2015A&A...581A..22A


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.11CEST19:43:28

2015A&A...581A..22A - Astronomy and Astrophysics, volume 581A, 22-22 (2015/9-1)

Carbon-enhanced metal-poor stars: a window on AGB nucleosynthesis and binary evolution. II. Statistical analysis of a sample of 67 CEMP-s stars.

ABATE C., POLS O.R., IZZARD R.G. and KARAKAS A.I.

Abstract (from CDS):

Many of the carbon-enhanced metal-poor (CEMP) stars that we observe in the Galactic halo are found in binary systems and show enhanced abundances of elements produced by the slow neutron-capture process (s-elements). The origin of the peculiar chemical abundances of these CEMP-s stars is believed to be accretion in the past of enriched material from a primary star in the asymptotic giant branch (AGB) phase of its evolution. We investigate the mechanism of mass transfer and the process of nucleosynthesis in low-metallicity AGB stars by modelling the binary systems in which the observed CEMP-s stars were formed. For this purpose we compare a sample of 67 CEMP-s stars with a grid of binary stars generated by our binary evolution and nucleosynthesis model. We classify our sample CEMP-s stars in three groups based on the observed abundance of europium. In CEMP-s/r stars the europium-to-iron ratio is more than ten times higher than in the Sun, whereas it is lower than this threshold in CEMP-s/nr stars. No measurement of europium is currently available for CEMP-s/ur stars. On average our models reproduce the abundances observed in CEMP-s/nr stars well, whereas in CEMP-s/r stars and CEMP-s/ur stars the abundances of the light-s elements (strontium, yttrium, zirconium) are systematically overpredicted by our models, and in CEMP-s/r stars the abundances of the heavy-s elements (barium, lanthanum) are underestimated. In all stars our modelled abundances of sodium overestimate the observations. This discrepancy is reduced only in models that underestimate the abundances of most of the s-elements. Furthermore, the abundance of lead is underpredicted in most of our model stars, independent of the metallicity. These results point to the limitations of our AGB nucleosynthesis model, particularly in the predictions of the element-to-element ratios. In our models CEMP-s stars are typically formed in wide systems with periods above 10000-days, while most of the observed CEMP-s stars are found in relatively close orbits with periods below 5000-days. This evidence suggests that either the sample of CEMP-s binary stars with known orbital parameters is biased towards short periods or that our wind mass-transfer model requires more efficient accretion in close orbits.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: AGB and post-AGB - binaries: general - stars: chemically peculiar - stars: Population II - Galaxy: halo

VizieR on-line data: <Available at CDS (J/A+A/581/A22): table1.dat table2.dat table3.dat table4.dat table5.dat table6.dat table7.dat table8.dat>

