2006A&A...451..651J


Query : 2006A&A...451..651J

2006A&A...451..651J - Astronomy and Astrophysics, volume 451, 651-670 (2006/5-4)

The Hamburg/ESO R-process enhanced star survey (HERES). III. HE 0338-3945 and the formation of the r + s stars.

JONSELL K., BARKLEM P.S., GUSTAFSSON B., CHRISTLIEB N., HILL V., BEERS T.C. and HOLMBERG J.

Abstract (from CDS):

We have derived abundances of 33 elements and upper limits for 6 additional elements for the metal-poor ([Fe/H]=-2.42) turn-off star HE 0338-3945 from high-quality VLT-UVES spectra. The star is heavily enriched, by about a factor of 100 relative to iron and the Sun, in the heavy s-elements (Ba, La, ...). It is also heavily enriched in Eu, which is generally considered an r-element, and in other similar elements. It is less enriched, by about a factor of 10, in the lighter s-elements (Sr, Y and Zr). C is also strongly enhanced and, to a somewhat lesser degree, N and O. These abundance estimates are subject to severe uncertainties due to NLTE and thermal inhomogeneities which are not taken into detailed consideration. However, an interesting result, which is most probably robust in spite of these uncertainties, emerges: the abundances derived for this star are very similar to those of other stars with an overall enhancement of all elements beyond the iron peak. We have defined criteria for this class of stars, r+s stars, and discuss nine different scenarios to explain their origin. None of these explanations is found to be entirely convincing. The most plausible hypotheses involve a binary system in which the primary component goes through its giant branch and asymptotic giant branch phases and produces CNO and s-elements which are dumped onto the observed star. Whether the r-element Eu is produced by supernovae before the star was formed (perhaps triggering the formation of a low-mass binary), by a companion as it explodes as a supernova (possibly triggered by mass transfer), or whether it is possibly produced in a high-neutron-density version of the s-process is still unclear. Several suggestions are made on how to clarify this situation.

Abstract Copyright:

Journal keyword(s): stars: populationii - stars: fundamental parameters - stars: abundances - Galaxy: halo - Galaxy: abundances - Galaxy: evolution

