2006A&A...459..125S


Query : 2006A&A...459..125S

2006A&A...459..125S - Astronomy and Astrophysics, volume 459, 125-135 (2006/11-3)

First stars X. The nature of three unevolved carbon-enhanced metal-poor stars.

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

Abstract (from CDS):

On the order of 20% of the very metal-poor stars in the Galaxy exhibit large carbon enhancements. It is important to establish which astrophysical sites and processes are responsible for the elemental abundance patterns of this early Galactic population. We seek to understand the nature of the progenitors of three main-sequence turnoff Carbon-Enhanced Metal-Poor (CEMP) stars, CS 31080-095, CS 22958-042, and CS 29528-041, based on a detailed abundance analysis. From high-resolution VLT/UVES spectra (R∼43000), we determine abundances or upper limits for Li, C, N, O, and other important elements, as well as 12C/13C isotopic ratios. All three stars have -3.30≤[Fe/H]≤-2.85 and moderate to high CNO abundances. CS 22958-042 is one of the most carbon-rich CEMP stars known ([C/Fe]=+3.2), while CS 29528-041 (one of the few N-enhanced metal-poor stars known) is one of the most nitrogen rich ([N/Fe]=+3.0). Oxygen is very high in CS 31080-095 ([O/Fe]=+2.35) and in CS 22958-042 ([O/Fe]=+1.35). All three stars exhibit [Sr/Fe]<0; Ba is not detected in CS 22958-042 ([Ba/Fe]←0.53), but it is moderately enhanced ([Ba/Fe]∼1) in the other two stars. CS 22958-042 displays one of the largest sodium overabundances yet found in CEMP stars ([Na/Fe]=+2.8). CS 22958-042 has 12C/13C=9, similar to most other CEMP stars without enhanced neutron-capture elements, while 12C/13C≥40 in CS 31080-095. CS 31080-095 and CS 29528-041 have A(Li)∼1.7, below the Spite Plateau, while Li is not detected in CS 22958-042. CS 22958-042 is a CEMP-no star, but the other two stars are in no known class of CEMP star and thus either constitute a new class or are a link between the CEMP-no and CEMP-s classes, adding complexity to the abundance patterns for CEMP stars. We interpret the abundance patterns in our stars to imply that current models for the presumed AGB binary progenitors lack an extra-mixing process, similar to those apparently operating in RGB stars.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: population II - Galaxy: abundances - stars: AGB and post-AGB

Simbad objects: 28

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Number of rows : 28
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 HE 0007-1832 Pe* 00 09 52.7815684392 -18 16 12.275163984     15.46     CEMP-no 19 0
2 HE 0024-2523 Pe* 00 27 27.6486469632 -25 06 28.289948508 15.067 15.32 14.91     CEMP-s 67 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 64 0
4 CD-24 266 BS* 00 40 47.9313619824 -24 07 34.183333668   12.955 12.656 12.441 12.216 CEMP-s 93 0
5 SKB 2 Pe* 00 41 39.8197621944 -26 18 54.460585116   13.338 12.221 11.704 11.321 CEMP-s 89 0
6 SB 960 Pe* 00 44 03.5698629048 -13 55 26.268999384   12.69 12.15 11.806 11.483 CEMP-s 108 0
7 CD-26 304 SB* 00 57 18.1374361752 -25 26 09.696130944   13.57 12.69 12.198 11.759 CEMP-s 70 1
8 HE 0107-5240 Pe* 01 09 29.1555567432 -52 24 34.202039148   15.89 15.07 15.10 14.283 CEMP-no 236 0
9 HE 0143-0441 Pe* 01 45 37.9166141208 -04 26 43.244756916     16.38     CEMP-s 28 0
10 BPS CS 22958-0042 Pe* 02 01 07.4297976264 -57 16 58.850811840   14.037 14.52 14.222 13.902 CEMP-no 36 0
11 BPS CS 29528-0041 Pe* 02 29 25.2514644552 -18 13 28.025186448 14.83 15.20 14.59 14.67   CEMP-no 26 0
12 BPS CS 29526-0110 Pe* 03 27 43.6392396600 -23 00 29.924362260   13.71 13.35 13.116 12.834 CEMP-r/s 49 0
13 G 77-61 Pe* 03 32 38.0920129269 +01 58 00.084645962   15.60 13.90 12.9   dC-J_CH5 129 0
14 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
15 2MASS J04442200-4513542 C* 04 44 22.0059867696 -45 13 54.232871592 13.219 13.51 12.989 12.672 12.372 CEMP-s 22 0
16 BPS CS 22877-0001 Pe* 13 13 55.3726775760 -12 11 41.666054388   12.78 12.38 11.695 11.218 CEMP-no 38 0
17 HE 1327-2326 Pe* 13 30 05.9394958608 -23 41 49.699340844 13.761 14.01 13.55 13.50 12.803 CEMP-no 232 0
18 BPS CS 30301-0015 Pe* 15 08 56.8432075560 +02 30 18.627466716   14.04 13.04   12.063 CEMP-s 45 0
19 LP 625-44 Pe* 16 43 14.0377103880 -01 55 30.411443424   12.84 11.68     CEMP-s 105 0
20 BPS CS 22880-0074 Pe* 20 46 03.2162534976 -20 59 14.110203840   13.84 13.27 12.770 12.382 CEMP-s 46 0
21 BPS CS 29498-0043 Pe* 21 03 52.1197651440 -29 42 50.344181712   14.8 13.72 13.013 12.406 CEMP-no 91 0
22 BPS CS 22898-0027 Pe* 21 05 45.0996805992 -18 36 57.501493128   13.26 12.76 12.476 12.094 CEMP-r/s 81 0
23 HE 2134-3940 Pe* 21 37 45.7673945880 -39 27 22.313379600   13.790 12.660 12.160 11.760 KIIvw 84 0
24 HE 2148-1247 Pe* 21 51 17.9096426016 -12 33 41.557315896   15.2 14.79     CEMP-r/s 46 0
25 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 433 0
26 BPS CS 29502-0092 Pe* 22 22 35.9982138384 -01 38 27.620508552   12.64 11.87 11.365 10.862 CEMP-no 51 0
27 HE 2323-0256 Pe* 23 26 29.8073738880 -02 39 58.036383180   15.12 14.36   13.358 CEMP-no 175 0
28 HE 2356-0410 Pe* 23 59 13.1419841280 -03 53 48.220213560   14.39 13.60 13.164 12.713 CEMP-no 84 0

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2023.02.02-19:58:17

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