Simbad objects: 66

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Number of rows : 66

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 224959 Pe* 00 02 08.0224361239 -02 49 12.239963584   10.6 9.55     C1,1_CH4 85 0
2 HE 0012-1441 Pe* 00 15 27.0563104549 -14 24 37.625530758     16.40     CEMP-s 13 0
3 HE 0024-2523 Pe* 00 27 27.6485410349 -25 06 28.291081599 15.067 15.32 14.91     CEMP-s 65 0
4 BPS CS 31062-0050 Pe* 00 30 31.0633474070 -12 05 10.873150611   13.7 13.05 12.681 12.309 CEMP-r/s 60 0
5 CD-24 266 BS* 00 40 47.9313778053 -24 07 34.183052519   12.955 12.656 12.441 12.216 CEMP-s 90 0
6 SB 960 Pe* 00 44 03.5698517387 -13 55 26.270588506   12.69 12.15 11.806 11.483 CEMP-s 102 0
7 CD-31 306 BS* 00 50 15.7694437410 -30 59 56.199734557   12.73 12.72     F3VkA2mA2 30 0
8 HD 5223 Pe* 00 54 13.6094686085 +24 04 01.522268338   9.88 8.47     C-H2IIIb: 111 0
9 CD-26 304 Pe* 00 57 18.1376089543 -25 26 09.699477820   13.57 12.69 12.198 11.759 CEMP-s 61 1
10 HE 0131-3953 Pe* 01 33 36.4629589511 -39 37 52.151224348     15.979   15.323 CEMP-s 21 0
11 HE 0143-0441 Pe* 01 45 37.9166316774 -04 26 43.245126791     16.38     CEMP-s 26 0
12 HE 0202-2204 Pe* 02 04 50.0173132195 -21 50 10.475032504     15.375   14.575 ~ 19 0
13 HE 0206-1916 Pe* 02 09 19.6320440873 -19 01 55.453412838   15.133 13.999 13.458 12.987 CEMP-s 20 0
14 V* V Ari Pe* 02 15 00.0771486824 +12 14 23.613348802   10.8 9.80     C-H3.5 101 0
15 HE 0212-0557 Pe* 02 15 02.5101220196 -05 43 23.652630023     14.70     CEMP-s 15 0
16 HE 0231-4016 Pe* 02 33 44.3982823256 -40 03 42.729622703   16.494 16.090 15.788 15.475 CEMP-s 16 0
17 HE 0322-1504 Pe* 03 24 40.1043420656 -14 54 24.354937888   15.809 14.294 13.133 12.556 CEMP-s 10 0
18 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
19 HE 0338-3945 Pe* 03 39 55.0065616032 -39 35 42.904334997   15.753 15.333 15.098 14.787 CEMP-r/s 34 0
20 HE 0430-4404 Pe* 04 31 38.1098924598 -43 57 48.718015460     15.724   15.166 CEMP-s 14 0
21 HE 0441-0652 Pe* 04 43 29.8848374750 -06 46 53.520153941   15.250 14.228 13.678 13.106 CEMP-s 14 0
22 HE 0507-1430 Pe* 05 10 07.6176498155 -14 26 31.742581973   16.06 14.40 13.693 13.104 C 9 0
23 HE 0534-4548 Pe* 05 36 06.2089378756 -45 46 55.873191934   15.23 13.80 13.14 12.515 CEMP-s 7 0
24 SDSS J091243.72+021623.6 Pe* 09 12 43.7230744402 +02 16 23.718454537           CEMP-s 20 0
25 SDSS J092401.85+405928.7 Pe* 09 24 01.8542953695 +40 59 28.800488000           CEMP-s 16 0
26 HE 1045-1434 Pe* 10 47 44.1846846709 -14 50 22.524820797   15.83 14.60 14.036 13.6 C 7 0
27 HE 1105+0027 Pe* 11 07 49.5058676910 +00 11 38.347372568   16.038 15.646 15.358 15.018 CEMP-s 23 0
28 BD+04 2466 PM* 11 26 49.1890409114 +03 51 51.646284678   11.22 10.67 10.45   KIIvw 68 0
29 HE 1135+0139 Pe* 11 38 09.8531116311 +01 22 44.046134820   16.322 15.829 15.484 15.084 CEMP-s 18 0
30 HE 1157-0518 Pe* 12 00 18.0606707304 -05 34 43.117547219   16.273 15.120 14.635 14.128 CEMP-s 11 0
31 HE 1305+0007 Pe* 13 08 03.8464221671 -00 08 47.501674274   13.98 12.223 11.541 11.071 CEMP-s 27 0
32 BPS BS 17436-0058 Pe* 13 36 46.0325084311 +45 03 08.641600570   14.57 13.83 13.401 12.974 CEMP-r/s 15 0
33 HE 1429-0551 Pe* 14 32 31.2973539286 -06 05 00.200024781   14.015 12.606 11.995 11.537 CEMP-s 18 0
