2006A&A...455..291S


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.03CET13:37:59

2006A&A...455..291S - Astronomy and Astrophysics, volume 455, 291-301 (2006/8-3)

First stars IX - Mixing in extremely metal-poor giants. Variation of the 12C/13C, [Na/Mg] and [Al/Mg] ratios.

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

Abstract (from CDS):

Extremely metal-poor (EMP) stars preserve a fossil record of the composition of the ISM when the Galaxy formed. It is crucial, however, to verify whether internal mixing has modified their surface composition, especially in the giants where most elements can be studied. We aim to understand the CNO abundance variations found in some, but not all EMP field giants analysed earlier. Mixing beyond the first dredge-up of standard models is required, and its origin needs clarification. The 12C/13C ratio is the most robust diagnostic of deep mixing, because it is insensitive to the adopted stellar parameters and should be uniformly high in near-primordial gas. We have measured 12C and 13C abundances in 35 EMP giants (including 22 with [Fe/H]←3.0) from high-quality VLT/UVES spectra analysed with LTE model atmospheres. Correlations with other abundance data are used to study the depth of mixing. The 12C/13C ratio is found to correlate with [C/Fe] (and Li/H), and clearly anti-correlate with [N/Fe], as expected if the surface abundances are modified by CNO processed material from the interior. Evidence for such deep mixing is observed in giants above log L/L=2.6, brighter than in less metal-poor stars, but matching the bump in the luminosity function in both cases. Three of the mixed stars are also Na- and Al-rich, another signature of deep mixing, but signatures of the ON cycle are not clearly seen in these stars. Extra mixing processes clearly occur in luminous RGB stars. They cannot be explained by standard convection, nor in a simple way by rotating models. The Na- and Al-rich giants could be AGB stars themselves, but an inhomogeneous early ISM or pollution from a binary companion remain possible alternatives.

Abstract Copyright:

Journal keyword(s): Galaxy: abundances - Galaxy: evolution - stars: abundances - stars: interiors - stars: supernovae: general - stars: evolution

Simbad objects: 35

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Number of rows : 35

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 2796 Pe* 00 31 16.9149599675 -16 47 40.792690842 9.58 9.28 8.50 8.14 8.67 Fw 180 0
2 CD-38 245 Pe* 00 46 36.1954714218 -37 39 33.555736375   12.733 11.929 13.39 10.996 KIIvw 204 0
3 BPS CS 22953-0003 Pe* 01 02 15.8722809261 -61 43 45.836705614   14.43 13.75 13.339 12.886 KIIvw 54 0
4 BPS CS 29518-0051 Pe* 01 24 10.0046408484 -28 15 21.119402152 13.567 13.62 13.02 12.594 12.162 ~ 31 0
5 BPS CS 31082-0001 Pe* 01 29 31.1311330115 -16 00 45.496485322 12.527 12.427 11.642 11.189 10.713 CEMP 247 0
6 HE 0239-1340 Pe* 02 41 42.3721693746 -13 28 10.604872550   14.73 13.97 13.566 13.080 CEMP-no 54 0
7 HE 0305-5442 Pe* 03 06 29.5014936276 -54 30 32.498352902   14.44 13.70 13.212 12.715 KIIvw 73 0
8 HE 0311-1046 Pe* 03 14 20.8495240680 -10 35 11.279671787   13.54 12.73 12.204 11.693 KIIvw 64 0
9 HE 0409-1212 Pe* 04 12 13.8814170981 -12 05 05.075798490   13.843 12.897   11.764 ~ 60 0
10 BPS CS 22186-0025 Pe* 04 24 32.7982638728 -37 09 02.518352449   14.99 14.24 13.740 13.269 ~ 34 0
11 BPS BS 16467-0062 Pe* 13 42 00.6325668250 +17 48 40.825137829   14.69 14.09 13.665 13.216 ~ 46 0
12 HD 122563 Pe* 14 02 31.8456299772 +09 41 09.942736952 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 763 0
13 BPS BS 16477-0003 Pe* 14 32 56.9230863125 +06 46 06.975505394   14.94 14.22 13.727 13.224 ~ 34 0
14 BPS CS 30325-0094 Pe* 14 54 39.2685324873 +04 21 38.098655567   13.02 12.32 11.849 11.376 ~ 44 0
15 BPS CS 22878-0101 Pe* 16 45 31.4514010341 +08 14 45.471045094   14.59 13.79   12.673 KIIvw 56 0
16 BD+17 3248 HB* 17 28 14.4691668039 +17 30 35.848406966   10.02 9.34     KIIvw 201 0
17 BPS CS 22891-0209 Pe* 19 42 02.1800028329 -61 03 44.536144090   13.03 12.18     KIIvw 53 0
18 UCAC2 7177623 Pe* 19 42 26.8930018981 -56 58 34.061929902   14.27 13.63     ~ 46 0
19 HD 186478 Pe* 19 45 14.1410795461 -17 29 27.071420634   10.116 9.302 8.527 7.961 K2III 131 0
20 UCAC2 5726991 Pe* 19 53 49.7800945675 -59 40 00.163969151   13.592 12.620   11.48 KIIvw 42 0
21 BD-18 5550 Pe* 19 58 49.7370363913 -18 12 11.142309703 10.18 10.03 9.35 9.04 8.74 CEMP-no 164 0
22 BPS CS 22873-0166 Pe* 20 19 22.0361305437 -61 30 15.121053020   12.818 11.802 11.52 10.57 KIIvw 47 0
23 BPS CS 22885-0096 Pe* 20 20 51.1729562140 -39 53 30.235406812   14.02 13.33     CEMP-no 82 0
24 BPS CS 22897-0008 Pe* 21 03 11.8563237063 -65 05 08.852932036   14.02 13.33     CEMP-no 63 0
25 BPS CS 29495-0041 Pe* 21 36 33.2901533828 -28 18 48.439267198 14.111 14.15 13.34   12.222 ~ 31 0
26 HE 2141-3741 Pe* 21 44 51.1647173336 -37 27 55.017357431   14.10 13.47     CEMP-no 53 0
27 BPS CS 22956-0050 Pe* 21 58 05.8339798574 -65 13 27.160917994   14.95 14.25 13.745 13.211 CEMP-no 36 0
28 BPS BS 17569-0049 Pe* 22 04 58.3605638072 +04 01 32.135813469 14.503 14.25 13.36 12.805 12.259 ~ 28 0
29 BPS CS 22892-0052 Pe* 22 17 01.6558480594 -16 39 27.051900047   14.03 13.20 13.06 12.19 KIIvw 416 0
30 BPS CS 29516-0041 Pe* 22 21 48.8261125099 +02 28 44.864481048 13.291 13.4 12.74 12.325 12.013 ~ 36 0
31 BPS CS 29516-0024 Pe* 22 26 15.3575399312 +02 51 46.325239449   14.43 13.57 13.011 12.416 ~ 33 0
32 BPS CS 29491-0053 Pe* 22 36 56.2964405478 -28 31 06.577841168   13.76 12.92 12.380 11.812 ~ 31 0
33 HE 2323-0256 Pe* 23 26 29.8073543039 -02 39 58.037206596   15.12 14.36   13.358 CEMP-no 172 0
34 HE 2334-0604 Pe* 23 37 28.6873335486 -05 47 56.594686365   14.03 13.28 12.768 12.249 KIIvw 68 0
35 BPS CS 22966-0057 Pe* 23 48 57.7535714010 -29 39 22.828517864 14.759   14.32   13.512 ~ 32 0

    Equat.    Gal    SGal    Ecl

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2020.12.03-13:37:59

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