-H3.5 102 0
6 BPS CS 29526-0110 Pe* 03 27 43.6395462631 -23 00 29.931204041   13.71 13.35 13.116 12.834 CEMP-r/s 47 0
7 LP 625-44 Pe* 16 43 14.0364804654 -01 55 30.408914037   12.84 11.68     CEMP-s 102 0
8 HD 187861 Pe* 19 56 26.9429735087 -65 22 08.017100343   10.42 9.18     C1,1p_CH 56 0
9 HD 189711 Pe* 20 01 03.7891766338 +09 30 51.154617612 12.71 10.43 8.37 7.02 5.96 C4,3_CH3:_Ba5 67 0
10 HD 196944 Pe* 20 40 46.0790261041 -06 47 50.650812411   9.01 8.40 8.08   CEMP-s 89 0
11 BPS CS 22880-0074 Pe* 20 46 03.2162078511 -20 59 14.111093923   13.84 13.27 12.770 12.382 CEMP-s 45 0
12 HD 198269 Pe* 20 48 36.7373846083 +17 50 23.700525129   9.41 8.12     C-H3IV: 79 0
13 BPS CS 22898-0027 Pe* 21 05 45.0995574992 -18 36 57.505496795   13.26 12.76 12.476 12.094 CEMP-r/s 80 0
14 HD 201626 Pe* 21 09 59.2669493692 +26 36 55.010503706 9.73 9.26 8.16 7.34 6.82 C-H2IV: 142 0

    Equat.    Gal    SGal    Ecl

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2021.02.24-22:11:13

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