34 HE 1430-1123 Pe* 14 33 33.6342643070 -11 37 07.194005873   16.504 16.127 15.787 15.403 CEMP-s 14 0
35 HE 1434-1442 Pe* 14 37 26.5892140416 -14 54 59.397681972     15.40   15.395 CEMP-s 15 0
36 HE 1443+0113 Pe* 14 46 16.3658075328 +01 01 09.896063145     15.74     CEMP-s 11 0
37 HE 1447+0102 Pe* 14 50 15.0437316915 +00 50 15.095951561   15.632 14.614 14.121 13.676 CEMP-s 14 0
38 BPS CS 30301-0015 Pe* 15 08 56.8433023195 +02 30 18.628172611   14.04 13.04   12.063 CEMP-s 43 0
39 HE 1523-1155 Pe* 15 26 41.0447354853 -12 05 42.658748491   14.571 13.225 12.622 12.138 CEMP-s 17 0
40 HE 1528-0409 Pe* 15 30 54.3051386889 -04 19 40.360773249   16.003 14.757 14.159 13.681 CEMP-s 12 0
41 LP 625-44 Pe* 16 43 14.0364804654 -01 55 30.408914037   12.84 11.68     CEMP-s 101 0
42 BPS BS 16080-0175 Pe* 16 51 08.8035263955 +57 12 27.769345139   14.80 14.35 13.986 13.672 CEMP-s 13 0
43 2MASS J17073392+5850598 RR* 17 07 33.9321584866 +58 50 59.711506875     16.10     CEMP-s 22 0
44 HD 187216 Pe* 19 24 18.3451130483 +85 21 57.185833557   11.2 9.56     C3,3_CH5: 67 2
45 HD 187861 Pe* 19 56 26.9429735087 -65 22 08.017100343   10.42 9.18     C1,1p_CH 54 0
46 BPS CS 22964-0161 SB* 20 03 25.5362187973 -38 38 35.324239028   14.9 14.41 14.63   CEMP-s 42 0
47 HD 196944 Pe* 20 40 46.0790261041 -06 47 50.650812411   9.01 8.40 8.08   CEMP-s 86 0
48 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
49 SDSS J204728.84+001553.8 Pe* 20 47 28.8403311345 +00 15 53.866927024           CEMP-s 16 0
50 HD 198269 Pe* 20 48 36.7373846084 +17 50 23.700525129   9.41 8.12     C-H3IV: 77 0
51 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
52 HD 201626 Pe* 21 09 59.2669493692 +26 36 55.010503706 9.73 9.26 8.16 7.34 6.82 C-H2IV: 139 0
53 HE 2134-3940 Pe* 21 37 45.7673672486 -39 27 22.314122762   13.790 12.660 12.160 11.760 KIIvw 81 0
54 BPS CS 22956-0028 SB* 21 44 48.7079276715 -63 22 09.738970394   13.317 13.0     CEMP-s 23 0
55 HE 2148-1247 Pe* 21 51 17.9099257554 -12 33 41.560711332   15.2 14.79     CEMP-r/s 43 0
56 HE 2150-0825 Pe* 21 53 00.1624663138 -08 11 18.216484225     14.959   14.316 ~ 13 0
57 HE 2158-0348 Pe* 22 00 39.9763616015 -03 34 12.069272984     15.71   14.726 CEMP-s 21 0
58 BPS CS 22881-0036 Pe* 22 07 58.4409012147 -40 44 16.477797121   14.42 13.95 13.633 13.278 CEMP-s 35 0
59 HE 2221-0453 Pe* 22 24 25.6259494936 -04 38 02.317507175   15.098 13.650 12.942 12.376 CEMP-s 18 0
60 HE 2227-4044 Pe* 22 30 19.0904785808 -40 29 13.060857009   15.445 14.925 14.606 14.280 CEMP-s 14 0
61 HE 2228-0706 Pe* 22 31 24.4713208955 -06 50 51.248155212   14.353 13.332 12.797 12.353 CEMP-s 13 0
62 HE 2232-0603 Pe* 22 34 47.4283794688 -05 48 17.344893935   16.861 16.51 15.894 15.591 ~ 16 0
63 HE 2240-0412 Pe* 22 42 58.0812212931 -03 56 34.098552342   16.318 15.807 15.496 15.168 CEMP-s 15 0
64 HE 2258-6358 Pe* 23 01 48.6557322965 -63 42 25.118860932   15.42 14.30 14.07   CEMP-s 8 0
65 BPS CS 30338-0089 Pe* 23 15 49.9734197926 +10 19 26.170969642   15.107 14.144 13.632 13.176 CEMP-s 16 0
66 BPS CS 22945-0017 Pe* 23 20 55.6263860111 -63 15 36.787084717   14.83 14.44 14.50   ~ 20 0

    Equat.    Gal    SGal    Ecl

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2020.07.11-19:43:28

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