Simbad objects: 44

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Number of rows : 44
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 HE 0024-2523 Pe* 00 27 27.6486469632 -25 06 28.289948508 15.067 15.32 14.91     CEMP-s 68 0
2 BPS CS 29497-0004 Pe* 00 28 06.9155612016 -26 03 04.269055032   14.76 14.07 13.583 13.116 ~ 57 0
3 BPS CS 31062-0050 Pe* 00 30 31.0646803224 -12 05 10.877225064   13.7 13.05 12.681 12.309 CEMP-r/s 65 0
4 CD-24 266 BS* 00 40 47.9313619824 -24 07 34.183333668   12.955 12.656 12.441 12.216 CEMP-s 94 0
5 SKB 2 Pe* 00 41 39.8197621944 -26 18 54.460585116   13.338 12.221 11.704 11.321 CEMP-s 90 0
6 SB 960 Pe* 00 44 03.5698629048 -13 55 26.268999384   12.69 12.15 11.806 11.483 CEMP-s 110 0
7 CD-26 304 SB* 00 57 18.1374361752 -25 26 09.696130944   13.57 12.69 12.198 11.759 CEMP-s 72 1
8 HE 0058-0244 Pe* 01 00 53.0234702616 -02 28 19.950391884   14.42 13.73 13.331 12.942 CEMP-r/s 37 0
9 BPS CS 22183-0031 Pe* 01 09 05.0900915136 -04 43 21.343580436   14.24 13.62 13.178 12.724 ~ 46 0
10 BD-16 251 RG* 01 29 31.1311443552 -16 00 45.495314460 12.527 12.427 11.642 11.189 10.713 CEMP 292 0
11 HE 0131-3953 Pe* 01 33 36.4628527632 -39 37 52.143313800     15.979   15.323 CEMP-s 23 0
12 HE 0202-2204 Pe* 02 04 50.0173418688 -21 50 10.473005688     15.375   14.575 ~ 20 0
13 HD 13979 Pe* 02 15 20.8534060680 -25 54 54.872825148   9.81 9.18     F/Gw 88 0
14 BPS CS 29526-0110 Pe* 03 27 43.6392396600 -23 00 29.924362260   13.71 13.35 13.116 12.834 CEMP-r/s 51 0
15 HE 0338-3945 Pe* 03 39 55.0068570984 -39 35 42.902896452   15.753 15.333 15.098 14.787 CEMP-r/s 36 0
16 HD 25532 HB* 04 04 11.0091849504 +23 24 27.103671072   8.87 8.24     F6IV-V 126 0
17 HE 0430-4901 Pe* 04 31 31.1369700144 -48 54 41.518597500     14.572   13.770 CEMP-s 14 0
18 HE 0432-0923 Pe* 04 34 25.6711921824 -09 16 50.513595636     15.165   14.140 ~ 14 0
19 HE 1046-1352 Pe* 10 48 29.9238143232 -14 08 11.828372532   15.390 14.714 14.309 13.879 CEMP-s 9 0
20 HE 1105+0027 Pe* 11 07 49.5058798584 +00 11 38.346763524   16.038 15.646 15.358 15.018 CEMP-s 27 0
21 HE 1127-1143 Pe* 11 29 50.6275439136 -12 00 12.581828208     15.885 15.434 15.002 ~ 14 0
22 HE 1135+0139 Pe* 11 38 09.8529236352 +01 22 44.044584024   16.322 15.829 15.484 15.084 CEMP-s 19 0
23 HD 105546 HB* 12 09 02.7215671248 +59 01 05.137388976   9.27 8.61 8.29   G2III: 115 0
24 HE 1219-0312 Pe* 12 21 34.1430245160 -03 28 39.636260184     15.940   15.043 ~ 40 0
25 HD 115444 Pe* 13 16 42.4590842616 +36 22 52.692135420   9.77 8.97 8.3 7.88 G9V 243 0
26 UCAC4 407-057901 Pe* 14 07 42.9724778472 -08 36 14.381637516   14.910 14.099 13.929 13.171 CEMP-s 12 0
27 BPS CS 30301-0015 Pe* 15 08 56.8432075560 +02 30 18.627466716   14.04 13.04   12.063 CEMP-s 45 0
28 BPS CS 30306-0132 Pe* 15 14 18.9191634456 +07 27 02.680959780   13.62 12.73 12.421 11.948 ~ 36 0
29 BD+11 2998 HB* 16 30 16.7822155632 +10 59 51.752312592   9.73 9.10     F8 84 0
30 LP 625-44 Pe* 16 43 14.0377103880 -01 55 30.411443424   12.84 11.68     CEMP-s 106 0
31 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2119 0
32 BD+17 3248 HB* 17 28 14.4690179544 +17 30 35.847574776   10.02 9.34     KIIvw 224 0
33 HD 166161 PM* 18 09 40.6841536776 -08 46 45.603012144 9.53 9.13 8.16     G0wF0 142 0
34 HD 196944 SB* 20 40 46.0815001992 -06 47 50.604476604   9.01 8.40 8.08   CEMP-rs 101 0
35 BPS CS 22880-0074 Pe* 20 46 03.2162534976 -20 59 14.110203840   13.84 13.27 12.770 12.382 CEMP-s 47 0
36 BPS CS 22898-0027 Pe* 21 05 45.0996805992 -18 36 57.501493128   13.26 12.76 12.476 12.094 CEMP-r/s 83 0
37 HE 2134-3940 Pe* 21 37 45.7673945880 -39 27 22.313379600   13.790 12.660 12.160 11.760 KIIvw 85 0
38 HE 2148-1247 Pe* 21 51 17.9096426016 -12 33 41.557315896   15.2 14.79     CEMP-r/s 47 0
39 BPS CS 22881-0036 Pe* 22 07 58.4409920904 -40 44 16.477523484   14.42 13.95 13.633 13.278 CEMP-s 38 0
40 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 449 0
41 HE 2224+0143 Pe* 22 27 23.1215289240 +01 58 33.066485508   14.54 13.83 13.208 12.733 ~ 21 0
42 BPS CS 29491-0069 Pe* 22 31 02.1859040712 -32 38 36.526573572   13.72 13.1 12.654 12.175 ~ 34 0
43 HD 218857 Pe* 23 11 24.5948299440 -16 15 04.026507912   9.60 9.0     G5/8w(a) 115 0
44 HE 2327-5642 Pe* 23 30 37.0896973176 -56 26 14.385030648   14.590 13.881 13.425 12.948 ~ 40 0

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